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Estonian Mean Snow Depth and Duration (1891-1994)

Summary

This data set contains the number of days of snow cover in days per year, and three 10-day snow depth means per month in centimeters from 262 stations across Estonia. The days of snow cover data extend from 1891 through 1994, while the snow depth means extend from 1891 through 1990. Some stations for some years have two data entries, one for a protected collection area, and one for an exposed collection area. Jaak Jaagus of the University of Tartu in Estonia contributed these data to the National Snow and Ice Data Center. Data are available via ftp.

NSIDC strongly encourages you to register as a user of this data product. As a registered user, you will be notified of updates and corrections. Please contact NSIDC User Services to register.

Citing These Data:

Jaagus, Jaak. 2000. Estonian mean snow depth and duration (1891-1994). Boulder, CO: National Snow and Ice Data Center. http://dx.doi.org/10.7265/N5X63JTN

The following example shows how to cite the use of this data set in a publication. For more information, see our Use and Copyright Web page.

1. Contacts
2. Overview
3. Detailed Data Description
4. Data Acquisition and Processing
5. Data Access and Related Collections
6. Acknowledgments
7. Document Information

1. Contacts

Investigator

Jaak Jaagus
Department of Geography
University of Tartu
Vanemuise 46, 51014 Tartu, Estonia
jjaagus@ut.ee

Technical Contact

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

2. Overview

The parameters contained in this data set are the number of days per year with snow, and the mean snow depth in centimeters (three 10-day snow depth means per month calculated for days 1-10, 11-20, and 21-last day of the month) for October through May. There are a total of 262 stations across Estonia. The data were originally provided to NSIDC in 1997, and were published by NSIDC in 2000. Data were acquired through state sponsored observation programs. The snow depth data begin 1 October 1881, and end 31 May 1990. Records for days with snow extend an additional four years for some stations, ending in 1994.

3. Detailed Data Description

Data Format

Data are stored in the following ASCII text files:

a single file containing the list of stations (stations.dat) for 255 stations
a single file containing the number of days with snow for all stations and years (days_of_snow.dat)
one file for each station containing the three 10-day snow depth means in centimeters for all years (stat_xxx.dat, where xxx is the 3-digit station number)
one file for each year containing the three 10-day snow depth means in centimeters for all stations (year_xxxx.dat, where xxxx is the 4-digit year)

Years are listed as hydrological years. For example, 1882 stands for the period that starts in October 1881 and goes through through May 1882. In the 1950s and 1960s some stations have two observations recorded for the same day. One observation is for an open (exposed) or unprotected collection area, and one is for a closed or protected collection area. In these cases, a negative station number indicates a record for measurement that was taken in a protected observation area. No snow is indicated by 0, and no data available for a particular day is indicated by -1.

Exposed sites are not protected from winds that may remove some snow, while protected sites are sheltered from the wind to some extent by trees or buildings. Usually, snow depth is higher in protected sites. Note that information on the surroundings of the observations sites was available to the data provider only from 1945 on. Therefore prior to 1945 some of the sites may be protected and yet are not marked as such.

Data Sample - Mean Snow Depth by station

The following sample is taken from the file stat_259.dat for station VOKA (259). The first line contains the station number, station name, station latitude, and station longitude in decimal degrees. All latitude values are positive (north). All longitude values are positive (east). The second line contains the months for which data are included. The remaining lines contain the station number, the year, and 24 mean snow measurements (three approximately 10-day means for each month). The first number for each month is the mean for the first 10 days of the month, the second number is the mean for the next 10 days, and the third number is the mean for the rest of the days in the month.

      259   VOKA             59.42     27.57
           Oct    Nov      Dec     Jan       Feb      Mar      Apr     May
   259   1932 0 0 1  2  0  0  3 11 15 13  8  0  4  5  3  5 13 14  2  0  0 0 0 0
   259   1933 0 0 0  0  0  0 -1 -1 -1  4  7 14 20 26 30 30 12  1  5  0  0 0 0 0
   259   1934 0 0 0  3  8  8  4  5  9  7  6  7 10 14  9 14 19  0  0  0  0 0 0 0
   259   1935 0 0 0  0  0  1  0  1  2  8  9  8 20 27 12 10  5  6  3  1  0 0 0 0
   259   1936 0 0 0  0  0  0  1  2  7  3  6  9 10 21 27 23 16 10  4  0  0 0 0 0
   259   1937 0 0 0  0  0  1  1  0  0  3 11  9 10 16 26 29 17  4  2  0  0 0 0 0
   259   1938 0 0 0  0  1  4 13 19 30 27 27 29 22 16 20 12  2  1  1  0  0 0 0 0
   259   1939 0 0 0 -1 -1 -1 -1 -1 -1 11  9  2  2  0  1  3  2  0  0  0  0 0 0 0
   259   1942 0 -1 -1 -1 -1 -1 -1 23 18 24 32 36 40 41 44 48 50 37 32 3 0 2 0 0
   259   1943 0 0 0  0  2 10 12 11  2 11 15 21 19 20 15  6  0  0  0  0  0 0 0 0
   259   1944 0 0 0  0  0  2  6  1  0 -1 -1 -1 -1 -1 -1 -1 -1 -1  0  0  0 0 0 0

