HR: 0800h
AN: A11C-0059    [Abstracts]
TI: Observational evidence of African desert dust intensification of easterly waves
AU: Jones, C
EM: cjones@icess.ucsb.edu
AF: Institute for Computational Earth System Science, University of California, Santa Barbara, Santa Barbara, CA 93106 United States
AU: * Mahowald, N
EM: mahowald@ucar.edu
AF: Institute for Computational Earth System Science, University of California, Santa Barbara, Santa Barbara, CA 93106 United States
AU: * Mahowald, N
EM: mahowald@ucar.edu
AF: National Center for Atmospheric Research, PO Box 3000, Boulder, CO 80307 United States
AU: Luo, C
EM: chaoluo@bren.ucsb.edu
AF: Institute for Computational Earth System Science, University of California, Santa Barbara, Santa Barbara, CA 93106 United States
AB: This paper presents indirect observational evidence that desert dust can modulate the amplitude of easterly waves in the Atlantic Ocean. Twenty two years of NCEP/NCAR reanalysis and dust from a global transport model are used to characterize the evolution of enhanced easterly waves. The results show that approximately 20% of the dust entrainment into the atmosphere over a broad region of North Africa is associated with easterly wave activity, suggesting that easterly waves may regulate desert dust entrainment into the atmosphere. About 10%-20% of the seasonal variability of desert dust concentrations across the North Atlantic is related to easterly waves, which suggests that easterly waves modulate the transport of desert dust. Lag composites of analysis increments (analysis minus first−guess) of geopotential height (700−hPa) anomalies indicate larger amplitudes in the analysis than in the first-guess fields. The results indicate that the temperature structure in the lower troposphere associated with easterly waves is warmer in the analysis than in first−guess fields by about 0.25K per day. We hypothesize that the differences in the amplitudes are due to radiative effects associated with African dust, which have been incorporated in the reanalysis by data assimilation but absent in the model first−guess.
DE: 0305 Aerosols and particles (0345, 4801)
DE: 0322 Constituent sources and sinks
DE: 0368 Troposphere--constituent transport and chemistry
SC: Atmospheric Sciences [A]
MN: 2004 AGU Fall Meeting