Monitoring High-Temporal-Resolution Convective Stability Indices Using the Ground-Based Atmospheric Emitted Radiance Interferometer (AERI) during the 3 May 1999 Oklahoma–Kansas Tornado Outbreak

Abstract

The Department of Energy Atmospheric Radiation Measurement Program has funded the development and installation of five atmospheric emitted radiance interferometer (AERI) systems around the Southern Great Plains Cloud and Radiation Test Bed located in Oklahoma and Kansas. The AERI instruments measure atmospheric emitted radiance to within 1% ambient radiance at 1 cm?1 spectral resolution from 520 to 3000 cm?1 (3?20 ?m) at 10-min temporal resolution. This high-spectral-resolution radiance information is inverted through a form of the infrared radiative transfer equation to produce temperature and water vapor profiles within the planetary boundary layer (to 3 km), effectively mapping the thermodynamic state of the lower troposphere. Taking advantage of the 10-min resolution of the AERI thermodynamic profiles, the convective destabilization during the 3 May 1999 Oklahoma?Kansas tornado outbreak is analyzed. Tropospheric changes involving the rapid (on the order of 1?2 h) dissipation of a capping temperature inversion within the planetary boundary layer, increasing boundary layer moisture, and a strong upper-level short wave lead to the systematic development of severe convection on this day. The AERI systems were able to monitor the trends in bulk atmospheric stability via diagnosed quantities such as surface-based parcel equivalent potential temperature, inversion intensity, convective available potential energy, and convective inhibition. The high temporal resolution of temperature and moisture profiling and bulk stability information is unique. Special radiosonde launches (nonsynoptic) are currently the only widely used means to determine this stability information. The array of five AERI instruments within Oklahoma and Kansas (collocated with wind profilers) offers the operational forecaster a unique and important data source for the thermodynamic evolution of the boundary layer, convective instability, and numerical weather prediction model validation.