ALBERT

Description: Four research surveys of Falkland Island waters were carried out to determine the distribution and abundance of the early life-history stages of Loligo gahi (d'Orbigny, 1835) in the austral winter of 1988 and the austral springs of 1990, 1991 and 1992. Juveniles were caught during three of the four surveys in both Bongo nets and an RMT8 net. In each case, greatest numbers were consistently caught in waters of ≤100 m to the south and east of East Falkland. The use of an opening/closing net in 1992 showed that most L. gahi juveniles aggregate close to the sea floor and are more available to the sampling gear by night than by day. Limited temperature data for the 1991 and 1992 surveys suggest that distribution on the coastal shelf may be associated with water-column structure. In 1992 when temperature data implied a mixed water column, juveniles were caught in deeper water than in 1991 when the water column was stratified. The results suggest that the spawning grounds of L. gahi are probably situated to the south and east of the Falkland Islands, at least for squid hatched in the austral winter/spring.

Description: A total of 40 (29 female and 11 male) Ross seals were sampled in January over three years. Seals were weighed, measured and age determined by counting dentine lines in teeth. Stomach contents were identified against reference material and species of helminths were determined using standard techniques. Asymptotes in body mass and length are reached at some nine years of age. Age class varied from 2–20 years. Antarctic silverfish Pleurogrammma antarcticum was the only fish species identified. Psychroteuthis glacialis dominated the squid component. Fish was dominant in three samples, squid was the exclusive component in two samples and a minor component in another two. Glandicephalus antarcticus, Diphyllobothrium wilsoni and Contracaecum spp were the dominant helminths present. The high proportion of empty or nearly empty stomachs conforms with the knowledge that this species moults and consequently fasts in January.

Description: Geographic variation in the squid Loligo forbesi was investigated using multivariate analysis of morphometric and meristic characters in samples of squid taken from 13 localities in the Northeast Atlantic Ocean. Two character sets, body morphometrics and beak morphometrics, indicated similar patterns of variation, with squid from the Azores differing markedly from those on the continental shelf. No consistent pattern was apparent in meristic data. Partial Mantel tests indicated that similarity matrices for morphological data were significantly correlated with distance matrices for (a) geographic proximity, (b) whether the capture site was on the continental shelf or the Azorean bank, and (c) (beak data only) average seasurface temperature at site of capture. Partial Mantel tests on allozyme data for the same individuals support hypothesis (b). The results suggest that L. forbesi in the Azores may reasonably be regarded as a distinct stock, differing significantly from L. forbesi on the continental shelf.

Description: Abralia trigonura is a small squid that is an important member of the mesopelagic boundary community around Hawaii. Squids were aged by examining statolith growth increments, and various reproductive parameters were measured. Female longevity is ∼6 mo, and they become sexually mature at ∼3.5 mo. Male longevity is the same, but they become sexually mature at ∼2.5 mo. This species appears to be a multiple spawner, and peculiarities in the number of eggs found in the oviducts suggests that they spawn every few days. Possible advantages of this reproductive mode are examined.

Description: The home range system of the coelacanth Latimeria chalumnae was investigated along 11 km coastline at Grande Comore, Western Indian Ocean, between 1987 and 1991. 67 individuals were identified on individual white dot patterns. The home range consisted of daytime caves where fish aggregated in groups of up to 14 individuals while at night individuals moved singly downwards to a depth of 250 to 300 m in search of food. Site fidelity of at least 5 yr was found. The coelacanths used several caves within their home ranges. Cave size, cave occupation rate, average and maximum group size and cave preferences were studied. Tracking experiments with ultrasonic transmitters revealed horizontal home ranges of at least 8 km width. Population estimates of 200 to 230 individuals at Grande Comore confirm earlier counts. Large home ranges and highly mobility in a topographically narrow habitat apparently favoured inbreeding of the small local island population.

