Climatic trends and regional climate models intercomparison over the CORDEX‐CAM (Central America, Caribbean, and Mexico) domain

Abstract

An intercomparison of three regional climate models (RCMs) (PRECIS‐HadRM3P, RCA4, and RegCM4) was performed over the Coordinated Regional Dynamical Experiment (CORDEX)—Central America, Caribbean, and Mexico (CAM) domain to determine their ability to reproduce observed temperature and precipitation trends during 1980–2010. Particular emphasis was given to the North American monsoon (NAM) and the mid‐summer drought (MSD) regions. The three RCMs show negative (positive) temperature (precipitation) biases over the mountains, where observations have more problems due to poor data coverage. Observations from the Climate Research Unit (CRU) and ERA‐Interim show a generalized warming over the domain. The most significant warming trend (≥0.34°C/decade) is observed in the NAM, which is moderately captured by the three RCMs, but with less intensity; each decade from 1970 to 2016 has become warmer than the previous ones, especially during the summer (mean and extremes); this warming appears partially related to the positive Atlantic Multidecadal Oscillation (+AMO). CRU, GPCP, and CHIRPS show significant decreases of precipitation (less than −15%/decade) in parts of the southwest United States and northwestern Mexico, including the NAM, and a positive trend (5–10%/decade) in June–September in eastern Mexico, the MSD region, and northern South America, but longer trends (1950–2017) are not statistically significant. RCMs are able to moderately simulate some of the recent trends, especially in winter. In spite of their mean biases, the RCMs are able to adequately simulate inter‐annual and seasonal variations. Wet (warm) periods in regions affected by the MSD are significantly correlated with the +AMO and La Niña events (+AMO and El Niño). Summer precipitation trends from GPCP show opposite signs to those of CRU and CHIRPS over the Mexican coasts of the southern Gulf of Mexico, the Yucatan Peninsula, and Cuba, possibly due to data limitations and differences in grid resolutions.

Assessing precipitation trends in the Americas with historical data: A review

“…Using multiple datasets, CRU, GPCP, and CHIRPS Cavazos et al () showed significant decreases of precipitation (less than −15%/decade) in parts of the southwest United States and northwest Mexico, including the NAMS, and a positive trend (5–10%/decade) in June–September in eastern Mexico and northern South America. However, longer trends (1950–2017) were not statistically significant.…”

“…However, longer trends (1950–2017) were not statistically significant. The caveat is that precipitation trends based on historical data (gridded) in Central America, including Mexico and the Caribbean, exhibit more uncertainty due to the lack of temporally continuous long‐term climate station data and sparse spatial coverage (Cavazos et al, ). A detailed review on precipitation trends in NAMS is discussed in Pascale et al ().…”

Aridity Trends in Central America: A Spatial Correlation Analysis

“…These trends are positive in the vast majority of the cases, but in some locations are negative. Except for a few places, precipitation trends are non-significant, although this depends greatly on the database used in the assessment ( [14,15]). Additionally, precipitation trends do not show a robust pattern over the isthmus as surface temperature do, because precipitation trends are constructed over multiscale processes ( [16,17]).…”

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“…The behavior in these patterns of increasing rainfalls has been associated to effects caused by El Niño Southern Oscillation (ENSO) and quality phases of PDO for the region (Pavia et al, 2006). From 1994, an increase in strong precipitation was observed in regions of the Sierra Madre Occidental studies; with a negative anomaly and a decrease of -32 mm/decade, in the last 30 years (Cavazos et al, 2019).…”

“…These tendencies have been associated to a greater increase in sea surface temperature (SST), causing a greater quantity of vertical moisture flux which generated an increase in convective events (Valdéz-Manzanilla, 2015). These increases have not been uniform in the entire area, although significant increases in temperature were identified in the region(Cavazos et al, 2019); precipitation patternspresented the most heterogeneous patterns, perhaps more associated to topographic effects. Precipitation showed a negative trend in the whole region of northwestern Mexico (Figure 3), in agreement with other Figura 2.…”