ALBERT

Description: The Aegean water masses and circulation structure are studied via two large-scale surveys performed during the late winters of 1988 and 1990 by the R/V Yakov Gakkel of the former Soviet Union. The analysis of these data sheds light on the mechanisms of water mass formation in the Aegean Sea that triggered the outflow of Cretan Deep Water (CDW) from the Cretan Sea into the abyssal basins of the eastern Mediterranean Sea (the so-called Eastern Mediterranean Transient). It is found that the central Aegean Basin is the site of the formation of Aegean Intermediate Water, which slides southward and, depending on their density, renews either the intermediate or the deep water of the Cretan Sea. During the winter of 1988, the Cretan Sea waters were renewed mainly at intermediate levels, while during the winter of 1990 it was mainly the volume of CDW that increased. This Aegean water mass redistribution and formation process in 1990 differed from that in 1988 in two major aspects: (i) during the winter of 1990 the position of the front between the Black Sea Water and the Levantine Surface Water was displaced farther north than during the winter of 1988 and (ii) heavier waters were formed in 1990 as a result of enhanced lateral advection of salty Levantine Surface Water that enriched the intermediate waters with salt. In 1990 the 29.2 isopycnal rose to the surface of the central basin and a large volume of CDW filled the Cretan Basin. It is found that, already in 1988, the 29.2 isopycnal surface, which we assume is the lowest density of the CDW, was shallower than the Kassos Strait sill and thus CDW egressed into the Eastern Mediterranean.

Description: Published

Description: 1841-1859

Description: JCR Journal

Description: reserved

Description: Five non-eddy-resolving oceanic general circulation models driven by atmospheric fluxes derived from the NCEP reanalysis are used to investigate the link between the Gulf Stream (GS) variability, the atmospheric circulation, and the Atlantic meridional overturning circulation (AMOC). Despite the limited model resolution, the temperature at the 200-m depth along the mean GS axis behaves similarly in most models to that observed, and it is also well correlated with the North Atlantic Oscillation (NAO), indicating that a northward (southward) GS shift lags a positive (negative) NAO phase by 0–2 yr. The northward shift is accompanied by an increase in the GS transport, and conversely the southward shift with a decrease in the GS transport. Two dominant time scales appear in the response of the GS transport to the NAO forcing: a fast time scale (less than 1 month) for the barotropic component, and a slower one (about 2 yr) for the baroclinic component. In addition, the two components are weakly coupled. The GS response seems broadly consistent with a linear adjustment to the changes in the wind stress curl, and evidence for baroclinic Rossby wave propagation is found in the southern part of the subtropical gyre. However, the GS shifts are also affected by basin-scale changes in the oceanic conditions, and they are well correlated in most models with the changes in the AMOC. A larger AMOC is found when the GS is stronger and displaced northward, and a higher correlation is found when the observed changes of the GS position are used in the comparison. The relation between the GS and the AMOC could be explained by the inherent coupling between the thermohaline and the wind-driven circulation, or by the NAO variability driving them on similar time scales in the models.

Description: This research was supported by the PREDICATE project of the European Community, and for M. Bentsen by the Research Council of Norway through RegClim, NOClim, and the Programme of Supercomputing.

Description: Published

Description: 2119–2135

Description: 3.7. Dinamica del clima e dell'oceano

Description: JCR Journal

Description: reserved

Description: A land surface model (LSM) has been included in the ECMWF Hamburg version 4 (ECHAM4) atmospheric general circulation model (AGCM). The LSM is an early version of the Organizing Carbon and Hydrology in Dynamic Ecosystems (ORCHIDEE) and it replaces the simple land surface scheme previously included in ECHAM4. The purpose of this paper is to document how a more exhaustive consideration of the land surface–vegetation processes affects the simulated boreal summer surface climate. To investigate the impacts on the simulated climate, different sets of Atmospheric Model Intercomparison Project (AMIP)-type simulations have been performed with ECHAM4 alone and with the AGCM coupled with ORCHIDEE. Furthermore, to assess the effects of the increase in horizontal resolution the coupling of ECHAM4 with the LSM has been implemented at different horizontal resolutions. The analysis reveals that the LSM has large effects on the simulated boreal summer surface climate of the atmospheric model. Considerable impacts are found in the surface energy balance due to changes in the surface latent heat fluxes over tropical and midlatitude areas covered with vegetation. Rainfall and atmospheric circulation are substantially affected by these changes. In particular, increased precipitation is found over evergreen and summergreen vegetated areas. Because of the socioeconomical relevance, particular attention has been devoted to the Indian summer monsoon (ISM) region. The results of this study indicate that precipitation over the Indian subcontinent is better simulated with the coupled ECHAM4–ORCHIDEE model compared to the atmospheric model alone.

Description: Published

Description: 255–278

Description: 3.7. Dinamica del clima e dell'oceano

Description: JCR Journal

Description: partially_open

Description: In this paper results from the application of an ocean data assimilation (ODA) system, combining a multivariate reduced-order optimal interpolator (OI) scheme with a global ocean general circulation model (OGCM), are described. The present ODA system, designed to assimilate in situ temperature and salinity observations, has been used to produce ocean reanalyses for the 1962–2001 period. The impact of assimilating observed hydrographic data on the ocean mean state and temporal variability is evaluated. A special focus of this work is on the ODA system skill in reproducing a realistic ocean salinity state. Results from a hierarchy of different salinity reanalyses, using varying combinations of assimilated data and background error covariance structures, are described. The impact of the space and time resolution of the background error covariance parameterization on salinity is addressed.

Description: This work has been funded by the ENACT Project (Contract EVK2-CT2001-00117) for A. Bellucci and P. Di Pietro, and partially by the ENSEMBLES Project (Contract GOCE-CT-2003-505539) for A. Bellucci.

Description: Published

Description: 3785-3807

Description: 3.7. Dinamica del clima e dell'oceano

Description: JCR Journal

Description: reserved

Description: The effect of horizontal resolution on tropical variability is investigated within the modified SINTEX model, SINTEX-F, developed jointly at INGV, IPSL and at the Frontier Research System. The horizontal resolutions T30 and T106 are investigated in terms of the coupling characteristics, frequency and variability of the tropical ocean-atmosphere interactions. It appears that the T106 resolution is generally beneficial even if it does not eliminate all the major systematic errors of the coupled model. There is an excessive shift west of the cold tongue and ENSO variability, and high resolution has also a somewhat negative impact to the variability in the East Indian Ocean. A dominant two-year peak for the NINO3 variabilty in the T30 model is moderated in the T106 as it shifts to longer time scale. At high resolution new processes come into play, as the coupling of tropical instability waves, the resolution of coastal flows at the Pacific Mexican coasts and improved coastal forcing along the coast of South America. The delayed oscillator seems the main mechanism that generates the interannual variability in both models, but the models realize it in different ways. In the T30 model it is confined close to the equator, involving relatively fast equatorial and near-equatorial modes, in the high resolution, it involves a wider latitudinal region and slower waves. It is speculated that the extent of the region that is involved in the interannual variability may be linked to the time scale of the variability itself.

Description: This research was partially supported by the Italy–USA Cooperation Program of the Italian Ministry of Environment and by the EU projects ENSEMBLES and DYNAMITE.

Description: Published

Description: 730-750

Description: 3.7. Dinamica del clima e dell'oceano

Description: JCR Journal

Description: reserved

Description: The Indian Summer Monsoon (ISM) is one of the main components of the Asian summer monsoon. It is well known that one of the starting mechanisms of a summer monsoon is the thermal contrast between land and ocean and that sea surface temperature (SST) and moisture are crucial factors for its evolution and intensity. The Indian Ocean, therefore, may play a very important role in the generation and evolution of the ISM itself. A coupled general circulation model, implemented with a high resolution atmospheric component, appears to be able to simulate the Indian summer monsoon in a realistic way. In particular, the features of the simulated ISM variability are similar to the observations. In this study, the relationships between ISM and Tropical Indian Ocean (TIO) SST anomalies are investigated, as well as the ability of the coupled model to capture those connections. The recent discovery of the Indian Ocean Dipole Mode (IODM) may suggest new perspectives in the relationship between ISM and TIO SST. A new statistical technique, the Coupled Manifold, is used to investigate the TIO SST variability and its relation with the Tropical Pacific Ocean (TPO). The analysis shows that the SST variability in the TIO contains a significant portion that is independent from the TPO variability. The same technique is used to estimate the amount of Indian rainfall variability that can be explained by the Tropical Indian Ocean SST. Indian Ocean SST anomalies are separated in a part remotely forced from the Tropical Pacific Ocean variability and a part independent from that. The relationships between the two SSTA components and the Indian monsoon variability are then investigated in detail.

Description: Published

Description: 3083-3105

Description: 3.7. Dinamica del clima e dell'oceano

Description: JCR Journal

Description: reserved

Description: An assessment of the present European operational marine monitoring and forecasting systems shows how observations, atmospheric forcing fields and ocean models combine to make useful oceanographic products possible.

Description: Published

Description: 1081-1090

Description: open

Description: Ensemble experiments are performed with five coupled atmosphere–ocean models to investigate the potential for initial-value climate forecasts on interannual to decadal time scales. Experiments are started from similar model-generated initial states, and common diagnostics of predictability are used. We find that variations in the ocean meridional overturning circulation (MOC) are potentially predictable on interannual to decadal time scales, a more consistent picture of the surface temperature impact of decadal variations in the MOC is now apparent, and variations of surface air temperatures in the North Atlantic Ocean are also potentially predictable on interannual to decadal time scales, albeit with potential skill levels that are less than those seen for MOC variations. This intercomparison represents a step forward in assessing the robustness of model estimates of potential skill and is a prerequisite for the development of any operational forecasting system.

Description: Published

Description: 1195-1203

Description: JCR Journal

Description: reserved

Description: The accuracy of all types of Vaisala radiosondes and two types of Snow White chilled-mirror hygrosondes was assessed in an intensive in situ comparison with reference hygrometers. Fourteen nighttime reference comparisons were performed to determine a working reference for the radiosonde comparisons. These showed that the night version of the Snow White agreed best with the references [i.e., the NOAA frost-point hygrometer (FPH) and University of Colorado cryogenic frost-point hygrometer (CFH)], but that the daytime version had severe problems with contamination in the humid upper troposphere. Since the RS92 performance was superior to the other radiosondes and to the day version of the Snow White, it was selected to be the working reference. According to the reference comparison, the RS92 has no bias in the mid- and lower troposphere, with deviations 〈±5% in relative humidity (RH). In the upper troposphere, the RS92 has a 5% RH wet bias, which is partly due to the RS92 time lag error and the termination of the heating cycle. It was shown that the time lag effects relating to Vaisala radiosondes can be corrected. Because these were nighttime comparisons, they can be considered to be free from solar radiation effects. Neither the radiosondes nor the Snow White succeeded in reproducing reference class hygrometer profiles in the stratosphere. According to the 29 radiosonde intercomparisons, the RS92 and the modified RS90 (FN) had the best mutual agreement and no bias. The disagreement is largest (〈±10% RH) at low temperatures (T ≪ −30°C), where the FN underestimated (overestimated) in high (low) ambient RH. In comparison with the RS92, the RS90 had a semilinearly increasing wet bias with decreasing temperature, where the bias was 10% RH at −60°C. The RS80-A suffers from a large temperature-dependent dry bias in high RH conditions, being over 30% RH at −60°C and 5% RH near 0°C. The RS80-A dry bias can be almost totally removed with the correction algorithm by Leiterer et al., which was chosen as the best available. The other approach tested tends to overcorrect in high RH conditions when T 〈 −50°C. For T 〉 −30°C it is ineffective and does not correct the RS80-A dry bias in high ambient RH.

