TITLE: Arctic Transitions in the Land-Atmosphere System Environmental Climate Data AUTHOR: Dr. Larry D. Hinzman Water and Environmental Research Center Institute of Northern Engineering University of Alaska Fairbanks P.O. Box 755860 Fairbanks, Alaska 99775-55860 Phone: (907) 474-7331 FAX: (907) 474-7979 e-mail: ffldh@uaf.edu FUNDING SOURE AND GRANT NUMBER: Support for this research was provided by the U.S. National Science Foundation under the Arctic Systems Science Programs (Grant Number OPP-9818066). DATA SET OVERVIEW: All the data are from eight climate stations in Alaska that were established as part of the Arctic Transitions in the Land-Atmosphere (ATLAS) research project. Six climate stations are located on the Seward Peninsula, three near Kougarok and three near Council. Two additional climate stations are located on the North Slope of Alaska at Ivotuk. These data are almost continuous from the time of establishment (July 1998 for Ivotuk, March 1999 for Kougarok and July 1999 for Council) through December 2003. The climate stations measure air temperature and relative humidity at several elevations, wind speed at several elevations, wind direction, snow depth, precipitation, and net radiation. The eight stations also measure soil temperature and soil moisture at various depths. Long wave and shortwave radiation data are measured at three sites, one in each main area. In the spring of 1999, three ATLAS climate stations were installed at Kougarok on the Seward Peninsula; one 3 m tower within the burned area of Niagara Creek (K1), one 10 m tower between Niagara Creek and Mauze Gulch (K2), and one 3 m tower in a shrub area in Mauze Gulch (K3). In the summer of 1999, three ATLAS climate stations were installed on the Seward Peninsula near Council - one 3 m tower (C1) in a lowland moss/tussock area that appears to be heavily thermokarsting, one 10 m tower (C2) near the top of a hill in the Melsing Creek drainage representing well drained moss/lichen vegetation, and one 3 m tower (C3) in the Guy Rowe Creek drainage, representing upland tundra. At Ivotuk two 3-meter towers were installed in July of 1998. The first site (moss met site 1) is in a moss/lichen/tussock area, the second site (shrub met site 2) is in a shrub area at Ivotuk. Additional instrumentation was installed, along with replacement of the 3m tower with a 10-meter tower at moss met site 1 in the Spring/Summer of 1999. The Water and Environmental Center ATLAS Project web site address is: http://www.uaf.edu/water/projects/atlas/atlas.html. Site Latitude Longitude Region K1-Kburn 65¦ 26.42' N 164 34.71' W Kougarok K2-Kmet 65¦ 25.70' N 164 38.61' W Kougarok K3-Kmauze 65¦ 27.58' N 164 38.29' W Kougarok C1-Grid 64¦ 50.60' N 163 43.32' W Council C2-Blueberry 64¦ 53.47' N 163 38.61' W Council C3-GuyRowe 64¦ 44.76' N 163 53.61' W Council Moss met site 1 68¦ 28.82' N 155 44.72' W Ivotuk Shrub met site 2 68¦ 29.20' N 155 44.57' W Ivotuk Site Parameters Measured (elevations) K1-Kburn Air temperature and relative humidity (1m,3m) Wind speed and direction (3m) Soil temperature and soil moisture (various depths) Net radiation Precipitation K2-Kmet Air temperature and relative humidity (1m,3m,10m) Wind speed and direction (1m,10m) Soil temperature and soil moisture (various depths) Net radiation Longwave and shortwave radiation Precipitation Snow depth K3-Kmauze Air temperature and relative humidity (1m,3m) Wind speed and direction (3m) Soil temperature and soil moisture (various depths) Net radiation Precipitation C1-Grid Air temperature and relative humidity (1m,3m) Wind speed and direction (3m) Soil temperature and soil moisture (various depths) Net radiation Precipitation Snow depth C2-Blueberry Air temperature and relative humidity (1m,3m,10m) Wind speed and direction (1m,10m) Soil temperature and soil moisture (various depths) Net radiation Longwave and shortwave radiation Precipitation Snow depth C3-GuyRowe Air temperature and relative humidity (1m,3m) Wind speed and direction (3m) Soil temperature and soil moisture (various depths) Net radiation Precipitation Snow depth Moss met site 1 Air temperature and relative humidity (1m,3m,10m) Wind speed and direction (1m,10m) Soil temperature and soil moisture (various depths) Net radiation Longwave and shortwave radiation Precipitation Snow depth Shrub met site 2 Air temperature and relative humidity (1m,3m) Wind speed and direction (1m,3m) Soil temperature and soil moisture (various depths) Net radiation Precipitation Snow depth INSTRUMENT DESCRIPTION: Climate sensors were measured every sixty seconds with hourly averages recorded on a datalogger (Campbell Scientific Inc., CR10X). Soil sensors were measured every 5 minutes. These 5 minute readings were averaged and recorded every three hours. Air temperature and relative humidity were measured using a Vaisala HMP45C sensor. The air temperature sensor had an operating range from -40 C to 60¦C, with an accuracy of ˜ 0.4¦C. The relative humidity sensor had an operating range from 0 - 100% with an accuracy of 2% below 90% and 3% above 90%. Wind speed and direction at 10 meter and 3 meter elevations were measured using a RM Young 05103 wind monitor. The RM Young 05103 had an accuracy of ˜ 0.3 m/s with a threshold velocity of 0.9 m/s and a distance constant of 2.7m for 63% recovery. The wind direction is the unit vector of the mean wind direction with an accuracy of ˜ 3¦; the standard deviation of the wind direction is also recorded. Wind speed at the 1 meter elevation was measured using 3 cup Met One anemometer. The Met one had a threshold velocity of 0.45 m/s, a distance constant of less than 4.5 m and an accuracy of ˜ 0.11 m/s. The recorded wind speed for both the RM Young and Met One sensors was an hourly mean horizontal wind speed. Precipitation was measured using a Texas Electronics TE525MM