Data Set Documentation

Daily Arctic Ocean Rawinsonde Data from Soviet Drifting Ice Stations

Summary

This data set, available via ftp, contains an archive of daily rawinsonde measurements of wind direction and speed, atmospheric pressure, humidity, air temperature, and geopotential height as well as suface-based observations of cloud cover (amount, type and height) from the Soviet North Pole series of drifting stations for the Arctic Ocean spanning April 19, 1954 to July 31, 1990. The database was assembled under the direction of Dr. J. Kahl with funding from the National Oceanic and Atmospheric Administration, the National Science Foundation, and the Electric Power Research Institute. The data were obtained from several different sources. All of these data are ultimately derived from the set of bound volumes of handwritten tables kept at the Arctic and Antarctic Research Institute (AARI) in St. Petersburg, Russia. Data are in ASCII text format.

For more information about the data set, please contact NSIDC User Services.

Table of Contents

1. Data Set Overview
2. Investigator(s)
3. Theory of Measurements
4. Equipment
5. Data Acquisition Methods
6. Observations
7. Data Description
8. Data Organization
9. Data Manipulations
10. Errors
11. Notes
12. Application of the Data Set
13. Future Modifications and Plans
14. Software
15. Data Access
16. Output Products and Availability
17. References
18. Document Information

1. Data Set Overview

The Daily Arctic Ocean Rawinsonde Data from Soviet Drifting Ice Stations data set is an archive of rawinsonde measurements of wind direction and speed, atmospheric pressure, humidity, air temperature, and geopotential height as well as surface-based observations of cloud cover (amount, type and height) from Soviet drifting stations in the Arctic Ocean for the region north of approximately 70 degrees North.

Data Set Identification

Daily Arctic Ocean Rawinsonde Data from Soviet Drifting Ice Stations

Data Set Introduction

This data set represents an archive of rawinsonde measurements of wind direction and speed, atmospheric pressure, humidity, air temperature, and geopotential height as well as surface-based observations of cloud cover (amount, type and height) recorded from Soviet North Pole drifting stations in the Arctic Ocean from April 19, 1954 to July 31, 1990.

Objective/Purpose

The Daily Arctic Ocean Rawinsonde Data from Soviet Drifting Ice Stations represents an archive compiled through data rescue efforts by J. Kahl and Russian scientists at the Arctic and Antarctic Research Institute (AARI) in St. Petersburg, Russia. It is intended as a unique data set for analysis of Arctic upper air processes and variability.

Summary of Parameters

The database consists of rawinsonde and cloud cover data from drifting stations north of approximately 70 degrees North.

Discussion

The database of rawinsonde measurements and cloud cover data from drifting Soviet stations in the Arctic Ocean was assembled under the direction of Dr. J. Kahl with funding from the National Oceanic and Atmospheric Administration, the National Science Foundation and the Electric Power Research Institute. The data were obtained from several different sources. All of these data are ultimately derived from the set of bound volumes of handwritten tables kept at the Arctic and Antarctic Research Institute (AARI) in St. Petersburg, Russia. The data were received in varying formats, ranging from ~20,000 soundings on individual floppy disk files to ~2,000 soundings from the World Data Center in Obninsk, Russia, to ~700 soundings published as tables in Russian.

Related Data Sets

2. Investigator(s)

Investigator(s) Name and Title

Jonathan D. Kahl, Principal Investigator, University of Wisconsin-Milwaukee, Milwaukee, Wisconsin

Mark C. Serreze, Investigator, National Snow and Ice Data Center, University of Colorado, Boulder, Colorado

Title of Investigation

Arctic Ocean Drifting Stations Sounding Archive: Data Base Documentation

Contact Information

NSIDC User Services
National Snow and Ice Data Center
CIRES, 449 UCB
University of Colorado
Boulder, CO 80309-0449  USA
phone: +1 303.492.6199
fax: +1 303.492.2468
form: Contact NSIDC User Services
e-mail: nsidc@nsidc.org

3. Theory of Measurements

This section is not applicable.