Description: In this study we show a teleconnection pattern relating Outgoing Longwave Radiation (OLR) anomalies over the western Pacific Ocean and sea surface temperature anomalies (SSTA) over the western Indian Ocean over two seasons (Sept-Oct-Nov and Dec-Jan-Feb) at zero lag from observations and atmospheric general circulation model (AGCM) integrations. This teleconnection pattern suggests that a positive SSTA in Sept-Oct-Nov (SON) and Dec-Jan-Feb (DJF) seasons over the western Indian Ocean increases the contemporaneous positive OLR anomalies over the western Pacific Ocean. This teleconnection pattern is also simulated by the Center for Ocean-Land- Atmosphere studies (COLA) AGCM forced with observed SST’s. From the experimental COLA AGCM runs (wherein the Pacific Ocean SST variability is suppressed except for the climatological annual cycle) it is diagnosed that the interannual variability of OLR over the western Pacific Ocean persists because of this teleconnection. In relation to this teleconnection pattern it is shown that there is a significant linear response of the SON and DJF equatorial zonal wind anomaly over the Pacific Ocean to contemporaneous SSTA over the western Indian Ocean which is comparable to that of the eastern and western Pacific Oceans. The experimental AGCM runs clearly show that this response of the equatorial zonal wind anomaly to the western Indian Ocean forcing shifts westward towards the Indian Ocean in the absence of Pacific SST variability.

Description: Published

Description: Skill in ensemble-mean dynamical seasonal climate hindcasts with a coupled land-atmosphere model and specified observed sea surface temperature is compared to that for long multi-decade integrations of the same model where the initial conditions are far removed from the seasons of validation. The evaluations are performed for surface temperature and compared among all seasons. Skill is found to be higher in the seasonal simulations than the multi-decadal integrations except during boreal winter. The higher skill is prominent even beyond the first month when the direct influence of the atmospheric initial state elevates model skill. Skill is generally found to be lowest during the winter season for the dynamical seasonal forecasts, equal to that of the long integrations, which show some of the highest skill during winter. The reason for the differences in skill during the non-winter months is attributed to the severe climate drift in the long simulations, manifest through errors in downward fluxes of water and energy over land and evident in soil wetness. The drift presses the land surface to extreme dry or wet states over much of the globe, into a range where there is little sensitivity of evaporation to fluctuations in soil moisture. Thus, the land-atmosphere feedback is suppressed, which appears to lessen the model’s ability to respond correctly over land to remote ocean temperature anomalies.

Description: Center for Ocean-Land-Atmosphere Studies

Description: Published

Description: In this paper, the circulations driven by deep heating and shallow heating are investigated through analytically solving a set of linear equations and examining circulations simulated by a dry primitive equation model. Special emphasis is placed on the low-level mass (moisture) convergence associated with the forced circulation and the maintenance of the shallow and deep heat sources. It is found that the forced circulation driven by shallow heating is more likely to be trapped horizontally near the heating area but relatively extended in the vertical. As a consequence, diabatic heating can not balance adiabatic cooling due to upward motion. At the levels slightly above the top of the heating, a negative vertical gradient of temperature perturbation appears. For the atmosphere driven by deep heating, however, the temperature perturbation cannot accumulate because the heating signals propagate away very fast, allowing an approximate equilibrium between the convective diabatic heating and adiabatic cooling due to upward motion. The converged moisture associated with circulation driven by shallow heating exceeds the amount needed to maintain the heat source. However, the circulation driven by deep heating does not feed back effectively to the moisture convergence, and thus can not be self-sustaining.

Description: Center for Ocean-Land-Atmosphere Studies - Calverton

Description: Published

Description: This paper is not subject to U.S. copyright. The definitive version was published in Journal of Atmospheric and Oceanic Technology 21 (2004): 1448–1461, doi:10.1175/1520-0426(2004)021〈1448:AOAPAD〉2.0.CO;2.

Description: The accuracy of velocities measured by a pulse-coherent acoustic Doppler profiler (PCADP) in the bottom boundary layer of a wave-dominated inner-shelf environment is evaluated. The downward-looking PCADP measured velocities in eight 10-cm cells at 1 Hz. Velocities measured by the PCADP are compared to those measured by an acoustic Doppler velocimeter for wave orbital velocities up to 95 cm s−1 and currents up to 40 cm s−1. An algorithm for correcting ambiguity errors using the resolution velocities was developed. Instrument bias, measured as the average error in burst mean speed, is −0.4 cm s−1 (standard deviation = 0.8). The accuracy (root-mean-square error) of instantaneous velocities has a mean of 8.6 cm s−1 (standard deviation = 6.5) for eastward velocities (the predominant direction of waves), 6.5 cm s−1 (standard deviation = 4.4) for northward velocities, and 2.4 cm s−1 (standard deviation = 1.6) for vertical velocities. Both burst mean and root-mean-square errors are greater for bursts with ub ≥ 50 cm s−1. Profiles of burst mean speeds from the bottom five cells were fit to logarithmic curves: 92% of bursts with mean speed ≥ 5 cm s−1 have a correlation coefficient R2 〉 0.96. In cells close to the transducer, instantaneous velocities are noisy, burst mean velocities are biased low, and bottom orbital velocities are biased high. With adequate blanking distances for both the profile and resolution velocities, the PCADP provides sufficient accuracy to measure velocities in the bottom boundary layer under moderately energetic inner-shelf conditions.

Description: This work was funded by the U.S. Geological Survey as part of the Southwest Washington Coastal Erosion Study

Description: 〈jats:p〉Sustained harmonic tremor signals were recorded by the seismographs of the German Neumayer Base seismological network in western Dronning Maud Land, Antarctica. These tremor episodes, lasting up to 16 hours, were recorded up to 820 kilometers from the source. Their spectra show narrow peaks with fundamental frequencies ranging from 0.5 to 6 hertz, more than 30 integer harmonic overtones, and frequency gliding, resembling volcanic tremor. Frequency‐wave number analysis suggested a moving source, which was recognized as iceberg B-09A traveling along the coast of eastern Antarctica. The most probable tremor sources are fluid-flow‐induced vibrations inside the iceberg's tunnel/crevasse systems.〈/jats:p〉

Description: Advances in computer power, new forecasting challenges, and new diagnostic techniques have brought about changes in the way atmospheric development and vertical motion are diagnosed in an operational setting. Many of these changes, such as improved model skill, model resolution, and ensemble forecasting, have arguably been detrimental to the ability of forecasters to understand and respond to the evolving atmosphere. The use of nondivergent wind in place of geostrophic wind would be a step in the right direction, but the advantages of potential vorticity suggest that its widespread adoption as a diagnostic tool on the west side of the Atlantic is overdue. Ertel potential vorticity (PV), when scaled to be compatible with pseudopotential vorticity, is generally similar to pseudopotential vorticity, so forecasters accustomed to quasigeostrophic reasoning through the height tendency equation can transfer some of their intuition into the Ertel-PV framework. Indeed, many of the differences between pseudopotential vorticity and Ertel potential vorticity are consequences of the choice of definition of quasigeostrophic PV and are not fundamental to the quasigeostrophic system. Thus, at its core, PV thinking is consistent with commonly used quasigeostrophic diagnostic techniques.

Description: Synoptic and mesoscale meteorology underwent a revolution in the 1940s and 1950s with the widespread deployment of novel weather observations, such as the radiosonde network and the advent of weather radar. These observations provoked a rapid increase in our understanding of the structure and dynamics of the atmosphere by pioneering analysts such as Fred Sanders. The authors argue that we may be approaching an analogous revolution in our ability to study the structure and dynamics of atmospheric phenomena with the advent of probabilistic objective analyses. These probabilistic analyses provide not only best estimates of the state of the atmosphere (e.g., the expected value) and the uncertainty about this state (e.g., the variance), but also the relationships between all locations and all variables at that instant in time. Up until now, these relationships have been determined by sampling in time by, for example, case studies, composites, and time-series analysis. Here the authors propose a new approach, ensemble synoptic analysis, which exploits the information contained in probabilistic samples of analyses at one or more instants in time. One source of probabilistic analyses is ensemble-based state-estimation methods, such as ensemble-based Kalman filters. Analyses from such a filter may be used to study atmospheric phenomena and the relationships between fields and locations at one or more instants in time. After a brief overview of a research-based ensemble Kalman filter, illustrative examples of ensemble synoptic analysis are given for an extratropical cyclone, including relationships between the cyclone minimum sea level pressure and other synoptic features, statistically determined operators for potential-vorticity inversion, and ensemble-based sensitivity analysis.

Description: The pioneering large-scale studies of cyclone frequency, location, and intensity conducted by Fred Sanders prompt similar questions about lesser-studied anticyclone development. The results of a climatology of closed anticyclones (CAs) at 200, 500, and 850 hPa, with an emphasis on the subtropics and midlatitudes, is presented to assess the seasonally varying distribution and hemispheric differences of these features. To construct the CA climatology, a counting program was applied to twice-daily 2.5° NCEP–NCAR reanalysis 200-, 500-, and 850-hPa geopotential height fields for the period 1950–2003. Stationary CAs, defined as those CAs that were located at a particular location for consecutive time periods, were counted only once. The climatology results show that 200-hPa CAs occur preferentially during summer over subtropical continental regions, while 500-hPa CAs occur preferentially over subtropical oceans in all seasons and over subtropical continents in summer. Conversely, 850-hPa CAs occur preferentially over oceanic regions beneath upper-level midocean troughs, and are most prominent in the Northern Hemisphere, and over midlatitude continents in winter. Three case studies of objectively identified CAs that produced heal waves over the United States, Europe, and Australia in 1995, 2003, and 2004, respectively, are presented to supplement the climatological results. The case studies, examining the subset of CAs than can produce heat waves, illustrate how climatologically hot continental tropical air masses produced over arid and semiarid regions of the subtropics and lower midlatitudes can become abnormally hot in conjunction with dynamically driven upper-level ridge amplification. Subsequently, these abnormally hot air masses are advected downstream away from their source regions in conjunction with transient disturbances embedded in anomalously strong westerly jets.

Description: Oklahoma Mesonetwork data are used to illustrate important atmospheric features that are not well shown by the usual synoptic data. For example, some shifts of wind from south to north that are shown as cold fronts on synoptic charts are not cold fronts by any plausible definition. As previously discussed by Fred Sanders and others, such errors in analysis can be reduced by knowledge of the wide variety of weather phenomena that actually exists, and by more attention to temperatures at the earth's surface as revealed by conventional synoptic data. Mesoscale data for four cases reinforce previous discussions of the ephemeral nature of fronts and deficiencies in the usual analyses of cold fronts. One type of misanalyzed case involves post-cold-frontal boundary layer air that is warmer than the prefrontal air. A second type is usually nocturnal, with a rise of local temperature during disruption of an inversion and a wind shift with later cooling that accompanies advection of a climatological gradient of temperature.

Description: The advent of the polar front theory of cyclones in Norway early in the last century held that the development of fronts and air masses is central to understanding midlatitude weather phenomena. While work on fronts continues to this day, the concept of air masses has been largely forgotten, superseded by the idea of a continuum. The Norwegians placed equal emphasis on the thermodynamics of airmass formation and on the dynamical processes that moved air masses around; today, almost all the emphasis is on dynamics, with little published literature on diabatic processes acting on a large scale. In this essay, the author argues that a lack of understanding of large-scale diabatic processes leads to an incomplete picture of the atmosphere and contributes to systematic errors in medium- and long-range weather forecasts. At the same time, modern concepts centered around potential vorticity conservation and inversion lead one to a redefinition of the term "air mass" that may have some utility in conceptualizing atmospheric physics and in weather forecasting.

