A simple mechanism for the climatological midsummer drought along the Pacific coast of Central America
Karnauskas, Kristopher B.
Busalacchi, Antonio J.
MetadataShow full item record
The global distribution, seasonal evolution, and underlying mechanisms for the climatological midsummer drought (MSD) are investigated using a suite of relatively high spatial and temporal resolution station observations and reanalysis data with particular focus on the Pacific coast of Central America and southern Mexico. Although the MSD of Central America stands out in terms of spatial scale and coherence, it is neither unique to the Greater Caribbean Region (GCR) nor necessarily the strongest MSD on Earth based on an objective analysis of several global precipitation data sets. A mechanism for the MSD is proposed that relates the latitudinal dependence of the two climatological precipitation maxima to the biannual crossing of the solar declination (SD), driving two peaks in convective instability and hence rainfall. In addition to this underlying local mechanism, a number of remote processes tend to peak during the apex of the MSD, including the North American monsoon, the Caribbean low-level jet, and the North Atlantic subtropical high, which may also act to suppress rainfall along the Pacific coast of Central America and generate interannual variability in the strength or timing of the MSD. However, our findings challenge the existing paradigm that the MSD owes its existence to a precipitation-suppressing mechanism. Rather, aided by the analysis of higher-temporal resolution precipitation records and considering variations in latitude, we suggest the MSD is essentially the result of one precipitation-enhancing mechanism occurring twice.
© ATMOSFERA, 2013. This article is posted here by permission of ATMOSFERA for personal use, not for redistribution. The definitive version was published in Atmósfera 26 (2013): 261-281.
Suggested CitationAtmósfera 26 (2013): 261-281
Showing items related by title, author, creator and subject.
Cold tropical Pacific Sea surface temperatures during the late sixteenth-century North American megadrought Cook, Benjamin I.; Williams, A. Park; Smerdon, Jason E.; Palmer, Jonathan; Cook, Edward R.; Stahle, David W.; Coats, Sloan (John Wiley & Sons, 2018-09-21)The late 16th‐century North American megadrought was notable for its persistence, extent, intensity, and occurrence after the main interval of megadrought activity during the Medieval Climate Anomaly. Forcing from sea ...
Kleppe, J. A.; Brothers, Daniel S.; Kent, Graham M.; Biondi, F.; Jensen, S.; Driscoll, Neal W. (Elsevier B.V., 2001-09-16)Droughts in the western U.S. in the past 200 years are small compared to several megadroughts that occurred during Medieval times. We reconstruct duration and magnitude of extreme droughts in the northern Sierra Nevada ...
Can Australian multiyear droughts and wet spells be generated in the absence of oceanic variability? Taschetto, Andrea S.; Sen Gupta, Alexander; Ummenhofer, Caroline C.; England, Matthew H. (American Meteorological Society, 2016-08-19)Anomalous conditions in the tropical oceans, such as those related to El Niño–Southern Oscillation and the Indian Ocean dipole, have been previously blamed for extended droughts and wet periods in Australia. Yet the extent ...