Description: Eleven fish species from the Weddell Sea (Antarctic) were examined for infestation with anisakid nematodes. Two species of the genus Contracaecum and the sealworm Pseudoterranova decipiens were isolated from the liver and the body cavity of fish affected. Only two specimens of P. decipiens (1.4%) partly invaded the belly flaps. The following fish species were infested by P. decipiens at the given prevalences: Cygnodraco mawsoni (74.4%), Trematomus scotti (23.2%), Pagetopsis maculatus (10.0%), Cryodraco antarcticus (7.1%), Trematomus lepidorhinus (3.0%), and Dolloidraco longedorsalis (2.7%). All of these, except Trematomus scotti, are new host records. Chaenodraco wilsoni, Chionodraco myersi, Gerlachea australis, Racovitzia glacialis and T. eulepidotus were not infested. The reasons for low prevalence and intensity of infestation are seen in the difficulties of P. decipiens in completing its benthic life cycle in the Weddell Sea environment, in the absence of shallow coastal waters due to the floating shelf-ice. Cygnodraco mawsoni is a crucial intermediate host, without which completion of the parasite life cycle might not be possible. In order to clarify the taxonomical position of Antarctic Pseudoterranova, morphological comparisons with specimens of P. decipiens from the German and Norwegian coast were made using scanning electron microscopy. Results revealed no differences; hence, all specimens studied belong to the same species P. decipiens.

Description: In this study a scenario is developed of two adjacent Mediterranean Water eddies (meddies) as they were observed merging and drifting through the Iberian Basin. Observations are based on four RAFOS floats (at 850–1050 dbar), two hydrographic surveys (centered roughly at 38°N, 24°W), and trajectories of surface drifters (drogued at 100 m). In April 1991, the meddy A was identified and labeled by surface drifters. During the revisit one month later two meddies were encountered, B1 and B2, in the vicinity of the former meddy A. The coalescence of B1 (subsequently identified as A, one month older) and B2 is inferred from a simple kinematic model describing the observed movement of the RAFOS floats for up to three months after the second CTD survey. The deduced vorticity front, radius ∼15 km, within B1 was of insufficient strength to keep the core waters of B1 isolated and prevent the absorption of B1 by B2. The resulting meddy (B1 + B2) showed a clear near-surface dynamical signal. Its deep root (1800 m) could explain the expulsion from the meddy of the remaining RAFOS float and surface drifter at the time of the meddy's collision with the Josephine Seamount. For the first time, a set of Lagrangian and hydrographic observations give direct evidence that neighboring meddies can merge as predicted by theoretical considerations.

Description: Coupling of physical, biological and chemical processes associated with particle resuspension and seston flux was investigated at three sites in the North Sea with contrasting water column (mixed/stratified) and seabed (cohesive/non-cohesive) characteristics.

Description: Global mean and eddy fields from a four-year experiment with a 1/6° × 1/5° horizontal resolution implementation of the CME North Atlantic model are presented. The time-averaged wind-driven and thermohaline circulation in the model is compared to the results of a 1/3° × 2/5° model run in very similar configuration. In general, the higher resolution results are found to confirm that the resolution of previous CME experiments is sufficient to describe many features of the large-scale circulation and water mass distribution quite well. While the increased resolution does not lead to large changes in the mean flow patterns, the variability in the model is enhanced significantly. On the other hand, however, not all aspects of the circulation have improved with resolution. The Azores Current Frontal Zone with its variability in the eastern basin is still represented very poorly. Particular attention is also directed toward the unrealistic stationary anticyclones north of Cape Hatteras and in the Gulf of Mexico.

Description: To avoid an explicit simulation of the overflows across the Greenland-Scotland ridge, many models of the large-scale ocean circulation seek to include the net effect of the inflowing dense water masses by restoring temperature and salinity near the ridge to observed conditions. In this paper the authors examine the effect of different datasets for the northern restoring condition in two versions, eddy resolving and non-eddy resolving, of the model of the North and equatorial Atlantic that has been developed in recent years as a Community Modeling Effort for WOCE. It is shown that the use of smoothed climatological fields of temperature and salinity south of the Denmark Strait leads to strong deficiencies in the simulation of the deep flow field in the basin. A switch to actual hydrographic data from the Denmark Strait ignites a rapid dynamic response throughout the North Atlantic, affecting the transport and vertical structure of the deep western boundary current and, by virtue of the JEBAR efffect, the transport of the horizontal gyres. Meridional overturning and northward heat transport too weak in the cases with climatological boundary conditions, increase to more realistic levels in the subtropical North Atlantic. The initial response to switches in the high-latitude thermohaline forcing is mediated by fast waves along the westurn boundary, leading to changes in the deep western boundary current in low latitudes after about two years in the non-eddy-resolving cast. The initial timescale depends on the horizontal grid spacing of the model; in the high-resolution case, the first signal reaches the equator in a few months. The adjustment to a new, dynamic quasi equilibrium involves Kelvin waves along the equator and Rossby wave in the interior and is attained in less than two decades throughout the North Atlantic. It is suggested that these fast dynamic adjustment processes could play an important role in possible fluctuations of the thermohaline circulation, or transitions between different equilibrium states of the coupled ocean–atmosphere system, and may have determined the timescale of the observed climatic transitions before and during the last deglaciation.

