TY  - JOUR
AU  - Chemel, C.
AU  - Russo, M.R.
AU  - Pyle, J.
AU  - Sokhi, R.S.
AU  - Schiller, C.
TI  - Quantifiying the Imprint of a Severe Hector Thunderstorm during ACTIVE/SCOUT-O3 onto the Water Content in the Upper Troposphere/Lower Stratosphere
JO  - Monthly Weather Review
VL  - 137
SN  - 0027-0644
CY  - Washington, DC [u.a.]
PB  - AMS
M1  - PreJuSER-1757
SP  - 2493 - 2514
PY  - 2009
N1  - We appreciate the tremendous efforts of the ACTIVE/SCOUT-O3 PIs as well as all those who made the IOPs so successful. MRR and JAP acknowledge the U. K. Natural Environment Research Council (NERC) and the U. K. National Center for Atmospheric Science (NCAS) for their funding as part of ACTIVE. MRR, JAP, and CS thank the European Commission for their funding as part of SCOUT-O3. The Australian Bureau of Meteorology is acknowledged for having made the BMRC/NCAR C-POL radar data available for this work. CC thanks E. D. Grell for providing help with the implementation of the add-on LES module for ARW. The images of Fig. 3 were derived from MTSAT-1R satellite imagery available from the Atmospheric Radiation Measurement (ARM) program archive. Time-consuming computations were performed with the HECToR and HPCx U. K. national supercomputing facilities, which were accessed through NCAS. We thank the Met Office and the NCAS Computational Modelling Services for helping with UM-related issues.
AB  - The development of a severe Hector thunderstorm that formed over the Tiwi Islands, north of Australia, during the Aerosol and Chemical Transport in Tropical Convection/Stratospheric-Climate Links with Emphasis on the Upper Troposphere and Lower Stratosphere (ACTIVE/SCOUT-O3) field campaign in late 2005, is simulated by the Advanced Research Weather Research and Forecasting (ARW) model and the Met Office Unified Model (UM). The general aim of this paper is to investigate the role of isolated deep convection over the tropics in regulating the water content in the upper troposphere/lower stratosphere (UT/LS). Using a horizontal resolution as fine as 1 km, the numerical simulations reproduce the timing, structure, and strength of Hector fairly well when compared with field campaign observations. The sensitivity of results from ARW to horizontal resolution is investigated by running the model in a large-eddy simulation mode with a horizontal resolution of 250 m. While refining the horizontal resolution to 250 m leads to a better representation of convection with respect to rainfall, the characteristics of the Hector thunderstorm are basically similar in space and time to those obtained in the 1-km-horizontal-resolution simulations. Several overshooting updrafts penetrating the tropopause are produced in the simulations during the mature stage of Hector. The penetration of rising towering cumulus clouds into the LS maintains the entrainment of air at the interface between the UT and the LS. Vertical exchanges resulting from this entrainment process have a significant impact on the redistribution of atmospheric constituents within the UT/LS region at the scale of the islands. In particular, a large amount of water is injected in the LS. The fate of the ice particles as Hector develops drives the water vapor mixing ratio to saturation by sublimation of the injected ice particles, moistening the air in the LS. The moistening was found to be fairly significant above 380 K and averaged about 0.06 ppmv in the range 380-420 K for ARW. As for UM, the moistening was found to be much larger (about 2.24 ppmv in the range of 380-420 K) than for ARW. This result confirms that convective transport can play an important role in regulating the water vapor mixing ratio in the LS.
KW  - J (WoSType)
LB  - PUB:(DE-HGF)16
UR  - <Go to ISI:>//WOS:000269348600006
DO  - DOI:10.1175/2008MWR2666.1
UR  - https://juser.fz-juelich.de/record/1757
ER  -