HR: 0800h
AN: C31A-0277    [Abstracts]
TI: Measuring and Modeling Snow Accumulation, Movement, and Ablation in Colorado Shrublands
AU: * Hiemstra, C A
EM: hiemstra@atmos.colostate.edu
AF: Department of Atmospheric Science, 1371 Campus Delivery Colorado State University, Fort Collins, CO 80523 United States
AU: Liston, G E
EM: liston@atmos.colostate.edu
AF: Department of Atmospheric Science, 1371 Campus Delivery Colorado State University, Fort Collins, CO 80523 United States
AU: Strack, J E
EM: jstrack@atmos.colostate.edu
AF: Department of Atmospheric Science, 1371 Campus Delivery Colorado State University, Fort Collins, CO 80523 United States
AU: Elder, K
EM: kelder@fs.fed.us
AF: USDA Forest Service, Rocky Mountain Research Station , 240 West Prospect RD , Fort Collins, CO 80526 United States
AB: Basin shrublands, featuring {\it Artemisia tridentata} and {\it Sarcobatus vermiculatus} shrubs accompanied by various graminoids, are widespread constituents of intermountain western U.S. landscapes. These shrublands are characterized by spatially heterogeneous winter snow covers interrupted by transient melting periods. The spatial heterogeneity of snow in shrubland landscapes is determined by interactions among topography, wind, net radiation, and vegetation structure (shrub vs. graminoid canopy dominants). Transient melting periods are typically produced by intermittent warm and dry phases where snow melts over much of the landscape, especially in wind-scoured grassy areas where snow depths are relatively shallow. Because snow is an important factor in the annual water and energy budgets of shrublands, it is important to quantify and understand snow accumulation, movement, and ablation processes in these landscapes. We employed snow depth observations and a snow evolution modeling system (SnowModel) to quantify and simulate snow depths in North Park, an intermountain basin in Colorado. Observations and simulations focused on a 0.25 km$^{2}$ study area centered on a 34 m tall meteorological tower deployed for the FLuxes Over Snow Surfaces (FLOSS) project (http://www.atd.ucar.edu/rtf/projects/floss/). Snow observations were measured along a series of transects, extending 400-600 m upwind of the tower, every 10 days from late December 2002 to late March 2003. The transects were designed to capture snow characteristics within shrub and graminoid cover types. Further, observations were used to parameterize and validate SnowModel. Hourly model simulations were performed from 1 October 2002 to 1 April 2003 using topographic, meteorological, and vegetation distribution data for the domain. Observed and modeled snow characteristics are described. Over 30,000 snow depth observations were collected during the field season. Snow cover in graminoid-dominated areas was shallow, less variable, and ablated quickly. In contrast, shrubs accumulated deeper, more variable snow depths that persisted longer. Model simulations were compared with these observations and indicated that the model reproduces the seasonal characteristics of snow in this system. Model similarities and deviations from observed values are detailed and related to potential refinements in our approach, scale issues, and driving data.
DE: 3322 Land/atmosphere interactions
DE: 1863 Snow and ice (1827)
SC: Cryosphere [C]
MN: 2004 AGU Fall Meeting