Description: RNA/DNA ratios in individual herring (Clupea harengus) larvae (collected from Kiel Bay, Baltic Sea, in 1989) were measured and proved suitable for determining nutritional status. Significant differences between fed and starving larvae appeared after 3 to 4 d of food deprivation in larvae older than 10 d after hatching. The RNA/DNA ratio showed an increase with age or length of the larvae and was less pronounced in starving larvae compared to fed larvae. The individual variability of RNA/DNA ratios in relation to larval length of fed larvae and of larvae deprived of food for intervals of 6 to 9 d is presented. Based on the length dependency and the individual variability found within the RNA/DNA ratios, a laboratory calibration is given to determine whether a larva caught in the field has been starving or not. An example for a field application is shown.

Description: We have investigated the seasonal cycle and the interannual variability of the tropical Indian Ocean circulation and the Indian summer monsoon simulated by a coupled ocean-atmosphere general circulation model in a 26- year integration. Although the model exhibits significant climate drift, overall, the coupled GCM simulates realistically the seasonal changes in the tropical Indian Ocean and the onset and evolution of the Indian summer monsoon. The amplitudes of the seasonal changes, however, are underestimated. The coupled GCM also simulates considerable interannual variability in the tropical Indian Ocean circulation, which is partly related to the El Niño/Southern Oscillation phenomenon and the associated changes in the Walker circulation. Changes in the surface wind stress appear to be crucial in forcing interannual variations in the Indian Ocean SST. As in the Pacific Ocean, the net surface beat flux acts as a negative feedback on the SST anomalies. The interannual variability in monsoon rainfall, simulated by the coupled GCM, is only about half as strong as observed. The reason for this is that the simulated interannual variability in the Indian monsoon appears to be related to internal processes within the atmosphere only. In contrast, an investigation based on observations shows a clear lead-lag relationship between interannual variations in the monsoon rainfall and tropical Pacific SST anomalies. Furthermore, the atmospheric GCM also fails to reproduce this lead-lag relationship between monsoon rainfall and tropical Pacific SST when run in a stand-alone integration with observed SSTs prescribed during the period 1970–1988. These results indicate that important physical processes relating tropical Pacific SST to Indian monsoon rainfall are not adequately modeled in our atmospheric GCM. Monsoon rainfall predictions appear therefore premature.

Description: The cause of decadal climate variability over the North Pacific Ocean and North America is investigated by the analysis of data from a multidecadal integration with a state-of-the-art coupled ocean-atmosphere model and observations. About one-third of the low-frequency climate variability in the region of interest can be attributed to a cycle involving unstable air-sea interactions between the subtropical gyre circulation in the North Pacific and the Aleutian low-pressure system. The existence of this cycle provides a basis for long-range climate forecasting over the western United States at decadal time scales.

