The use of TOVS observations for the identification of tropopause-level thermal anomalies

The evolution of tropopause-level thermal patterns is generally not well re presented by the conventional observational network, especially over the oc eans. An alternative is provided by satellite observations which are global and frequent. In particular, from the TIROS-N (Television Infra-Red Observ ation Satellite) Operational Vertical Sounder (TOVS) which flies on-board N ational Oceanic and Atmospheric Administration satellites, an estimate of t he temperature of the lower stratosphere (TLS) can be derived using the Imp roved Initialization Inversion algorithm. In this study, the degree of reli ability of TLS for describing tropopause-level thermal structures and varia tions is examined. For three intensive observation periods (16, 17 and 18) of the Fronts and Atlantic Storm-Track EXperiment, conducted in January and February 1997 over the North Atlantic Ocean, TLS fields are described; the ir advantage, compared with the use of raw microwave data, is illustrated; TLS variations are also studied in connection with other dynamical variable s which can be obtained by the French Action de Recherche Petite Echelle Gr ande Echelle operational model analysis. Finally, the suitability of TLS as a possible forecasting aid over mid-oceanic regions is promoted.