This archive of daily rawinsonde measurements of wind direction and
speed, atmospheric pressure, humidity, air temperature, and
geopotential height as well as surface-based observation of cloud
cover (amount, type and height) from Soviet North Pole drifting
stations 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. Soundings were recorded from April 19, 1954 to July 31,
1990 at drifting stations located in the Arctic Ocean, north of
approximately 70 degrees North. 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 21 ASCII text format files with an average size of under 10 MB.
The data are available via ftp.
Daily Arctic Ocean Rawinsonde Data from Soviet Drifting Ice Stations, Version 1
Get Data
DOWNLOADING DATA VIA HTTPS
An Earthdata Login account is required to access these data. Please visit the Earthdata Login registration page to register for an account. Once you have logged in, data can be downloaded via a Web browser, command line, or client. For help with downloading data, please see Options Available for Bulk Downloading Data from HTTPS with Earthdata Login.
Geographic Coverage
| Parameter(s): |
|
|---|---|
| Spatial Coverage: |
|
| Spatial Resolution: | Not Specified |
| Temporal Coverage: |
|
| Temporal Resolution: | Not specified |
| Data Format(s): |
|
| Platform(s) | OCEAN WEATHER STATIONS |
| Sensor(s): | RAWINSONDES |
| Version: | V1 |
| Data Contributor(s): | Jonathan Kahl, Mark Serreze |
| Metadata XML: | View Metadata Record |
Data Citation
As a condition of using these data, you must cite the use of this data set using the following citation. For more information, see our Use and Copyright Web page.
Kahl, J. 1997. Daily Arctic Ocean Rawinsonde Data from Soviet Drifting Ice Stations, Version 1. [Indicate subset used]. Boulder, Colorado USA. NSIDC: National Snow and Ice Data Center. doi: https://doi.org/10.5067/AH8D9CN70VN6. [Date Accessed].Detailed Data Description
The Daily Arctic Ocean Rawinsonde Data from the 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, such as, amount, type, and height, from Soviet North Pole drifting stations in the Arctic Ocean for the region north of 70 degrees North, from April 19, 1954 to July 31, 1990.
This data 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, with funding from the National Oceanic and Atmospheric Administration, the National Science Foundation, and the Electric Power Research Institute. It is intended as a unique data set for analysis of Arctic upper air processes and variability. 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.
Data are in ASCII text format.
Data granularity is one file per station per time period.
Each file contains:
- Number of soundings in the file
- Header of first sounding
- Transmission levels for first sounding (one measurement level per record)
- Header of second sounding
- Transmission levels for second sounding (one measurement level per line) etc.
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 the section titled: Variables in Header of Each Sounding. For variables and formats contained in the transmission levels, see the section titled: Variables in Transmission Levels of Each Sounding.
Variables in Header of Each Soundings
-
STATION
- North Pole station number. Missing values are -99. Occupies columns 1-3.
-
STN_IND
- STATION NUMBER INDICATOR: Positive single digit. Specifies the type of station number given in the Condigital station variable.
0 = WBAN NUMBER
1 = AIR FORCE AUGMENTED WMO NUMBER
2 = SHIP CALL SIGN
3 = MOBILE PLATFORM CALL SIGN
4 = MOBILE PLATFORM ID (Assigned by NCDC)
5 = WMO/CARDS NUMBER
6 = FIXED PLATFORM CALL SIGN
7 = OTHER STATION NUMBER (Origin unknown)
8 = RESERVED
9 = NO STATION NUMBERMissing values are 9. Occupies column 5.ELEV
ELEVATION: The height of the launch site in meters used in Condigital soundings. Missing values are 9999.9. Occupies columns 7-13. - Four-digit year of sounding observation. Missing values are 9999. Occupies columns 15-18.
-
MONTH
- Two-digit month of sounding observation. Missing values are 99. Occupies columns 20-21.
-
DAY
- Two-digit day of sounding observation. Missing values are 99. Occupies columns 23-24.
-
GMT_HOUR
- Two-digit GMT hour of sounding observation. Usually 00, 06, 12, or 18. However, for those days that had more than four soundings, there will be soundings with additional hours. Missing values are -9. Occupies columns 26-27.