Description: Historically, the atmospheric sciences have tended to treat problems of weather and climate separately. The real physical system, however, is a continuum, with short-term (minutes to days) “weather” fluctuations influencing climate variations and change, and, conversely, more slowly varying aspects of the system (typical time scales of a season or longer) affecting the weather that is experienced. While this past approach has served important purposes, it is becoming increasingly apparent that in order to make progress in addressing many socially important problems, an improved understanding of the connections between weather and climate is required. This overview summarizes the progress over the last few decades in the understanding of the phenomena and mechanisms linking weather and climate variations. The principal emphasis is on developments in understanding key phenomena and processes that bridge the time scales between synoptic-scale weather variability (periods of approximately 1 week) and climate variations of a season or longer. Advances in the ability to identify synoptic features, improve physical understanding, and develop forecast skill within this time range are reviewed, focusing on a subset of major, recurrent phenomena that impact extratropical wintertime weather and climate variations over the Pacific–North American region. While progress has been impressive, research has also illuminated areas where future gains are possible. This article concludes with suggestions on near-term directions for advancing the understanding and capabilities to predict the connections between weather and climate variations.

Description: Fred Sanders' career extended over 55 yr, touching upon many of the revolutionary transformations in the field of meteorology during that period. In this paper, his contributions to the transformation of synoptic meteorology, his research into the nature of explosive cyclogenesis, and related advances in the ability to predict these storms are reviewed. In addition to this review, the current status of forecasting oceanic cyclones 4.5 days in advance is presented, illustrating the progress that has been made and the challenges that persist, especially for forecasting those extreme extratropical cyclones that are marked by surface wind speeds exceeding hurricane force. Last, Fred Sanders' participation in a forecast for the historic 1947 snowstorm (that produced snowfall amounts in the New York City area that set records at that time) is reviewed along with an attempt to use today's operational global model to simulate this storm using data that were available at the time. The study reveals the predictive limitations involved with this case based on the scarcity of upper-air data in 1947, while confirming Fred Sanders' forecasting skills when dealing with these types of major storm events, even as a young aviation forecaster at New York's LaGuardia Airport.

Description: A case study of a double dryline on 22 May 2002 is presented. Mobile, 3-mm-wavelength Doppler radars from the University of Massachusetts and the University of Wyoming (Wyoming cloud radar) were used to collect very fine resolution vertical-velocity data in the vicinity of each of the moisture gradients associated with the drylines. Very narrow (50–100 m wide) channels of strong upward vertical velocity (up to 8 m s–1) were measured in the convergence zone of the easternmost dryline, larger in magnitude than reported with previous drylines. Distinct areas of descending motion were evident to the east and west of both drylines. Radar data are interpreted in the context of other observational platforms available during the International H2O Project (IHOP-2002). a variational ground-based mobile radar data processing technique was developed and applied to pseudo-dual-Doppler data collected during a rolling range-height indicator deployment. It was found that there was a secondary (vertical) circulation normal to the easternmost moisture gradient; the circulation comprised an easterly component near-surface flow to the east, a strong upward vertical component in the convergence zone, a westerly return, flow above the convective boundary layer, and numerous regions of descending motion, the most prominent approximately 3–5 km to the east of the surface convergence zone.

Description: Fred Sanders' teaching and research contributions in the area of quasigeostrophic theory are highlighted in this paper. The application of these contributions is made to the topic of extreme cold-season precipitation events in the Saint Lawrence valley in the northeastern United States and southern Quebec. This research focuses on analyses of Saint Lawrence valley heavy precipitation events. Synoptic- and planetary-scale circulation anomaly precursors are typically identified several days prior to these events. These precursors include transient upper-level troughs, strong moisture transports into the region, and anomalously large precipitable water amounts. The physical insight of Fred Sanders' work is used in the analysis of these composite results. Further details of this insight are provided in analyses of one case of heavy precipitation.

Description: Sanders designed a barotropic tropical cyclone (TC) track prediction model for the North Atlantic TC basin that became known as the Sanders barotropic (SANBAR) model. It predicted the streamfunction of the deeplayer mean winds (tropical circulation vertically averaged from 1000 to 100 hPa) that represents the vertically averaged tropical circulations. Originally, the wind input for the operational objective analysis (OA) consisted of winds measured by radiosondes and 44 bogus winds provided by analysis at the National Hurricane Center (NHC), which corresponded to the vertically averaged flow over sparsely observed tropical, subtropical, and midlatitude oceanic regions. The model covered a fixed regional area and had a grid size of ~ 154 km. It estimated the initial storm motion solely on the basis of the large-scale flow from the OA, not taking into account the observed storm motion. During 1970, the SANBAR model became the first dynamical TC track model to be run operationally at NHC. Track forecasts of SANBAR were verified from the 1971 TC season when track model verifications began at NHC until its retirement after the 1989 Atlantic TC season. The average annual SANBAR forecast track errors were verified relative to Climatology and Persistence (CLIPER), the standard no-skill track forecast. Comparison with CLIPER determines the skill of track forecast methods. Verifications are presented for two different versions of the SANBAR model system used operationally during 1973–84 and 1985–89. In homogeneous comparisons (i.e., includes only forecasts for the same initial times) for the former period, SANBAR's track forecasts were slightly better than CLIPER at 24–48-h forecast intervals; however, from 1985 to 1989 the average SANBAR track forecast errors from 24–72 h were ~10% more skillful than homogeneous CLIPER track forecasts.

Description: In the last decade, Fred Sanders was often critical of current surface analysis techniques. This led to his promoting the use of surface potential temperatures to distinguish between fronts, baroclinic troughs, and non-frontal baroclinic zones, and to the development of a climatology of surface baroclinic zones. In this paper, criticisms of current surface analysis techniques and the usefulness of surface potential temperature analyses are discussed. Case examples are used to compare potential temperature analyses and current National Centers for Environmental Prediction analyses. The 1-yr climatology of Sanders and Hoffman is reconstructed using a composite technique. Annual and seasonal mean potential temperature analyses over the continental United States, southern Canada, northern Mexico, and adjacent coastal waters are presented. In addition, gridpoint frequencies of moderate and strong potential temperature gradients are calculated. The results of the mean potential temperature analyses show that moderate and strong surface baroclinic zones are favored along the coastlines and the slopes of the North American cordillera. Additional subsynoptic details, not found in Sanders and Hoffman, are identified. The availability of the composite results allows for the calculation of potential temperature gradient anomalies. It is shown that these anomalies can be used to identify significant frontal baroclinic zones that are associated with weak potential temperature gradients. Together the results and reviews in this paper show that surface potential temperature analyses are a valuable forecasting and analysis tool allowing analysts to distinguish and identify fronts, baroclinic troughs, and nonfrontal baroclinic zones.

Description: The nature of the different types of surface boundaries that appear in the southern plains of the United States during the convectively active season is reviewed. The following boundaries are discussed: fronts, the dryline, troughs, and outflow boundaries, The boundaries are related to their environment and to local topography. The role these boundaries might play in the initiation of convective storms is emphasized. The various types of boundary-related vertical circulations and their dynamics are discussed. In particular, quasigeostrophic and semigeostrophic dynamics, and the dynamics of solenoidal circulations, density currents, boundary layers, and gravity waves are considered. Miscellaneous topics pertinent to convective storms and their relationship to surface boundaries such as along-the-boundary variability, boundary collisions, and the role of vertical shear are also discussed. Although some cases of storm initiation along surface boundaries have been well documented using research datasets collected during comprehensive field experiments, much of what we know is based only on empirical forecasting and nowcasting experience. It is suggested that many problems relating to convective-storm formation need to be explored in detail using real datasets with new observing systems and techniques, in conjunction with numerical simulation studies, and through climatological studies.

Description: This paper begins with a review of basic surface frontogenesis concepts with an emphasis on fronts located over sloping terrain adjacent to mountain barriers and fronts located in large-scale baroclinic zones close to coastlines. The impact of cold-air damming and differential diabatic heating and cooling on frontogenesis is considered through two detailed case studies of intense surface fronts. The first case, from 17 to 18 April 2002, featured the westward passage of a cold (side-door) front across coastal eastern New England in which 15°–20°C temperature decreases were observed in less than one hour. The second case, from 28 February to 4 March 1972, featured a long-lived front that affected most of the United States from the Rockies to the Atlantic coast and was noteworthy for a 50°C temperature contrast between Kansas and southern Manitoba, Canada. In the April 2002 case most of New England was initially covered by an unusually warm, dry air mass. Dynamical anticyclogenesis over eastern Canada set the stage for a favorable pressure gradient to allow chilly marine air to approach coastal New England from the east. Diabatic cooling over the chilly (5°–8°C) waters of the Gulf of Maine allowed surface pressures to remain relatively high offshore while diabatic heating over the land (31°–33°C temperatures) enabled surface pressures to fall relative to over the ocean. The resulting higher pressures offshore resulted in an onshore cold push. Frontal intensity was likely enhanced prior to leaf out and grass green-up as virtually all of the available insolation went into sensible heating. The large-scale environment in the February–March 1972 case favored the accumulation of bitterly cold arctic air in Canada. Frontal formation occurred over northern Montana and North Dakota as the arctic air moved slowly southward in conjunction with surface pressure rises east of the Canadian Rockies. The arctic air accelerated southward subsequent to lee cyclogenesis–induced pressure falls ahead of an upstream trough that crossed the Rockies. The southward acceleration of the arctic air was also facilitated by dynamic anticyclogenesis in southern Canada beneath a poleward jet-entrance region. Frontal intensity varied diurnally in response to differential diabatic heating. Three types of cyclogenesis events were observed over the lifetime of the event: 1) low-amplitude frontal waves with no upper-level support, 2) low-amplitude frontal waves that formed in a jet-entrance region, and 3) cyclones that formed ahead of advancing upper-level troughs. All cyclones were either nondeveloping or weak developments despite extreme baroclinicity, likely the result of large atmospheric static stability in the arctic frontal zone and unfavorable alongfront stretching deformation. Significant frontal–mountain interactions were observed over the Rockies and the Appalachians.

Description: Over 50 yr have passed since the publication of Sanders' 1955 study, the first quantitative study of the structure and dynamics of a surface cold front. The purpose of this chapter is to reexamine some of the results of that study in light of modern methods of numerical weather prediction and diagnosis. A simulation with a resolution as high as 6-km horizontal grid spacing was performed with the fifth-generation-Pennsylvania State University-National Center for Atmospheric Research (PSU-NCAR) Mesoscale Model (MM5), given initial and lateral boundary conditions from the National Centers for Environmental Precipitation-National Center for Atmospheric Research (NCEP-NCAR) reanalysis project data from 17 to 18 April 1953. The MM5 produced a reasonable simulation af the front, albeit its strength was not as intense and its movement was not as fast as was analyzed by Sanders. The vertical structure of the front differed from that analyzed by Sanders in several significant ways. First, the strongest horizontal temperature gradient associated with the cold front in the simulation occurred above a surface-based inversion, not at the earth's surface. Second, the ascent plume at the leading edge of the front was deeper and more intense than that analyzed by Sanders. The reason was an elevated mixed layer that had moved over the surface cold front in the simulation, allowing a much deeper vertical circulation than was analyzed by Sanders. This structure is similar to that of Australian cold fronts with their deep, well-mixed, prefrontal surface layer. These two differences between the model simulation and the analysis by Sanders may be because upper-air data from Fort Worth, Texas, was unavailable to Sanders. Third, the elevated mixed layer also meant that isentropes along the leading edge of the front extended vertically. Fourth, the field of frontogenesis of the horizontal temperature gradient calculated from the three-dimensional wind differed in that the magnitude of the maximum of the deformation term was larger than the magnitude of the maximum of the tilting term in the simulation, in contrast to Sanders' analysis and other previously published cases. These two discrepancies may be attributable to the limited horizontal resolution of the data that Sanders used in constructing his cross section. Last, a deficiency of the model simulation was that the postfrontal surface superadiabatic layer in the model did not match the observed well-mixed boundary layer. This result raises the question of the origin of the well-mixed postfrontal boundary layer behind cold fronts. To address this question, an additional model simulation without surface fluxes was performed, producing a well-mixed, not superadiabatic, layer. This result suggests that surface fluxes were not necessary for the development of the well-mixed layer, in agreement with previous research. Analysis of this event also amplifies two research themes that Sanders returned to later in his career, First, a prefrontal wind shift occurred in both the observations and model simulation at stations in western Oklahoma. This prefrontal wind shift was caused by a lee cyclone departing the leeward slopes of the Rockies slightly equatorward of the cold front, rather than along the front as was the case farther eastward. Sanders' later research showed how the occurrence of these prefrontal wind shifts leads to the weakening of fronts. Second, this study shows the advantage of using surface potential temperature, rather than surface temperature, for determining the locations of the surface fronts on sloping terrain.

