National Snow and Ice Data Center. 1996. Arctic Ocean Snow and Meteorological Observations from Drifting Stations: 1937, 1950-1991. Version 1.0. CD-ROM available from nsidc@kryos.colorado.edu, NSIDC, University of Colorado at Boulder. For an overview of the documentation on this CD-ROM, please refer to \document\0readme.txt. For more information about the CD-ROM directory structure and filenames, see \document\cd.txt. For more information about the data format see \document\format.txt. For more information about the GeoVu data browse software see \document\geovu.txt. You are now reading: Data Description (\document\data.txt) CONTENTS I. Introduction II. Combined Data (\combined\*.*) III. Meteorological Data (\met\*.*) A. Air Pressure B. Air and Snow Surface Temperature C. Air Temperature and Relative Humidity D. Wind Velocities and Directions E. Clouds IV. Position Data (\position\*.*) V. Precipitation Data (\precip\*.*) VI. Solar Radiation Data (\solar\*.*) VII. Snow Data (\snow\*.*) A. Snow Lines B. Snow Stakes VIII. Wind Data (\wind\*.*) IX. References I. INTRODUCTION This data description document is an edited summary of documents provided to the University of Washington Polar Science Center by the Arctic and Antarctic Research Institute (AARI). For the combined data, the document briefly describes the data processing procedures used to merge the measured data into the combined (daily-averaged data set. For each of the four types of measured data, this document identifies the data parameters, and briefly describes the collection methods and instruments. For a complete description of the CD-ROM directory structure and filenames, please refer to \document\cd.txt. The data on this CD-ROM are high quality in-situ observations from drifting ice stations in the Arctic Ocean, taken from 1950 through 1991. The data on the CD-ROM include: - A combined file containing daily averages of all the observations at each station. This file is in the top level \combined\ directory. The data are ASCII text and are visible to the GeoVu browse software. A description is provided in section II of this document. - Edited, merged, quality-checked and otherwise processed files, at the original temporal and spatial resolution. These files are in the top level directories as shown in the contents list above as items III through VIII. These files are all ASCII text, and all are visible to the GeoVu browse software except \snow\measured\lwc.dat and \snow\measured\density.dat. Descriptions of the edited and merged files are provided in sections III through VIII of this document. Information about GeoVu browse software is provided in the file \document\geovu.txt. - Quality-checked data in the original temporal and spatial resolution, and in the format provided by AARI. These files are in the top level directory \original\. The files are ASCII text; they are not visible to the GeoVu browse software. Descriptions of these data are the same as above, in sections III through VIII of this document. File and record format descriptions are provided in \document\format.txt. II. COMBINED DATA (\combined\*.*) The combined data set consists of daily-averaged meteorological data from the original three- or six-hourly observations, merged with the daily observations of precipitation, radiation, and snow depth. In addition to the observed variables, each record in the data set contains the station ID as well as the year, month, date, and latitude and longitude of the observation. Latitude and longitude are linearly interpolated from the original randomly-timed position records, to obtain daily positions. Many data fields in the combined data set contain missing data flags (9999). The reason for the missing data is that this combined.dat file contains radiation data for only NP- 16 through NP-31, while the meteorological data are presented for NP-1 through NP-31. III. METEOROLOGICAL DATA (\met\*.