-
GMT_MINUTE
- Two-digit GMT minute of sounding observation. Missing values are -9. Occupies columns 28-29.
-
STD_GMT_TIME
- Two-digit standard GMT time from Aerostan data set. Missing values are -9. Occupies columns 31-32.
-
LOCAL_TIME
- Three-digit local time used in Floppy soundings. Missing values are -9. Occupies columns 34-36.
-
RELSE_TIME
- The hour and minute of the actual release, expressed as HHMM. Used in Condigital soundings. Missing values are 9999. Occupies columns 38-41
-
LATITUDE
- The station latitude in degrees North. Missing values are 99.99. Occupies columns 43-47.
-
LONGITUDE
- The station longitude in degrees East. Missing values are 999.99. Occupies columns 49-54.
-
MIN_ALTITUDE
- Altitude in meters of first transmission level in sounding. Missing values are -9999999. Negative values generally indicate cases where the surface pressure is < 1000 mb and the first reported level is the mandatory 1000 mb level. Occupies columns 56-63.
-
MAX_ALTITUDE
- Altitude in meters of last transmission level in sounding. Missing values are -9999999. Occupies columns 65-72.
-
OBSN_TYPE
- Type of observation given in Condigital soundings:
01 = radio/rawinsonde
02 = rocketsonde
03 = satellite
04 = dropsonde
05 = aircraft flight level report
06 = Profiler
07 = PIBAL
08 = APOB
09 = RAWIN (RADAR winds only)
10 = Rawinsonde (RADAR winds)
11 = Radiosonde (optical theodolite)
12 = Rawinsonde (OMEGA NAVAID)
13-98 = reservedMissing values are 99. Occupies columns 74-75. -
QC_EFFORT
- Used in Condigital soundings.
- QUALITY CONTROL EFFORT: Intended for use in conjunction with the DATA_SRCE field for determining if the appendices of the Condigital documentation must be referenced for decoding the ELEMENT QUALITY flags. If QC EFFORT=0, the ELEMENT QUALITY flags defined within the body of this document apply, regardless of the DATA_SRCE. If the QC EFFORT > 0, the ELEMENT QUALITY flags will be defined in Appendix nn of the Condigital document (where nn = the value contained in the DATA_SRCE element).
0 = NCDC QC after 12/92
1 = NCDC QC prior to 1/93
2 = QC at source
3-7 = reserved
8 = no QC
9 = unknownMissing values are 9. Occupies column 77. -
DATA_SRCE
- DATA SOURCE/FORMAT: This field indicates the data source for the Condigital soundings only. See appendices keyed to the data source values for details concerning the original source.
00 = TD6103 (NMC)
01 = TD6201 (U.S. National data set prior to 1/93)
02 = Standard Nonreal-Time Data Transfer Format
(Mostly MicroART - post 12/92)
03 = Mini Rawin System Format (MRS)
04 = TDAT/WDAT Format
06 = Manuscript
07 = Range standard
08 = MIT
09 = NCAR
10 = TDF54
11 = TDF56
12 = other PC-based, semiautomated reduction system
13 = Canadian upper air archives
14 = Former USSR
15 = Peoples' Republic of China (PRC)
16 = Argentina
17 = British Antarctica
18 = Hong Kong
19 = Korea
18-98 = reserved
99 = unknownMissing values are 99. Occupies columns 79-80. -
NUM_LVLS
- NUMBER OF LEVELS: This is the number of data levels found in the sounding. Missing values are 0. Occupies columns 82-84.
- INST_CODE
- INSTRUMENT CODE: Seven-character string from Aerostan data set. Missing values are "???????." Occupies columns 86-92.
- CLOUD_AMOUNT
- CLOUD AMOUNT from Aerostan data set. Tenths of sky covered. Missing values are -9. Occupies columns 94-95.
