Equilibrium climate modeling with a one dimensional coupled atmosphere-ocean model

December 1987.Includes bibliographical references.Sponsored by NSF ATM-8415127

On the properties of cirrus clouds over the tropical West Pacific

June 2002.Includes bibliographical references.Sponsored by DOE/ARM DE-FG03-94ER61748.Sponsored by DOE/ARM DE-FG03-98ER62569

Microwave remote sensing algorithms for cirrus clouds and precipitation

Sponsored by NASA NAG-5-1592S

Polarized radiative transfer modeling: an application to microwave remote sensing of precipitation

April 1990.Includes bibliographical references.Sponsored by NASA NAG8-643

Theoretical and observational comparison of cirrus cloud radiative properties, A

August 1989.Includes bibliographical references.Sponsored by NSF ATM-8812353.Sponsored by NSF ATM-8519160.Sponsored by DOD AFOSR-88-0143.Sponsored by ONR N00014-87-K-0228/P00001

Evaluation of International Satellite Cloud Climatology Project (ISCCP) D2 cloud amount changes and their connections to large-scale dynamics

August 2005.Includes bibliographical references (pages 88-91).The International Satellite Cloud Climatology Project (ISCCP) D2 dataset exhibits a 2.6% per decade decrease in the global all-cloud cloud amount from July 1983 through September 2001. This result is consistent with other recent findings that provide evidence that the cloud amount has decreased on a decadal-scale. Such changes in cloud amount should have an obvious impact on the climate system through changes in heating and the radiation budget of the atmosphere. However, the changes evident in the ISCCP data seem too large to be accepted without question. Because these data are used as a verification tool for the global climate modeling community, it is imperative that the nature of these changes are better understood and verified for similarities with other data sources. Otherwise, climate studies might be comparing their results with faulty information. This study represents an attempt to characterize and verify the ISCCP D2 cloud amount changes. One possible reason why the ISCCP D2 trend might be too large is the presence of artifacts in the data related to changes in the number of geosynchronous satellites in orbit. This leads to changes in the viewing angle for each pixel in the dataset and explains roughly one-third of the trend in the global cloud amount. In order to account for this phenomenon, this study focuses on the region from 90°E to 180° and 30°N to 30°S where the satellite coverage has been relatively constant. It is shown that the slope of the cloud amount change in this region is still very large. This leaves open the possibility that there is other contamination in the ISCCP data, and calls into question the validity of the large cloud amount trend. Several steps are taken to examine the nature of the cloud amount changes in this region. First of all, the changes in the ISCCP cloud amount data are characterized by three criteria: where and when the changes are occurring and the types of clouds expressing them. These patterns are examined for features that appear physically reasonable. These patterns can then be checked against patterns obtained from the NOAA Interpolated OLR and PATMOS-A cloud amount datasets. These data, from sensors mounted on polar-orbiting satellites, do not experience the viewing-angle problem of ISCCP but should still corroborate evidence of real cloud amount changes. The most unique aspect of this study is the use of reanalysis data to look for signals of climate change that are related to changes in the ISCCP cloud amount data. The average ISCCP all-cloud cloud amount for the region of interest is regressed onto wind fields, geopotential height fields, divergence fields, and other data that represent how the climate has changed over the span of the ISCCP dataset. Maps of regression coefficients represent how those fields change in response to a unit increase in cloud amount. These patterns help to identify atmospheric phenomena that are connected with variations in cloud amount in the region of interest. Furthermore, the true cloud amount trend in the region of interest can be diagnosed by making time series of how well the regression maps project onto reanalysis fields at each time step. These "proxy cloud time series" represent how the true cloud amount must be changing to effect the observable changes in the reanalysis data. Both results provide a unique way to discover whether the ISCCP D2 cloud amount changes are also evident in other data sources. It is shown that the cloud amount changes evident in the ISCCP D2 dataset are indicative of changes in the intensity and location of convection associated with the Inter-Tropical Convergence Zone (ITCZ). The spatial patterns of these changes are somewhat consistent with the NOAA Interpolated OLR and PATMOS-A cloud amount datasets. However the trends in the regionally averaged time series of these data are not significantly different from zero. This supports the conclusion that the ISCCP trend is too large. Using data from the NCEPNCAR reanalysis and the ERA-40 reanalysis, it is shown that the changes in the ISCCP D2 cloud amount time series in the region of interest are highly correlated with changes in the Walker-Hadley circulation. The patterns of these changes are consistent with the redistribution of convection indicated by each of the satellite datasets, and appear to be associated with ENSO since they are also consistent with the results of Bjerknes (1969). The reanalysis data also provide independent confirmation that the actual cloud amount in the region of interest is likely not changing in a statistically significant way during the period spanned by the ISCCP D2 dataset. Therefore, while the variability of cloud amount due to ENS0 is evidently captured by the ISCCP D2 dataset, the long-term trend in the ISCCP cloud amount is likely not physically realistic.Research was supported by NASA Research grant NNG04GB97G and in part by a one-year AMS Graduate Fellowship

Absorption of solar radiation by heterogeneous atmospheres: a new approach to Monte Carlo modeling

February, 1998.Bibliography: pages [137]-141.Sponsored by Dept. of Energy DE-FG-03-94ER61748.Sponsored by Dept. of Energy DE-FG-03-95ER61985.Sponsored by Dept. of Energy DE-FG-03-97ER62357

Satellite microwave sensing of oceanic cloud liquid water: application to the earth radiation budget and climate

March 1995.Sponsored by NASA Graduate Student Fellowship in Global Change Research NGT-30046.Sponsored by NASA Research NAG-8-981.Sponsored by NOAA NA37RJ0202

On retrieving profiles of CO2 in the lower atmosphere using spectroscopy in the near and far infrared: a preliminary study

Includes bibliographical references.Sponsored by DOE/ARM DE0FG03-94ER61748.Sponsored by NOAA NA17RJ1228

Microwave brightness temperature and its relation to atmospheric general circulation features

August 1989.Includes bibliographical references.Sponsored by NSF ATM-8617856