Data Sample - Mean Snow Depth by Year

The following sample is from the file year_1899.dat for the year 1899. The first line contains header information. The remaining lines contain the station number, station name, station latitude, station longitude, and 24 mean snow measurements (three approximately 10-day means for each month). The first number for each month is the mean for the first 10 days of the month, the second number is the mean for the next 10 days, and the third number is the mean for the remaining days in the month.

STAT_N STAT_NAME      LAT    LON      Oct    Nov    Dec   Jan      Feb      Mar       Apr     May

   203    TAHKUNA       59.10  22.58     0 0 0  0 0 1  0 3 2 12 10 16 23 19 16 -1 -1 -1  7  0  0 0 0 0
   169    RAKVERE       59.35  26.37     0 0 1  0 0 1  0 1 0 12 17 24 43 37 43 42 37 41 31  2  1 0 0 0
   180    RUHNU         57.78  23.27     0 1 0  0 0 0  0 3 4  5 10  9 18 22 19 34 33 39 35  8  1 0 0 0
   260    VORMSI        59.03  23.12     0 6 1  0 0 1  0 0 0  5  5  5  6  2  4 10  4  8  6  0  1 0 0 0
   211    TARTU         58.38  26.72     0 0 2  0 0 0  0 5 4 18 29 22 23 16 25 34 31 32 10  0  0 0 0 0
   254    VILJANDI      58.37  25.58     0 0 2  0 0 1  0 5 5 11 17  4 10  4  6 19  4  5  1  1  0 1 0 0
   255    VILSANDI      58.38  21.82     0 0 0  0 0 0  0 1 1  2  1  0  1  0  0  4  1  4  0  0  0 1 0 0

Data Sample - Number of Days With Snow

The following sample shows excerpts from the days_of_snow.dat file. The columns are: station number, station name, year, days of snow.

   140  OSMUSSAAR     1892   102
   146  PAKRI         1892   116
   166  PA'RNU        1892   134
   180  RUHNU         1892   159
   203  TAHKUNA       1892   131
   255  VILSANDI      1892    84
   260  VORMSI        1892   127
   125  NAISSAAR      1893   158
   127  NARVA-JOESUU  1893   107
   140  OSMUSSAAR     1893   135
   146  PAKRI         1893   126
   180  RUHNU         1893   144
   203  TAHKUNA       1893   156
   255  VILSANDI      1893   120
	.
	.
	.
	
   287  KO'PI         1934   129
   290  RASINA        1934   117
   291  PINDI         1934   123
   292  KUREKYLA      1934   123
     1  ABRUKA        1935    58
    14  ELLAMAA       1935    75
    24  HELME         1935    52
    27  HIRVLI        1935    80
    28  HOLDRE        1935   101
    31  IISAKU-I      1935   117
    34  JO'GEVA       1935    83
    41  JA'NEDA       1935   101
    42  JA'RVSELJA    1935   102
    43  JA'A'RJA      1935    66
    52  KEHRA         1935   117
    55  KERI          1935    48
    57  KIHNU         1935    55
    63  KOHILA        1935   105
    64  KOHTLA        1935   101
	 .
	 .
	 .