- CLOUD_AMOUNT_QLTY
- CLOUD AMOUNT QUALITY from Aerostan data set. Missing values are -9. Occupies columns 97-98. 0 = No quality control
1 = correct
2 = doubtful value
3 = error
4 = corrected value
5 = original value missing; value produced
9 = missing data -
LOWER_CLOUD
- LOWER INFERIOR CLOUDS from Aerostan data set. Missing values are -9. Occupies columns 100-101.
0 = absence of clouds
1 = cumulus humilis
2 = cumulus humilis together with stratocumulus
3 = cumulonimbus calvus together with cumulus, stratocumulus or stratus
4 = stratocumulus cumulogenitus
5 = stratocumulus
6 = stratus and/or fractonimbus
7 = fractonimbus under altostratus or nimbostratus
8 = cumulus humilis together with cumulus congestus
9 = cumulonimbus capillatus, stratocumulus, stratus -
LOWER_CLOUD_QLTY
- LOWER INFERIOR CLOUDS QUALITY from Aerostan data set. Missing values are -9. Occupies columns 103-104. Refer to CLOUD_AMOUNT_QLTY for values.
- CLOUD_HEIGHT
- CLOUD HEIGHT from Aerostan data set (height of cloud base). Missing values are -9. Occupies columns 106-107.
0 = < 50 m
1 = 50-100 m
2 = 100-200 m
3 = 200-300 m
4 = 300-600 m
5 = 600-1000 m
6 = 1000-1500 m
7 = 1500-2000 m
8 = 2000-2500 m
9 = > 2500 m -
CLOUD_HEIGHT_QLTY
- CLOUD HEIGHT QUALITY from Aerostan data set. Missing values are -9. Occupies columns 109-110. Refer to CLOUD_AMOUNT_QLTY for values.
- MID_CLOUD
- MIDDLE CLOUD TYPE from Aerostan data set. Missing values are -9. Occupies columns 112-113.
1 = altostratus translucidus
2 = altostratus opacus or nimbostratus
3 = altocumulus translucidus
4 = altocumulus translucidus lenticularis
5 = altocumulus translucidus duplicatus or altocumulus opacus
6 = altocumulus cumulogenitus
7 = altocumulus opacus or duplicatus
8 = altocumulus cumuliformis, floccus, or castellatus
9 = altocumulus together with cirrus -
MID_CLOUD_QLTY
- MIDDLE CLOUD SHAPE QUALITY from Aerostan data set. Missing values are -9. Occupies columns 115-116. Refer to CLOUD_AMOUNT_QLTY for values.
- HIGH_CLOUD
- HIGH_LEVEL CLOUDS TYPE from Aerostan data set. Missing values are -9. Occupies columns 118-119.
1 = cirrus filosus
2 = cirrus densus
3 = cirrus nothus
4 = cirrus uncinus
5 = cirrus, cirrostratus
6 = cirrus, cirrostratus
7 = cirrostratus (all sky)
8 = cirrostratus (part of sky)
9 = cirrocumulus -
HIGH_CLOUD_QLTY
- HIGH_LEVEL CLOUDS SHAPE QUALITY from Aerostan data set. Missing values are -9. Occupies columns 121-122. Refer to CLOUD_AMOUNT_QLTY for values.
One or more of the following three text fields will appear at the end of each sounding's header in columns 124-325. For a given sounding, COMMENTS and OTHERFILEDATA may or may not be present but ORIGINAL_LATLON will always be there. No matter how many of the following three text fields are present, they will always occur in the order given below and will always begin in column 121.
Variables in Transmission Levels of Each Sounding
-
COMMENTS
- May or may not be present. Floppy data set contained key sequences of unknown meaning. If they were present for a given sounding, they will appear directly after HIGH_CLOUD_QLTY. This field can be 0 to 100 characters long (when present, usually contains 3-10 characters).
-
OTHERFILEDATA
- May or may not be present. Soundings which are the product of merging two different sources may contain a text field containing the following:
TXT: YEAR MONTH DAY GMT_HOUR GMT_MINUTE LATITUDE LONGITUDE 3km data: PRESSURE TEMPERATURE HUMIDITY WIND_DIRECTION WIND_VELOCITY DPDP.
