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High Resolution Dynamics Limb Sounder

Gravity wave momentum fluxes in monsoon regions

Measurements from HIRDLS are used to quantify gravity wave momentum fluxes generated from monsoon regions across the globe over the three years 2005-2007. Momentum fluxes in the altitude range 16-60km over monsoon regions in both hemispheres show good correlations with convective data from NOAA's Outgoing Longwave Radiation time series and precipitation data from the Tropical Rainfall Monitoring Mission. A temporary increase in measured momentum flux, of approximately 50% over temporal background values, is observed during the ~4 month boreal monsoon period over the 10N-30N latitude band, with around half of the annual momentum flux for this latitude range measured during this period.

Above: a strong gravity signal observed over the Andes in mid-2006.

Wright and Gille. (2011), HIRDLS observations of gravity wave momentum fluxes over the monsoon regions, J. Geophys. Res., 116, D12103, doi:10.1029/2011JD015725

Above: longitude-time plot of: (top) HIRDLS gravity wave momentum flux in 0.2-100 mb pressure region, (middle) TRMM precipitation and (bottom) NOAA OLR, showing sharp monsoon peaks for the Indian, American and African monsoons.