Aqua AMSR-E, MODIS, MESH, and MERRA-2 matched dataset

Potentially severe storm cases over CONUS are identified where the contiguous MESH95 local maxima exceeds 10 mm, spaced by at least 28 km², based on GridRad suite version 4.2 (Homeyer and Bowman 2021). Matched overpasses with Aqua are determined by the Langley Automated Sensor Inter-Calibration System (LASICS), enabling collocation of MESH cells, AMSR-E, and MODIS data within ±15 minutes (Gopalan et al. 2021). For each MESH cell observed, passive-microwave polarization corrected temperature (PCT)-defined features (PCTFs) are defined using a thresholding boundary of 200 K in the 89-GHz PCT. Using a 200 K 89-GHz PCT threshold isolates deeper convection, which is our focus of study (Mohr and Zipser 1996; Mohr et al. 1999; Cecil 2009). Summary characteristics (10-89 GHz PCT, areas, maxima and minima) are saved for each PCTF. From 2002 to 2011, we identified 45,157 MESH cells that were likely observed by Aqua. 12,062 of these are uniquely matched to an AMSR-E PCTF, using a +/-15 minute matching window and selecting the nearest MESH centroid within 35 km radius from the minimum 37-GHz PCT pixel.

Besides the PCTF characteristics, MODIS cloud-top parameters are extracted from the most extreme MODIS IR T_b – MERRA-2 tropopause temperature (IRMT) pixel within a 27-km square centered on each MESH cell centroid after parallax correction. For areal IR-derived metrics (e.g., frequency of prominent anvil pixels and area of cold cloud with IR T_b pixels below 225 K), the 27-km square is centered on the most extreme IRMT pixel that is assigned to each MESH cell. 

Lastly, following the method of Murillo et al. (2021), Fisher’s linear discriminant analysis (LDA; Wilks 2019) is applied to each MESH cell using MERRA-2 total precipitable water (TPW) and 0-6 km wind shear to flag probable MESH false alarms, which tend to occur in high TPW and low shear environments (Murillo et al. 2021). These steps result in 2,845 storms satisfying the MESH, PCTF, and OT criteria.