88th Annual Meeting (20-24 January 2008)

Tuesday, 22 January 2008: 11:45 AM
Using lightning and high resolution spaceborne precipitation products to monitor and understand North American Monsoon processes
222 (Ernest N. Morial Convention Center)
Stephen W. Nesbitt, University of Illinois, Urbana, IL; and N. J. Schiffer
In this study, we will demonstrate the utility of using operational Long Range Detection Network (LRDN) cloud-to-ground flash data, alongside GOES infrared brightness temperatures, high resolution precipitation products (such as PERSIANN, Hydroestimator, TRMM 3B42, and CMORPH), as well as Tropical Rainfall Measuring Mission Lightning Imaging Sensor (LIS) and Precipitation Radar (PR) measurements to quantify the characteristics of convection over the Sierra Madre Occidental in Mexico during the North American Monsoon. In particular, variations in the vigor and horizontal structure of monsoon convection as a function of elevation are found, as well as resultant variations in conditional rain rate that add up to the observed climatology of rainfall along the western slopes of the Sierra Madre Occidental.

In addition, intraseasonal variations in monsoon convection can be examined using the above datasets. Preliminary results show that the rainfall to lightning flash ratio (or rain yield) differs substantially with the onset of the monsoon in the region. Vertical reflectivity profiles from the precipitation radar will be examined to explain causal mechanisms for this shift in rainfall characteristics. We will also examine how convective characteristics change with synoptic and mesoscale meteorological forcing mechanisms known to modulate monsoon rainfall, including gulf surges, tropical easterly waves (TEWs), tropical upper tropospheric troughs (TUTTs), the intensity of the Gulf of California Low Level Jet (LLJ), and the position of the subtropical high pressure systems relative to the monsoon domain.

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