Interannual and intra-annual variability of rainfall in Haiti (1905–2005)

Journal Article · Fri Sep 19 00:00:00 EDT 2014 · Climate Dynamics

DOI:https://doi.org/10.1007/s00382-014-2326-y· OSTI ID:1565282

Moron, Vincent ^[1]; Frelat, Romain ^[2]; Jean-Jeune, Pierre Karly ^[3]; Gaucherel, Cédric ^[2]

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1. Aix-Marseille Univ., Marseille (France); Columbia Univ., New York, NY (United States)
2. French Inst. of Pondicherry IFP-CNRS, Pondicherry (India)
3. Natural Resources and Rural Development (MARNDR) Ministry of Agriculture, Port-au-Prince (Haiti)

The interannual variability of annual and monthly rainfall in Haiti is examined from a database of 78 rain gauges in 1905–2005. The spatial coherence of annual rainfall is rather low, which is partly due to Haiti’s rugged landscape, complex shoreline, and surrounding warm waters (mean sea surface temperatures >27 °C from May to December). The interannual variation of monthly rainfall is mostly shaped by the intensity of the low-level winds across the Caribbean Sea, leading to a drier- (or wetter-) than-average rainy season associated with easterly (or westerly) anomalies, increasing (or decreasing) winds. The varying speed of low-level easterlies across the Caribbean basin may reflect at least four different processes during the year: (1) an anomalous trough/ridge over the western edge of the Azores high from December to February, peaking in January; (2) a zonal pressure gradient between Eastern Pacific and the tropical Northern Atlantic from May/June to September, with a peak in August (i.e. lower-than-average rainfall in Haiti is associated with positive sea level pressure anomalies over the tropical North Atlantic and negative sea level pressure anomalies over the Eastern Pacific); (3) a local ocean–atmosphere coupling between the speed of the Caribbean Low Level Jet and the meridional sea surface temperature (SST) gradient across the Caribbean basin (i.e. colder-than-average SST in the southern Caribbean sea is associated with increased easterlies and below-average rainfall in Haiti). This coupling is triggered when the warmest Caribbean waters move northward toward the Gulf of Mexico; (4) in October/November, a drier- (or wetter-) than-usual rainy season is related to an almost closed anticyclonic (or cyclonic) anomaly located ENE of Haiti on the SW edge of the Azores high. This suggests a main control of the interannual variations of rainfall by intensity, track and/or recurrence of tropical depressions traveling northeast of Haiti. In conclusion, during this period, the teleconnection of Haitian rainfall with synchronous Atlantic and Eastern Pacific SST is at a minimum.

• Research Organization: Oak Ridge National Lab. (ORNL), Oak Ridge, TN (United States). Oak Ridge Leadership Computing Facility (OLCF)
• Sponsoring Organization: USDOE Office of Science (SC), Biological and Environmental Research (BER); National Oceanic and Atmospheric Administration (NOAA)
• OSTI ID: 1565282
• Journal Information: Climate Dynamics, Vol. 45, Issue 3-4; ISSN 0930-7575
• Publisher: Springer-Verlag
• Country of Publication: United States
• Language: English

Related Subjects

54 ENVIRONMENTAL SCIENCES
Meteorology & Atmospheric Sciences
Haiti
Caribbean basin
Rainfall variability
Precipitation regime
Ocean–atmosphere coupling