4. Equipment

Sensor/Instrument Description

Please review the rawinsonde instrument description.

Collection Environment

Drifting stations in the Arctic Ocean

5. Data Acquisition Methods

Summary of Individual Data Sources

Original Data Set Name (1) Where Keypunch Was Performed North Pole Stations Approx. No. of Soundings Notes
Floppy CAO, AARI 3-6,8-9,12-17,22,26 20,000 Mostly upper portions (> 3km) of soundings
Aerostan captured via GTS(2) 22,26,28,31 2,000 Obtained from World Data Center, Obninsk
Condigital NCDC 4,5 1,300 Data published in Russia (AARI 1959). Recorded in NCDC standard format.
3km AARI 4,6-17, 19,21-22,26 20,000 Lower portions of soundings (0-3km)
Books UWM 6,7 700 Data published in Russia (AARI 1960; 1962).
(1) The original data set name is arbitrary -- used for identification purposes only.
(2) Global Telecommunications System

Data Compilation

Merging of Data Sets

A major part of the data processing effort involved merging the original data sets (see Summary of Individual Data Sources in section 5) into a single archive. The primary focus of the merge procedure was blending the lower portions (original data set "3km") together with the upper portions (original data set "floppy"). A secondary focus was eliminating redundancy, as many soundings were present in more than one original data source.

Although, in theory, a unique match should be made between the lower (set "3km") and upper (set "floppy") portions of each sounding, in practice this often was not the case. Keypunch errors, combined with ambiguities in release times and longitude units often prevented an unambiguous match. Some soundings were thus unable to be merged, resulting in a number of soundings that extend only to 3 kilometers in altitude, or that begin slightly above 3 kilometers. In order to facilitate identification of such soundings, the minimum and maximum altitude of the sounding is included in the header record of each sounding (see section 5.1).

Quality Control

Quality Control of Latitude/Longitude Positions:

After the merging task was completed, station positions were plotted along with monthly positions provided by AARI (Dr. A. Timerev, Arctic and Antarctic Research Institute, personal communication 1995) and positions given by the NSIDC drifting stations CD-ROM (National Snow and Ice Data Center, Applied Physics Laboratory and Arctic and Antarctic Research Institute 1996). General agreement was found between positions given by the three data sources. With the following exceptions (stations NP03 and NP26), station positions from NSIDC were used because they had already been subjected to quality control procedures (I. Rigor, Polar Science Center, University of Washington, personal communication 1995).

NP03: A detailed table of positions corresponding to each sounding release was provided by Dr. A. Timerev of AARI. These positions were used in the final archive.

NP26: The correct positions were determined to be a "reflection" of the NSIDC drifting stations CD-ROM positions about 180 degrees longitude.

6. Observations

Data Notes

All soundings (except for the Aerostan archive) were entered into a computer via manual keypunch operators during 1989 through 1995. The majority of the keypunch activities were carried out at the Central Aerological Observatory (CAO) in Moscow, Russia, and at the Arctic and Antarctic Research Institute (AARI) in St. Petersburg, Russia. Small portions of the data set were keypunched at the University of Wisconsin-Milwaukee (UWM) and at the NOAA National Climatic Data Center (NCDC).

7. Data Description

Spatial Characteristics

Spatial Coverage

North polar regions:

Spatial Coverage Map

Locations of profiles measured by rawinsonde at Soviet drifting ice stations during 1954-1990. The stations drift with the prevailing winds and surface currents in the Arctic Ocean. Taken together, the measurements provide reasonably complete coverage over the Arctic ice cap. At any given time, however, data are only available at locations along the drift path.

spatialmap

Temporal Characteristics

Temporal Coverage

Soundings in the record were collected from April 19, 1954 to July 31, 1990. The average duration of each station is 2.4 years. (There were a total of 31 North Pole stations.) Typically, one to three stations were in operation at any one time. There are no significant temporal gaps in this database.

