DOI: 10.5061/dryad.d51c5b06j
title: Data from: Smoke-driven changes in photosynthetically active radiation during the U.S. agricultural growing season

description: Wildfire smoke is frequently present over the U.S. during the agricultural
 growing season and will likely increase with climate change. Studies of
 smoke impacts have largely focused on air quality and human health;
 however, understanding smoke’s impact on photosynthetically active
 radiation (PAR) is essential for predicting how smoke affects plant
 growth. We compare surface shortwave irradiance and diffuse fraction (DF)
 on smoke-impacted and smoke-free days from 2006-2020 using data from
 multifilter rotating shadowband radiometers at ten U.S. Department of
 Agriculture (USDA) UV-B Monitoring and Research Program stations and smoke
 plume locations from operational satellite products. On average, 20% of
 growing season days are smoke-impacted, but smoke prevalence increases
 over time (r = 0.60, p &lt; 0.05). Smoke presence peaks in the mid- to
 late growing season (i.e., July, August), particularly over the northern
 Rocky Mountains, Great Plains, and Midwest. We find an increase in the
 distribution of PAR DF on smoke-impacted days, with larger increases at
 lower cloud fractions. On clear-sky days, daily average PAR DF increases
 by 10 percentage points when smoke is present. Spectral analysis of
 clear-sky days shows smoke increases DF (average: +45%) and decreases
 total irradiance (average: -6%) across all six wavelengths measured from
 368-870 nm. Optical depth measurements from ground and satellite
 observations both indicate that spectral DF increases and total spectral
 irradiance decreases with increasing smoke plume optical depth. Our
 analysis provides a foundation for understanding smoke’s impact on PAR,
 which carries implications for agricultural crop productivity under a
 changing climate.
description: This dataset contains information on surface-level
 photosynthetically active radiation, smoke plume location, aerosol optical
 depth, and cloud fraction from four publicly available sources:
 U.S. Department of Agriculture's UV-B Monitoring
 and Research Program (UVMRP) National Oceanic and
 Atmospheric Administration/National Enviromental Satellite, Data, and
 Information Service's Hazard Mapping System (HMS) Smoke
 Product National Aeronautics and Space
 Administration's Multi-Angle Implementation of Atmospheric Correction
 (MAIAC) Land Aerosol Optical Depth Product (MCD19A2)
 National Aeronautics and Space Administration's Moderate
 Resolution Imaging Spectroradiometer (MODIS) Atmosphere L3 Daily Product
 (MOD08_D3, MYD08_D3) The dataset covers 10
 UVMRP stations located across the contiguous U.S.: 
 Davis, California Pullman,
 Washington Pawnee, Nunn, Colorado
 Poplar, Montana Fargo, North
 Dakota Billings, Oklahoma Grand
 Rapids, Minnesota Bondville, Illinois
 Starkville, Mississippi Geneva, New
 York These sites were selected to provide
 broad spatial coverage of the regions analyzed in the Brey et al. (2018)
 smoke climatology, capture much of the smoke variability across the U.S.,
 align with agricultural areas, and reduce the impact of metropolitan air
 pollution. The UVMRP staff were instrumental in providing the underlying
 UVMRP data and advise on working with the data. Extensive cleaning was
 conducted to remove data anomalies, quality control issues, and high solar
 zenith angles (&gt; 75 degrees). Additional processing of underlying
 records created additional factors, such as average diffuse fraction, used
 for analysis. We also averaged values to a daily resolution.
 A detailed description of the site selection, data cleaning, and
 data processing methods used to produce this final merged dataset are
 available in the article by Corwin et al. entitled "Smoke-driven
 changes in photosynthetically active radiation during the U.S.
 agricultural growing season."