Detecting Smoke from Forest Fires Using USDA Shadow-band Radiometers James Slusser USDA UV-B Monitoring and Research Program Natural Resource Ecology Laboratory Colorado State University

Purposes of USDA UVB Monitoring and Research Program Furnishes basic information necessary to support research on potential damaging effects of UVB on agriculture, forests, and livestock Provides UV climatology data to agricultural and scientific researchers Supplies ground truth for satellite retrievals and model development Establishes long-term record of UVB to assess trends

Quebec Fires, 7 July 2002

SeaWIFS image 7 July 2002 showing USDA sites

Three measures of aerosol and smoke loading are: Aerosol optical depth (AOD) quantifies the attenuation of the direct Solar beam. The AOD is proportional to total column loading of particles of the same size. Angstrom exponent gives the wavelength dependence of the AOD. Large particles (such as cloud drops or ice crystals) are spectrally neutral (alpha close to 0). The very smallest particles, molecules, have an inverse (wavelength) to the fourth dependence (alpha equal to 4). Most aerosols have alpha between 1 and 3. Single scattering albedo is the ratio of scattering to scattering plus absorption. For non absorbing particles it equals 1.0.

Effects of thick urban haze on irradiances Model no aerosols Beltsville, MD July 17, 1999

Non- absorbing aerosols

TOMS Aerosol Index for May 15, 1998

Effects of thick smoke on 368 nm UV irradiances Baton Rouge, LA May 15, 1998

Absorbing aerosols

Direct Diffuse Total Direct to diffuse ratio

Begin Beltsville Slides

Beltsville, MD

Begin New York Slides

Begin Colorado Slides

18 June 2002

Langley Calibration

Logistics Basic cost around $12,500 Requires 110 VAC and phone line OR batteries and memory card Can be polled in real time as Web site Calibration is established in situ during clear days Wind and ancillary instruments can be logged as well USDA would be willing to assist with data analysis on a per cost basis

Conclusions 1.Visible Shadow-band radiometers provide aerosol and cloud information critical to forest fire air quality studies. 2.Low cost ($12.5K) and automated operation are attractive features. 3.This method provides fine temporal resolution useful for studying smoke plumes. 4.Ancillary information (e.g. T, RH, wind speed and direction) can be logged simultaneously. 5.USDA would be glad to work with USFS on data analysis.