August 1, 2011.
Snowpack in the arid/semi-arid western United States is a critical element of the hydrologic cycle as water is stored in the winter and released in the spring and summer. The warmer seasons rely heavily on this water source for various purposes including economic (farming), environmental and recreational demands. Moderate Imaging Spectroradiometer (MODIS) sensors were used in this project to measure seasonal variability in global vegetation phenology and productivity. MODIS data was used to calculate Normalized Difference Vegetation Index (NDVI) to estimate net primary production of subalpine forests in the Sierra Nevada mountain range. Preliminary results indicate that variability in forest greenness is related to water availability. In this regard, the potential utility of MODIS-based reconstructed snow water equivalent (SWE) to evaluate controls on forest water stress was assessed. Future satellite missions (e.g. SMAP) aimed at detecting soil moisture will provide further insight into snowpack controls on the ecology of sub-alpine forests. In this regard, in situ sensors were combined with remotely sensed observations to improve our understanding of the terrestrial water balance and link snowpack quantities to vegetation water stress. We found that snow disappearance timing is well correlated with peak soil moisture. Future efforts will utilize these data to reveal spatial consistencies between snow ablation and soil dry down rates.
Biogeochemistry | Hydrology
Dr. Noah Molotch
NASA Jet Propulsion Laboratory (JPL)
This material is based upon work supported by the S.D. Bechtel, Jr. Foundation and by the National Science Foundation under Grant No. 0952013. Any opinions, findings, and conclusions or recommendations expressed in this material are those of the authors and do not necessarily reflect the views of the S.D. Bechtel, Jr. Foundation or the National Science Foundation.