*) The measured meteorological data on this CD-ROM include three- or six-hourly and daily meteorological observations of: - air pressure (mb) - air temperature (degrees C) - relative humidity (%) - surface winds, including wind speed (m/s) and wind direction (degrees) - clouds including total cloud amounts (tenths)and low cloud amounts (tenths) In general, meteorological observations were carried out according to a unified method presented in "Directions to meteorological stations and posts" (1985) using instruments as described below for each meteorological parameter. A. AIR PRESSURE Pressures were measured by using two mercury barometers, one as the main instrument, and the other as a control. Pressure measurements from the control (calibration) barometer were taken at regular intervals; readings from the main barometer are provided here. Air pressure is given in KPa referred to a temperature of 0 degrees C and standard gravity force, i.e. gravity at a latitude of 45 degrees at sea level. To measure atmospheric pressure, a station cistern mercury barometer (SP-A) and an inspector's mercury siphon-cistern barometer (IP) were used. The main parameters of the SP-A are: range of the instrument: 810-1070 KPa maximum error: < or = 0.5 KPa accuracy of reading: 0.1 KPa scale spacing of cosine: 0.1 KPa scale spacing: 1.0 KPa range of the barometric thermometer: -5 - +45 degrees C error of the barometric thermometer: 0.5 degrees C The main parameters of the IP are: range of the instrument: 570-1070 KPa maximum error: 0.3 KPa accuracy of reading: 0.05 KPa scale spacing of cosine: 0.05 KPa scale spacing: 1.0 KPa range of the barometer thermometer: -5 - +45 degrees C B. AIR AND SNOW SURFACE TEMPERATURE Above 30 degrees C, air and snow surface temperature were measured using mercury thermometers. Below 30 degrees C, alcohol thermometers were used. Starting with NP-21, the temperature of dry and wet-bulb thermometers as well as the temperature of the snow/ice cover were measured using wire resistance thermometers recorded electronically. Measurements of snow-ice cover temperature were carried out only in the winter. Because of intensive insolation, repeated diurnal freezing and thawing cycles, and pronounced spatial heterogeneity of the surface in summer (melting snow, melted ice, ponds), such measurements cannot be considered representative. In order to measure the temperature above -30 degrees C and to determine the relative humidity, dry and wet-bulb meteorological psychrometric thermometers (TM-4) were used in a "gilled" shelter (similar to a Stevenson's Screen). The main parameters of the TM-4 are: range of the instrument: -35 to +40 degrees C scale spacing: 0.2 degrees C measurement error over the range from +0C to +50C: < or = 0.2 degrees C < 0C: < or = 0.3 degrees C At air temperatures below -30 degrees C, alcohol meteorological thermometers TM-9 were used in order to measure the air as well as the snow-ice surface temperature. The main parameters of the TM-9 are: range of the instrument: -65 to +25 degrees C scale spacing: 0.5 degrees C measurement error over the range from +20 to -20C: 0.5 degrees C -30 to -40C: 0.8 degrees C -40 to -50C: 1.0 degrees C -50 to -60C: 1.5 degrees C Starting with NP-21, copper wire resistance thermometers (MT-102) were used as the wet-bulb thermometer as well as to measure the air and snow-ice surface temperature. The main parameters of the MT-102 are: range of the instrument: -60 - +50 degrees C temperature resistance coefficient: 430x10 -5x10W/degrees C rated resistance of the thermometer (at 0C): 2501 W delay(s) in the air at ambient velocity of 2m/s: < or = 40 measurement error (including recorder uncertainty): +0.2 degrees C C. AIR TEMPERATURE AND RELATIVE HUMIDITY Air temperature and relative humidity were measured in barometric booths (Stevenson Screens) with natural ventilation at a height of 2 m. Relative humidity (f) at a temperature above -10 degrees C was determined by psychrometry, which is based on measuring air temperature and the temperature of a wet-bulb thermometer, i.e. the temperature of thermodynamic equilibrium between expenditures of heat of evaporation from the moistened surface and the head inflow to the thermometer from the environment. Values of f were calculated using the psychrometric table (Table 1) below. The results obtained using psychrometry were compared with a hair hygrometer in order to check and correct the hygrometer reading at