Description: A hierarchy of ENSO (El Niño/Southern Oscillation) prediction schemes has been developed which includes statistical schemes and physical models. The statistical models are, in general, based on advanced statistical techniques and can be classified into models which use either low-frequency variations in the atmosphere (sea level pressure or surface wind) or upper ocean heat content as predictors. The physical models consist of coupled ocean-atmosphere models of varying degrees of complexity, ranging from simplified coupled models of the lsquoshallow waterrsquo-type to coupled general circulation models. All models, statistical and physical, perform considerably better than the persistence forecast on predicting typical indices of ENSO on lead times of 6 to 12 months. The most successful prediction schemes, the fully physical coupled ocean-atmosphere models, show significant prediction abilities at lead times exceeding one year period. We therefore conclude that ENSO is predictable at least one year in advance. However, all of this applies to gross indices of ENSO such as the Southern Oscillation Index. Despite the demonstrated predictability, little is known about the predictability of specific features known to be associated with ENSO (e.g. Indian Monsoon rainfall, Southern African drought, or even off-equatorial sea surface temperature). Nor has the relative importance for prediction of different regional anomalies or different physical processes yet been established. A seasonal dependence in predictability is well established, but the processes responsible for it are not fully understood.

Description: The Cenozoic margins of the Norwegian-Greenland Sea offer ideal conditions for passive margin studies. A series of structural elements, first observed on these margins, led to the concept of volcanic passive margins. Questions still remain about the development of such features and the location of the boundary between oceanic and continental crust. Despite the thin sediment cover of the margins, seismic reflection data are not able to image the deeper structures due to the occurrence of igneous rocks at shallow depth. This paper presents a 320-km long profile perpendicular to the strike of the main structural units of the Lofoten Margin in Northern Norway. A geological model is proposed, based on observations made with ocean bottom seismographs, which recorded seismic refraction data and wide angle reflections, along with a seismic reflection profile covering the same area. Ray-tracing was used to calculate a geophysical model from the shelf area into the Lofoten basin. The structures typical of a volcanic passive margin were found, showing that the Lofoten Margin was influenced by increased volcanic activity during its evolution. The ocean/continent transition is located in a 30-km wide zone landwards of the Vøring Plateau escarpment. The whole margin is underlain by a possibly underplated, high velocity layer. Evidence for a pre-rift sediment basin landwards of the escarpment, overlain by basalt flows, was seen. These structural features, related to extensive volcanism on the Lofoten Margin, are not as distinct as further south along the Norwegian Margin. Viewed in the light of the hot-spot theory of White and McKenzie (1989) the Lofoten Margin can be interpreted as a transitional type between volcanic and non-volcanic passive margin.

Description: Based on a combined data set of sea surface temperature, zonal surface wind stress and upper ocean heat content the dynamics of the El Niño phenomenon is investigated. In a reduced phase space spanned by the first four EOFs two different stochastic models are estimated from the data. A nonlinear model represented by a simulated neural network is compared with a linear model obtained with the principal oscillation pattern (POP) analysis. While the linear model is limited to damped oscillations onto a fix point attractor, the nonlinear model recovers a limit cycle attractor. This indicates that the real system is located above the bifurcation point in parameter space supporting self-sustained oscillations. The results are discussed with respect to consistency with current theory.

Description: The annual cycle of meridional heat transport in the North and equatorial Atlantic Ocean is studied by means of the high-resolution numerical model that had been developed in recent years as a Community Modeling Effort for the World Ocean Circulation Experiment. Similar to previous model studies, there is a winter maximum in northward heat transport in the equatorial Atlantic and a summer maximum in midlatitudes. The seasonal variation in heat transport in the equatorial Atlantic, with a maximum near 8°N, is associated with the out-of-phase changes in heat content to the north and south of that latitude in connection with the seasonal reversal of the North Equatorial Countercurrent. The amplitude of the heat transport variation at 8°N depends on model resolution: forcing with the monthly mean wind stresses of Hellerman–Rosenstein (HR) gives an annual range of 2.1 PW in the case of a 1/3° meridional grid, and 1.7 PW in the case of a 1° grid, compared to 1.4 PW in a previous 2° model. Forcing with the wind stresses of Isemer–Hasse (IH) gives 2.5 PW in the 1/3° and 2.2 PW in the 1° model case. The annual range of heat transport in the subtropical North Atlantic is much less dependent on resolution but sensitive to the wind stress: it increases from 0.5 PW in the case of HR forcing to almost 0.8 PW with IH forcing. The annual cycle of heat transport can be understood in terms of wind-driven variations in the meridional overturning; variations in horizontal gyre transport have only little effect both in the equatorial and in the subtropical Atlantic. In all model solutions the seasonal variations in the near-surface meridional Ekman transport are associated with deep seasonal overturning cells. The weak shear of the deep response suggests that the large variations in heat transport on seasonal and shorter time scales should be of little consequence for observational estimates of mean oceanic heat transports relying on one-time hydrographic surveys.