Description: Today, even with state-of-the-art observational, data assimilation, and modeling systems run routinely on supercomputers, there are often surprises in the prediction of snowstorms, especially the “big ones,” affecting coastal regions of the mid-Atlantic and northeastern United States. Little did the author know that lessons from Fred Sanders' synoptic meteorology class at the Massachusetts Institute of Technology (1967) would later (late 1980s) inspire him to pursue practical issues of predictability in the context of the development of ensemble prediction systems, strategies, and applications for providing information on the inevitable case-dependent uncertainties in forecasts. This paper is a brief qualitative and somewhat colloquial overview, based upon this author's personal involvement and experiences, intended to highlight some basic aspects of the source and nature of uncertainties in forecasts and to illustrate the sort of value added information ensembles can provide in dealing with uncertainties in predictions of East Coast snowstorms.

Description: One characteristic of Fred Sanders' research is his ability to take a topic that is believed to be well understood by the research community and show that interesting research problems still exist. Among Sanders' considerable contributions to synoptic meteorology, those concerned with surface cold fronts have been especially influential. After a brief historical review of fronts and frontal analysis, this chapter presents three stages in Sanders' career when he performed research on the structure, dynamics, and analysis of surface cold fronts. First, his 1955 paper, "An investigation of the structure and dynamics of an intense surface frontal zone," was the first study to discuss quantitatively the dynamics of a surface cold front. In the 1960s, Sanders and his students further examined the structure of cold fronts, resulting in the unpublished 1967 report to the National Science Foundation, "Frontal structure and the dynamics of frontogenesis." For a third lime in his career, Sanders published several papers (1995–2005) revisiting the structure and dynamics of cold fronts. His 1967 and 1995–2005 work raises the question of the origin and dynamics of the surface pressure trough and/or wind shift that sometimes precedes the temperature gradient (hereafter called a prefrontal trough or prefrontal wind shift, respectively). Sanders showed that the relationship between this prefrontal feature and the temperature gradient is fundamental to the strength of the front. When the wind shift is coincident with the temperature gradient, frontogenesis (strengthening of the front) results; when the wind shift lies ahead of the temperature gradient, frontolysis (weakening of the front) results. a number of proposed mechanisms for the formation of prefrontal troughs and prefrontal wind shifts exist. Consequently, much research remains to be performed on these topics.

Description: When a forecast is assessed, a single value for a verification measure is often quoted. This is of limited use, as it needs to be complemented by some idea of the uncertainty associated with the value. If this uncertainty can be quantified, it is then possible to make statistical inferences based on the value observed. There are two main types of inference: confidence intervals can be constructed for an underlying “population” value of the measure, or hypotheses can be tested regarding the underlying value. This paper will review the main ideas of confidence intervals and hypothesis tests, together with the less well known “prediction intervals,” concentrating on aspects that are often poorly understood. Comparisons will be made between different methods of constructing confidence intervals—exact, asymptotic, bootstrap, and Bayesian—and the difference between prediction intervals and confidence intervals will be explained. For hypothesis testing, multiple testing will be briefly discussed, together with connections between hypothesis testing, prediction intervals, and confidence intervals.

Description: Studies using International Satellite Cloud Climatology Project (ISCCP) data have reported decreases in cloud optical depth with increasing temperature, thereby suggesting a positive feedback in cloud optical depth as climate warms. The negative cloud optical depth and temperature relationships are questioned because ISCCP employs threshold assumptions to identify cloudy pixels that have included partly cloudy pixels. This study applies the spatial coherence technique to one month of Advanced Very High Resolution Radiometer (AVHRR) data over the Pacific Ocean to differentiate overcast pixels from the partly cloudy pixels and to reexamine the cloud optical depth–temperature relationships. For low-level marine stratus clouds studied here, retrievals from partly cloudy pixels showed 30%–50% smaller optical depths, 1°–4°C higher cloud temperatures, and slightly larger droplet effective radii, when they were compared to retrievals from the overcast pixels. Despite these biases, retrievals for the overcast and partly cloudy pixels show similar negative cloud optical depth–temperature relationships and their magnitudes agree with the ISCCP results for the midlatitude and subtropical regions. There were slightly negative droplet effective radius–temperature relationships, and considerable positive cloud liquid water content–temperature relationships indicated by aircraft measurements. However, cloud thickness decreases appear to be the main reason why cloud optical depth decreases with increasing temperature. Overall, cloud thickness thinning may explain why similar negative cloud optical depth–temperature relationships are found in both overcast and partly cloudy pixels. In addition, comparing the cloud-top temperature to the air temperature at 740 hPa indicates that cloud-top height generally rises with warming. This suggests that the cloud thinning is mainly due to the ascending of cloud base. The results presented in this study are confined to the midlatitude and subtropical Pacific and may not be applicable to the Tropics or other regions.

Description: A statistical model to analyze different time scales of the variability of extreme high sea levels is presented. This model uses a time-dependent generalized extreme value (GEV) distribution to fit monthly maxima series and is applied to a large historical tidal gauge record (San Francisco, California). The model allows the identification and estimation of the effects of several time scales—such as seasonality, interdecadal variability, and secular trends—in the location, scale, and shape parameters of the probability distribution of extreme sea levels. The inclusion of seasonal effects explains a large amount of data variability, thereby allowing a more efficient estimation of the processes involved. Significant correlation with the Southern Oscillation index and the nodal cycle, as well as an increase of about 20% for the secular variability of the scale parameter have been detected for the particular dataset analyzed. Results show that the model is adequate for a complete analysis of seasonal-to-interannual sea level extremes providing time-dependent quantiles and confidence intervals.

Description: The interannual and intraseasonal variability of West African vegetation over the period 1982–2002 is studied using the normalized difference vegetation index (NDVI) from the Advanced Very High Resolution Radiometer (AVHRR).The novel independent component analysis (ICA) technique is applied to extract the main modes of the interannual variability of the vegetation, among which two modes are worth describing. The first component (IC1) describes NDVI variability over the Sahel from August to October. A strong photosynthetic activity over the Sahel is related to above-normal convection and rainfall within the intertropical convergence zone (ITCZ) in summertime and is partly associated with colder (warmer) SST in the eastern tropical Pacific (the Mediterranean). The second component (IC2) depicts a dipole pattern between the Sahelian and Guinean regions during the northern summer followed by a southward-propagating signal from October to December. It is associated with a north–south dipole in convection and rainfall induced by variations in the latitudinal location of the ITCZ as a response to the occurrence of the tropical Atlantic dipole.The analysis of the intraseasonal variability of the Sahelian vegetation relies on the analysis of the seasonal marches and their main phenological stages. Green-up usually starts in early July and shows a very low year-to-year variability, while senescence ends by mid-November and is prone to larger interannual variability. Six types of vegetative seasonal marches are discriminated according to variations in the timing of phenological stages as well as in the greening intensity. These types appear to be strongly dependent on rainfall distribution and amount, particularly those recorded in late August. Finally, year-to-year memory effects are highlighted: NDVI recorded during the green-up phase in year j appears to be strongly related to the maximum NDVI value recorded at year j − 1.

Description: Based on the data of optimum interpolation sea surface temperature (OISST), the temporal correlations of the sea surface temperature anomaly (SSTA) in the South China Sea (SCS) are studied by using the rescaled range analysis (R/S) and detrended fluctuation analysis (DFA). The results show that the scaling exponents of SSTAs are larger than 0.8. This finding indicates that the SSTAs in the SCS exhibit persistent long-range time correlation of the fluctuations and the interval spreads over a wide period, from about 1 month to 4.5 yr (4∼235 weeks). In addition, the “degree” of the correlations depends very much on the geographic locations: near to the coastal regions, the value is small, while far from the coastline, the value is relatively larger. This means that SSTAs in the central SCS are smoother than those of the coastal regions. The persistence of SST in the SCS may be used as a “minimum skill” to assess the ocean models and to evaluate their performance.

Description: Winds at the Salt Lake City International Airport (SLC) during the April–October period from 1948 to 2003 have been observed to shift to the north (up-valley direction) between late morning and afternoon on over 70% of the days without precipitation. Lake-breeze fronts that develop as a result of the differential heating between the air over the nearby Great Salt Lake and that over the lake’s surroundings are observed at SLC only a few times each month. Fewer lake-breeze fronts are observed during late July–early September than before or after that period. Interannual fluctuations in the areal extent of the shallow Great Salt Lake contribute to year-to-year variations in the number of lake-breeze frontal passages at SLC. Data collected during the Vertical Transport and Mixing Experiment (VTMX) of October 2000 are used to examine the structure and evolution of a lake-breeze front that moved through the Salt Lake Valley on 17 October. The onset of upslope and up-valley winds occurred within the valley prior to the passage of the lake-breeze front. The lake-breeze front moved at roughly 3 m s−1 up the valley and was characterized near the surface by an abrupt increase in wind speed and dewpoint temperature over a distance of 3–4 km. Rapid vertical mixing of aerosols at the top of the 600–800-m-deep boundary layer was evident as the front passed.

Description: This study combines the experimental measurements with large-eddy simulation (LES) data of a neutral planetary boundary layer (PBL) documented by a 60-m tower instrumented with eight sonic anemometers, and a high-resolution Doppler lidar during the 1999 Cooperative Atmospheric and Surface Exchange Study (CASES-99) experiment. The target of the paper is (i) to investigate the multiscale nature of the turbulent eddies in the surface layer (SL), (ii) to explain the existence of a −1 power law in the velocity fluctuation spectra, and (iii) to investigate the different nature of turbulence in the two sublayers within the SL, which are the eddy surface layer (ESL; lower sublayer of the SL lying between the surface and about 20-m height) and the shear surface layer (SSL; lying between the ESL top and the SL top). The sonic anemometers and Doppler lidar prove to be proper instruments for LES validation, and in particular, the Doppler lidar because of its ability to map near-surface eddies.This study shows the different nature of turbulence in the ESL and the SSL in terms of organized eddies, velocity fluctuation spectra, and second-order moment statistics. If quantitative agreement is found in the SSL between the LES and the measurements, only qualitative similarity is found in the ESL due to the subgrid-scale model, indicating that the LES captures part of the physics of the ESL. The LES helps explain the origin of the −1 power-law spectral subrange evidence in the velocity fluctuation spectra computed in the SL using the CASES-99 dataset: strong interaction between the mean flow and the fluctuating vorticities is found in the SL, and turbulent production is found to be larger than turbulent energy transfer for k1z 〉 1 (k1 being the longitudinal wavenumber and z the height), which is the condition of the −1 power-law existence.

