A CLIMATOLOGY OF AIRBORNE DUST FOR THE RED RIVER VALLEY OF NORTH-DAKOTA

The Red River Valley of North Dakota has been identified as one of the highest potential dust production regions in the United Stales. This paper provides a climatological summary of the airborne dust environme nt in the region using historical meteorological data for Fargo, North Dakota. Data for the period 1948-1994 were extracted for all 3-hourly weather observations which recorded an obstruction to vision due to d ust, blowing dust or dust storms. Data were compiled on the year, mont h, day and hour of each observation, as well as the horizontal visibil ity, wind speed, wind direction, and other present weather occurring a t the time of each event. Airborne dust events in the Red River Valley of the North normally involve local entrainment of dust, and show a s trong peak in the frequency of occurrence during the afternoon and spr ing seasons, although a secondary winter peak is also present. Dust ev ents have decreased in frequency over the study period, apparently in response to improved farm management practices. Most events fall into two basic categories: winter events generated by passing cold fronts o r strong regional pressure gradients, and often accompanied by blowing snow and light snow showers, and spring events triggered by the passa ge of cyclones and fronts, and normally not accompanied by other preva iling weather at the time of the observation. Results are discussed in relation to the unique soil, meteorological and surface cover conditi ons of the Red River Valley of North Dakota. (C) 1998 Elsevier Science Ltd. All rights reserved.