rain gauge, which measures rainfall in 0.1 mm increments. The gauge had an accuracy of ˜1% for rain events with an intensity of less than 10 mm/hr. Precipitation data was only collected during the summer months. Net radiation was measured using a Frischen type net radiometer, REBS model Q7, with a wind speed dependant dome cooling correction applied. The net radiometers were installed during the summer season only. Incoming and reflected shortwave radiation were measured at three sites (Kougarok K2, Council C2 and Ivotuk moss met site 1) using a pair of pyranometers, model PSP, manufactured by Eppley Inc. Incoming and emitted longwave radiation were measured at the same three sites using a pair of Eppley Inc. pyrgeometers, model PIR. Reliable operation of both the pyranometers and pyrgeometers occurs from May through September; although radiation data may be reported during the winter period, the quality of these data cannot be assured because there is no way to be certain the radiation domes were snow-free. Soil temperatures are measured with Alpha brand thermistors, model 14A5001-C2 in a half bridge configuration with a 15 Kohm resistor with a low temperature coefficient. Soil moisture is measured using a Campbell Scientific CS615 Water Content Reflectometer. The probe outputs a square wave. The period of this wave is recorded and then later converted to soil moisture based on a standard calibration equation. The accuracy of these probes is variable and is described in CSI instrumentation manuals. Snow depths were measured with a Campbell Scientific SR50 Ultrasonic Distance Sensor every three hours. The accuracy of this sensor is ( 1 cm or 0.4% of the distance between the snow surface and the sensor (whichever is greater), with external temperature compensation. DATA COLLECTION AND PROCESSING: Data is collected manually from each site several times per year. Data is initially checked for missing data and out of range values for each parameter measured. Missing data is assigned the value of 7777, and bad data points are assigned the value of 6999. Air temperature, relative humidity, wind speed, wind direction are plotted and examined. Missing and bad data are assigned the appropriate values. Precipitation data is plotted and examined. During the winter, snowfall collects in the rain gauge orifice and subsequently drains into the gauge once the air temperature rises above 0¦C. Precipitation data is plotted with air temperature and precipitation data recorded during the transition from below freezing temperatures to above freezing temperatures is removed. The precipitation data is a measure of rainfall, precipitation that falls as snow is not measured. In each of the three areas (Council, Kougarok and Ivotuk) an intercomparison of measured precipitation is performed. Soil temperatures are recorded at each site as raw resistance values. A resistance temperature curve is used to calculate a corresponding temperature for each raw resistance value. Soil moisture measurements are converted from a raw period measurement to an un-calibrated soil moisture values using a standard calibration equation provided by Campbell Scientific. Shortwave and longwave radiation values are plotted an examined. At sites with longwave, shortwave and net radiation sensors, the net radiation balance is calculated using both long and shortwave sensors and compared to the independently measured net radiation. Snow depth readings are temperature corrected and then smoothed to remove excess noise in the data. DATA FORMAT: Date files are in comma-delimited text format. Each data file contains a header recorded describing the data file. Data are compiled and tabulated in annual data sets for each site. These data are further subdivided into data sets of various types: meteorological, radiation, soil and snow depth. The file naming convention lists the site name first followed by an underscore then the data type followed by another underscore and then finally the year and the '.csv' extension. An example would be C1_met_2001.csv. The header record for each file contains the site name, type of data, latitude, longitude, start of data, end of data, the bad data identifier and missing data identifier. The header record for each file is in the following format: Water and Environmental Research Center, University of Alaska Fairbanks ATLAS Project; Primary Contact; Larry D. Hinzman ffldh@uaf.edu Site: Type of data: ( 4 types: meteorological, soil, radiation, snow depth) Latitude: Longitude: Start: End: 6999 = bad or missing data 7777 = data not recorded The next record in the header of each file are labels for each column of data. The parameters are labeled with corresponding elevation and measurement units. Time is given for each record in Alaska standard time (AKST). The time records were not adjusted for daylight savings time. DATA REMARKS: Generally the quality of the data is thought to be very good. During the late fall, winter and early spring air temperature, relative humidity, wind speed and wind direction sensors can all experience rime ice or freezing precipitation. When this occurs the data collected by these sensors may be adversely affected. The sites are visited approximately every three months and the sensors are cleaned. The soil moisture data is generally considered a relative indicator of soil moisture. A calibration equation was not determined for each individual site, but rather a general equation was used for soils with an electrical conductivity of less than 1.0 dS m-1. As with all sensors placed in the active layer in the Arctic, the soil moisture and soil temperature sensors are subject to an annual freeze and thaw cycle, this has caused some of the sensors to fail prematurely. Sensor outages occur periodically due to animal damage and equipment failure.