Cloud Statistics and Radiative Properties in the Tropics

Focusing on two regions over the East and West Tropical Pacific, cloud properties and their temporally averaged distributions are studied. These distributions will better explain how clouds and tropical convection control the radiation balance, among other things, in this region. Previous work (Hartmann et. al. 1994) was able to show that radiative forcing in convective systems in the tropics, on average, tend to balance at or near zero. It was hypothesized that this is not mere coincidence but this balance is due to climate feedbacks that are not fully understood. One limitation to previous work was the inability to “see” lower cloud levels when there is extensive cloud cover aloft. A data set provided by CloudSat’s cloud profiling data (CPR) will aid in the acquisition of a more complete data set that will allow for more improved calculations throughout the entire column. The acquisition of this more complete data set will allow for a more detailed and more accurate description of clouds and their radiative influence. The scope of this problem has many origins. One of these limitations is the ineffectiveness of climate models to accurately predict the influence of clouds. Given the innate uncertainty associated with climate models, it is necessary to work toward reducing uncertainty within model parameterizations. Studies were conducted in two 20 X 20 regions over the East and West Pacific. Statistics were gathered using A-Train data from the regions of interest for various time averages. Data was compiled in accordance with the 42 cloud classifications set forth by ISCCP based on optical depth and cloud top pressure. The cloud properties are calculated using CloudSat’s cloud profiling radar (CPR) and accompanying A-Train instrumentation using a suite of research algorithms. Cloud type frequency as well as cloud property distributions are calculated over varying time averages for the regions of interest. Theses distributions are then organized as per the ISCCP cloud types. Analysis of this data reveal not only the cloud occurrence but also the importance of their structure and properties as it pertains to energy balance.