Satellite observations and numerical simulations of jet-front gravity waves over North America and North Atlantic Ocean

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Title: Satellite observations and numerical simulations of jet-front gravity waves over North America and North Atlantic Ocean
Author: Zhang, Meng
Abstract: In this study , a month -long simulation of gravity waves over North America and North Atlantic Ocean is performed using the mesoscale model MM5 for January 2003 , verified with Advanced Microwave Sounding Unit -A (AMSU -A ) radiance observations in the upper troposphere and lower stratosphere . According to the monthly mean statistics , four regions of strong gravity wave activities are found both in the simulation and the AMSU -A observations : northwestern Atlantic , Appalachian Mountains , Rocky Mountains and Greenland , respectively . Those over the northwestern Atlantic Ocean are strongly associated with the midlatitude baroclinic jet -front systems , while the other three regions are apparently collocated with high topography . Imbalance diagnosis and numerical sensitivity experiments of a strong gravity wave event during January 18 -22 show that the gravity waves are strongly linked to the unbalanced flow in the baroclinic jet -front system . The gravity waves are usually radiated from the upper tropospheric jet exit region with maximum nonlinear balance equation residual ( ? NBE ; key indicator of flow imbalance ) , distinctly different from other surface sources . Flow imbalance related strongly to tropopause folding and frontogenesis of the large -scale background flow . Similar wave characteristics are simulated in experiments with different microphysics and grid resolutions . The ? NBE is again shown to be a good predictor for jet -front related gravity waves , suggesting its potential application to gravity wave parameterizations for global and climate models .
URI: http : / /hdl .handle .net /1969 .1 /85995
Date: 2008-10-10

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Satellite observations and numerical simulations of jet-front gravity waves over North America and North Atlantic Ocean. Available electronically from http : / /hdl .handle .net /1969 .1 /85995 .

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