HR: 08:30h
AN: H51G-03    [Abstracts]
TI: The Mid-Summer Drought: large scale forcing and interannual variability.
AU: * SMALL, R J
EM: SMALL@HAWAII.EDU
AF: International Pacific Research Center, School of Ocean and Earth Science and Technology, University of Hawaii, 2525 Correa Rd , Honolulu, HI 96822, United States
AU: DESZOEKE, S P
EM: SIMON.DESZOEKE@NOAA.GOV
AF: NOAA/ESRL/PSD3, 325 BROADWAY, Boulder, CO 80305, United States
AU: XIE, S
EM: XIE@HAWAII.EDU
AF: International Pacific Research Center, School of Ocean and Earth Science and Technology, University of Hawaii, 2525 Correa Rd , Honolulu, HI 96822, United States
AU: XIE, S
EM: XIE@HAWAII.EDU
AF: Department of Meteorology, School of Ocean and Earth Science and Technology, University of Hawaii, 2525 Correa Rd , Honolulu, HI 96822, United States
AB: A mid-summer drought (MSD) is experienced in southern Mexico, Central America, the Caribbean, as well as North American states bordering the Gulf of Mexico. The timing and magnitude of the drought affects agriculture in this region, so it is important to understand the mechanisms governing its formation and its variability. This presentation discusses some potential controlling factors of the MSD. A linear baroclinic model is used to investigate the influence of large scale diabatic heat anomalies on the local circulation. It is found that the seasonal progression of the Pacific Inter-Tropical Convergence Zone, which moves northward following warm sea surface temperature during the early summer, and of the Atlantic (Bermuda) sub-tropical high, which moves westward, are the most important remote factors that contribute towards the low level easterly flow and divergence during the MSD. It is also shown that the circulation associated with the MSD precipitation deficit helps to maintain the deficit by inducing low level anticyclonic flow and easterlies across Central America. We investigate how the MSD is modified by the Madden-Julian-Oscillation, which has a prominent signature in the region in summer: it appears that the phasing of the Madden-Julian-Oscillation is important to interannual modifications of the MSD.
UR: http:iprc.soest.hawaii.edu/~justins/
DE: 1812 Drought
DE: 3309 Climatology (1616, 1620, 3305, 4215, 8408)
DE: 3314 Convective processes
DE: 3339 Ocean/atmosphere interactions (0312, 4504)
SC: Hydrology [H]
MN: 2007 Joint Assembly