The Challenge of Estimating Precipitation on Alaska's North Slope
| Jessica Cherry | International Arctic Research Center |
| Mark Ivey | Sandia National Laboratories |
| Jeffrey Zirzow | Sandia National Laboratories |
| Sutanay Choudhury | Pacific Northwest National Laboratory |
Category: Instruments
Snow on the Tundra in Barrow, Alaska. Photo by J. Cherry
Sparse observations, cold temperatures, and high winds make estimation of precipitation in Northern Alaska particularly challenging. Long-term monitoring of precipitation at Barrow and other North Slope stations has depended on gauges that are susceptible to systematic measurement biases. These undercatch biases are caused by deformation of the boundary layer atmosphere by the gauge itself in the form of turbulence and are directly proportional to wind speed. Solid precipitation is far more susceptible to the undercatch problem than is liquid precipitation because of the difference in wind resistance of a liquid drop versus a frozen flake. The World Meteorological Organization sponsored the Solid Precipitation Gauge Intercomparison Project for which Barrow was a test site. Several gauges were installed there alongside a Double Fenced Intercomparison Reference (DFIR) and statistical corrections were developed to correct for undercatch biases. Unfortunately, there are still several unsystematic biases for which it is difficult to correct statistically including unrepresentative siting of the gauge and mechanical failure. These shortcomings have motivated the authors to continue to seek new technologies for estimation of solid precipitation in the Arctic. The authors are testing a new solid precipitation sensor at Barrow, the Total Precipitation Sensor (TPS), which represents a departure from the gauge approach. The TPS was installed at the ARM Climate Research Facility in Barrow after testing and evaluation in Fairbanks. This device is designed to overcome the biases associated with gauges. Measurement of snowfall at Barrow is continued with standard gauges as well as the DFIR. The National Oceanic and Atmospheric Administration (NOAA) also maintains a new gauge there, the Geonor, on an experimental basis. A team of researchers from the University of Alaska Fairbanks and the Cold Region Research Lab has installed a state-of-the-art snow research station at the Barrow Environmental Observatory including a solid-state snow pillow (for measurement of snow water equivalent), ultrasonic depth sensors, and a Wyoming snow gauge. Estimation of the solid precipitation at Barrow is important for our basic understanding of the water cycle and climate variability on the North Slope and other arctic regions. Understanding the precipitation component of the climate system is also important for ongoing monitoring and intensive observational campaigns conducted at the ARM Climate Research Facility in Barrow.
http://www.iarc.uaf.edu/highlights/2007/northern_alaska_1/index.php
This poster will be displayed at ARM Science Team Meeting.