regular intervals at air temperatures above -10 degrees C. At the temperature above -10C, the psychrometric pair of the dry and wet-bulb thermometers TM-4 was used in order to measure f. The preliminary error estimate of f is given in Table 1. Table 1. Measurement Range and Error of Relative Air Humidity by Means of the Psychrometric Pair Air Measurement Error as a Percentage of the Temperature Measured Value of Relative Humidity (%) (degrees C) 100 80 20 10 ----------- --------------------------------------- 10 3 4 11 20 0 4 6 17 35 -5 5 9 25 50 -10 7 12 35 70 At air temperatures below -10 degrees C, the model MV-1 meteorological hygrometer was used to measure relative air humidity. The main parameters of the MV-1 are: range of the instrument: 30 - 100% measurement error: up to 10% scale spacing: 1% operating temperature range: -50 - +55 degrees C D. WIND VELOCITIES AND DIRECTIONS The most significant changes during the operating period of the North Pole (NP) drifting stations were in methods and means for measurement of wind velocity and direction, which vary from the rudimentary hand-held anemometers with "make- it-yourself" wind direction indicators to the modern recording instruments used since NP-22. Also, the height of installation of the wind velocity sensors has varied from 2 to 11 m. The anemometer M63-M was used beginning with NP-23 through NP-31. Table 2 lists the instrument numbers and heights of installation of the wind velocity sensors used for the measurement of wind velocity and direction. Table 3 provides the main parameters of the instrument. The years of operation for each drifting station are listed in \document\project.txt. Table 2. Instruments and Installation Heights Used for the Measurement of Wind Velocity and Direction Station Instrument(s) Height (Dates) -------------------------------------------- NP-1 MS-13 2 m NP-2 8I0001M 8 m NP-3 MS-13; 8I0001M 8 m NP-4 8I0001M; FVL 8 m NP-5 FVL 6 m NP-6 FVL; FVT 8 m NP-7 FVL; FVT 10 m NP-8 FVL; FVT 8 m NP-9 FVL; FVT 8 m NP-10 M-49 6 m NP-11 FVL; FVT; M-47 8 m NP-12 M-49 10 m NP-13 M-47; M12 6 m NP-14 M-47;M-63 8 m NP-15 M-63 6 m NP-16 M-49 10 m NP-17 M-63 10 m NP-18 M-49; M-12 6.4 m (11/68 - 05/69) 8.5 m (05/69 - 10/71) NP-19 M-64; M63M 6.4 m (12/69 - 10/70) 7.5 m (11/70 - 01/71) 9.5 m (02/71 - 11/72) 12.0 m (11/72 - 03/73) NP-20 M-47 8 m (05/70 - 04/71) 6 m (05/71 - 05/72) NP-21 M-47 10 m NP-22 M-64; M-63M 10 m NP-23 M-63M 10 m NP-24 M-63M 10 m NP-25 M-63M 10 m NP-26 M-63M 11 m NP-27 M-63M 10 m NP-28 M-63M 10 m NP-29 M-63M 10 m NP-30 M-63M 10 m NP-31 M-63M 10 m Table 3. Main Parameters of the Instruments Used for the Measurement of Wind Velocity and Direction Threshold Sensitivity Range Range Measurement for speed & Speed Direction Speed Direction direction Instrument (m/s) (degree) (m/s) (degree) (m/s) ---------- ----- --------- ----- -------- ---------- MS-13 1-20 - (0.3+0.06V) - 0l.8/- 810001M 1-15 0-360 1.0 10 1.0/1.0 FVL 1-20 0-360 * * * (at 16 compass points) FVT 1-40 0-350 * * * M-49 1.5-59 0-360 (0.5+0.05V) 10 1.2/1.2 M-47 1.5-50 0-360 (0.5+0.05V) 10 1.2/1.2 M-64 1.0-4.0 0-360 (0.5+0.05V) 10 0.8/1.5 M-12 1.0-4.0 0-360 (0.5+0.05V) 11.25 0.7/0.9 (at 16 compass points) M-63 1.0-4.0 0-360 (0.5+0.05V) 10 0.8/1.5 M-63M 1.0-4.0 0-360 (0.5+0.05V) 10 0.6/1.0 Notes for Table 3: 1. MS-13 measures only wind velocity. 2. Measurement area of wind vanes with light and heavy boards (FVL, FVT) depends on the observer's experience. The error is not less than +/- 1 meter per second for velocity and +/- 0.5 point (11 degrees) for direction. 3. M=12, M-47, M-64, M-63, M-63M allow registering the wind velocity averaged over 10 minutes; MS-13 allows registering velocity averaged over 2-10 minutes. 4. V in formulas for velocity measurement area is the measured wind velocity, m/s. E. CLOUDS Quantitative characteristics of cloudiness (total and low cloudiness) and the form of clouds were determined according to the recommendations of "Directions to meteorological stations and posts" (1985), and Makhover and Nudel'man (1987). The quantity of clouds (cloudiness) was defined by the total amount of sky covered by clouds, estimated in tenths of coverage. IV. POSITION DATA (\position\*.