Description: The effects of natural and anthropogenic heterogeneity on a hydrological simulation are evaluated using a distributed biosphere hydrological model (DBHM) system. The DBHM embeds a biosphere model into a distributed hydrological scheme, representing both topography and vegetation in a mesoscale hydrological simulation, and the model system includes an irrigation scheme. The authors investigated the effects of two kinds of variability, precipitation variability and the variability of irrigation redistributing runoff, representing natural and anthropogenic heterogeneity, respectively, on hydrological processes. Runoff was underestimated if rainfall was placed spatially uniformly over large grid cells. Accounting for precipitation heterogeneity improved the runoff simulation. However, the negative runoff contribution, namely, the situation that mean annual precipitation is less than evapotranspiration, cannot be simulated by only considering the natural heterogeneity. This constructive model shortcoming can be eliminated by accounting for anthropogenic heterogeneity caused by irrigation water withdrawals. Irrigation leads to increased evapotranspiration and decreased runoff, and surface soil moisture in irrigated areas increases because of irrigation. Simulations performed for the Yellow River basin of China indicated streamflow decreases of 41% due to irrigation effects. The latent heat flux in the peak irrigation season [June–August (JJA)] increased 3.3 W m−2 with a decrease in the ground surface temperature of 0.1 K for the river basin. The maximum simulated increase in the latent heat flux was 43 W m−2, and the ground temperature decrease was 1.6 K in the peak irrigation season.

Description: A method for routinely verifying numerical weather prediction surface marine winds with satellite scatterometer winds is introduced. The marine surface winds from the Australian Bureau of Meteorology’s operational global and regional numerical weather prediction systems are evaluated. The model marine surface layer is described. Marine surface winds from the global and limited-area models are compared with observations, both in situ (anemometer) and remote (scatterometer). A 2-yr verification shows that wind speeds from the regional model are typically underestimated by approximately 5%, with a greater bias in the meridional direction than the zonal direction. The global model also underestimates the surface winds by around 5%–10%. A case study of a significant marine storm shows that where larger errors occur, they are due to an underestimation of the storm intensity, rather than to biases in the boundary layer parameterizations.

Description: The applicability of axisymmetric theory of angular momentum conserving circulations to the large-scale steady monsoon is studied in a general circulation model with idealized representations of continental geometry and simple physics. Results from an aquaplanet setup with localized subtropical forcing are compared with a continental case. It is found that the meridional circulation that develops is close to angular momentum conserving for cross-equatorial circulation cells, both in the aquaplanet and in the continental cases. The equator proves to be a substantial barrier to boundary layer meridional flow; flow into the summer hemisphere from the winter hemisphere tends to occur in the free troposphere rather than in the boundary layer. A theory is proposed to explain the location of the monsoon; assuming quasiequilibrium, the poleward boundary of the monsoon circulation is collocated with the maximum in subcloud moist static energy, with the monsoon rains occurring near and slightly equatorward of this maximum. The model results support this theory of monsoon location, and it is found that the subcloud moist static energy distribution is determined by a balance between surface forcing and advection by the large-scale flow.

Description: This paper concerns the calculation of the probability of exceedance of wave crest elevation. The statistics have been calculated for broadbanded, unidirectional, deep-water sea states by incorporating a fully nonlinear wave model into a spectral response surface method. This is a novel approach to the calculation of statistics and, as all of the calculations are performed in the probability domain, avoids the need for long time-domain simulations. Furthermore, in contrast to theoretical distributions, the broadbanded, fully nonlinear nature of the sea state can be considered. The results have been compared with those of fully nonlinear time-domain simulations and are shown to be in good agreement. The results indicate that in unidirectional seas the crest elevations of the largest waves can be much higher than would be predicted by linear or second-order theory. Hence, the occurrence of locally long crested sea states offers a possible explanation for the formation of freak or rogue waves.

Description: Nearly one-half of the earth’s terrestrial surface is susceptible to drought, which can have significant social, economic, and environmental impacts. Therefore, it is important to develop better descriptions and models of the processes linking the land surface and atmosphere during drought. Using data collected during the International H2O Project, the study presented here investigates the effects of variations in the environmental factors driving the latent heat flux (λE) during drought conditions at a rangeland site located in the panhandle of Oklahoma. Specifically, this study focuses on the relationships of λE with vapor pressure deficit, wind speed, net radiation, soil moisture content, and greenness fraction. While each of these environmental factors has an influence, soil moisture content is the key control on λE. The role of soil moisture in regulating λE is explained in terms of the surface resistance to water vapor transfer. The results show that λE transitioned between being water or energy limited during the course of the drought. The implications of this on the ability to understand and model drought conditions and transitions into or out of droughts are discussed.

Description: Common Land Model (CLM) and Land Surface Process (LSP) model simulations are compared to measured values for a 13-day dry-down period with a rapidly decreasing near-surface water table for a marsh wetland community in Florida. LSP was able to provide reasonable estimates without any modifications to the model physics. To obtain reasonable simulations using CLM, the baseline TOPMODEL baseflow generation and the bottom drainage mechanisms were not employed and the lower layers were allowed to remain saturated. In addition, several of CLM’s default wetland vegetation parameters were replaced with grassland parameters. Even after these modifications, CLM underestimated soil water storage. However, both model-simulated soil temperatures showed very good agreement as compared to measured temperatures, capturing both the soil warming during the study period and the diurnal fluctuations. Modeled surface energy fluxes also agreed well with measured values. LSP’s inability to consistently capture latent heat fluxes appears to be linked to its canopy resistance scaling functions. Other minor issues were that CLM’s rooting depth greatly exceeded observed depths and that CLM did not move water in the vadose zone from lower to upper layers during the nighttime as observed in the measurements. Overall, these results suggest that LSP can be applied to characterize a marsh dry down, but that minor modifications could greatly improve results. CLM demonstrated considerable potential, but requires some changes to model physics and default parameters prior to application to wetlands at a subgrid scale.

Description: In March 2003 several autonomous underwater vehicle (AUV) missions were carried out under sea ice in the western Bellingshausen Sea. Data from the upward-looking acoustic Doppler current profiler (ADCP) on the “Autosub” AUV indicate a strongly oscillating horizontal velocity of the ice due to ocean swell. Swell period, height, direction, and directional spread have been computed every 800 m from the ice edge to 10 km inward for three missions. Exponential, period-dependent attenuation of waves propagating through sea ice was observed. Mean period increased with distance from the ice edge. The wave field refracted during propagation. The directional wave spread does not seem to relate to distance from the ice edge, although higher frequencies tended to be more spread. If suitably deployed, an ordinary ADCP may be used with this technique to study both scalar and directional properties of waves in open or ice-covered water.

Description: Wind-sea generation was observed during two experiments off the coast of North Carolina. One event with offshore winds of 9–11 m s−1 directed 20° from shore normal was observed with eight directional stations recording simultaneously and spanning a fetch from 4 to 83 km. An opposing swell of 1-m height and 10-s period was also present. The wind-sea part of the wave spectrum conforms to established growth curves for significant wave height and peak period, except at inner-shelf stations where a large alongshore wind-sea component was observed. At these short fetches, the mean wave direction θm was observed to change abruptly across the wind-sea spectral peak, from alongshore at lower frequencies to downwind at higher frequencies. Waves from another event with offshore winds of 6–14 m s−1 directed 20°–30° from shore normal were observed with two instrument arrays. A significant amount of low-frequency wave energy was observed to propagate alongshore from the region where the wind was strongest. These measurements are used to assess the performance of some widely used parameterizations in wave models. The modeled transition of θm across the wind-sea spectrum is smoother than that in the observations and is reproduced very differently by different parameterizations, giving insights into the appropriate level of dissipation. Calculations with the full Boltzmann integral of quartet wave–wave interactions reveal that the discrete interaction approximation parameterization for these interactions is reasonably accurate at the peak of the wind sea but overpredicts the directional spread at high frequencies. This error is well compensated by parameterizations of the wind input source term that have a narrow directional distribution. Observations also highlight deficiencies in some parameterizations of wave dissipation processes in mixed swell–wind-sea conditions.

Description: Seven sets of 2D particle image velocimetry data obtained in the bottom boundary layer of the coastal ocean along the South Carolina and Georgia coast [at the South Atlantic Bight Synoptic Offshore Observational Network (SABSOON) site] are examined, covering the accelerating and decelerating phases of a single tidal cycle at several heights above the seabed. Additional datasets from a previous deployment are also included in the analysis. The mean velocity profiles are logarithmic, and the vertical distribution of Reynolds stresses normalized by the square of the free stream velocity collapse well for data obtained at the same elevation but at different phases of the tidal cycle. The magnitudes of 〈u′u′〉, 〈w′w′〉, and −〈u′w′〉 decrease with height above bottom in the 25–160-cm elevation range and are consistent with the magnitudes and trends observed in laboratory turbulent boundary layers. If a constant stress layer exists, it is located below 25-cm elevation. Two methods for estimating dissipation rate are compared. The first, a direct estimate, is based on the measured in-plane instantaneous velocity gradients. The second method is based on fitting the resolved part of the dissipation spectrum to the universal dissipation spectrum available in Gargett et al. Being undervalued, the direct estimates are a factor of 2–2.5 smaller than the spectrum-based estimates. Taylor microscale Reynolds numbers for the present analysis range from 24 to 665. Anisotropy is present at all resolved scales. At the transition between inertial and dissipation range the longitudinal spectra exhibit a flatter than −5/3 slope and form spectral bumps. Second-order statistics of the velocity gradients show a tendency toward isotropy with increasing Reynolds number. Dissipation exceeds production at all measurement heights, but the difference varies with elevation. Close to the bottom, the production is 40%–70% of the dissipation, but it decreases to 10%–30% for elevations greater than 80 cm.

Description: Scalar exchange between San Francisco Bay and the coastal ocean is examined using shipboard observations made across the Golden Gate Channel. The study consists of experiments during each of the following three “seasons”: winter/spring runoff (March 2002), summer upwelling (July 2003), and autumn relaxation (October 2002). Within each experiment, transects across the channel were repeated approximately every 12 min for 25 h during both spring and neap tides. Velocity was measured from a boat-mounted ADCP. Scalar concentrations were measured at the surface and from a tow-yoed SeaSciences Acrobat. Net salinity exchange rates for each season are quantified with harmonic analysis. Accuracy of the net fluxes is confirmed by comparison with independently measured values. Harmonic results are then decomposed into flux mechanisms using temporal and spatial correlations. In this study, the temporal correlation of cross-sectionally averaged salinity and velocity (tidal pumping flux) is the largest part of the dispersive flux of salinity into the bay. From the tidal pumping flux portion of the dispersive flux, it is shown that there is less exchange than was found in earlier studies. Furthermore, tidal pumping flux scales strongly with freshwater flow resulting from the density-driven movement of a tidally trapped eddy and stratification-induced increases in ebb–flood frictional phasing. Complex bathymetry makes salinity exchange scale differently with flow than would be expected from simple tidal asymmetry and gravitational circulation models.

