Large-scale Characteristics of Tropical Convective Systems through the Prism of Cloud Regime.

We employ the Cloud Regime (CR) concept to identify large-scale tropical convective systems and investigate their characteristics in terms of organization and precipitation. The tropical CRs (TCRs) are derived from Moderate Resolution Imaging Spectroradiometer (MODIS) Cloud Optical Thickness (COT) and Cloud Top Pressure (CTP) two-dimensional joint histograms. We focus on the TCRs that have relatively low CTPs and high COTs, as well as heavy precipitation, namely TCR1 (convective core-dominant), TCR2 (various high clouds), and TCR3 (anvils). The horizontal size of aggregates of TCR1, 2, or 3 occurrences (TCR123) is identified as the number of contiguous 1°×1° grid cells occupied by either of these three TCRs. For the small to intermediate size aggregates (TCR123 size 20 to 160 one-degree grid cells), there is large variability in the fraction of the aggregate each TCR occupies, but generally TCR2 exhibits the highest fraction. As the total system size grows, the variability shrinks and for the largest systems ratios eventually converge to 0.3, 0.2, and 0.5 for TCR1, 2, and 3, respectively. The mean precipitation of convective core-rich TCR1 is generally high for the systems of intermediate size (80-160 one-degree grid cells), but with the highest mean coming from smaller systems of 20-40 grid cells. For the largest systems, their mean precipitation in areas containing cores (TCR1) are relatively low with suppressed variation. The mean precipitation rates of TCR2 and TCR3 in a TCR123 aggregate tend to be stronger when accompanying TCR1 mean precipitation rate is also high.