Evaluating the Atmosphere–Land Exchange Inverse Evaporative Stress Index for the Alaskan Environment to Determine Wildfire Likelihood

Alaska’s wildfire season has progressively increased in duration and intensity over the last decade, leaving forested areas subject to devastating destruction. These increases in wildfire occurrence are due to gradual rises in land surface temperature, decreases in precipitation levels, and lack of soil moisture throughout the state. This causes concerns for air pollution as well as the destruction of homes and wildlife habitats within or around forests. The Alaska Disasters project team used remotely sensed data obtained from Aqua Moderate Resolution Imaging Spectroradiometer (MODIS), Terra MODIS, Suomi National Polar-orbiting Partnership (NPP) Visible Infrared Imaging Radiometer Suite (VIIRS), and National Oceanic and Atmospheric Administration-20 (NOAA-20) VIIRS from April through September of 2004, 2005, 2015, and 2018 to observe vegetation and moisture changes in affected areas before and after wildfires. Using the Atmosphere-Land Exchange Inverse (ALEXI) Evaporative Stress Index (ESI) generated by the NASA Short-term Prediction Research and Transition Center (SPoRT), the team determined that the ALEXI ESI provided lead time on the evaluation of vegetation stress when compared to MODIS products. The team members completed this analysis by using Pearson’s correlation coefficient to determine that the correlation between the ALEXI ESI output and various vegetation monitoring indices were low, suggesting that the ALEXI ESI is identifying areas of stressed vegetation where the plant is still green. The team then compared the utility of the ALEXI ESI to the Canadian Fire Weather Index (FWI) to evaluate the benefit of using ALEXI ESI in conjunction with current decision-making processes in Alaska.