Global Distribution of Tropical Deep Convection: Different Perspectives from TRMM Infrared and Radar Data

Abstract

Cold cloud features (CCFs) are defined by grouping six full years of Tropical Rainfall Measuring Mission (TRMM) infrared pixels with brightness temperature at 10.8-m wavelength (T B11 ) less than or equal to 210 and 235 K. Then the precipitation radar (PR)-observed precipitation area and reflectivity profiles inside CCFs are summarized and compared with the area and minimum temperature of the CCFs. Comparing the radar with the infrared data, significant regional differences are found, quantified, and used to describe regional differences in selected properties of deep convective systems in the Tropics. Inside 4 million CCFs, 35% (57%) of cold cloud area with T B11 Յ 235 K (210 K) have rain detected by the PR near the surface. Only ϳ1% of the area of T B11 Յ 210 K have 20 dBZ reaching 14 km. CCFs colder than 210 K occur most frequently over the west Pacific Ocean, but 20-dBZ echoes extending above 10 km in this region are disproportionately rare by comparison to many continental regions. Ratios of PR-detected raining area to area of T B11 Յ 235 K are higher over central Africa, Argentina, and India than over tropical oceans. After applying these ratios to the climatological Global Precipitation Index (GPI) tropical rainfall estimates, the regional distribution is more consistent with the rainfall retrieval from the PR. This suggests that the discrepancy between GPI-and PR-retrieved rainfall can be partly explained with the nonraining anvil. Categorization of CCFs based on the minimum T B11 , size of CCFs, and 20-dBZ heights demonstrates that 20-dBZ echoes above 17 km occur most frequently over land, while the coldest clouds occur most frequently over the west Pacific. The vertical distances between the cloud-top heights determined from T B11 and PR 20-dBZ echo-top heights are smaller over land than over ocean and may be considered as another proxy for convective intensity.

Observations of aerosol‐induced convective invigoration in the tropical east Atlantic

“…A majority of the DCCs analyzed are located in the lower latitudes and are associated with the Intertropical Convergence Zone. The locations of more frequent DCCs align well with what is shown in Liu et al [2007], although it should be noted that cloud fraction is not the variable shown here.…”

A daytime climatological distribution of high opaque ice cloud classes over the Indian summer monsoon region observed from 25-year AVHRR data

“…Radar and/or microwave measurements (e.g. Alcala and Dessler, 2002;Liu and Zipser, 2005;Houze Jr. et al, 2007;Liu et al, 2007;Hong et al, 2008) certainly add a new dimension to the remote sensing of convective systems, however the emphasis should be on the synthesis of measurements made at different spectral ranges and the synergistic use of them to exploit their strengths in improving our understanding of cloudprecipitation interactions.…”

Daily Indian Precipitation Analysis Formed from a Merge of Rain-Gauge Data with the TRMM TMPA Satellite-Derived Rainfall Estimates

“…A large-scale diurnal model of the Asian monsoon was also studied by TRMM data (Krishnamurti and Kisthwal 2000). At a much finer spatial scale, the TRMM PR data were used to study the characteristics and life cycle of the monsoon convection and rain in the northern Indian subcontinent and part of the Himalayas (Bhatt and Nakamura 2005;Houze et al 2007;Liu et al 2007). The hydrologic cycle for the tropics was also studied by TRMM data (Roads 2003).…”