Signatures of midsummer droughts over Central America and Mexico
The annual cycle of precipitation over most parts of Central America and southern Mexico is climatologically characterizedby a robust bimodal distribution, normally termed as the midsummer drought (MSD), influencing a large range of agriculturaleconomic and public insurances. Compared to studies foc...
| Published in: | Climate Dynamics |
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| Main Authors: | , , , |
| Format: | Article in Journal/Newspaper |
| Language: | English |
| Published: |
Springer-Verlag
2022
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| Subjects: | |
| Online Access: | https://doi.org/10.1007/s00382-022-06505-9 http://ecite.utas.edu.au/154034 |
| Summary: | The annual cycle of precipitation over most parts of Central America and southern Mexico is climatologically characterizedby a robust bimodal distribution, normally termed as the midsummer drought (MSD), influencing a large range of agriculturaleconomic and public insurances. Compared to studies focusing on mechanisms underpinning the MSD, less researchhas been undertaken related to its climatological signatures. This is due to a lack of generally accepted methods throughwhich to detect and quantify the bimodal precipitation accurately. The present study focuses on characterizing the MSDclimatological signatures over Central America and Mexico using daily precipitation observations between 1979 and 2017,aiming to provide a comprehensive analysis of MSD in fine scale over this region. This was completed using a new methodof detection. The signatures were analyzed from three aspects, namely (1) climatological mean states and variability; (2)connections with large scale modes of climate variability (El NioSouthern Oscillation (ENSO) and the MaddenJulianOscillation (MJO)); and (3) the potential afforded by statistical modelling. The development of MSDs across the region isattributed to changes of surface windpressure composites, characterized by anomalously negative (positive) surface pressureand onshore (offshore) winds during the peak (trough) of precipitation. ENSOs modulation of MSDs is also shown bymodifying the surface windpressure patterns through MSD periods, inducing the intensified North Atlantic SubtropicalHigh and associated easterlies from the Caribbean region, which induce relatively weak precipitation at corresponding timepoints and subsequently intensify the MSD magnitude and extend the MSD period. Building on previous research whichshowed MSDs tend to start/end in MJO phases 1 and 8, a fourthorder polynomial was used here to statistically model theprecipitation time series during the rainy season. We show that the strength of the bimodal precipitation can be well modelledby the coefficient of the ... |
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