*) Positions of the drifting stations were determined mostly by means of terrestrial astronomical observations. Sun fixes and star observations were made daily as season and weather permitted. Positioning errors are estimated to have been 3-5 km. Starting with North Pole station NP-25, positions were determined using satellite technology. NP-31 used the Satellite Navigation system. AARI reviewed all position data for this project using the original meteorological records. The position data files received from AARI contained only observations that were actually made. They were delivered by AARI in files separate from the meteorological observations. The position data were in Moscow time, but were converted to UMT (GMT) at the Polar Science Center. Positions for day 360 of 1988 through day 60 of 1989 were missing from the NP-31 record. This gap has been filled by linear interpolation. In the \combined\, \met\, \solar\, and \snow\averaged\ directories, these observed positions have been interpolated after some quality control to provide an approximate position for each meteorological observation. A simple linear interpolation scheme was used between reported observations in the three- and six-hourly files in the directory \original\position\. The positions in \met\metnp*.dat and in the radiation data files are interpolated. Interpolated positions were used in the combined data file of daily averaged data, combined\combined.dat. V. PRECIPITATION DATA (\precip\*.*) Precipitation was measured using a shielded rain gauge mounted on a geodesic frame. The upper section of the bucket was 2 m high (Somov, 1954). This method was used for all the North Pole stations, NP-1 through NP-31. The precipitation data are amount (mm) and type (solid, mixed, rain). VI. SOLAR RADIATION DATA (\solar\*.* and \original\solar\*.*) The radiation data for stations NP-17 through NP-31 are presented with the meteorological variables for those same stations, for the convenience of the user, in the file \solar\dailyavg.dat. These daily-averaged solar radiation measurements are also included in the combined data set \combined\combined.dat. The large combined data set has many "missing data" flags because it includes the meteorological and snow data for all stations, NP-1 through NP-31. The daily-averaged solar radiation data are also presented in tabular form in the directory \original\solar\. Each table has a header containing year, month, station number, variable name and units. The variables and associated filenames are: - diffuse radiation (W/m^2) \original\solar\spd*.tab - direct radiation (W/m^2) \original\solar\sps*.tab - global radiation (W/m^2) \original\solar\spg*.tab - reflected radiation (W/m^2) \original\solar\spr*.tab - albedo (%) \original\solar\spa*.tab - net radiation (budget)( W/m^2) \original\solar\spb*.tab The radiation data have been previously published in Marshunova and Mishin (1994), which contains a complete description of the measurement techniques and data processing. The text is provided on this CD-ROM in ASCII text format as \document\aari\handbook.txt. The published data tables are also included on this CD-ROM (\document\aari\marshun\tables\table*.txt). Original solar radiation units were Mj*(m^-2)*(day^-1)*100 for all values except albedo, which is in percent. A conversion factor of 8.64-1 was applied to the radiation data in the combined data set, so that the data could be provided in the more commonly used units of W/m^2. VII. SNOW DATA (\snow\*.*) The snow data on this CD-ROM include: - surface temperature (degrees C) - snow depths along snow lines (cm) - snow depths at stakes (cm) - density (g/cm^3) - liquid water content (mm) Regular snow measurements were begun in 1953 at NP-3. Consistent techniques were used at all stations, NP-3 through NP-31. A complete description of the snow data is provided in Radionov et al., 1997), a draft translation of which is provided in \document\aari\radionov.txt. Radionov et al. is also in press at Gidrometeoizdat, St. Petersburg, Russia. A translation is in progress at the University of Washington, which will be published as a University of Washington Applied Physics Laboratory (APL) Technical