Caribbean Air Chemistry and Dispersion Conditions

Mark Jury

doi:10.3390/atmos8080151

Abstract

The meteorological influences on Caribbean air chemistry are studied using in-situ, satellite and model data. Although African dust plumes join locally generated pollutants, concentrations are relatively low in the eastern Caribbean due to geographic remoteness and steady oceanic trade winds. Urban-industrial emissions from big cities (e.g., Kingston, Santo Domingo, San Juan), agricultural emissions from the south, and volcanic emissions from Montserrat contribute a noticeable burden. Conditions over Puerto Rico in the dry season (December–May) provide a focus for statistical analysis of air chemistry constituents and weather variables that describe dispersion conditions. Monthly and daily air indices are formed by summing the normalized values of fine aerosols and particulates, long- and short-lived trace gases from in-situ, satellite and model sources. The spatial correlation of a daily Puerto Rico air index onto regional dewpoint temperature, air pressure and outgoing longwave radiation fields in December–May 2005–2015 reveals the northward movement of a dry tongue and trough. At the climate timescale, Pacific El Nino conditions favor an increase of spring-time air pollution corresponding to anomalous inflow from Africa and the southern Caribbean coast. Composite weather patterns for a group of high air index values reflect divergent trade winds and a strong jet stream that imparts anticyclonic vorticity, subsidence and low humidity. This new understanding will underpin better air quality forecasts for Puerto Rico and the wider Caribbean.

Highlights

Air pollution concentrations tend to be low, yet levels are rising due to rapid growth in transport, industrial and energy-related emissions [1]
Rainy weather and cleaner air prevails from June to November, so the focus was on the dry winter–spring season
While the Saharan dust plumes are prevalent in mid-summer, hospital respiratory admissions tend to peak in March–April

Summary

Introduction

Trade winds and dry weather that prevail much of the time are interspersed with passing troughs and cyclones in summer. Air pollution concentrations tend to be low, yet levels are rising due to rapid growth in transport, industrial and energy-related emissions [1]. Air quality does not always meet international guidelines [2] due to local and remote emissions, and short-periods of quiescent weather [3,4,5,6,7]. Air pollutants often accumulate during the dry season in wind shadows to the west of mountains. Air quality monitoring and field surveys across Latin America [10,12,13,14,15,16] have improved our understanding, but logistical and technical issues contribute to data gaps

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Conclusion