These are alternate values for some of the header and 3km level variables. This text field will start with the letters "TXT: " and continue with values for the above listed variables. After the value for LONGITUDE is given, the words "3km data:" may appear with the above listed variables following.
-
ORIGINAL_LATLON
- Will be present in every sounding. Most soundings have new latitude and longitude position data from one of two independent sources, with the exception of those soundings whose dates were out of range for the independent sources. All soundings have this text field, which begins with the words "Old latlon" and follows with the position data from its original source. (Old latlon, LATITUDE LONGITUDE.)
-
LEVEL_CODE
- LEVEL CODE is from the Aerostan data set. Missing values are 99. Occupies columns 1-2.
01 = surface
02 = significant level (not at mandatory level)
03 = tropopause (significant level)
04 = significant level for wind (not at mandatory level)
05 = max wind (not at mandatory level)
06 = level of wind shift (not at mandatory level)
10 = mandatory level (for pressure or altitude)
11 = surface and standard level coincide
12 = significant level (occurs at mandatory level)
13 = tropopause (occurs at mandatory level)
14 = significant wind level (occurs at mandatory level)
15 = max wind (occurs at mandatory level)
16 = wind shift (occurs at mandatory level) -
ALTITUDE
- Height of the pressure level in whole meters. Missing values are -999999. Occupies columns 4-10.
-
A_ALT_QLTY
- Aerostan's quality indicator for the ALTITUDE field. Missing values are -9. Occupies columns 12-13. Refer to CLOUD_AMOUNT_QLTY for values.
-
K_ALT_QLTY
- Kahl's quality indicator for the ALTITUDE field. Occupies column 15.
0 = FAIL
1 = PASS -
PRESSURE
- AIR PRESSURE of the data level in hPa. Missing values are 9999.99. Occupies columns 17-23.
-
A_PRES_QLTY
- Aerostan's quality indicator for the PRESSURE field. Missing values are -9. Occupies columns 25-26. Refer to CLOUD_AMOUNT_QLTY for values.
-
K_PRES_QLTY
- Kahl's quality indicator for the PRESSURE field. Occupies column 28.
0 = FAIL
1 = PASS -
TEMPERATURE
- AIR TEMPERATURE in degrees Celsius. Missing values are 99.99. Occupies columns 30-35.
-
A_TEMP_QLTY
- Aerostan's quality indicator for the TEMPERATURE field. Missing values are -9. Occupies columns 37-38. Refer to CLOUD_AMOUNT_QLTY for values.
-
K_TEMP_QLTY
- Kahl's quality indicator for the TEMPERATURE field. Occupies column 40.
0 = FAIL
1 = PASS -
HUMIDITY
- RELATIVE HUMIDITY ranging from 0 to 100 percent. Missing values are -99.9. Occupies columns 42-46.
- K_HUMID_QLTY
- Kahl's quality indicator for the HUMIDITY field. Occupies column 48.
0 = FAIL
1 = PASS -
WIND_DIRECTION
- WIND DIRECTION ranging from 0 to 360 degrees. Missing values are 999. Occupies columns 50-52.
-
A_WIND_DIR_QLTY
- Aerostan's quality indicator for the WIND DIRECTION field. Missing values are -9. Occupies columns 54-55. Refer to CLOUD_AMOUNT_QLTY for values.
- K_WIND_DIR_QLTY
- Kahl's quality indicator for the WIND_DIRECTION field. Occupies column 57.
0 = FAIL
1 = PASS -
WIND_VELOCITY
- WIND VELOCITY in meters/second. Missing values are -99.9. Occupies columns 59-63.
-
A_WIND_SPD_QLTY
- Aerostan's quality indicator for the WIND VELOCITY field. Missing values are -9. Occupies columns 65-66. Refer to CLOUD_AMOUNT_QLTY for values.
-
K_WIND_SPD_QLTY
- Kahl's quality indicator for the WIND_VELOCITY field. Occupies column 68.