Station Locations

The list of stations (stations.dat) contains the station number, station name, latitude and longitude coordinates in decimal degrees, and the collection start and end years at each station. The names have been translated into English using the latin alphabet. Note the following four vowel transliterations in particular:

Estonian Vowel	English Transliteration
Ä Ö Õ Ü	A' O' O~ Y

The following stations were located in a protected area:

  1   ABRUKA
  2   AHJA
  5   ALLIKU
11   ARUVALLA
14   ELLAMAA
15   ELVA
17   ESNA
19   HAAPSALU
26   HIMMISTE
27   HIRVLI
30   HYYRU
32   IISAKU-II
33   JAANI
39   JA'GALA
40   JA'LEVERE
45   KAMBJA
49   KASARI
58   KIISA
61   KLOOSTRIMETSA
69    KONNUVERE
72    KOORVERE
81    KUUSTLE
87    KA'RDLA-I

91    KA'RU
94    KYKITA
96    LAOSE
105    LUGUSE
111    MEHIKOORMA
114    METSKYLA
117    MULGI-N
127    NARVA-JO~ESUU
132    NA'A'RI
133    OANDU
137   OOSTRIKU
139    OREKYLA
140    OSMUSSAAR
144    PAJUBA
149    PAUNKYLA
151    PIIGASTE
158    PRANGLI-N
161    PURTSE
163    PO~LTSAMAA
164    PO~O~SASPEA
177    ROHUKYLA
180    RUHNU
181    RO~IKA

182    RA'PINA
186    SIMUNA
192    SURJU
198    SO~RU
201    SA'NNA
204    TAHKUSE
205    TALLINN,MAJA
208    TAMSALU
215    TIPU
222    TUDU
224    TO'LLISTE
225    TO'RVA
227    TO'RVE
232    UUE-LO'VE
235    VALGA
236    VALMA
245    VASKNARVA
247    VASTSEMETSA
249    VETLA
251    VIHTERPALU
254    VILJANDI
257    VIRTSU
261    VO~HMA

Spatial and Temporal Coverage

The stations in this data set are bound by a southernmost latitude of 57.0 degrees North, northernmost latitude of 60.0 degrees North, westernmost longitude of 21.0 degrees East, and easternmost longitude of 29.0 degrees East. The earliest snow depth data begin 1 October 1881. The last record ends 31 May 1990. Depth data are means for days 1-10, 11-20, and 21-last day of the month, for October through May. The length of the data record varies depending on the station. The stations.dat file gives the start and end years for each station. Records for days with snow extend an additional four years for some stations, ending in 1994.

4. Data Acquisition and Processing

Instrument and Measurement Technique

Between 1945 and 1991, data were collected according to procedures as described in the documentation for other Former Soviet Union Meteorological data sets such as the Former Soviet Union Hydrological Snow Surveys data set. Data collected before 1940 and after 1991 followed similar procedures at Estonian Hydrometeorological stations.

In the 1950s and 1960s there are two depth measurements for some locations: one at an open area and one at a covered or protected area. Some stations were permanently located in a protected area and are listed in the Station Locations section.

Processing and Quality Assessment at NSIDC

At NSIDC, we reformatted data files to make them easier to use. We removed stations from the station list for which there were no data listed in the data files.

We looked at the mean and standard deviation of snow depth in both open and closed sites to establish that the values and seasonal pattern are reasonable, and looked at a time series of number of days of snow to establish that there are no obvious outliers. We performed no other quality assessment, and changed none of the data values.

A cursory comparison with data from Central Asian Snow Cover from Hydrometeorological Surveys (see Related Data Sets) showed some matches and some differences, but no obvious systematic inconsistencies.

Users of these data should be aware that snowfall is notoriously difficult to measure. Since the spatial variability of snow depth is great and detailed metadata on the observation locations and instrumentation is not available, care should be taken in using these data.

5. Data Access and Related Collections

Downloading the Data Files

You may obtain all files in this data set from the ftp site (ftp://sidads.colorado.edu/pub/DATASETS/NOAA/G01174/).

Related NSIDC Data Collections

National Snow and Ice Data Center. 2001. Central Asian Snow Cover from Hydrometeorological Surveys. Boulder, CO: National Snow and Ice Data Center. Digital Media.
Krenke, A. 1998, updated 2004. Former Soviet Union Hydrological Snow Surveys. Boulder, CO: National Snow and Ice Data Center. Digital Media.
Armstrong, R. 2001. Historical Soviet Daily Snow Depth Version 2 (HSDSD). Boulder, CO: National Snow and Ice Data Center. CD-ROM.

Please search our data catalog for other NSIDC snow data sets.

6. Acknowledgments

This data set has been made available through the generosity of Dr. Jaak Jaagus, Department of Geography, University of Tartu, Estonia.

The NOAA team (F. Fetterer, Lead) maintains this product at NSIDC. C. Haggerty and D. Van Westrum prepared the data for publication at NSIDC. This work was supported by funding from NOAA�s National Environmental Satellite, Data, and Information Service and the National Geophysical Data Center.