Description: As part of a program aimed at developing a long-duration, subsurface mooring, known as Ultramoor, several modern acoustic current meters were tested. The instruments with which the authors have the most experience are the Aanderaa RCM11 and the Nortek Aquadopp, which measure currents using the Doppler shift of backscattered acoustic signals, and the Falmouth Scientific ACM, which measures changes in travel time of acoustic signals between pairs of transducers. Some results from the Doppler-based Sontek Argonaut and the travel-time-based Nobska MAVS are also reported. This paper concentrates on the fidelity of the speed measurement but also presents some results related to the accuracy of the direction measurement. Two procedures were used to compare the instruments. In one, different instruments were placed close to one another on three different deep-ocean moorings. These tests showed that the RCM11 measures consistently lower speeds than either a vector averaging current meter or a vector measuring current meter, both more traditional instruments with mechanical velocity sensors. The Aquadopp in use at the time, but since updated to address accuracy problems in low scattering environments, was biased high. A second means of testing involved comparing the appropriate velocity component of each instrument with the rate of change of pressure when they were lowered from a ship. Results from this procedure revealed no depth dependence or measurable bias in the RCM11 data, but did show biases in both the Aquadopp and Argonaut Doppler-based instruments that resulted from low signal-to-noise ratios in the clear, low scattering conditions beneath the thermocline. Improvements in the design of the latest Aquadopp have reduced this bias to a level that is not significant.

Description: The energy pathways in geostrophic turbulence are explored using a two-layer, flat-bottom, f-plane, quasigeostrophic model forced by an imposed, horizontally homogenous, baroclinically unstable mean flow and damped by bottom Ekman friction. A systematic presentation of the spectral energy fluxes, the mean flow forcing, and dissipation terms allows for a comprehensive understanding of the sources and sinks for baroclinic and barotropic energy as a function of length scale. The key new result is a robust inverse cascade of kinetic energy for both the baroclinic mode and the upper layer. This is consistent with recent observations of satellite altimeter data over the South Pacific Ocean. The well-known forward cascade of baroclinic potential and total energy was found to be very robust. Decomposing the spectral fluxes into contributions from different terms provided further insight. The inverse baroclinic kinetic energy cascade is driven mostly by an efficient interaction between the baroclinic velocity and the barotropic vorticity, the latter playing a crucial catalytic role. This cascade can be further enhanced by the baroclinic mode self-interaction, which is only present with nonuniform stratification (unequal layer depths). When model parameters are set such that modeled eddies compare favorably with observations, the inverse baroclinic kinetic energy cascade is actually much stronger than the well-known inverse cascade in the barotropic mode. The upper-layer kinetic energy cascade was found to dominate the lower-layer cascade over a wide range of parameters, suggesting that the surface cascade and time mean density stratification may be sufficient for estimating the depth-integrated cascade from ocean observations. This may find useful application in inferring the kinetic to gravitational potential energy conversion rate from satellite measurements.

Description: AUSTIN, TEXAS--Here at the 17th Annual National Conference on Artificial Intelligence, four teams of engineers fielded mechanical contestants in the first annual urban ruin search-and-rescue competition--a simulated catastrophe created to test intelligent lifesaving robots that may one day lead rescuers to people trapped in the precarious rubble of collapsed buildings. The competition indicated that the technology still has a way to go.〈br /〉〈span class="detail_caption"〉Notes: 〈/span〉Sincell, M -- New York, N.Y. -- Science. 2000 Aug 11;289(5481):846a.〈br /〉〈span class="detail_caption"〉Record origin:〈/span〉 〈a href="http://www.ncbi.nlm.nih.gov/pubmed/17839147" target="_blank"〉PubMed〈/a〉

Description: Disaffection with the European Union's (E.U.'s) flagship research effort has found a sympathetic ear in the program's upper echelons. Last week, the E.U.'s top two research officials said they are pushing for big changes in the successor to Europe's 5-year, $17 billion Framework 5, including stronger efforts to coordinate research across the continent and to support innovative projects.〈br /〉〈span class="detail_caption"〉Notes: 〈/span〉Koenig, R -- New York, N.Y. -- Science. 2000 Sep 22;289(5487):2019b.〈br /〉〈span class="detail_caption"〉Record origin:〈/span〉 〈a href="http://www.ncbi.nlm.nih.gov/pubmed/17799385" target="_blank"〉PubMed〈/a〉

Description: Eighth graders from the United States are still running in the middle of the global pack when it comes to science and math achievement, according to the latest results from the Third International Mathematics and Science Study. And Asian nations continue to lead the way, with Singapore and Taiwan emerging as the star performers among the 38 participating countries. The news is not good for U.S. science and math educators, who have spent much of the decade pursuing reforms aimed at raising student achievement.〈br /〉〈span class="detail_caption"〉Notes: 〈/span〉Holden, C -- New York, N.Y. -- Science. 2000 Dec 8;290(5498):1866.〈br /〉〈span class="detail_caption"〉Record origin:〈/span〉 〈a href="http://www.ncbi.nlm.nih.gov/pubmed/17742044" target="_blank"〉PubMed〈/a〉

Description: 〈br /〉〈span class="detail_caption"〉Notes: 〈/span〉Brisbin, I L Jr -- Austad, S -- Jacobson, S K -- New York, N.Y. -- Science. 2000 Nov 10;290(5494):1093b.〈br /〉〈span class="detail_caption"〉Record origin:〈/span〉 〈a href="http://www.ncbi.nlm.nih.gov/pubmed/17743252" target="_blank"〉PubMed〈/a〉

Description: 〈br /〉〈span class="detail_caption"〉Notes: 〈/span〉Brownell, R L Jr -- Tillman, M F -- di Sciara, G N -- Berggren, P -- Read, A J -- New York, N.Y. -- Science. 2000 Dec 1;290(5497):1696a.〈br /〉〈span class="detail_caption"〉Record origin:〈/span〉 〈a href="http://www.ncbi.nlm.nih.gov/pubmed/17798206" target="_blank"〉PubMed〈/a〉

Description: Officials at NASA's Ames Research Center in Moffett Field, California, would like to trade the use of part of their land for a new building largely dedicated to NASA's nascent astrobiology program, the core of which is a 2-year-old virtual institute based at Ames. Although some scientists applaud the idea, others say that it undermines the idea of a virtual institute and that operating costs would take money away from higher priorities. Two panels have offered conflicting opinions, which may be aired at a meeting next week.〈br /〉〈span class="detail_caption"〉Notes: 〈/span〉Lawler, A -- New York, N.Y. -- Science. 2000 Jul 7;289(5476):23a.〈br /〉〈span class="detail_caption"〉Record origin:〈/span〉 〈a href="http://www.ncbi.nlm.nih.gov/pubmed/17832956" target="_blank"〉PubMed〈/a〉

Description: 〈br /〉〈span class="detail_caption"〉Notes: 〈/span〉Mehl-Madrona, L -- Katz, M -- Curry, E P -- Bribiesca, L B -- New York, N.Y. -- Science. 2000 Jul 14;289(5477):245b-6b.〈br /〉〈span class="detail_caption"〉Record origin:〈/span〉 〈a href="http://www.ncbi.nlm.nih.gov/pubmed/17750401" target="_blank"〉PubMed〈/a〉

Description: 〈br /〉〈span class="detail_caption"〉Notes: 〈/span〉Steele, E J -- Blanden, R V -- New York, N.Y. -- Science. 2000 Jun 30;288(5475):2318d-9d.〈br /〉〈span class="detail_caption"〉Record origin:〈/span〉 〈a href="http://www.ncbi.nlm.nih.gov/pubmed/17769837" target="_blank"〉PubMed〈/a〉

Description: 〈br /〉〈span class="detail_caption"〉Notes: 〈/span〉Farr, N L -- New York, N.Y. -- Science. 2000 Jun 9;288(5472):1747c.〈br /〉〈span class="detail_caption"〉Record origin:〈/span〉 〈a href="http://www.ncbi.nlm.nih.gov/pubmed/17836686" target="_blank"〉PubMed〈/a〉

Description: Relativistic outflows or "jets" are collimated streams of high-energy electrons that emit synchrotron radiation at radio wavelengths and have bulk velocities that are a substantial fraction of the speed of light. They trace the outflow of enormous amounts of energy and matter from a central supermassive black hole in distant radio galaxies. As Fender explains in this Perspective, much smaller, more local sources may also produce such jets. Data presented by Paredes et al. point toward association of one such source, a relatively faint x-ray binary, with a gamma-ray source. This and similar pairs may contribute substantially to the production of high-energy particles and photons within our galaxy.〈br /〉〈span class="detail_caption"〉Notes: 〈/span〉Fender, R P -- New York, N.Y. -- Science. 2000 Jun 30;288(5475):2326.〈br /〉〈span class="detail_caption"〉Record origin:〈/span〉 〈a href="http://www.ncbi.nlm.nih.gov/pubmed/17769841" target="_blank"〉PubMed〈/a〉

Description: 〈br /〉〈span class="detail_caption"〉Notes: 〈/span〉Bunnett, J F -- New York, N.Y. -- Science. 2000 Dec 8;290(5498):1895b.〈br /〉〈span class="detail_caption"〉Record origin:〈/span〉 〈a href="http://www.ncbi.nlm.nih.gov/pubmed/17742052" target="_blank"〉PubMed〈/a〉

Description: Twice burned by mission failures last year, NASA managers last week unveiled a new 15-year blueprint for Mars exploration. The revamped strategy allows for doing more science, but at a slower pace, while delaying a sample return until well into the next decade.〈br /〉〈span class="detail_caption"〉Notes: 〈/span〉Lawler, A -- New York, N.Y. -- Science. 2000 Nov 3;290(5493):915a-6a.〈br /〉〈span class="detail_caption"〉Record origin:〈/span〉 〈a href="http://www.ncbi.nlm.nih.gov/pubmed/17749180" target="_blank"〉PubMed〈/a〉

Description: Most materials become narrower in cross section when stretched, but some materials, such as foams, have the counterintuitive property of becoming fatter when stretched (they have a negative Poisson's ratio). In this Perspective, Lakes discusses how his unusual property may arise in isotropic and anisotropic materials. He highlights the study by Baughman et al., who show that anisotropic materials with a negative Poisson's ratio in one direction can be incompressible, i.e., without an overall change in volume upon stretching. This behavior is predicted for materials with very high density, such as neutron star crusts, or very low density, such as ion plasmas, and the validity of the prediction is demonstrated with experimental data for ion plasmas.〈br /〉〈span class="detail_caption"〉Notes: 〈/span〉Lakes, R -- New York, N.Y. -- Science. 2000 Jun 16;288(5473):1976-7.〈br /〉〈span class="detail_caption"〉Record origin:〈/span〉 〈a href="http://www.ncbi.nlm.nih.gov/pubmed/17835108" target="_blank"〉PubMed〈/a〉

Description: Maryland is the most research-intensive state in the country, according to a new report that describes in unprecedented detail where the federal government's annual $80 billion research budget is spent. Its authors hope the report will raise public awareness about research as well as inform politicians.〈br /〉〈span class="detail_caption"〉Notes: 〈/span〉Mervis, J -- New York, N.Y. -- Science. 2000 Jun 23;288(5474):2115b.〈br /〉〈span class="detail_caption"〉Record origin:〈/span〉 〈a href="http://www.ncbi.nlm.nih.gov/pubmed/17758899" target="_blank"〉PubMed〈/a〉

Description: Until the past year, Alex Chao, a senior physicist at the Stanford Linear Accelerator Center, tended to keep his views to himself. But the Wen Ho Lee case turned Chao into a reluctant activist who has contributed money for Lee's defense, helped organize rallies in the San Francisco Bay area, and talked to his neighbors about the injustice he believes Lee and other Asian Americans have suffered.〈br /〉〈span class="detail_caption"〉Notes: 〈/span〉Lawler, A -- New York, N.Y. -- Science. 2000 Nov 10;290(5494):1073.〈br /〉〈span class="detail_caption"〉Record origin:〈/span〉 〈a href="http://www.ncbi.nlm.nih.gov/pubmed/17743249" target="_blank"〉PubMed〈/a〉

