Climatic Controls on the Frequency, Magnitude and Distribution of Dust Storms: Examples from India/Pakistan, Mauritania and Mongolia

Abstract

Analysis of terrestrially observed meteorological data is used to fill some of the gaps in our knowledge of the dust storm systems in a number of world regions.

In NW India and Pakistan, dust is raised from the alluvial soils of the Ganges and Indus and the Thar desert by localised convective cells (′Andhi′), while synoptic scale dust-raising and transport is caused by the ′Loo′ wind, a pressure gradient airflow. Mapping of twice-daily meteorological reports enables tracking of dust events which follow distinct patterns of dust transport. A tentative model of dust raising and transport in the area is proposed.

Below-average rainfall in the Sahelian latitudes of Mauritania, West Africa, which began in the late 1960s, has been partly instrumental in causing increases in dust-raising activity. At Nouakchott, data show the drought to have continued into 1986, with continued high levels of dust storm activity. Correlations of annual dust storm frequency with 3-year antecedent rainfall averages at Nouakchott, show significant relationships.

The frequency and distribution of dust storms in the Mongolian People′s Republic are mapped, showing highest activity in the Gobi desert and Great Lakes regions. The seasonality of dust storms (which occur largely in the spring) is controlled by ground surface conditions, the frequency of dust-raising meteorological systems, and in some areas by the actions of human populations. At Ulan Bator, increases in dust storms during the 1980s are related to human activities in and around the city.