Temporal Resolution

daily

Data Characteristics

Parameter/Variable

Air pressure, atmospheric temperature, cloud characteristics, wind characteristics, humidity, geopotential height.

Data Source

Rawinsonde measurements were digitized from hard copy reports.

Data Range

See section 8. Data Organization.

Sample Data Record

The following is an excerpt of soundings taken from April 20, 1954 to April 14, 1955. Please note that the limitations of this document impose a line length of 80 characters which may result in a "wrap-around" of each record. Data formats are fully described in Section 8.

723
003 9  9999.9 1954 04 20 0000 -9 166 9999 86.60 182.80     3850    13000 99 9 99 018 
??????? -9 -9 -9 -9 -9 -9 -9 -9 -9 -9     Old latlon 86.60 182.85 E
99    3850 -9 1  600.00 -9 1 -32.10 -9 1 -99.9 0 210 -9 1   5.0 -9 1 9 99.9 -9 0 -99 
?????????????? ??
99    4000 -9 1  587.00 -9 1 -33.30 -9 1 -99.9 0 208 -9 1   5.0 -9 1 9 99.9 -9 0 -99 
?????????????? ??
99    5000 -9 1  509.00 -9 1 -40.80 -9 1 -99.9 0 204 -9 1   7.0 -9 1 9 99.9 -9 0 -99 
?????????????? ??
99    5120 -9 1  500.00 -9 1 -41.50 -9 1 -99.9 0 204 -9 1   7.0 -9 1 9 99.9 -9 0 -99 
?????????????? ??
99    5820 -9 1  448.00 -9 1 -48.90 -9 1 -99.9 0 215 -9 1   6.0 -9 1 9 99.9 -9 0 -99 
?????????????? ??
99    6000 -9 1  439.00 -9 1 -48.90 -9 1 -99.9 0 217 -9 1   6.0 -9 1 9 99.9 -9 0 -99 
?????????????? ??
99    6620 -9 1  400.00 -9 1 -48.90 -9 1 -99.9 0 207 -9 1   6.0 -9 1 9 99.9 -9 0 -99 
?????????????? ??
99    7000 -9 1  377.00 -9 1 -48.90 -9 1 -99.9 0 210 -9 1   7.0 -9 1 9 99.9 -9 0 -99 
?????????????? ??
99    7360 -9 1  357.00 -9 1 -48.90 -9 1 -99.9 0 207 -9 1   7.0 -9 1 9 99.9 -9 0 -99 
?????????????? ??
99    7810 -9 1  334.00 -9 1 -45.50 -9 1 -99.9 0 197 -9 1   7.0 -9 1 9 99.9 -9 0 -99 
?????????????? ??

8. Data Organization

Data Granularity

Data represent one-dimensional vertical soundings, which include measurements of wind direction and speed, atmospheric pressure, humidity, air temperature, and geopotential height. Surface-based observations of cloud characteristics (amount, type and height) are also provided. Data granularity is one file per station per time period; file sizes are approximately 1 to 24 MB.

Data Format

Files are named np_**sound.dat, where ** stands for a North Pole station numbered 03 through 31 (example: np_03sound.dat). Each of the 21 files contains soundings with various start and end dates. File sizes vary. The files 03-31 are ordered chronologically, and span April 20, 1954 to July 31, 1990. Data from the North Pole Stations 18, 20, 23-25, 27 and 29-30 are not available. Data are in ASCII text format.

Each file contains:

The number of soundings in the file appears only once as the first line of each file and occupies columns 9-12. For variables and formats contained in the sounding headers, see Variables in Header of Each Sounding. For variables and formats contained in the transmission levels, see Variables in Transmission Levels of Each Sounding.

9. Data Manipulations

A major part of the data processing effort involved merging the original data sets (see Summary of Individual Data Sources in section 5) into a single archive. The primary focus of the merge procedure was blending the lower portions (original data set "3km") together with the upper portions (original data set "floppy"). A secondary focus was eliminating redundancy, as many soundings were present in more than one original data source.

