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1.
E-BOOK
Demystifying Climate Models : A Users Guide to Earth System Models (2016)
Berlin, Heidelberg, New York, London : SpringerOpen
Keywords: Civil engineering ; Climate change management
Notes: This book demystifies the models we use to simulate present and future climates, allowing readers to better understand how to use climate model results. In order to predict the future trajectory of the Earth’s climate, climate-system simulation models are necessary. When and how do we trust climate model predictions? The book offers a framework for answering this question. It provides readers with a basic primer on climate and climate change, and offers non-technical explanations for how climate models are constructed, why they are uncertain, and what level of confidence we should place in them. It presents current results and the key uncertainties concerning them. Uncertainty is not a weakness but understanding uncertainty is a strength and a key part of using any model, including climate models. Case studies of how climate model output has been used and how it might be used in the future are provided. The ultimate goal of this book is to promote a better understanding of the structure and uncertainties of climate models among users, including scientists, engineers and policymakers.
Pages: XVII, 274 S., 4 schwarz-weiß Abbildungen, 58 Farbabbildungen
ISBN: 978-3-662-48957-4
2.
NASA TECHNICAL REPORTS
Development of Two-Moment Cloud Microphysics for Liquid and Ice Within the NASA Goddard Earth Observing System Model (GEOS-5) (2013)
CASI
Publication Date: 2015-01-12
Description: This work presents the development of a two-moment cloud microphysics scheme within the version 5 of the NASA Goddard Earth Observing System (GEOS-5). The scheme includes the implementation of a comprehensive stratiform microphysics module, a new cloud coverage scheme that allows ice supersaturation and a new microphysics module embedded within the moist convection parameterization of GEOS-5. Comprehensive physically-based descriptions of ice nucleation, including homogeneous and heterogeneous freezing, and liquid droplet activation are implemented to describe the formation of cloud particles in stratiform clouds and convective cumulus. The effect of preexisting ice crystals on the formation of cirrus clouds is also accounted for. A new parameterization of the subgrid scale vertical velocity distribution accounting for turbulence and gravity wave motion is developed. The implementation of the new microphysics significantly improves the representation of liquid water and ice in GEOS-5. Evaluation of the model shows agreement of the simulated droplet and ice crystal effective and volumetric radius with satellite retrievals and in situ observations. The simulated global distribution of supersaturation is also in agreement with observations. It was found that when using the new microphysics the fraction of condensate that remains as liquid follows a sigmoidal increase with temperature which differs from the linear increase assumed in most models and is in better agreement with available observations. The performance of the new microphysics in reproducing the observed total cloud fraction, longwave and shortwave cloud forcing, and total precipitation is similar to the operational version of GEOS-5 and in agreement with satellite retrievals. However the new microphysics tends to underestimate the coverage of persistent low level stratocumulus. Sensitivity studies showed that the simulated cloud properties are robust to moderate variation in cloud microphysical parameters. However significant sensitivity in ice cloud properties was found to variation in the dispersion of the ice crystal size distribution and the critical size for ice autoconversion. The implementation of the new microphysics leads to a more realistic representation of cloud processes in GEOS-5 and allows the linkage of cloud properties to aerosol emissions.
Keywords: Geosciences (General)
Type: GSFC-E-DAA-TN11166
Format: application/pdf
3.