0 = FAIL
1 = PASS -
LVL_QUAL
- LEVEL QUALITY INDICATOR: Denotes the results of Condigital's quality controls applied to this level. Range is 0 to 9 as follows:
|
0 |
All available elements are correct |
|
1 |
One or more elements are suspect; no replacement level exists |
|
2 |
One or more elements are suspect; a replacement level exists |
|
3 |
Operator (observer) deleted, no replacement level follows |
|
4 |
NCDC edit/quality control has determined this level to be highly suspect |
|
5-6 |
Reserved |
|
7 |
Unknown |
|
8 |
Replacement level |
|
9 |
The level has not been checked |
-
Missing values are 9. Occupies column 70.
-
DPDP
- DEW POINT DEPRESSION (DEW POINT DEFICIT) at the current level in degrees Celsius. Missing values are 99.9. Occupies columns 72-75.
-
A_DPD_QLTY
- Aerostan's quality indicator for the DEW POINT DEFICIT field. Missing values are -9. Occupies columns 77-78. Refer to CLOUD_AMOUNT_QLTY for values.
-
K_DPD_QLTY
- Kahl's quality indicator for the DPDP field. Occupies column 80.
0 = FAIL
1 = PASS -
TYP_LVL
- TYPE OF LEVEL: Condigital's code indicating the reason for selection of the level. Range of values is 00-99.
|
00 |
Operator deleted level |
|
01 |
Operator added level |
|
02 |
Aircraft report |
|
03 |
Dropsonde |
|
04 |
Rocketsonde |
|
05 |
Profiler |
|
06 |
Reserved |
|
07 |
Reserved |
|
08 |
Reserved |
|
09 |
Begin missing data (all elements) |
|
10 |
End missing data (all elements) |
|
11 |
Begin missing temperature data/doubtful altitude |
|
12 |
End missing temperature data |
|
13 |
Begin missing relative humidity/dew point depression data |
|
14 |
End missing relative humidity/dew point depression data |
|
15 |
Begin doubtful altitude data |
|
16 |
Begin doubtful temperature, altitude data |
|
17 |
End doubtful temperature data |
|
18 |
Reserved |
|
19 |
Reserved |
|
20 |
Interpolated (generated) mandatory pressure level |
|
21 |
Interpolated (generated) level other than a mandatory pressure level |
|
22 |
Highest level reached before balloon descent because of icing or turbulence |
|
23 |
Balloon re-ascended beyond previous highest level |
|
24 |
Base pressure for stability index |
|
25 |
Zero-degree crossing for the RADAT message |
|
26 |
Tropopause |
|
27 |
Maximum wind level |
|
28 |
Below surface level |
|
29 |
Reserved |
|
30 |
Reserved |
|
31 |
Surface level |
|
32 |
Mandatory pressure level |
|
33 |
Within 20 hectopascals (mb) of the surface |
|
34 |
Flight termination level |
|
35 |
Relative humidity level selection terminated |
|
36 |
Pressure less than 10 hectopascals |
|
37 |
Mandatory temperature level |
|
38 |
Significant temperature level |
|
39 |
Significant relative humidity level |
|
40 |
Winds at constant height (above ground level) |
|
41 |
Mandatory wind level |
|
42 |
Significant wind level |
|
43 |
Incremental wind level (e.g., 1-minute, fixed regional) |
|
44 |
Significant thermodynamic level (reason for selection is unknown) |
|
45 |
High resolution data sample |
|
46 |
Other/unspecified |
|
47 |
Generated winds at incremental heights |
|
48-50 |
Reserved |
|
51-99 |
***Used for those levels that satisfy the criteria for multiple types*** |
|
51-58 |
Reserved |
|
59 |
Begin missing data (all elements) at a tropopause level |
|
60 |
End missing data (all elements) at a tropopause level |
|
61 |
Begin missing temperature data at a tropopause level |
|
62 |
End missing temperature data at a tropopause level |
|
63 |
Begin missing relative humidity/dew point depression data at a tropopause level |
|
64 |
End missing relative humidity/dew point depression data at a tropopause level |
|
65 |
Begin doubtful altitude data at a tropopause level |
|
66 |
Begin doubtful temperature, altitude data at a tropopause level |
|
67 |
End doubtful temperature data at a tropopause level |
|
68 |
Reserved |
|
69 |
Begin missing data (all elements) at a mandatory pressure level |
|
70 |
End missing data (all elements) at a mandatory pressure level |
|
71 |
Begin missing temperature data at a mandatory pressure level |
|
72 |
End missing temperature data at a mandatory pressure level |
|
73 |
Begin missing relative humidity/dew point depression data at a mandatory pressure level |
|
74 |
End missing relative humidity/dew point depression data at a mandatory pressure level |