Although, in theory, a unique match should be made between the lower (set "3km") and upper (set "floppy") portions of each sounding, in practice this often was not the case. Keypunch errors, combined with ambiguities in release times and longitude units often prevented an unambiguous match. Some soundings were thus unable to be merged, resulting in a number of soundings that extend only to 3 kilometers in altitude, or that begin slightly above 3 kilometers. In order to facilitate identification of such soundings, the minimum and maximum altitude of the sounding is included in the header record of each sounding.

After the merging task was completed, station positions were plotted along with monthly positions provided by AARI (Dr. A. Timerev, Arctic and Antarctic Research Institute, personal communication 1995) and positions given by the NSIDC drifting stations CD-ROM (National Snow and Ice Data Center, Applied Physics Laboratory and Arctic and Antarctic Research Institute 1996). General agreement was found between positions given by the three data sources. With the following exceptions (stations NP03 and NP26), station positions from NSIDC were used because they had already been subjected to quality control procedures (I. Rigor, Polar Science Center, University of Washington, personal communication 1995).

NP03: A detailed table of positions corresponding to each sounding release was provided by Dr. A. Timerev of AARI. These positions were used in the final archive.

NP26: The correct positions were determined to be a "reflection" of the NSIDC drifting stations CD-ROM positions about 180 degrees longitude.

10. Errors

Sources of Error

Following the experience in assembling the Historical Arctic Rawinsonde Archive (Serreze et al. 1992; Kahl et al. 1993), it was decided that all data values present in the individual soundings, including quality indicators, would be retained. This approach gives users the option of making their own determination of data quality. Nevertheless, a rudimentary quality control procedure, which is described briefly below and more fully in Serreze et al. 1992, has been applied. This procedure consists of identifying "gross" errors, such as negative wind speeds, and also "probable" errors, such as extreme values. The latter two quality checks, which give codes of 0 (failed) or 1 (passed) are referred to as "Kahl's quality indicators." Only the "Aerostan" and "Condigital" data sets (see Summary of Individual Data Sources in section 5) contained quality indicators prior to being processed by Kahl.

Gross errors, such as negative wind speeds, negative geopotential heights, geopotential height decreasing with decreasing pressure, etc., were flagged first. Data values that passed this check were subjected to a "seasonally adjustable limits check," which is described in the following excerpt from Serreze et al. (1992).

The seasonally adjustable limits check worked as follows. Data from all [land-based] stations for 1987 were stratified by season into 15 atmospheric layers bounded by pressure levels. Seasons are defined as December-February (winter), March-May (spring), June-August (summer) and September-November (autumn). Since all checks are based on pressure, no check on the pressure values, themselves, is performed.

Initial frequency histograms of geopotential height, temperature, wind direction, and wind speed were compiled for each layer and for each season in 1987. Extreme outliers were eliminated by discarding values that were more than four standard deviations from the respective means. Since wind speed does not follow a normal distribution, these values were first converted into log wind speed. Means and standard deviations for the remaining data were then recomputed. Using these data as representative sample means and standard deviations of the complete data set, any value that was greater than +/- 4 standard deviations from the sample mean for the respective season and layer was then flagged. The means and standard deviations used in the limits check are given in the Appendix.

An implicit assumption in the error checking routine is that the layer mean is representative of the mean for any level within that layer. Since a large number of atmospheric levels are used in the check, this is a tolerable assumption for testing temperature, wind direction, and wind speed. It was found to be inappropriate for geopotential height, however, due to the logarithmic decay of pressure with increasing elevation.

