Evaluation of GOES Satellite Data for use in the Grassland Fire Danger Index Journal of Operational Meteorology

Determining fire fuel status remains a challenge across the Great Plains of the United States, where grasses and shrubs are the primary land covers and fuels for fires. This study compared two methods of estimating the Curing Index, an indicator of the moisture level of vegetation, that is included in the Grassland Fire Danger Index (GFDI): i) a satellite method using data acquired by the Geostationary Operational Environmental Satellite (GOES) Advanced Baseline Imager and ii) a method using a Growing Season Index (GSI) that includes observed meteorological conditions to estimate plant growth. Curing Index (CI) values were calculated for 2021 and 2022 at 47 Remote Automated Weather Stations (RAWS) that had dominant land cover types of either grassland or shrubland vegetation. Differences in the Curing Index of >50% were observed at various times from spring through autumn between the two methods. Differences in Curing Index between the two methods resulted in differences in GFDI, which changed the fire danger rating category within the National Fire Danger Rating System. The greatest differences in grassland and shrubland GFDI values included greater values of GFDI in the summer months when GSI was used to compute the CI. Also, during both years, the CI computed with the GSI displayed an autumn green-up during a dry early autumn that was not observed by satellite data. The early autumn green-up displayed by the GSI-based CI, when vegetation is normally in senescence, was attributed to a decrease in the vapor pressure deficit component of the GSI.