NASA TECHNICAL REPORTS
Publication Date: 2014-03-09
Description: Several different ice nucleation parameterizations in two different General Circulation Models (GCMs) are used to understand the effects of ice nucleation on the mean climate state, and the Aerosol Indirect Effects (AIE) of cirrus clouds on climate. Simulations have a range of ice microphysical states that are consistent with the spread of observations, but many simulations have higher present-day ice crystal number concentrations than in-situ observations. These different states result from different parameterizations of ice cloud nucleation processes, and feature different balances of homogeneous and heterogeneous nucleation. Black carbon aerosols have a small (0.06 Wm(exp-2) and not statistically significant AIE when included as ice nuclei, for nucleation efficiencies within the range of laboratory measurements. Indirect effects of anthropogenic aerosols on cirrus clouds occur as a consequence of increasing anthropogenic sulfur emissions with different mechanisms important in different models. In one model this is due to increases in homogeneous nucleation fraction, and in the other due to increases in heterogeneous nucleation with coated dust. The magnitude of the effect is the same however. The resulting ice AIE does not seem strongly dependent on the balance between homogeneous and heterogeneous ice nucleation. Regional effects can reach several Wm2. Indirect effects are slightly larger for those states with less homogeneous nucleation and lower ice number concentration in the base state. The total ice AIE is estimated at 0.27 +/- 0.10 Wm(exp-2) (1 sigma uncertainty). This represents a 20% offset of the simulated total shortwave AIE for ice and liquid clouds of 1.6 Wm(sup-2).
Keywords: Meteorology and Climatology
Type: GSFC-E-DAA-TN8104, Journal of Geophysical Research; Volume 112; Issue D20, 27
Format: application/pdf
4.
NASA TECHNICAL REPORTS
Sensitivity Studies of Dust Ice Nuclei Effect on Cirrus Clouds with the Community Atmosphere Model CAM5 (2012)
CASI
Publication Date: 2014-03-09
Description: In this study the effect of dust aerosol on upper tropospheric cirrus clouds through heterogeneous ice nucleation is investigated in the Community Atmospheric Model version 5 (CAM5) with two ice nucleation parameterizations. Both parameterizations consider homogeneous and heterogeneous nucleation and the competition between the two mechanisms in cirrus clouds, but differ significantly in the number concentration of heterogeneous ice nuclei (IN) from dust. Heterogeneous nucleation on dust aerosol reduces the occurrence frequency of homogeneous nucleation and thus the ice crystal number concentration in the Northern Hemisphere (NH) cirrus clouds compared to simulations with pure homogeneous nucleation. Global and annual mean shortwave and longwave cloud forcing are reduced by up to 2.0+/-0.1Wm (sup2) (1 uncertainty) and 2.4+/-0.1Wm (sup2), respectively due to the presence of dust IN, with the net cloud forcing change of 0.40+/-0.20W m(sup2). Comparison of model simulations with in situ aircraft data obtained in NH mid-latitudes suggests that homogeneous ice nucleation may play an important role in the ice nucleation at these regions with temperatures of 205-230 K. However, simulations overestimate observed ice crystal number concentrations in the tropical tropopause regions with temperatures of 190- 205 K, and overestimate the frequency of occurrence of high ice crystal number concentration (greater than 200 L(sup-1) and underestimate the frequency of low ice crystal number concentration (less than 30 L(sup-1) at NH mid-latitudes. These results highlight the importance of quantifying the number concentrations and properties of heterogeneous IN (including dust aerosol) in the upper troposphere from the global perspective.
Keywords: Geophysics
Type: GSFC-E-DAA-TN8100, Atmospheric Chemistry and Physics; Volume 12; 12061-12079
Format: application/pdf
5.
NASA TECHNICAL REPORTS
A Multi-Sensor Perspective on the Interannual Variability of Tropical Temperature, Water Vapor, and Clouds (2010)
Other Sources
Publication Date: 2011-11-08
Description: The motivation for this work is to better characterize the controls on the tropical upper tropospheric/lower stratospheric (UTLS) temperature and humidity.
Keywords: Meteorology and Climatology
Type: American Geophysical Union Fall Meeting; 17 Dec. 2010; San Francisco, CA; United States
Format: text
6.
NASA TECHNICAL REPORTS
A Multi-Sensor Perspective on the Interannual Variable of Tropical Temperature and Water Vapor (2010)
Other Sources
Publication Date: 2011-11-08
Description: The motivation for this study was to better characterize the controls on the tropical upper tropospheric/lower stratospheric (UTLS) temperature and humidity.