To check the geopotential heights, this logarithmic relationship was used. Taking the log of pressure at the bottom (P1) and top (P2) of the layer in which the observed pressure (P) fell, a weight, W, was calculated:

W = [LOG(P)-LOG(P2)]/[LOG(P1)-LOG(P2)] (1)

Next, ZL1 and ZH1, respectively, are defined as the lowest and highest allowable geopotential height at the base of the layer, and similarly ZL2 and ZH2 as the lowest and highest allowed limits of the top of the layer (with limits taken as +/- 4 standard deviations from the mean). Then ZL and ZH are calculated, which by incorporating the weight W, define the limits of allowable geopotential height for the value of P:

ZL = W*[ZL1-ZH1] + ZH1 (2)

ZH = W*[ZL2-ZH2] + ZH2 (3)

The allowable value of Z at pressure level P in the sounding is thus

ZL <= Z <= ZH (4)

Since atmospheric moisture can be highly variable, with considerable uncertainties in cold Arctic conditions, the dew point depression data was simply screened to flag negative values and any values exceeding an arbitrary high threshold of 35C. Those wishing to use these data are referred to Elliot and Gaffen (1991) who provide an overview of problems in rawinsonde moisture data.

11. Notes

This section is not applicable.

12. Application of the Data Set

The archive is useful for Arctic meteorological and climatological research and investigations of global climate change.

13. Future Modifications and Plans

The Soviet North Pole drifting ice station program terminated in 1990. Consequently, there will be no temporal updates. The dataset may be updated when errors are found.

14. Software

Software Access

No software is distributed with these data.

15. Data Access

Data are available via FTP.

Contact Information

NSIDC User Services
National Snow and Ice Data Center
CIRES, 449 UCB
University of Colorado
Boulder, CO 80309-0449  USA
phone: +1 303.492.6199
fax: +1 303.492.2468
form: Contact NSIDC User Services
e-mail: nsidc@nsidc.org

Data Center Identification

National Snow and Ice Data Center (NSIDC)

16. Output Products and Availability

This section is not applicable.

17. References

Arctic and Antarctic Research Institute. 1959. Observational data of the drifting scientific research stations "North Pole-4" and "North Pole-5" for the years 1956/57. Leningrad.

Arctic and Antarctic Research Institute. 1960. Observational data of the drifting scientific research stations "North Pole-6" and "North Pole-7" for the years 1957/58. Leningrad.

Arctic and Antarctic Research Institute. 1962. Trudy 249 of the Institute of Arctic and Antarctic Research. Observational data of the drifting scientific research stations "North Pole-6" and "North Pole-7" for the years 1958/59. Leningrad.

Elliot, W. P., and D. J. Gaffen. 1991. On the utility of rawinsonde humidity archived for climate studies. Bulletin of the American Meteorological Society 72(10): 1507-20.

Kahl, J. D., M. C. Serreze, R. S. Stone, S. Shiotani, M. Kisley, and R. C. Schnell. 1993. Tropospheric temperature trends in the Arctic: 1958-1986. Journal of Geophysical Research 98: 12825-38.

National Snow and Ice Data Center, Applied Physics Laboratory, Polar Science Center, and Arctic and Antarctic Research Institute. 1996. Arctic Ocean Snow and Meteorological Observations from Drifting Stations, 1937, 1950-1991. CD-ROM available from nsidc@nsidc.org. Boulder, Colorado: NSIDC, University of Colorado at Boulder.

Serreze, M. C., J. D. Kahl, and S. Shiotani. 1992. The Historical Arctic Rawinsonde Archive Documentation Manual. Special Report No. 2. National Snow and Ice Data Center, Cooperative Institute for Research in Environmental Sciences, University of Colorado, Boulder, Colorado.

18. Document Information

Revision Date: May 4, 1998
Review Date: February 12, 1998
Document ID: NSIDC-0060

Citation:

We kindly request that you cite the use of this data set in a publication using the following citation. For more information, see our Use and Copyright Web page.

Kahl, J. 1998. Daily Arctic Ocean rawinsonde data from Soviet drifting ice stations. Boulder, CO: National Snow and Ice Data Center. Digital media.

Document Curators: NSIDC Writers
Document URL: http://nsidc.org/data/docs/daac/nsidc0060_soviet_rawinsonde.gd.html