Ground and Satellite Observations (2005-2011): Senator Beck Basin, Southwestern Colorado

The Center for Snow and Avalanche Studies (CSAS; www.snowstudies.org) provides ground-based observations of temperature, relative humidity, snowpack depth, and longwave downward flux in the San Juan Mountains, at the Senator Beck Study Plot (37.9°N - 107.725°W at 3719 m, in alpine tundra) and Swamp Angel Study Plot (37.9°N - 107.711°W at 3368 m, in a sub-alpine meadow). The longwave fluxes are measured with a Kipp and Zonen model CG4 pyrgeometer, which has a 180º field of view. The CG4 is designed to minimize the effects of window heating in direct sunlight, during daylight measurements. The air temperature and relative humidity are measured with a Campbell-Vaisala model CS500-U Humitter®. All measurements are obtained every 5 seconds and available as hourly averages during the period 2005-2010.The data are archived and described on: http://www.snowstudies.org/ Here we compiled the data into single ncdf files per site for the entire period of operation. In addition, we collected NASA-MODIS cloud product observations (MOD06 and MYD06) files, namely cloud fraction and cloud optical thickness and created a new file for the Senator Beck study plot, where coincident ground and satellite observations are selected. This new dataset is a subset of the ground observations only files. 1. Hourly Ground Based Data From Two Plots: Senator Beck and Swamp Angel Study Plots These are hourly observations from the two plots between 2005-2011. In addition, a few other variables were estimated. These include: specific humidity (based on relative humidity, temperature and pressure), upward longwave radiation (based on soil surface temperature), surface pressure for Senator Beck plot (from surface pressure at Swamp Angel plot), and cloud mask (based on solar radiation). Please see the "Readme" file provided for each data file for a detail description of the data content. 2. Ground and Satellite Data: Senator Beck Plot only This data include only the coincident hourly observations from ground and satellite (MODIS) at the Senator Beck site. Therefore, there are generally two observations per day. Day and night flag is also assigned to the data. The satellite observations included here are: (1) cloud fraction and (2) cloud optical depth (during overcast conditions only)