Description:

These movies present atmospheric transport, temperature and precipitation during the three months June - August for the years 1991 - 1995 with a 4 four time step, over the Eastern US. Atmospheric transport is presented in the form of three day back and forward trajectories from 20 locations evenly distributed over the Eastern US. The temperature field and precipitation fields are outputs of the National Meteorological center's Nested Grid Model (NGM).

Purpose:

These movies can be used as a resource to provide meteorological context to the interpretation of air quality data.

Method:

The trajectories are the same as those in the movies: Back Trajectories over the Eastern US during the summers of 1991-1995 and Forward Trajectories over the Eastern US during the summers of 1991-1995. The temperature data is taken from the NGM meteorological data, and is at an approximately height of 150 meters above the surface. The precipitation is also from the NGM data.

Interpretation:

These movie provides meteorological information that can be used to begin to assess the role of transport, transformations, and removal of atmospheric pollutants on receptor concentrations. The trajectories identify the pathway of airmasses in route to the receptors and from the sources. They also identify whether the airmass is stagnating, recirculating, or part of a well defined flow field. The temperature is often a good indication of the kinetic activity of an airmass. For example high ozone concentrations are normally associated with high temperatures. Precipitation is a very efficient removal mechanism for many gaseous pollutants and aerosols. A precipitating airmass generally has low pollutant concentrations.