Regional influence of ocean–atmosphere teleconnections on the timing and duration of MODIS-derived snow cover in British Columbia, Canada

Alexandre R Bevington,William C Floyd,Vanessa N Foord,Hardy P Griesbauer,Hunter E Gleason

doi:10.5194/tc-13-2693-2019

Alexandre R Bevington, William C Floyd + Show 3 more

Open Access

https://doi.org/10.5194/tc-13-2693-2019

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Abstract

Abstract. We use the twice-daily Moderate Resolution Imaging Spectroradiometer (MODIS) snow cover product to study the regional influence of the Oceanic Niño Index (ONI) and Pacific Decadal Oscillation (PDO) on snow cover in British Columbia (BC). We apply a locally weighted regression (LOWESS) interpolation to the MODIS normalized difference snow index (NDSI) time series to detect the timing and duration of snow. We confirm the general consensus from many previous in situ studies that both ONI and PDO have significant impacts on snow cover in BC. We add to this knowledge by performing seasonal and regional analysis using established hydrozones and explore variation in our results by elevation bins of 500 m. We calibrated our method with in situ snow water equivalent (SWE) data and found an optimal NDSI threshold of 30 for detecting continuous snow cover. We separate automatic snow weather station data into calibration (75 %) and validation (25 %) subsets and obtain mean absolute errors between the MODIS and in situ observations for the start, end, and duration of 8.7, 8.9, and 13.1 d for the calibration data and 12.7, 12.6, and 16.6 d for the validation data, respectively. In general, the start date of snow is poorly correlated with both ONI and PDO, whereas the end date and duration are strongly negatively correlated. Regional patterns emerge wherein northern and southern BC are most correlated with the PDO and the ONI, respectively. These relationships are generally stronger at lower elevations and vary spatially. This study demonstrates that the suitability of ocean–atmosphere teleconnections as predictors of the timing and duration of snow varies throughout BC.

Highlights

The timing and duration of seasonal snow cover have been shown to influence a number of landscape processes, namely soil moisture and drought (e.g., Fang and Pomeroy, 2008), wildfire activity and intensity (e.g., Westerling et al, 2006), freshwater availability (e.g., Barnett et al, 2005), flooding (e.g., Barnett et al, 2005), plant ecology (e.g., Jonas et al, 2008), and wildlife behavior (e.g., Boelman et al, 2019)
Using the remaining 25 % of the ASWSs, which we use as a validation dataset, we find bias-corrected mean absolute error (MAE) of 12.7, 12.6, and 16.6 d for SDON, SDOFF, and SDDUR, respectively (Fig. 5)
The main objective of this study was to evaluate the suitability of using daily M*D10A1 imagery to understand the regional influence of ocean–atmosphere teleconnections on SDON, SDOFF, and SDDUR in British Columbia (BC), a region of nearly 1 million km2 with a low density of snow observations

Summary

Introduction

The timing and duration of seasonal snow cover have been shown to influence a number of landscape processes, namely soil moisture and drought (e.g., Fang and Pomeroy, 2008), wildfire activity and intensity (e.g., Westerling et al, 2006), freshwater availability (e.g., Barnett et al, 2005), flooding (e.g., Barnett et al, 2005), plant ecology (e.g., Jonas et al, 2008), and wildlife behavior (e.g., Boelman et al, 2019). The winter snowpack differs in timing and duration throughout the province and is influenced by, among other processes, climate change Bevington et al.: Timing of snow cover in British Columbia

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