Evaluation of Radiometrics MP-3000A Computed Convective Indices

In support of NOAA/ATDD's Convective Initiation Program (CI) Summer 2014 Field Study, ATDD deployed its Radiometrics Microwave Profiler (MP-3000A) remote atmospheric sounding system at Auburn University's Belle Mina Research Station, Alabama. The primary measurement goal was to obtain daytime high temporal resolution atmospheric profiles of temperature and humidity which could be used to develop a high-resolution four-dimensional depiction of the lower atmospheric boundary layer for the Belle Mina region as well as provide a high-resolution boundary-layer sounding database for evaluation of NOAA's High Resolution Rapid Refresh (HRRR) model. ATDD installed the Microwave Profiler (MP) at its Belle Mina Research site for the period June 25, 2014 through October 10, 2014. Two sets of local radiosonde soundings (ATDD Belle Mina and Redstone Arsenal) were used to evaluate the performance of the MP-3000.

The focus of this paper is on the performance of the MP-3000A with respect to calculation of the Convective Available Potential Energy (CAPE) index. While other indices, such as Lifted Index (LI) or K Index, are discussed, ATDD's CI Program focused on CAPE as the primary indicator of potential for convective activity. Databases for both radiosondes and Radiometrics soundings were evaluated for CAPE.; this report primarily details the inter-comparison of calculated CAPE between the MP-3000A and acquired radiosondes profiles.

In general, while for the measurement intensive the mean difference in calculated CAPE between the two systems is roughly 1000 J/kg, there is similarity in temporal variation of CAPE across the measurement period. It's interesting to note that the same magnitude in the delta between radiosonde and radiometer exists across the evaluation period. As CAPE is an integrated measure of stability, the cold bias associated with the Radiometrics MP3000A measured temperature profile is reflected in the much larger calculated CAPE. Over the three day measurement intensive, the Radiometrics system indicated moderately unstable conditions while the acquired radiosondes only indicated a marginally unstable atmosphere.