|
75 |
Begin doubtful altitude data at a mandatory pressure level |
|
76 |
Begin doubtful temperature, altitude data at a mandatory pressure level |
|
77 |
End doubtful temperature data at a mandatory pressure level |
|
78-80 |
Reserved |
|
81 |
Level satisfies requirements for selection as a mandatory pressure level and as a tropopause level |
|
82 |
Level satisfies requirements for selection as a mandatory pressure level and as a significant level |
|
83 |
Level satisfies requirements for selection as a mandatory pressure level and as the surface level |
|
84 |
Highest level reached before balloon descent because of icing or turbulence and is a mandatory level |
|
85 |
Balloon re-ascended beyond previous highest level and is a mandatory level |
|
86 |
Base pressure for stability index and is a mandatory level |
|
87 |
Zero-degree crossing for the RADAT message and is a mandatory level |
|
88 |
Maximum wind level and is a mandatory level |
|
89 |
Tropopause level, maximum wind level, and mandatory level |
|
90 |
Tropopause level and is a maximum wind level |
|
91-99 |
Reserved |
-
ELEMENT_QLTY
- Condigital field. ELEMENT QUALITY FLAGS: These fields contain the result of any quality control procedures for identifying suspect and doubtful individual elements, and elements that failed QC checks. Descriptions of the element quality flags are contained in the appendices, which are keyed to the DATA_SRCE field. If, for example, the DATA_SRCE is 01 (source = TD6201), the appendix is numbered 02, etc. The Element Quality is assigned a value equivalent to the least correct flag.
- The range of values is listed in each applicable appendix. Although the range of values for element quality flags are specific for each data source, as a general rule, any combination of ASCII characters, except lowercase letters and "#," is allowed in this element.
|
Record Position |
Element Name |
|
41-42 |
EQET (Elapsed Time) |
|
43-44 |
EQP (Pressure/Ranging) |
|
45-46 |
EQH (Height) |
|
47-48 |
EQT (Temperature) |
|
49-50 |
EQU (Humidity) |
|
51-52 |
EQD (Dew Point Depression) |
|
53-54 |
EQWDS (Wind Direction/Speed) |
-
Missing values are "??????????????." Occupies columns 86-99.
-
NCDC_USE
- Condigital field: Reserved for internal NCDC use. Missing values are *quot;??." Occupies columns 101-102.
Files are named np_**sound.dat
Where:
** stands for a North Pole station numbered 03 through 31.
Example data file:np_03sound.dat
Each of the 21 files contain 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.
The parameters for this data set represent 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 such as amount, type, and height.
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).
Spatial Coverage
North polar regions:
- Minimum latitude: 70 N
- Maximum latitude: 90 N
- Minimum longitude: 180 W
- Maximum longitude: 180 E
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.
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
The following is an excerpt of soundings taken from April 20, 1954 to April 14, 1955.
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 ?????????????? ?? |
A major part of the data processing effort involved merging the original data sets into a single archive. Refer to Summary of Individual Data Sources. 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.
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 contain quality indicators prior to being processed by Kahl. Refer to the Summary of Individual Data Sources section of this document.
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.
Data Acquisition and Processing
Please review the rawinsonde instrument description.
Merging of Data Sets
A major part of the data processing effort involved merging the original data sets into a single archive. Refer to the Summary of Individual Data Sources section of this document. 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.
References and Related Publications
Contacts and Acknowledgments
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
NSIDC User Services
Phone: 1 303 492-6199
Email: nsidc@nsidc.org
Scientists
Research Grants
Scientific Publications
Informatics Research
NSIDC Scientific Expeditions




