Master's Theses

Date of Award

2015

Document Type

Thesis

Department

Earth and Atmospheric Sciences

First Advisor

Z. Johnny Luo

Keywords

Clouds, Resmore sensing, convection

Abstract

Clouds an important component of the earth-climate system and play a critical role in affecting energy and water cycle of the planet. In particular, tropical convective clouds account for the majority of the precipitation that fall on the Earth's surface. Multiple active satellite missions in recent decade such as TRMM (Tropical Rainfall Measurement Mission), and CloudSat have provided fruitful new insight into the internal structures of these tropical convective clouds. In conjunction with cloud data from ISCCP (International Satellite Cloud Climatology Project), that is based passive remote sensing technology in the visible and infrared spectrum, this allows for a more coherent understanding of the dynamic structure of tropical clouds.

In this study, we focus on the synergy between Cloudsat and TRRM radar reflectivity data in a CFAD (Contoured Frequency by Altitude Diagram) framework and apply a clustering analysis to identify distinct clusters. The properties of these clusters were also further analyzed with regards to their cloud top height and radar echo top height. In addition, they were compared with both the visible/infrared and infrared-only Weather States (WSs) from ISCCP.

Results show that there are four tropical clusters containing three precipitating cloud regimes and one non-precipitating cloud regime. Signatures of deep convection, cumulus congestus, and shallow precipitating clouds were identified in the three precipitating cloud clusters. Regions of shallow precipitating clouds are mostly associated with sinking air motion, while deep convective and congestus cloud regimes were present in regions of rising air motion. Comparison with collocated ISCCP WS data shows broad agreement, although that ISCCP tends to show lower frequency of convective cloud regimes and higher occurrence frequency of non-convective cloud regimes due to differences in remote sensing techniques and spectra used.

 
 

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