Observations of Atmospheric Temperature Structure from an Airborne Microwave Temperature Profiler

Abstract:

A newly-designed Microwave Temperature Profiler (MTP) was developed at JPL for the NSF-NCAR Gulfstream-V aircraft. The MTP is a scanning microwave radiometer that measures thermal emission in the 50-60 GHz oxygen complex. It scans from near-zenith to near-nadir, measuring brightness temperatures forward, above, and below the aircraft at 17 s intervals. A statistical retrieval method derives temperature profiles from the measurements, using proximate radiosonde profiles as a priori information. MTP data examples from recent experiments, comparisons with simultaneous temperature profiles from the Airborne Vertical Atmospheric Profiling System (AVAPS), and a method for blending MTP and AVAPS temperature profiles will be presented.

The Mesoscale Predictability Experiment (MPEX; May-June, 2013) investigated the utility of sub-synoptic observations to extend convective-scale predictability and otherwise enhance skill in regional numerical weather prediction over short forecast periods. This project relied on MTP and AVAPS profiles to characterize atmospheric structure on fine spatial scales. Comparison of MTP profiles with AVAPS profiles confirms uncertainty specifications of MTP. A profile blending process takes advantage of the high resolution of AVAPS profiles below the aircraft while utilizing MTP profiles above the aircraft. Ongoing research with these data sets examines double tropopause structure in association with the sub-tropical jet, mountain lee waves, and fluxes at the tropopause. The attached figure shows a mountain lee wave signature in the MTP-derived isentrope field along the flight track during an east-west segment over the Rocky Mountains. A vertically propagating wave with westward tilt is evident on the leeward side of the mountains at around 38 ksec.

The Deep Propagating Gravity Wave Experiment over New Zealand (DEEPWAVE; June-July, 2014) investigated the dynamics of gravity waves from the surface to the lower thermosphere. MTP and AVAPS measurements during DEEPWAVE will contribute to the understanding of gravity waves generation and propagation across the tropopause into the stratosphere. Comparison of MTP and AVAPS temperature profiles will be presented at the meeting, along with preliminary examples of gravity wave signatures in the data.