The Central American Midsummer Drought: Regional Aspects and Large-Scale Forcing Public Deposited

http://ir.library.oregonstate.edu/concern/defaults/9k41zg13t

Descriptions

Attribute NameValues
Creator
Abstract or Summary
  • The midsummer drought (MSD) is a diminution in rainfall experienced during the middle of the rainy season in southern Mexico and Central America, as well as in the adjacent Caribbean, Gulf of Mexico, and eastern Pacific seas. The aim of this paper is to describe the regional characteristics of the MSD and to propose some possible forcing mechanisms. Satellite and in situ data are used to form a composite of the evolution of a typical MSD, which highlights its coincidence with a low-level anticyclone centered over the Gulf of Mexico and associated easterly flow across Central America. The diurnal cycle of precipitation over the region is reduced in amplitude during midsummer. The MSD is also coincident with heavy precipitation over the Sierra Madre Occidental (part of the North American monsoon). Reanalysis data are used to show that the divergence of the anomalous low-level flow during the MSD is the main factor governing the variations in precipitation. A linear baroclinic model is used to show that the seasonal progression of the Pacific intertropical convergence zone (ITCZ), which moves northward following warm sea surface temperature (SST) during the early summer, and of the Atlantic subtropical high, which moves westward, are the most important remote factors that contribute toward the low-level easterly flow and divergence during the MSD. The circulation associated with the MSD precipitation deficit helps to maintain the deficit by reinforcing the low-level anticyclonic flow over the Gulf of Mexico. Surface heating over land also plays a role: a large thermal low over the northern United States in early summer is accompanied by enhanced subsidence over the North Atlantic. This thermal low is seen to decrease considerably in midsummer, allowing the high pressure anomalies in the Atlantic and Pacific Oceans to extend into the Gulf of Mexico. These anomalies are maintained until late summer, when an increase in rainfall from the surge in Atlantic tropical depressions induces anomalous surface cyclonic flow with westerlies fluxing moisture from the Pacific ITCZ toward Central America.
Resource Type
DOI
Date Available
Date Issued
Citation
  • Small, Richard Justin O., Simon P. de Szoeke, Shang-Ping Xie, 2007: The Central American Midsummer Drought: Regional Aspects and Large-Scale Forcing*. Journal of Climate, 20, 4853–4873.
Series
Keyword
Rights Statement
Funding Statement (additional comments about funding)
Publisher
Language
Replaces
Additional Information
  • description.provenance : Made available in DSpace on 2012-04-18T23:01:22Z (GMT). No. of bitstreams: 1 deSkoekeSimonP.CEOAS.CentralAmericanMidsummer.pdf: 5193598 bytes, checksum: 6a4c5c1260a54605b17e5fec7e57c8e1 (MD5) Previous issue date: 2007-10
  • description.provenance : Submitted by Deborah Campbell (deborah.campbell@oregonstate.edu) on 2012-04-18T23:01:22Z No. of bitstreams: 1 deSkoekeSimonP.CEOAS.CentralAmericanMidsummer.pdf: 5193598 bytes, checksum: 6a4c5c1260a54605b17e5fec7e57c8e1 (MD5)

Relationships

In Administrative Set:
Last modified: 07/21/2017

Downloadable Content

Download PDF
Citations:

EndNote | Zotero | Mendeley

Items