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Kelly Elder, Don Cline, Glen E. Liston, and Richard Armstrong

1. Introduction Snowpack measurements have been taken in North America for nearly 100 years, with the objective of increasing our ability to forecast runoff from snow-covered regions. Point measurements have been the norm, although short transects from snow courses provide a limited representation of the variability of the spatial nature of snow water equivalent (SWE). The snowpack telemetry (SNOTEL) system of the Natural Resources Conservation Service (NRCS) gives regional SWE information in a

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Glen E. Liston, Daniel L. Birkenheuer, Christopher A. Hiemstra, Donald W. Cline, and Kelly Elder

Abstract

This paper describes the Local Analysis and Prediction System (LAPS) and the 20-km horizontal grid version of the Rapid Update Cycle (RUC20) atmospheric analyses datasets, which are available as part of the Cold Land Processes Field Experiment (CLPX) data archive. The LAPS dataset contains spatially and temporally continuous atmospheric and surface variables over Colorado, Wyoming, and parts of the surrounding states. The analysis used a 10-km horizontal grid with 21 vertical levels and an hourly temporal resolution. The LAPS archive includes forty-six 1D surface fields and nine 3D upper-air fields, spanning the period 1 September 2001 through 31 August 2003. The RUC20 dataset includes hourly 3D atmospheric analyses over the contiguous United States and parts of southern Canada and northern Mexico, with 50 vertical levels. The RUC20 archive contains forty-six 1D surface fields and fourteen 3D upper-air fields, spanning the period 1 October 2002 through 31 September 2003. The datasets are archived at the National Snow and Ice Data Center (NSIDC) in Boulder, Colorado.

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Kelly Elder, Angus Goodbody, Don Cline, Paul Houser, Glen E. Liston, Larry Mahrt, and Nick Rutter

above the ground surface. Lower-level measurements were collected 2–4 m above ground level, depending on anticipated maximum snow depth. Lower measurements were made at 2 m above ground level in the North Park mesocell study area (MSA; shallow and transient snowpacks), 3 m above ground level in the Fraser MSA (moderate snowpacks), and 4 m above ground level in the Rabbit Ears MSA (deep snowpacks). Air temperature, relative humidity, wind speed, and wind direction were measured at 10 m and at the

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Glen E. Liston, Christopher A. Hiemstra, Kelly Elder, and Donald W. Cline

covered three 25 km × 25 km areas in north-central Colorado ( Fig. 1 ). Each MSA was chosen because it represented a distinct cold region physiographic regime, as defined by the area’s topography, forest cover, meteorology, and snow characteristics. Nested within each of these MSAs were three 1 km × 1 km intensive study areas (ISAs). Snow-related observations for the ISAs included ground-based snow depth and density measurements ( Elder et al. 2008a ). Snow observations for the MSAs included airborne

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Glen E. Liston and Christopher A. Hiemstra

) used it to grid snow depths and SWE over North America. At the next level of complexity are data assimilation schemes that use methods such as the various adaptations of Kalman filters ( Gelb 1974 ; Evensen 1994 ), which account for relative observation and model-simulation uncertainty. Sun et al. (2004) used an extended Kalman filter to assimilate SWE observations for land surface model initial conditions. Slater and Clark (2006) used an ensemble Kalman filter to improve SWE estimates in

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Robert E. Davis, Thomas H. Painter, Rick Forster, Don Cline, Richard Armstrong, Terry Haran, Kyle McDonald, and Kelly Elder

measurement swaths of 1400 (inner beam) and 1800 km (outer beam), covering approximately 70% of the earth on a daily basis and 90% global coverage every 2 days. Overlapping orbit tracks at higher latitudes improves SeaWinds temporal coverage. For the CLPX, SeaWinds backscatter was compiled as a daily product. Data for the CLPX are provided as gridded daily backscatter measurements, in American Standard Code for Information Interchange (ASCII) files compiled monthly. Data are provided from ascending and

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Nick Rutter, Don Cline, and Long Li

1. Introduction Snow is an important component of the global water and energy cycles, and in many regions is vital to both health and commerce. Annual maximum snow cover, including supraglacial snow, can exceed 4.3 × 10 6 km 2 (∼55% of land area) in the conterminous United States, 15.5 × 10 6 km 2 (∼74%) in North America ( Frei et al. 1999 ), and 52.5 × 10 6 km 2 (∼35%) globally ( NSIDC 2005 ). Numerical models that accurately simulate snowpack energy and mass-balance processes are

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John Pomeroy, Chad Ellis, Aled Rowlands, Richard Essery, Janet Hardy, Tim Link, Danny Marks, and Jean Emmanuel Sicart

. 1975 ), productivity ( Eagleson 2002 ), and stage of succession ( Ross et al. 1986 ; Parker et al. 2002 ). It is possible to link the canopy transmittance of shortwave radiation to laser remote sensing observations of forest structure ( Parker et al. 2002 ). For discontinuous stands, shortwave irradiance into gaps and the north edge of gaps (in the Northern Hemisphere) is much greater than that under more shaded parts of the canopy ( Satterlund 1983 ). The previously cited literature suggests the

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D. Marks, A. Winstral, G. Flerchinger, M. Reba, J. Pomeroy, T. Link, and K. Elder

1. Introduction Water from melting snow is a critical resource in western North America and other similar regions of the world. Across the intermountain western United States, most of the landscape is arid or semiarid, receiving less than 30 cm of annual precipitation. About 15% of the land area is above 2000 m, and it generally receives substantially more annual precipitation, 70%–90% of which has historically fallen as snow ( Anderson et al. 1976 ). The seasonal snow cover has acted as a

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Rafał Wójcik, Konstantinos Andreadis, Marco Tedesco, Eric Wood, Tara Troy, and Dennis Lettenmeier

sites, we used hourly precipitation data based on 1/8th degree (∼12 km) hourly merged gauge–radar precipitation product available from the North American Land Data Assimilation System (NLDAS). Driven by the above mentioned meteorological forcings, VIC was integrated with the time step of 1 h at both FA and FHQ sites. The three SEMs described in section 3 were then forced with the ground temperature, snow temperature, depth, density, and grain size from VIC. The estimates of T b were obtained for

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