Description: Energy requirements of resting Adélie (Pygoscelis adeliae), Gentoo (P. papua) and Chinstrap (P. antarcticd) penguin chicks were determined with respect to body mass via respirometry in Antarctica. Resting metabolic rates of all Pygoscelid penguin chicks were similar (ANOVA p=0.91) and best described by E=0.0096 M0.98 (n=24, r2=0.97), where E is power (W) and M is mass (g). Using the results obtained here and data published in the literature, I determined a) the amount of food needed from hatching to fledging as 29.8, 31.7 and 56.4 kg per chick for Adélie, Chinstrap and Gentoo penguins, respectively and b) the average amount of food left daily to the parent after feeding the brood throughout the breeding period. Parents keep only a minimum of food for themselves just prior to the time when chicks begin forming crèches. Thereafter, nest relief intervals are increased, and the amount of food parents can keep for themselves rises. The results of both models are discussed with respect to available data on Pygoscelid penguin food requirements.

Description: Multiple opening-closing nets of 0.05 mm mesh size were employed to study the community structure and vertical distribution of microcopepods at selected stations in the Red Sea, Arabian Sea and Eastern Mediterranean Sea down to a maximum depth of 1850 m. Calanoids, cyclopoids (Oithona and Paroithona) and poecilostomatoids (mainly Oncaea) were the 3 most abundant orders. In the epipelagic zone (0–100 m), these orders occurred at similar abundance levels, whereas in the meso- and bathypelagic zones the poecilostomatoid genus Oncaea dominated numerically by about 60–80% of all copepodids. The species diversity of Oncaea in the Red Sea is compared with preliminary results from the two adjacent regions. In the deep Eastern Mediterranean Sea, the number of species appears to be similar to that in the deep Red Sea and low as compared to the deep Arabian Sea. In this latter area an extremely speciose Oncaea fauna was found at depth below the oxygen-minimum-zone (900–1850 m). The results are related to the differences in the hydrographic conditions of these 3 areas.

Description: Many researchers use external recording or transmitting devices to elucidate the marine ecology of fish, mammals and birds. Deleterious effects of these instruments on the parameters researchers wish to measure are hardly ever discussed in the literature. Research has shown that, in penguins, volume and cross-sectional area of instruments negatively correlate with swimming speed. dive depth and breeding success, and that device colour affects bird behaviour. Here, a large (200 g, cross-sectional area 2100 mm2) streamlined device was attached to the lower back of Adélie penguins (Pygoscelis adeliae on Ardley Island, South Shetland Island in 1992) and its effects on bird swimming speed and energetics were measured in a water canal in Antarctica. Although the device was 10.5% of penguin cross-sectional area, swimming speed was reduced by only 8.3% and mean power input increased by only 5.6% while swimming. Although our streamlined device was five times more voluminous than one of our older units, the effect on swimming energetics could be reduced by 87%.

Description: Cicosal sea surface height (SSH) data in the tropical and midlatitude North Atlantic are analyzed with and without water vapor (WV) correction to study the WV influence on along-track SSH anomaly profits, mesoscale SSH variability, wavenumber spectra, and objectively mapped fields of SSH anomaly. Three different WV datasets were used, one from the Fleet Numerical Oceanographic Center (FNOC) model and two from the Special Sensor Microwave/Imager (SSM/I) based on different WV retrieval algorithms. These WV dataset show significant differences, in particular in the tropics. However, the method for deriving SSH anomalies from altimeter height data Alters out much of the WV corrections. The residual WV effect on SSH anomaly is shown to be most significant in the seasonally migrating intertropical convergence zone of the tropical Atlantic: there the SSM/I corrections reduce the along-track mesoscale SSH variability by typically 1–1.5 cm. On seasonal timescales the maximum WV effect in this region is characterized by a 2–3-cm rms difference between SSH anomaly with and without SSM/I WV corrections, whereas FNOC corrections have almost no effect. Inferred seasonal velocity variations in the North Equatorial Countercurrent core (4° – 6°N) in the region of maximum WY influence (30° – 40°W) are reduced by about 20% and 30%, depending on whether SSM/I corrections by Emery or Wentz are used