Description: Academic scientists are hoping that two new reports calling for increased funding of research and education and an improved climate for commercializing new technology will finally boost an R&D budget that has been stagnant since 1996. One report argues for a variety of measures to reduce the country's reliance on such low-tech commodities as agriculture and precious metals and stimulate innovation. The second report, based on an innovation summit held in February, recommends spending $1.4 billion over 5 years on research, facilities, and education.〈br /〉〈span class="detail_caption"〉Notes: 〈/span〉Finkel, E -- New York, N.Y. -- Science. 2000 Oct 13;290(5490):255-7.〈br /〉〈span class="detail_caption"〉Record origin:〈/span〉 〈a href="http://www.ncbi.nlm.nih.gov/pubmed/17734105" target="_blank"〉PubMed〈/a〉

Description: Angered and emboldened by the Wen Ho Lee case, many Asian-American researchers at national laboratories are decrying their status as "high-tech coolies"--and demanding change. It's a sudden and surprising turn of events for a community that traditionally has avoided political organization, legal recourse, and conflict with authority. And given the growing numerical muscle of Asian Americans in both public and private labs, the budding movement--if sustained--will be felt far beyond the secure fences of the Department of Energy's weapons labs.〈br /〉〈span class="detail_caption"〉Notes: 〈/span〉Lawler, A -- New York, N.Y. -- Science. 2000 Nov 10;290(5494):1072-7.〈br /〉〈span class="detail_caption"〉Record origin:〈/span〉 〈a href="http://www.ncbi.nlm.nih.gov/pubmed/17743248" target="_blank"〉PubMed〈/a〉

Description: For several years now, road runoff and erosion stemming in part from the operations of the Plum Creek Timber Co. have choked Elk Creek, known as the best bull trout spawning stream in the West, with sediment, raising fears of even further decline in this endangered species. Now, in an effort to mitigate its harmful effects and avert regulatory action, Plum Creek has designed a Native Fish Habitat Conservation Plan covering 17 fish species, including the bull trout.〈br /〉〈span class="detail_caption"〉Notes: 〈/span〉Wuethrich, B -- New York, N.Y. -- Science. 2000 Jul 21;289(5478):385.〈br /〉〈span class="detail_caption"〉Record origin:〈/span〉 〈a href="http://www.ncbi.nlm.nih.gov/pubmed/17840573" target="_blank"〉PubMed〈/a〉

Description: The National Institute of General Medical Sciences (NIGMS) is using a novel funding approach to bind together researchers in cutting-edge fields at many institutions, allowing them to transcend their individual areas of expertise. NIGMS has awarded $5 million a year for 5 years to a group of scientists studying cellular signaling. To speed their findings into the public domain and make them available for use in drug testing, members of the project have agreed to post new results in a public database and forgo some patent and authorship claims.〈br /〉〈span class="detail_caption"〉Notes: 〈/span〉Fisher, K -- New York, N.Y. -- Science. 2000 Sep 15;289(5486):1854a.〈br /〉〈span class="detail_caption"〉Record origin:〈/span〉 〈a href="http://www.ncbi.nlm.nih.gov/pubmed/17839925" target="_blank"〉PubMed〈/a〉

Description: In this month's essay, Paul J. Crutzen and Veerabhadran Ramanathan chart some of the courses by which atmospheric sciences evolved from their beginnings, with curious scientists teasing apart the complexity of the air they breathe, into an ever more multidisciplinary enterprise that routinely generates globally consequential knowledge. The authors chronicle developments in chemistry and meteorology up to the early 1970s, before the possibility of human influence beyond the local scale became actualized. To illustrate how humanity's hand has grown to have global effects, they zero in on two contemporary issues: atmospheric ozone and global warming.〈br /〉〈span class="detail_caption"〉Notes: 〈/span〉New York, N.Y. -- Science. 2000 Oct 13;290(5490):299-304.〈br /〉〈span class="detail_caption"〉Record origin:〈/span〉 〈a href="http://www.ncbi.nlm.nih.gov/pubmed/17734112" target="_blank"〉PubMed〈/a〉

Description: Steve C. Wang is a lecturer in the Department of Statistics at Harvard University. He earned his B.S. from Cornell University and his Ph.D. in statistics from the University of Chicago. He has taught statistics and mathematics at the University of Chicago and Williams College. His research interests include applying statistics to paleobiology, endocrine diseases, and image recognition.〈br /〉〈span class="detail_caption"〉Notes: 〈/span〉Wang, S C -- New York, N.Y. -- Science. 2000 Sep 1;289(5484):1477.〈br /〉〈span class="detail_caption"〉Record origin:〈/span〉 〈a href="http://www.ncbi.nlm.nih.gov/pubmed/17839518" target="_blank"〉PubMed〈/a〉

Description: A New York congressman who sided with environmentalists to kill a nuclear research reactor at Brookhaven National Laboratory in Upton, New York, has been defeated in a stunning primary upset. Representative Michael Forbes lost last week by a narrow margin to Regina Seltzer, the 71-year-old widow of a Brookhaven chemist. The defeat is welcome news to many Brookhaven scientists.〈br /〉〈span class="detail_caption"〉Notes: 〈/span〉Lawler, A -- New York, N.Y. -- Science. 2000 Sep 22;289(5487):2021b.〈br /〉〈span class="detail_caption"〉Record origin:〈/span〉 〈a href="http://www.ncbi.nlm.nih.gov/pubmed/17799387" target="_blank"〉PubMed〈/a〉

Description: Whether the University of Belgrade was ruined or saved in May 1998 depends on one's political views. That was when the regime of Slobodan Milosevic pushed through the Serb parliament the University Act, a law that gave the minister of higher education the right to appoint deans at Serbian universities.〈br /〉〈span class="detail_caption"〉Notes: 〈/span〉Stone, R -- New York, N.Y. -- Science. 2000 Oct 27;290(5492):691.〈br /〉〈span class="detail_caption"〉Record origin:〈/span〉 〈a href="http://www.ncbi.nlm.nih.gov/pubmed/17780504" target="_blank"〉PubMed〈/a〉

Description: Four months before it goes into effect, a $605 million program to help Canadian universities attract and retain the best scientific talent has ignited a furor within Canadian academe. Research-intensive universities have begun aggressively shopping for prospective candidates, using the new chairs as bait. Smaller universities say that has left them fending off talent raids.〈br /〉〈span class="detail_caption"〉Notes: 〈/span〉Kondro, W -- New York, N.Y. -- Science. 2000 Jun 23;288(5474):2112.〈br /〉〈span class="detail_caption"〉Record origin:〈/span〉 〈a href="http://www.ncbi.nlm.nih.gov/pubmed/17758896" target="_blank"〉PubMed〈/a〉

Description: Europe is in a growth phase--growing in size as several countries are negotiating to join the European Union (EU) and growing in maturity as its institutions evolve to meet better the needs of its citizens. One aspect of this maturation is the realization that the EU structures to support science have failed in many respects and need a drastic overhaul. The European Life Scientists Organization (ELSO) was created last year to pull together molecular life scientists into a coherent body that can work toward improving conditions for research in Europe.〈br /〉〈span class="detail_caption"〉Notes: 〈/span〉Simons, K -- Featherstone, C -- New York, N.Y. -- Science. 2000 Nov 10;290(5494):1099-101.〈br /〉〈span class="detail_caption"〉Record origin:〈/span〉 〈a href="http://www.ncbi.nlm.nih.gov/pubmed/17743255" target="_blank"〉PubMed〈/a〉

Description: As magnetic devices become smaller and faster, it is becoming increasingly important to understand the dynamics of magnetic domains on small spatial and temporal scales. In their Perspective, Miltat and Thiaville highlight the report by Acremann et al., whose magnetooptical microscope combines state of the art space and time resolution, thus allowing the precessional motion of magnetic domains to be studied directly. The dynamics they observe are complex, indicating that in both the space and time domains, neither the magnetization nor the applied field should be viewed as uniform.〈br /〉〈span class="detail_caption"〉Notes: 〈/span〉Miltat, J -- Thiaville, A -- New York, N.Y. -- Science. 2000 Oct 20;290(5491):466-7.〈br /〉〈span class="detail_caption"〉Record origin:〈/span〉 〈a href="http://www.ncbi.nlm.nih.gov/pubmed/17844284" target="_blank"〉PubMed〈/a〉

Description: 〈br /〉〈span class="detail_caption"〉Notes: 〈/span〉Murphy, K -- Frazer, K A -- Loots, G -- Rubin, E M -- New York, N.Y. -- Science. 2000 Jun 30;288(5475):2319a.〈br /〉〈span class="detail_caption"〉Record origin:〈/span〉 〈a href="http://www.ncbi.nlm.nih.gov/pubmed/17769838" target="_blank"〉PubMed〈/a〉

Description: Stone slabs bearing images of an animal and a half-human, half-beast figure were uncovered during excavations by an Italian team at the Fumane Cave northwest of Verona. The images are believed to be at least as ancient as some found in the Grotte Chauvet in southern France--the current record holder at 32,000 years--and possibly even older. More important, cave art experts say, the new paintings bolster other evidence that humans engaged in sophisticated symbolic expression much earlier than once thought.〈br /〉〈span class="detail_caption"〉Notes: 〈/span〉Balter, M -- New York, N.Y. -- Science. 2000 Oct 20;290(5491):419-21.〈br /〉〈span class="detail_caption"〉Record origin:〈/span〉 〈a href="http://www.ncbi.nlm.nih.gov/pubmed/17844275" target="_blank"〉PubMed〈/a〉

Description: Newt Gingrich introduces the concept of an "opportunities-based budget", as an approach to federal research and development funding. Policy-makers should not frame the debate on science funding in terms of percentage of increase. Rather, a systematic analysis of the promise of opportunities should be conducted and the funds allotted accordingly. This article is a call to rethink how lawmakers are funding the discoveries upon which future generations will rely.〈br /〉〈span class="detail_caption"〉Notes: 〈/span〉Gingrich, N -- New York, N.Y. -- Science. 2000 Nov 17;290(5495):1303.〈br /〉〈span class="detail_caption"〉Record origin:〈/span〉 〈a href="http://www.ncbi.nlm.nih.gov/pubmed/17787232" target="_blank"〉PubMed〈/a〉

Description: Europe's most advanced high-security pathogen lab has claimed its first human casualty--and it hasn't even opened for business. On 28 June, the Marcel Merieux Foundation, which funded the construction of the $8 million facility in Lyons, banned lab director Susan Fisher-Hoch from the premises and launched legal proceedings to dismiss her. Fisher-Hoch's most egregious offense, it appears, was speaking with the press.〈br /〉〈span class="detail_caption"〉Notes: 〈/span〉Balter, M -- New York, N.Y. -- Science. 2000 Jul 14;289(5477):228b-9b.〈br /〉〈span class="detail_caption"〉Record origin:〈/span〉 〈a href="http://www.ncbi.nlm.nih.gov/pubmed/17750397" target="_blank"〉PubMed〈/a〉

Description: 〈br /〉〈span class="detail_caption"〉Notes: 〈/span〉The International Human Genome Sequencing Consortium -- New York, N.Y. -- Science. 2000 Sep 1;289(5484):1471b.〈br /〉〈span class="detail_caption"〉Record origin:〈/span〉 〈a href="http://www.ncbi.nlm.nih.gov/pubmed/17839516" target="_blank"〉PubMed〈/a〉

