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Impact of the inflow moisture on the evolution of a warm conveyor belt
Author(s) -
Schäfler Andreas,
Harnisch Florian
Publication year - 2014
Publication title -
quarterly journal of the royal meteorological society
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.744
H-Index - 143
eISSN - 1477-870X
pISSN - 0035-9009
DOI - 10.1002/qj.2360
Subject(s) - environmental science , inflow , outflow , tropopause , cyclone (programming language) , atmospheric sciences , predictability , moisture , latent heat , meteorology , climatology , troposphere , geology , quantum mechanics , field programmable gate array , computer science , physics , computer hardware
This case study of a warm conveyor belt ( WCB ) event that was probed on a research flight during the THORPEX (The Observing‐System Research and Predictability Experiment) Pacific Asian Regional Campaign ( T‐PARC ) field experiment in 2008, investigates the sensitivity of the forecast of the WCB , the associated cyclone and the downstream waveguide to the moisture content in the inflow region of the WCB . By assimilating water vapour profiles of a differential absorption lidar ( DIAL ) into the European Centre for Medium Range Weather Forecasts ( ECMWF ) Integrated Forecasting System ( IFS ), the inflow moisture in the analysis fields is adjusted and humidity is reduced in a broad region around the flight track. The initial reduction of moisture in the WCB inflow affects the latent heat release along the WCB , as well as the potential vorticity ( PV ) production at lower levels. This change led to a substantially lower outflow height of the forecasted WCB . Further, the height of the tropopause was reduced up to 20 hPa, which caused a change in the jet stream wind speeds of up to 15% downstream. Although the impact on the developing surface cyclone was small, improvements of the PV structure as well as of the kinetic energy could be identified.