Description: We reconstructed past variations in CO2 partial pressure (local PCO2) in the surface waters of the East Atlantic equatorial upwelling zone over the last 330,000 years, based on the δ13C record of the (marine) organic matter in ‘Meteor’ core 16772. To deduce the initial δ13Corganic values of plankton and the CO2 solubility in surface water, the δ13C record was adjusted for i) past variations in (winter) sea surface temperature, ii) variations in the δ13C composition of inorganic carbon dissolved in the surface waters, using the δ13C values of G. ruber (white), and iii) isotopic fractionation during the degradation of settling organic matter in the water column and on the sediment surface. The calculated paleo-PCO2 variations in the surface waters show a strong signal at the obliquity frequency and are approximately parallel to the VOSTOK ice-core record of atmospheric PCO2 over the last 140,000 years. Holocene PCO2 values varied within the range of modern local PCO2, which is 350–400 ppmv compared to a pre-industrial atmospheric pCO2 level of 280 ppmv. This positive anomaly demonstrates the persistent CO2 release from upwelled subsurface water. The glacial-to-interglacial amplitudes of local PCO2 (at the core site) exceeded those of atmospheric pCO2 by 20–60%, with values of less than 250 to 300 ppmv during cold isotopic stages, which indicate a decreased net carbon outgassing from the ocean to the atmosphere. The close correlation between high paleo-PCO2 and low paleo-nutrient contents and paleoproductivity (r=0.7–0.8) suggests that the local PCO2 variations resulted mainly from CO2 transfer by phytoplankton production, especially over the last 170,000 years.

Description: Vesteris Seamount is a solitary submarine volcano located at 73-degrees-30' N, 9-degrees-10' W in the Greenland Basin. Steeply rising from a base depth of 3100 m to a minimum depth of approximately 130 m and striking 030-degrees/210-degrees, the feature lies approximately 300 km east of the east Greenland margin on an otherwise nearly flat and featureless seafloor. The main body of the seamount appears to have been formed episodically, the last of which culminated about 110 000 years ago. Subsequent, lower intensity volcanic activity continued sporadically until about 25 000 years ago, as evidenced by ash layers found in cores near the base of the feature. The smoothed surfaces at the summit make it likely that the seamount actually broached the surface during the Weichselian glacial period, between 8000 and 13 000 years ago. Two multibeam bathymetric investigations aboard PFS Polarstern during ARKTIS II/4 (1984) and ARKTIS VII/1 (1990), combined with geologic sampling. single-channel seismic profiling and underwater television coverage, have resulted in a new interpretation of both the morphology and origins of the seamount. Data collected aboard Polarstern from ARKTIS II/4 (1984) have been previously reported by Hempel et al. (1991), however, when combined with the ARKTIS VII/1 (1990) data set, a more detailed interpretation of the morphology and structure was feasible. This included the elongated shape of the feature and showed the existence of several small volcanic cones on the seamount flanks.

Description: Standing stock and size composition of the zooplankton comunity (〉100 μm) were studied in four depth strata of the upper 200 m of the water column during a “Meteor” cruise to the central Red Sea and Gulf of Aden in spring 1987. The central Red Sea was divided into a northern area of higher salinity and a less saline southern part. Both areas exhibited significant differences in zooplankton abundance and standing stock. The latter increased by the ratio 1:2:3 from the northern central Red Sea to its southern part and further south to the Gulf of Aden. For size structure analysis samples were fractionated into three size classes (100 to 300, 300 to 500, 500 to 5000 μm). In the central Red Sea the smallest size was dominant whereas in the Gulf of Aden the largest size fraction played a greater relative role than in the central Red Sea. This shift in size structure of the zooplankton community from the Red Sea to the Gulf of Aden is apparently primarily related to ecosystem difference between both areas, leading to a change in species composition. In addition, size reduction of individual species common to both seas may be of some significance in the extreme environment of the Red Sea.

