Easterly waves and precipitation over northern South America and the Caribbean

Abstract

The Easterly Waves (EWs) have been highlighted as one of the different spatiotemporal processes that influence hydro-climatology over northern South America and the Caribbean Sea, particularly during boreal summer. Previous studies recognize the EWs among the most important features of the rainy season in northern South America, suggesting the occurrence of precipitation as the main meteorological response to the passage of these disturbances. However, it is shown in this work that not all the EWs that propagate over northern South America and the Caribbean Sea have such an effect. Almost 50% of the EWs moving over the region during the 1983-2018 period were accompanied by the inhibition of precipitation and clear skies, as depicted by anomalies from the Climate Data Record of Precipitation Estimation from Remotely Sensed Information Using Artificial Neural Networks precipitation dataset and the National Oceanic and Atmospheric Administration interpolated Outgoing Longwave Radiation dataset. This work intends to address the relationship between these atmospheric perturbations and the occurrence or inhibition of precipitation, as well as a plausible connection with the Madden-Julian Oscillation (MJO). In particular, horizontal components of wind and relative vorticity, together with low and upper troposphere divergence, were used to identify and characterize the EW activity over northern South America and the Caribbean Sea. Results suggest an influence of the MJO on the effects that the EWs have on convection and precipitation over the region, as well as the direction in which such perturbances continue their westward propagation.

A New Look into the South America Precipitation Regimes: Observation and Forecast

“…However, its spatial and temporal precipitation variability is due to several factors, such as the complex topography, the influence of moisture transport by the Caribbean Sea and the Pacific and Atlantic Oceans, MCSs, and synoptic disturbances, such as easterly waves (EWs) [2,3,71,235]. EWs respond to 50% of summer rainfall in northern SA [236], but 50% of their occurrences between 1983 and 2018 were associated with precipitation inhibition and clear skies [237].…”

Atmospheric circulation types controlling rainfall in the Central American Isthmus

“…In the Central America and Caribbean regions ERA5 has been utilized with reasonable success in precipitation studies (Centella‐Artola et al ., 2020; García‐Franco et al ., 2020; García‐Franco et al ., 2021; Giraldo‐Cardenas et al ., 2021), in future projections of droughts and the CLLJ (Depsky and Pons, 2020; Vichot‐Llano et al ., 2021, respectively), drought related issues (Pascale et al ., 2021; Stewart et al ., 2021) and in assessing the trends of the Caribbean trade wind inversion (Ramseyer and Miller, 2021).…”

Tropical Easterly Waves Over Costa Rica and Their Relationship to the Diurnal Cycle of Rainfall

“…2004; Seastrand et al., 2015). However, it has been suggested that TEWs may be responsible for up to half of the rainfall accumulation in some regions over the tropical Americas (Dominguez et al., 2020), which in turn may significantly modulate the seasonality of rainfall over the region (Giraldo‐Cardenas et al., 2022; Gomes et al., 2019; Jury, 2020). Thus, TEWs are broadly important for understanding tropical regional rainfall and its variability, including extreme rainfall events.…”