An Assessment of Detecting Mesoscale Rainfall From Mid-Latitude Cyclones Using GOES Imagery Data

摘要

This study examined the capability of current geostationary satellite sensors in resolving and monitoring important mesoscale rain areas. Shallow mesoscale precipitation patterns were analyzed with radar and recording rain gage data associated with mid-latitude cyclones in New England. These cyclones were characterized by relatively little stratiform cloudiness in the upper troposphere. Radar thresholding was used to determine the spatial and temporal scales of small mesoscale areas (SMSAs), large mesoscale areas (LMSAs), and major echoes. Radar rainfall estimates were used to determine the relative amount of rainfall contributed by the mesoscale features. Radar analysis of the three cases showed that the spatial scale of major echoes, LMSAs, and SMSAs were large enough for detection by GOES sensors. Major echoes and the LMSAs contained within them were found to have lifetimes that are long relative to the half-hour interval between GOES transmissions. The duration of some SMSAs and all cells, however, was on the same order as the time interval between GOES transmissions. In addition, radar rainfall estimates showed that the major echoes, LMSAs, and SMSAs were the major contributors to mesoscale rainfall. For the cases examined in this study, GOES sensors were not capable of distinguishing the individual mesoscale precipitation areas detected by radar. Therefore, GOES sensors do not appear adequate for developing satellite rainfall estimation techniques to specify shallow mesoscale precipitation.