Description: The application of microwave radiometry for rainfall estimation is discussed. The first part presents a description of processes by which hydrometeors affect microwave radiation. In order to show the state-of-art of rainfall estimation with space-borne microwave radiometry five algorithms are intercompared in the second part. Two are based on scattering, one on emission and two are mixed algorithms, which include both emission and scattering. The algorithms are applied to SSM/I observations over the Atlantic Ocean. The retrieved rainfall rates by the different algorithms partly differ a great deal. The differences depend on climatic regions, demonstrating that the algorithms are probably tuned to certain atmospheric conditions. The question arises whether a globally applicable algorithm is possible at all. A severe problem is the validation of the retrieved precipitation because hardly any direct observations are available. Thus an intercomparison of algorithms is today the only way to understand the behaviour of a scheme in different weather and climate situations and assess its results.

Description: In March/April 1991 hydrographic parameters (salinity, temperature) and hydrochemical parameters (concentrations of phosphate, nitrate, nitrite, ammonia, silicate and pH) were measured continuously in the surface water of the Baltic Sea and the North Sea. The hydrographic parameters were determined by means of a TS,pH probe and the chemical parameters were determined by means of an Auto Analyser. The cruise track through the Baltic Proper, the western Baltic Sea, the transition area to the North Sea and the North Sea with the mouth of the river Elbe was around 2050 nautical miles long and included some 2100 data-points. The different phases of the Baltic Sea's spring diatom bloom were inferred from the different nutrient concentrations measured; a comparison with the hydrographic data revealed that the bloom was largely unconnected to the hydrography. The same situation was encountered in the North Sea except that the spring bloom there had already reached a later phase. In those regions of the Baltic Sea where a plankton bloom had already occurred or was still under way, strong patchiness of the hydrochemical parameters was also observed; it was sometimes possible to relate it to the topography. This patchiness was far less pronounced in the North Sea and in regions of the Baltic Sea where conditions were still wintry. This paper discusses the advantages and possible applications of the method of continuous measurement of hydrochemical parameters across large areas with high temporal and spatial resolution.

Description: Observations of upper-ocean western boundary current (WBC) transports reveal asymmetries between the Northern and the Southern Hemispheres of the Atlantic Ocean. To find out what mechanism might cause these asymmetries the linearized steady-state vorticity equation is applied to the interior of a layer of constant thickness representing the upper Atlantic Ocean. WBC transports are then required to balance the interior volume flux deficit. The ocean is forced by climatological wind stress at the surface; thermohaline forcing is introduced by vertical motion at the lower boundary. A series of model runs using selected combinations of different basin geometries, wind stress fields, and thermohaline forcing patterns yields the following results: asymmetries of WBC transports cannot be explained by the topography shape of coastlines. The wind stress causes 12 Sv (Sv ≡ 1 × 106 m3 s −1) cross-equatorial transport to the north but it cannot account for the other WBC asymmetries. These can be explained by superimposing a thermohaline flow component to the wind-driven circulation. The best agreement with observations could be obtained from a model run driven by a sinking rate of 20 Sv in the northern North Atlantic and 4 Sv in the Weddell Sea compensated by 15 Sv return flow from other oceans via the Agulhas Current or Drake Passage and uniform upwelling of 9 Sv in the Atlantic. In tropical and subtropical latitudes this run reproduces all observed asymmetries, but in subpolar latitudes the model fails. Further conclusions can be drawn from the model results. (i) Up to 20 Sv northward transport of Antarctic Intermediate Water is needed at about 10°S to explain the difference of modeled transports and observations. For the same reasons an Antilles Current of up to 16 Sv is required. (ii) The major part of the northward heat transport in the North Atlantic has to occur via the tropical countercurrents and the North Equatorial Current. Only less than 7 Sv take the shortest way to the Caribbean via the Guyana Current. (iii) Fifty-six percent of the Florida Straits transport is wind driven.

