Using MODIS estimates of fractional snow cover area to improve streamflow forecasts in interior Alaska

Journal Article · 21 May 2019 · Hydrology and Earth System Sciences (Online)

DOI: https://doi.org/10.5194/hess-23-2439-2019 · OSTI ID:1525817

Bennett, Katrina E.  ^[1]; Cherry, Jessica E. ^[2]; Balk, Ben ^[3]; Lindsey, Scott ^[4]

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1. Univ. of Alaska, Fairbanks, AL (United States); Los Alamos National Lab. (LANL), Los Alamos, NM (United States)
2. Univ. of Alaska, Fairbanks, AL (United States); Alaska Pacific River Forecast Center, Anchorage, AL (United States)
3. Deltares USA, Silver Spring, MD (United States)
4. Alaska Pacific River Forecast Center, Anchorage, AL (United States)

Remotely sensed snow cover observations give an opportunity to improve operational snow melt and stream flow forecasting in remote regions. This is particularly true in Alaska, where remote basins and a spatially and temporally sparse gaging network plague efforts to understand and forecast the hydrology of subarctic boreal basins and where climate change is leading to rapid shifts in basin function. In this study,the operational framework employed by the United States (US) National Weather Service, including the Alaska Pacific River Forecast Center, is adapted to integrate Moderate Resolution Imaging Spectroradiometer (MODIS) remotely sensed observations of fractional snow cover area (fSCA) to determine if these data improve streamflow forecasts in interior Alaska river basins. Two versions of MODIS fSCA are tested against a base case extent of snow cover derived by aerial depletion curves: the MODIS 10A1(MOD10A1) and the MODIS Snow Cover Area and Grain size (MODSCAG) product over the period 2000–2010. Observed runoff is compared to simulated runoff to calibrate both iterations of the model. MODIS-forced simulations haveimproved snow depletion timing compared with snow telemetry sites in the basins, with discernable increases in skill for the streamflow simulations.The MODSCAG fSCA version provides moderate increases in skill but is similar to the MOD10A1 results. The basins with the largest improvement in streamflow simulations have the sparsest streamflow observations.Considering the numerous low-quality gages (discontinuous, short, or unreliable) and ungauged systems throughout the high-latitude regions of the globe, this result is valuable and indicates the utility of the MODIS fSCAdata in these regions. Additionally, while improvements in predicted discharge values are subtle, the snow model better represents the physical conditions of the snow pack and therefore provides more robust simulations,which are consistent with the US National Weather Service's move toward a physically based National Water Model. Physically based models may also be more capable of adapting to changing climates than statistical models corrected to past regimes. This work provides direction for both the Alaska Pacific River Forecast Center and other forecast centers across the US to implement remote-sensing observations within their operational framework, to refine the representation of snow, and to improve streamflow forecasting skill in basins with few or poor-quality observations.

• Research Organization: Los Alamos National Lab. (LANL), Los Alamos, NM (United States)
• Sponsoring Organization: USDOE Office of Science (SC), Biological and Environmental Research (BER) (SC-23)
• Grant/Contract Number: 89233218CNA000001
• OSTI ID: 1525817
• Report Number(s): LA-UR--18-21603
• Journal Information: Hydrology and Earth System Sciences (Online), Journal Name: Hydrology and Earth System Sciences (Online) Journal Issue: 5 Vol. 23; ISSN 1607-7938
• Publisher: European Geosciences Union (EGU)Copyright Statement
• Country of Publication: United States
• Language: English