Through GSL research, the Rapid Refresh (RAP) and the High-Resolution Rapid Refresh (HRRR) models now use satellite data and chemistry to calculate fire size and biomass burning emissions to predict the height of smoke plumes and their subsequent spread. The HRRR smoke field improves low-visibility forecasts in areas impacted by wildfires.
RAP and HRRR are the first models in the U.S. to forecast smoke’s impact on a number of weather variables. Based on satellite observations of fire location and intensity, HRRR predicts the movement of smoke in three dimensions across the country over 48 hours, simulating how the weather will impact smoke movement and concentrations, also how smoke will affect visibility, temperature, and wind. HRRR is valuable for notifying those downwind of a fire about what is heading their way.
Wildfire managers may move or redeploy crews based on where heavy smoke will be. Community leaders want to know how much smoke will affect their residents and public health managers can prepare for potential health impacts on their community. During wildfires, first responders and air traffic controllers rely on HRRR to assess visibility. Fire crews consult it when deciding where to pitch base camps or to stage resources. And after a fire passes through, EPA crew workers use it to determine whether the smoke has lifted enough to travel to burned areas to clean up hazardous waste.
The HRRR-Smoke project was initiated by the JPSS program to address the needs of the Western NWS offices.
Central to HRRR-Smoke is an important metric called fire radiative power, or FRP. Fire radiative power is a measurement of the amount of heat released by a given fire, in megawatts, detected with the VIIRS instruments on Suomi-NPP and NOAA-20. A large fire, for example, might reach about 4,000 megawatts per pixel. Calculating a fire’s heat or intensity also helps scientists pinpoint its location. The model combines this FRP data with wind speed, rain, and atmospheric temperature, along with information from vegetation maps. Sagebrush burns differently than a ponderosa pine, and the more the scientists know about what’s burning, the better the simulations.
These measurements are mapped to a three-dimensional grid that extends nearly 16 miles into the atmosphere. What results is a detailed forecast of the amount of smoke produced, the direction it’s traveling, and its plume height. HRRR-Smoke spits out 18 hour forecasts every hour, and four times a day, extends out to 48hours.
The forecasts are visualized as two plots: “Near-surface smoke” refers to the smoke about 26 feet from the ground, the kind responsible for burning eyes and worsening asthma. “Vertically integrated smoke” is all of the smoke in a vertical column, including smoke high in the Earth’s atmosphere. That’s the smoke you see at sunrise and sunset.
GSL participates in the global community development of WRF-Chem, a next-generation coupled weather/air quality numerical prediction system based on the Weather Research and Forecasting (WRF) model. Gas-phase chemistry and aerosol processes are tightly coupled to meteorology with the WRF model structure. WRF-Chem has a large international user base. (Jordan Schnell)
GSL was part of the team that developed the Global Ensemble Forecast System - Aerosols (GEFS-Aerosols) model. GEFS-Aerosols is an atmospheric composition model that integrates weather and air quality forecast to produce week-long forecasts of aerosol components including wildfire smoke, soot, organic carbon, particulate sulfate, dust, sea salt, and volcanic ash. This model was implemented into NOAA operations on September 23, 2020 and is the culmination of a successful 5-year collaborative effort between OAR< NWS, and NESDIS to bring together NOAA's atmospheric composition research and transition these innovations into operational forecasts.