Description: Scientists studying the latest high-resolution photos of the martian south polar ice cap think they may have found additional clues to its ebb and flow. These hints of the planet's bizarre atmosphere come from a new class of dramatic-looking terrain features whose dark, multilimbed, vaguely radial designs have earned them the moniker "black spiders," and another group of dusky, spreading features called "dark fans." At a recent gathering here of Mars researchers, a planetary scientist proposed that the spiders might be subsurface gas channels, visible through an unusually transparent section of the martian ice.〈br /〉〈span class="detail_caption"〉Notes: 〈/span〉Lovett, R A -- New York, N.Y. -- Science. 2000 Sep 15;289(5486):1853a-4a.〈br /〉〈span class="detail_caption"〉Record origin:〈/span〉 〈a href="http://www.ncbi.nlm.nih.gov/pubmed/17839924" target="_blank"〉PubMed〈/a〉

Description: 〈br /〉〈span class="detail_caption"〉Notes: 〈/span〉Karpen, J T -- Krimigis, S M -- Appleby, J F -- Lawler, A -- New York, N.Y. -- Science. 2000 Aug 25;289(5483):1296.〈br /〉〈span class="detail_caption"〉Record origin:〈/span〉 〈a href="http://www.ncbi.nlm.nih.gov/pubmed/17772991" target="_blank"〉PubMed〈/a〉

Description: 〈br /〉〈span class="detail_caption"〉Notes: 〈/span〉C Clarke, S A -- New York, N.Y. -- Science. 2000 Aug 4;289(5480):727.〈br /〉〈span class="detail_caption"〉Record origin:〈/span〉 〈a href="http://www.ncbi.nlm.nih.gov/pubmed/17819565" target="_blank"〉PubMed〈/a〉

Description: The Large Magellanic Cloud (LMC), a satellite of the Milky Way, is an important yardstick by which most intergalactic distances are measured. But as Cole explains in this Perspective, how far away the LMC is remains a matter of dispute, with far reaching implications in cosmology. But observations of Cepheids and of eclipsing binaries, two types of stars that allow absolute luminosity and thus absolute distances to be determined, are promising to resolve this important issue in the not too distant future.〈br /〉〈span class="detail_caption"〉Notes: 〈/span〉Cole, A A -- New York, N.Y. -- Science. 2000 Aug 18;289(5482):1149-50.〈br /〉〈span class="detail_caption"〉Record origin:〈/span〉 〈a href="http://www.ncbi.nlm.nih.gov/pubmed/17833402" target="_blank"〉PubMed〈/a〉

Description: By exploiting the symmetry of randomness, three mathematicians have revealed the geometric underpinnings of the frenetic random dance called Brownian motion. The methods they used seem likely to apply to other random processes, some as familiar as the flow of water through a filter. The proof was presented at the recent Current Developments in Mathematics 2000 conference sponsored by Harvard University and the Massachusetts Institute of Technology.〈br /〉〈span class="detail_caption"〉Notes: 〈/span〉Mackenzie, D -- New York, N.Y. -- Science. 2000 Dec 8;290(5498):1883-4.〈br /〉〈span class="detail_caption"〉Record origin:〈/span〉 〈a href="http://www.ncbi.nlm.nih.gov/pubmed/17742050" target="_blank"〉PubMed〈/a〉

Description: When a diatomic molecule is broken up into its constituent atoms, these very energetic atoms provide a large driving force for further reaction. Diatomic molecules often do not undergo productive chemistry, however, because the energy needed to break the diatomic bond is also high. In his Perspective, Thorp discusses the work by MacBeth et al., who have synthesized a nonheme iron complex that reacts with O2 to produce two equivalents of a metal-oxo complex. The complex elegantly mimic the ability of some enzymes to influence metal ion coordination spheres.〈br /〉〈span class="detail_caption"〉Notes: 〈/span〉Thorp, H H -- New York, N.Y. -- Science. 2000 Aug 11;289(5481):882-3.〈br /〉〈span class="detail_caption"〉Record origin:〈/span〉 〈a href="http://www.ncbi.nlm.nih.gov/pubmed/17839155" target="_blank"〉PubMed〈/a〉

Description: A new finding, based on x-rays from distant neutron stars, could be the first clear evidence of a weird relativistic effect called frame dragging, in which a heavy chunk of spinning matter wrenches the space-time around it like an eggbeater. Using data from NASA's Rossi X-ray Timing Explorer, three astronomers in Amsterdam found circumstantial evidence for frame dragging in the flickering of three neutron stars in binary systems. They announced their results in the 1 September issue of The Astrophysical Journal.〈br /〉〈span class="detail_caption"〉Notes: 〈/span〉Schilling, G -- New York, N.Y. -- Science. 2000 Sep 1;289(5484):1448a.〈br /〉〈span class="detail_caption"〉Record origin:〈/span〉 〈a href="http://www.ncbi.nlm.nih.gov/pubmed/17839511" target="_blank"〉PubMed〈/a〉

Description: Forest fires burning in the western United States have already scorched over 2.5 million hectares this summer. Now a federal proposal to prevent them by paying loggers to cut smaller trees is generating heat among ecologists, who say the approach may not be right for all forests--or all fires.〈br /〉〈span class="detail_caption"〉Notes: 〈/span〉Macneil, J S -- New York, N.Y. -- Science. 2000 Sep 1;289(5484):1448b-9b.〈br /〉〈span class="detail_caption"〉Record origin:〈/span〉 〈a href="http://www.ncbi.nlm.nih.gov/pubmed/17839512" target="_blank"〉PubMed〈/a〉

Description: Titanic explosions that emit powerful flashes of energetic gamma rays are one of astronomy's hottest mysteries. Now an analysis of the nearest gamma ray burst yet detected has added weight to the popular theory that they are expelled during the death throes of supermassive stars.〈br /〉〈span class="detail_caption"〉Notes: 〈/span〉Schilling, G -- New York, N.Y. -- Science. 2000 Jul 7;289(5476):29.〈br /〉〈span class="detail_caption"〉Record origin:〈/span〉 〈a href="http://www.ncbi.nlm.nih.gov/pubmed/17832958" target="_blank"〉PubMed〈/a〉

Description: The results of Chinese field trials reinforce the accepted scientific wisdom that planting different varieties of a crop in the same field holds down the spread of certain diseases and improves yields. And this time researchers seem to have convinced farmers, too.〈br /〉〈span class="detail_caption"〉Notes: 〈/span〉Normile, D -- New York, N.Y. -- Science. 2000 Aug 18;289(5482):1122b-3b.〈br /〉〈span class="detail_caption"〉Record origin:〈/span〉 〈a href="http://www.ncbi.nlm.nih.gov/pubmed/17833396" target="_blank"〉PubMed〈/a〉

Description: Last month the High Energy Transient Explorer 2, the first satellite dedicated to spotting gamma ray bursts, rocketed successfully into orbit, bolstering a handful of x-ray satellites whose instruments are trained on the mysterious explosions. But some researchers say setbacks to the fleet have left unfortunate gaps in coverage.〈br /〉〈span class="detail_caption"〉Notes: 〈/span〉Schilling, G -- New York, N.Y. -- Science. 2000 Nov 3;290(5493):927.〈br /〉〈span class="detail_caption"〉Record origin:〈/span〉 〈a href="http://www.ncbi.nlm.nih.gov/pubmed/17749185" target="_blank"〉PubMed〈/a〉

Description: Most astrophysicists puzzling over what causes gamma ray bursts--short, intense explosions of high-energy photons that occur deep in space--now agree that the answer is a hypernova, the blast of energy released when a supermassive star collapses into a black hole. Two papers in this issue of Science (pp. 953 and 955), reporting on new x-ray observations of two gamma ray bursts, argue that the hypernova model tells only half of the story. On its way to becoming a black hole, the authors propose, the supermassive star actually collapses twice.〈br /〉〈span class="detail_caption"〉Notes: 〈/span〉Schilling, G -- New York, N.Y. -- Science. 2000 Nov 3;290(5493):926-7.〈br /〉〈span class="detail_caption"〉Record origin:〈/span〉 〈a href="http://www.ncbi.nlm.nih.gov/pubmed/17749184" target="_blank"〉PubMed〈/a〉

Description: When the dimensions of matter are reduced to the nanometer scale and beyond, strange properties often emerge. In their Perspective, Tosatti and Prestipino discuss the weird gold nanowire structures reported by Kondo and Takayanagi. They explain why the wires may be helical and only form certain "magic" sizes. Other metals may form similarly strange structures with unusual properties.〈br /〉〈span class="detail_caption"〉Notes: 〈/span〉Tosatti, E -- Prestipino, S -- New York, N.Y. -- Science. 2000 Jul 28;289(5479):561-3.〈br /〉〈span class="detail_caption"〉Record origin:〈/span〉 〈a href="http://www.ncbi.nlm.nih.gov/pubmed/17832069" target="_blank"〉PubMed〈/a〉

Description: 〈br /〉〈span class="detail_caption"〉Notes: 〈/span〉Cottrell, R D -- Tarduno, J A -- Sager, W W -- Koppers, A A -- New York, N.Y. -- Science. 2000 Jun 30;288(5475):2283a.〈br /〉〈span class="detail_caption"〉Record origin:〈/span〉 〈a href="http://www.ncbi.nlm.nih.gov/pubmed/17769831" target="_blank"〉PubMed〈/a〉

Description: Primitive meteorites provide a glimpse into the early history of our solar system, but some of the most primitive meteorites are also rarely found on Earth. In his Perspective, Grossman explains why the fall of the Tagish Lake meteorite on 18 January 2000 in British Columbia, Canada, was a lucky event for meteorite researchers. The first analysis of the meteorite is reported by Brown et al. Well-preserved organic matter in the meteorite provides a unique opportunity to study the nature and origin of organic matter that may have accreted on early Earth and played a role in the origin of life.〈br /〉〈span class="detail_caption"〉Notes: 〈/span〉Grossman, J N -- New York, N.Y. -- Science. 2000 Oct 13;290(5490):283-5.〈br /〉〈span class="detail_caption"〉Record origin:〈/span〉 〈a href="http://www.ncbi.nlm.nih.gov/pubmed/17734110" target="_blank"〉PubMed〈/a〉

Description: 〈br /〉〈span class="detail_caption"〉Notes: 〈/span〉Schlesinger, M E -- Ramankutty, N -- Andronova, N -- Margolis, M -- Kerr, R A -- New York, N.Y. -- Science. 2000 Jul 28;289(5479):547b-8b.〈br /〉〈span class="detail_caption"〉Record origin:〈/span〉 〈a href="http://www.ncbi.nlm.nih.gov/pubmed/17832062" target="_blank"〉PubMed〈/a〉

Description: Last week, computer industry titan Gordon Moore and his wife, Betty, announced that they are creating a $5-billion-plus foundation to support scientific research, conservation, and higher education. Once fully funded within a few years, the foundation is expected to rank among the dozen largest charities based in the United States.〈br /〉〈span class="detail_caption"〉Notes: 〈/span〉Malakoff, D -- New York, N.Y. -- Science. 2000 Nov 24;290(5496):1481b.〈br /〉〈span class="detail_caption"〉Record origin:〈/span〉 〈a href="http://www.ncbi.nlm.nih.gov/pubmed/17771219" target="_blank"〉PubMed〈/a〉

Description: When University of California, Irvine, developmental biologist Susan Bryant married David Gardiner, Gardiner took a soft-money position as a researcher at Irvine. Because Gardiner was flexible in his goals and committed to raising children, it seemed a better choice than trying to get two jobs somewhere else, he recalls. And 17 years and two children later, Gardiner says that decision was right for them as a couple--and that he has learned to endure the indignities that come with the territory.〈br /〉〈span class="detail_caption"〉Notes: 〈/span〉Barinaga, M -- New York, N.Y. -- Science. 2000 Sep 22;289(5487):2025.〈br /〉〈span class="detail_caption"〉Record origin:〈/span〉 〈a href="http://www.ncbi.nlm.nih.gov/pubmed/17799388" target="_blank"〉PubMed〈/a〉