Concentration Archive

Click HERE for an archive of 1998 forecast concentrations

Trajectory Archive

Click HERE for an archive of 1998 forecast trajectories

Concentration/smoke Comparison

Click HERE for a comparison of modeled concentrations vs satellite observed smoke on May 26, 1998.

Trajectory/smoke Comparison

Click HERE for a comparison of modeled trajectories to satellite observed smoke on May 15, 1998.

Experimental Particulate Forecast Details

Particulate concentration (PM10) (ug/m3) forecast maps based on the forest fires burning in Mexico and Central American are summarized in the table above. Concentrations are given as 6-hourly averages out to 48 hours. The HYSPLIT model is first run for the previous two days using a series of short-term forecasts obtained from NOAA's National Centers for Environmental Prediction (NCEP) Global Avation Model (AVN) to create a residual plume for initialization. Pollutant particles are then tracked and dispersed based on current forecast meteorological fields (out to 48 hours) obtained from NCEP's AVN model using the 0000 or 1200 UTC forecasts.

Calculations are made on a 25 km horizontal resolution concentration grid, The underlying meteorological grid resolution is now 111 km. Fire source locations (hot spots) are obtained from satellite analyses produced by the NOAA/NESDIS Satellite Services Division and by the NOAA/NCEP Hydrological Prediction Center (HPC) . However, a gross estimate of particle emissions is based upon typical forest fire values given by Levine (1994, NASA, Langley Research Center) and other investigators. Pollutant particles are released each hour of the analysis/forecast from each emission grid cell with the appropriate mass, corresponding to the appropriate total point emissions in that cell.

Numerous uncertainties exist in these forecast products including the current fire sizes and locations, and the relatively coarse horizontal and vertical resolution of the AVN meteorological model forecast fields. Also, the model is not initialized with older smoke (greater than 2 days old) which may have travelled far beyond the source area. Therefore, these predictions can only be used as a general tool for assessing the movement of new smoke. We hope to have more understanding of the model uncertainties as the results are evaluated.

Forecast Trajectory Details

CAUTION - Trajectory origins are on a 2 x 2 degree latitude-longitude grid. There may or may not be fires at these origins.

Isobaric forecast trajectories are computed using the current NOAA NCEP global Medium Range Forecast (MRF) model output. The MRF is initialized at NCEP once a day (00 UTC). The 48-h trajectory forecasts begin daily at 12 UTC through the duration of the MRF data for three altitudes, 750 m, 1500 m, and 3000 m AGL.