Monitoring lake ice seasons in southwest Alaska with MODIS images
Spencer P, Miller AE, Reed B, Budde M. 2008. Monitoring lake ice seasons in southwest Alaska with MODIS images. In Pecora 17 Conference: The Future of Land Imaging… Going Operational. Denver, Colorado. November 16 to 20, 2008
Impacts of global climate change are expected to result in greater variation in the seasonality of snowpack, lake ice, and vegetation dynamics in southwest Alaska. All have wide-reaching physical and biological ecosystem effects in the region. We used Moderate Resolution Imaging Spectroradiometer (MODIS) Rapidfire browse images, snow cover extent, and vegetation index products for interpreting interannual variation in the duration and extent of snowpack, lake ice, and vegetation dynamics for southwest Alaska. The approach integrates multiple seasonal metrics across large ecological regions. The general annual pattern of the lake ice season in southwest Alaska begins as water cools when fall storms sweep in from the North Pacific. Ice forms on high altitude or small lakes by Oct/Nov, with larger lakes usually freezing over by Dec/Jan. Warm mid-winter storms often hit the study area, bringing wind, rain and melting temperatures that result in several inches of water on the ice or partial break-up of the ice pack. The return of cold, still Arctic high pressure refreezes the lakes until spring break-up in April and May. Throughout the observation period (2001–2007), snow cover duration was stable within ecoregions, with variable start and end dates. The start of the lake ice season lagged the snow season by 2 to 3 months. Within a given lake, freeze-up dates varied in timing and duration, while break-up dates were more consistent. Vegetation phenology varied less than snow and ice metrics, with start-of-season dates comparatively consistent across years. Higher than average temperatures during the El Niño winter of 2002-2003 were expressed in anomalous ice and snow season patterns. We are developing a consistent, MODIS-based dataset that will be used to monitor temporal trends of each of these seasonal metrics and to map areas of change for the study area.
- Type
- Conference Proceeding Paper
- Authors
- Spencer, Page; Miller, Amy; Reed, Bradley; Budde, Michael
- Units
- SWAN
- Keywords
- lake ice, Moderate Resolution Imaging Spectroradiometer, MODIS, remote sensing, snow cover, vegetation dynamics
- Subjects
- Ecological Framework: Air and Climate | Weather and Climate | Weather and Climate , Ecological Framework: Geology and Soils | Geomorphology | Lake Features and Processes , Ecological Framework: Biological Integrity | Focal Species or Communities | Vegetation Complex