Keywords: Meteorology and Climatology
Type: A-Train Symposium; 27 Oct. 2010; New Orleans, LA; United States
Format: text
7.
Paper (German National Licenses)
Simulation of the effect of doubled atmospheric CO2 on the climate of northern and central California (1995)
Springer
Climatic change 30 (1995), S. 295-325 
ISSN: 1573-1480
Source: Springer Online Journal Archives 1860-2000
Topics: Geosciences , Physics
Notes: Abstract A Local Climate Model (LCM) is described that can provide a high-resolution (10 km) simulation of climate resulting from a doubling of atmospheric CO2 concentrations. A canonicalregression function is used to compute the monthly temperature (mean of daily-maximum-temperature) and precipitation for any point, given a set of predictor variables. Predictor variables represent the influence of terrain, sea-surface temperature (SST), windfields, CO2 concentration, and solar radiation on climate. The canonical-regression function is calibrated and validated using empirical windfield, SST, and climate data from stations in the western U.S. To illustrate an application of the LCM, the climate of northern and central California is simulated for a doubled CO2 (600 ppmv) and a control scenario (300 ppmv CO2). Windfields and SSTs used to compute predictor variables are taken from general circulation model simulations for these two scenarios. LCM solutions indicate that doubling CO2 will result in a 3 C° increase in January temperature, a 2 C° increase in July temperature, a 16 mm (37%) increase in January precipitation, and a 3 mm (46%) increase in July precipitation.
Type of Medium: Electronic Resource
8.
PAPER (OA)
Overview of IGAC/SPARC Chemistry-Climate Model Initiative (CCMI) Community Simulations in Support of Upcoming Ozone and Climate Assessments (2013)
SPARC Newsletter, 40 (Januar). pp. 48-66.
Publication Date: 2016-06-20
Repository Name: Oceanrep Geomar
Type: Article, NonPeerReviewed
Format: text
9.
PAPER CURRENT
Publication Date: 2000-01-01
Print ISSN: 0022-4928
Electronic ISSN: 1520-0469
Topics: Geography , Geosciences , Physics
10.
PAPER CURRENT
A modeling study of the effects of aerosols on clouds and precipitation over East Asia (2011)
Springer Science + Business Media
Publication Date: 2011-12-01
Description: The National Center for Atmospheric Research Community Atmosphere Model (version 3.5) coupled with the Morrison–Gettelman two-moment cloud microphysics scheme is employed to simulate the aerosol effects on clouds and precipitation in two numerical experiments, one representing present-day conditions (year 2000) and the other the pre-industrial conditions (year 1750) over East Asia by considering both direct and indirect aerosol effects. To isolate the aerosol effects, we used the same set of boundary conditions and only altered the aerosol emissions in both experiments. The simulated results show that the cloud microphysical properties are markedly affected by the increase in aerosols, especially for the column cloud droplet number concentration (DNC), liquid water path (LWP), and the cloud droplet effective radius (DER). With increased aerosols, DNC and LWP have been increased by 137% and 28%, respectively, while DER is reduced by 20%. Precipitation rates in East Asia and East China are reduced by 5.8% and 13%, respectively, by both the aerosol’s second indirect effect and the radiative forcing that enhanced atmospheric stability associated with the aerosol direct and first indirect effects. The significant reduction in summer precipitation in East Asia is also consistent with the weakening of the East Asian summer monsoon, resulting from the decreasing thermodynamic contrast between the Asian landmass and the surrounding oceans induced by the aerosol’s radiative effects. The increase in aerosols reduces the surface net shortwave radiative flux over the East Asia landmass, which leads to the reduction of the land surface temperature. With minimal changes in the sea surface temperature, hence, the weakening of the East Asian summer monsoon further enhances the reduction of summer precipitation over East Asia. ©2011 Springer-Verlag
Print ISSN: 0177-798X
Electronic ISSN: 1434-4483
Topics: Geosciences , Physics