Description: A method is presented to infer cloud liquid water path (LWP in kg/m2) over the ocean from passive microwave measurements of SSM/I. The algorithm to retrieve LWP is based on simulated satellite observations. They are calculated with a radiative transfer model applied to about 3000 radiosonde ascents over the Atlantic Ocean. Since radiosonde observations do not contain direct information about cloud water and ice, these parameters are parameterized based on relative humidity and temperature using modified adiabatic liquid water density profiles. A multiple linear regression is applied to the simulated radiances and the calculated LWP to derive the algorithm. The retrieval accuracy based on the regression analysis including instrumental noise is 0.03 kg/m2. Validation of the LWP-algorithm was pursued through a comparison with measurements of a ground-based 33 GHzmicrowave radiometer on board of R.V. “Poseidon” during the International Cirrus Experiment 1989 at the North Sea (ICE'89). The LWP values agree within the range of uncertainty caused by the different sampling characteristics of the observing systems. The retrieval accuracy for clear-sky cases determined using colocated METEOSAT data over the North Sea is 0.037 kg/m2 and confirms the accuracy estimated from regression analysis for the low liquid water cases. The algorithm was used to derive maps of monthly mean LWP over the Atlantic Ocean. As an example the Octobers of the 5 years 1987–1991 were selected to demonstrate the interannual variability of LWP. The results were compared with the cloud water content produced by the climate model ECHAM-T2 from the Max-Planck-Institut Hamburg. Observations during ICE'89 were used to check the accuracy of the applied radiative transfer model. Brightness temperatures were calculated from radiosonde ascents launched during the overpass of DMSP-F8 in cloud-free situations. The channel-dependent differences range from about −2 to 3 K. The possibility to identify different cloud types using microwave and infrared observations was examined. The main conclusion is that simultaneous microwave and infrared measurements enable the separation of dense cirrus and cirrus with underlying water clouds. A classification of clouds with respect to their top heights and LWP was carried out using a combination of SSM/I derived LWP and simultaneously recorded Meteosat IR-data during ICE'89.

Description: Accurate measurement of fluctuations in temperature and humidity are needed for determination of the surface evaporation rate and the air-sea sensible heat flux using either the eddy correlation or inertial dissipation method for flux calculations. These measurements are difficult to make over the ocean, and are subject to large errors when sensors are exposed to marine air containing spray droplets. All currently available commercial measurement devices for atmospheric humidity require frequent maintenance. Included in the objectives of the Humidity Exchange over the Sea program were testing and comparison of sensors used for measuring both the fluctuating and mean humidity in the marine atmosphere at high wind speeds and development of techniques for the protection of these sensors against contamination by oceanic aerosols. These sensors and droplet removal techniques are described and comparisons between measurements from several different systems are discussed in this paper. To accomplish these goals, participating groups devised and tested three methods of removing sea spray from the sample airstream. The best performance was given by a rotating semen device, the “spray Ringer.” Several high-frequency temperature and humidity instruments, based on different physical principles, were used in the collaborative field experiment. Temperature and humidity fluctuations were measured with sufficient accuracy inside the spray removal devices using Lyman-α hygrometers and a fast thermocouple psychrometer. Comparison of several types of psychrometers (using electric thermometers) and a Rotronic MP-100 humidity sensor for measuring the mean humidity illustrated the hysteresis of the Rotronic MP-100 device after periods of high relative humidity. Confidence in the readings of the electronic psychrometer was established by in situ calibration with repeated and careful readings of ordinary hand-held Assman psychrometers (based on mercury thermometers). Electronic psychrometer employing platinum resistance thermometers perform very well.

Description: Some species of wide-spread tropical squids and pelgic octopuses (Histioteuthis hoylei, Alloposus mollis and others), based on beak findings in sperm whale stomachs, were common in the 1950s and early 1960s and widely distributed along the Kuril' Islands, eastern Kamchatka, in the Bering Sea, near the Aleutian Islands and the Gulf of Alaska, but later they were never recorded north of northwastern Honshu or southeast of the southern Kuril's. In 1990-1992 the squid Watasenia scintillans extended north to the middle Kuril's and, in smaller quantities, to the northern Kuril's while H. hoylei extended to the western Bering Sea. In the summer of 1992, Ancistrocheirus lesueurii, Mastigoteuthis dentata?, Eledonella pygmaea, and Allopsus mollis were also caught off the Shikotan, Kunashir, and Iturup Islands. A. lesueurii and E. pygmaea were caught in the Russian EEZ for the first time. We discuss why the warm-water species appear in the Russian Far Eastern seas again, after a long period of absence.