Simple Method of Determination of Ground-Based Aerosol Sources Using Back Trajectory Analysis Results

Kalinskaya D. V., Suslin V. V.

A simple method of spatio-temporal localization of the ground-based aerosol sources, using the results of back trajectory analysis (BTA), is described in the paper. The key parameter of the method is the derivative of pressure by time (P’t). A positive value corresponds to an upward air flow, negative one corresponds to a downward air flow. Two conditions are needed to satisfy in order to identify the ground source of aerosols in a specific location of the Earth: air mass is in the surface layer (below 700 mbar); P’t > 20 mbar/hour, that is equivalent to an upstream flow with a velocity of several cm/s or more. Latter condition corresponds to the mesoscale vertical movements of the same signs of the air volumes with the horizontal dimensions of the order of 10–100 km. The value of 20 mbar/h is based on the analysis of the long-term (2007–2012) array of data of BTA for AERONET station Sevastopol. We also tried to take into account the process of «aerosol removing with precipitation». The criterion for a downward air flow is: P’t < −20 mbar/h. If this condition is satisfied, it means that the atmospheric layer does not contain aerosol captured earlier by upstream flows from Earth’s surface. Method validation was carried out using data of Sevastopol station (network AERONET) and satellite optical scanner MODIS. The relation between the area of origin and specific aerosol optical properties was observed at Sevastopol station (network AERONET). The featureы of its impact on the results of the standard atmospheric correction of MODIS measurements have been shown on the example of dust aerosol from two arid zones. The results of this study will be useful to specialists, solving the problem of atmospheric correction of measurements of upward radiance on top of the atmosphere in visible range of spectrum above the water surface.

Download original text