Report. A. SNOW LINES (\snow\measured\snowline.dat) Snow depths were measured every 10 m along a line 500 to 1000 m long when the depth was at least 5 cm and more than 50% of the surrounding area was snow covered. Direction of the line was chosen randomly, and deviated from a straight line only to avoid hummocks. Subsequent snow lines were measured 3 m from the previous line. Bad data are flagged by -99. Averages of the snow lines are provided in the directory \snow\averaged\. Snow densities and liquid water content (i.e. snow water equivalent) were also measured along each line, but only every 100 m. These data are provided in \snow\measured\density.dat and \snow\measured\lwc.dat. B. SNOW STAKES (\snow\measured\snwstake.dat) Near the NP stations, about 100 m from the nearest building, daily measurements of snow depth were made at three corners of a 25 m square area marked by stakes. This file contains the average of the three measurements. Months having fewer than 31 days show "666" as placeholders in the data fields. "999" is the missing data flag. The original "three stake" data can be found in \original\snwstake\np*.* VIII. WIND DATA (\wind\np.wuv) These files are the same as \met\metnp_**.dat except the wind data are expressed by U and V components instead of as wind speed and wind direction. The wind data were decomposed into U and V components from rectangular coordinates, using the procedure developed by the Arctic Ocean Buoy Program (now International Arctic Buoy Program, IABP) at the University of Washington. The equation showing this conversion is: r = reported wind speed theta = reported wind direction phi = (longitude - theta)*3.1415927/180 U-component of wind = r*cos(phi) V component of wind = r*sin(phi) Reference: Thorndike, A. S. and R. Colony. 1983. Objective analysis of atmospheric pressure and sea ice motion over the Arctic Ocean. In: Thorndike, A. S., R. Colony and E. Mun~oz, Arctic Ocean Buoy Program Data Report, 1 January 1982 - 31 December 1982. Polar Science Center, University of Washington, p. 123-132. IX. REFERENCES Directions to meteorological stations and posts. 1985. Iss. 3. Part 1. Leningrad: Gidrometeoizdat. Makhover, Z. M., and L. A. Nudel'man. 1987. The Aviation- Climatological Characteristics of the Northern Hemisphere (Aviatsionno-klimaticheskie kharakteristiki severnovo polusharia), Volume 1: Cloudiness, Moscow, Gidrometeoizdat. Marshunova, M. S., and A. A. Mishin. 1994. Handbook of the radiation regime of the Arctic Basin: Results from the Drift Stations. V. F. Radionov and R. Colony, eds., University of Washington Applied Physics Laboratory Technical Report APL-UW TR9413, 52 pp. plus appendices. Radionov, V. F., N. N. Bryazgin, and E. I. Aleksandrov. 1997. Snow cover of the Arctic Basin. L. M. Ctrovich, ed., St. Petersburg, Gidrometeoizdat, in press. English translation by I. Solovyova and T. C. Grenfell. Somov, M. M., ed. 1954-55. Observations of the drifting research station of 1950-1951 (Materialy nablyudeniy nauchno-issledovatel'skoy drayfushchey stantsii, 1950-51 goda.) Arkticheskiy Nauchno-Issledovatel'skiy Institut, Leningrad, Vol. III, Section 8, p. 6. American Meteorological Society translation. This file is one of six documentation files for this CD- ROM. The other five are: 0readme.txt provides an overview of the CD-ROM content; includes pointers to documentation files and instructions for citing use of the data in publications cd.txt describes the directory structure and filenames on the CD-ROM format.txt describes the record format of each type of file on the CD-ROM geovu.txt describes the GeoVu menu-driven data display and visualization software, how to obtain it via ftp and install it on your computer; also describes the basic GeoVu commands project.txt describes the history of the Russian North Pole Drifting Stations, the utility and relevance of the station observations, and the collaboration to rescue the data; includes the project acknowledgments For assistance or additional information, please contact: NSIDC User Services E-mail: nsidc@kryos.colorado.edu CIRES, Campus Box 449 Phone: 303-492-6199 University of Colorado Fax: 303-492-2468 Boulder, CO 80309-0449 USA