A numerical study of tropical cross-tropopause transport by convective overshoots

Abstract

Abstract.Observations obtained during the Tropical Convection, Cirrus and Nitrogen Oxides (TROCCINOX) golden day have revealed the presence of ice particles up to 410 K (18.2 km) 2 km above the local tropopause. The case was investigated using a three-dimensional quadruply nested non-hydrostatic simulation and Meteosat Second Generation (MSG) observations. The simulation reproduced the measurements along the flight track fairly well. A reasonable agreement with MSG observations was also achieved: the 10.8-µm brightness temperature (BT) minimum of 187 K was reproduced (a value 6 K colder than the environmental coldpoint temperature) as was the positive BT difference between the 6.2-and 10.8-µm bands, an overshoot signature. The simulation produced several overshooting plumes up to 410 K yielding an upward transport of water vapour of a few tons per second across the tropical tropopause. The estimated mass flux agrees with those derived from over tracer budgets, indicating that convection transports mass across the tropopause.

Impact of land convection on temperature diurnal variation in the tropical lower stratosphere inferred from COSMIC GPS radio occultations

“…Successfully reproduced by nonhydrostatic cloud resolving models (e.g. Chaboureau et al, 2007;Grosvenor et al, 2007;Liu et al, 2010), these updrafts of 35 m s −1 to 80 m s −1 vertical velocity result in local injection of adiabatically cooled air into the lower stratosphere and a local cooling by e.g. 21 K at 18.2 km in the case simulated by Jensen et al (2007).…”

“…Such convective updrafts of adiabatically cooled air and ice crystals across the tropopause are well captured by mesoscale cloud resolving models (Chaboureau et al, 2007;Jensen et al, 2007;Grosvenor et al, 2007;Chemel et al, 2009;Liu et al, 2010), but, because of their non-hydrostatic nature, they are missed by global meteorological and climate models. The relative importance of the contribution of such continental convective updrafts compared to their oceanic counterparts is suggested by the higher concentration of tropospheric trace gases in the TTL above continents reported by space-borne N 2 O, CH 4 and CO profiles measurements (Ricaud et al, 2007(Ricaud et al, , 2009.…”

Impacts of Stratospheric Sudden Warming Event on Tropical Clouds and Moisture Fields in the TTL: A Case Study

“…2d and 2f). This suggests a cross-tropopause vertical transport of water vapor by deep convection (Chaboureau et al 2007). …”

Radio occultation bending angle anomalies during tropical cyclones

“…We downloaded from the Comprehensive Large Array Data Stewardship System (CLASS) the GOES VARiable IMaGer data (GVAR IMG) in "area" format with native spatial resolution acquired by GOES11 and GOES12. Using the BT at 6.8 microns (band 3), which is sensitive to the water vapour, and the BT at 10.7 microns (band 4), it is possible to detect convective systems (Schmetz et al, 1997;Chaboureau et al, 2007). In clear sky conditions and low level clouds, the BT in the water vapour channel is lower than the BT at 10.7 microns.…”