Using Spectral Indices To Determine the Effects of the Summer 2021 North American Heat Wave at Mount Rainier, Washington

Abstract

Quality of life at Mount Rainier and the surrounding region is dependent on annual snowpack and subsequent snowmelt. Winter storm observations, snowpack, and the rate of snowmelt all play critical roles in determining the health of the environment. To help analyze these factors, users and consumers rely on remotely sensed data to analyze the past, present, and future of the area. The Normalized Difference Snow Index (NDSI) and Normalized Difference Vegetation Index (NDVI), collected from satellite imagery, are two spectral indices used with analyzing snowpack and vegetation health to assist risk mitigation for wildfires, glacial change, and river ecosystems. This project used NDSI and NDVI to determine if the 2021 North American heat wave had any significant effects on vegetation health, snowpack, and glacial size over a five-year study period. Landsat 8 satellite imagery was acquired, corrected for any atmospheric bias, and processed through GIS techniques. Despite yearly fluctuation of warmer and cooler years, results show a progressive increase in snowmelt with 2021 showing the highest percentage during the study period and the highest differential from the mean of all years in the study. Vegetation labeled as “Healthy” saw the biggest decrease between consecutive years from 2020-2021. Also in 2021, Mount Rainier saw its glaciers recede to their lowest total area since 2005. Conclusions show that general warming trends are occurring in the Pacific Northwest and the heat wave exacerbated total glacial area, total snow area, and vegetation health. This Masters project contributes to future extreme weather anomalies and related results.