Observed characteristics of dust storm events over the western United States using meteorological, satellite, and air quality measurements

摘要

To improve dust storm identification over the westernUnited States, historical dust events measured by air quality and satelliteobservations are analyzed based on their characteristics in data sets ofregular meteorology, satellite-based aerosol optical depth (AOD), and airquality measurements. Based on the prevailing weather conditions associatedwith dust emission, dust storm events are classified into the following fourtypical types:(1) The key feature of cold front-induced dust storms istheir rapid process with strong dust emissions.(2) Events caused bymeso- to small-scale weather systems have the highest levels of emissions.(3) Dust storms caused by tropical disturbances show a stronger airconcentration of dust and last longer than those in (1) and (2).(4) Dust storms triggered by cyclogenesis last the longest.In this paper, sampleevents of each type are selected and examined to explore characteristicsobserved from in situ and remote-sensing measurements. These characteristicsinclude the lasting period, surface wind speeds, areas affected, averageloading on ground-based optical and/or air quality measurements, peakloading on ground-based optical and/or air quality measurements, and loadingon satellite-based aerosol optical depth. Based on these analyses, wecompare the characteristics of the same dust events captured in differentdata sets in order to define the dust identification criteria. The analysesshow that the variability in mass concentrations captured by in situmeasurements is consistent with the variability in AOD from stationary andsatellite observations. Our analyses also find that different data sets arecapable of identifying certain common characteristics, while each data setalso provides specific information about a dust storm event. For example,the meteorological data are good at identifying the lasting period and area impacted by a dust event; the ground-based air quality and opticalmeasurements can capture the peak strength well; aerosol optical depth (AOD)from satellite data sets allows us to better identify dust-storm-affectedareas and the spatial extent of dust. The current study also indicates thatthe combination of in situ and satellite observations is a better method tofill gaps in dust storm recordings.