USCRN SOIL MOISTURE CLIMATOLOGY (SMC01) FILES
UPDATED: 2020-02-04
README CONTENTS:
1. GENERAL INFORMATION
2. DATA VERSION / STATUS UPDATES
3. FILE AND FILENAME FORMATS
4. DATA FIELDS / FORMATS / IMPORTANT NOTES
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1. GENERAL INFORMATION
The U.S. Climate Reference Network (USCRN) was designed to monitor the climate
of the United States using research quality instrumentation located within
representative pristine environments that are unlikely to experience
anthropogenic land use change over the next 50 years. Soil moisture and soil
temperature are among the network's primary variables measured in triplicate.
The basic layer mean soil moisture and temperature data are available in Daily
and Hourly file sets at the USCRN web site under quality controlled data sets:
https://www.ncdc.noaa.gov/crn/qcdatasets.html
Volumetric soil moisture is difficult to interpret in a relative sense without
reference to a climatology. The USCRN Soil Moisture Climatology (SMC) files
contain the MEAN, MEDIAN, interquartile range (IQR), and decimal fraction of
available data that are valid (VALID) for each hour of the year at 5, 10, 20,
50, and 100 cm depth soil layers as well as for a top soil layer (TOP) and
column soil layer (COLUMN). The TOP layer consists of an average of the 5 and
10 cm depths, while the COLUMN layer includes all available depths at a
location, either two layers or five layers depending on soil depth.
All statistics are derived from the period-of-record values for the hour in
question, and all the valid values for that same hour of the day during the
surrounding 15 days before and after that day. The MEAN is the average of all
the values that are valid; observations that are not flagged for quality,
frozen state, or missing are considered VALID. The MEDIAN (50th percentile)
and the interquartile range (IQR = 75th percentile - 25th percentile) are
based on the empirical cumulative distribution function of the valid values.
For more information on the definitions of the variables and the methods used
for their calculation, please consult the referenced Theoretical Basis Document.
The initial climatology is derived from the period of record through 2019,
with the expectation that the climatology will be updated annually after each
year's observations are finalized.
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2. DATA VERSION / STATUS UPDATES
Status and Version Information for U.S. Climate Reference Network Standardized
Soil Moisture (SSM) Dataset.
This is the initial Version 1.0.
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3. FILE AND FILENAME FORMATS
The soilclim01 directory contains a single CSV text file for the
period-of-record climatology of each USCRN station. Files contain a climatology
generated for each month-day-hour in a calendar year. Climatology files are
updated annually approximately a month after the end of the calendar year. The
file name convention is:
CRNSMC01TT-${name}.csv
CRNSMC01 = filename prefix to denote CRN soilclim01 data
TT = 2-character file format number (currently 01)
${name} = station name (state_location_vector) (e.g. AZ_Tucson_11_W)
The 2-character sequence TT indicates the file format number and is updated
when the file format is changed.
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4. DATA FIELDS / FORMATS
Each station file contains CSV formatted fields with a single month-
day-hour's data per line. A summary table of the fields and a detailed listing
of field definitions are shown below.
All hourly data are calculated over the 60-minute period *ending* at the UTC
and LST times shown. Please note that the station's Local Standard Time is
always used, regardless of its Daylight Savings status.
Field# Name Units
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1 WBANNO XXXXX
2 MONTH MM
3 DAY DD
4 HOUR HH
5 MEAN_5_CM m^3/m^3
6 MEDIAN_5_CM m^3/m^3
7 IQR_5_CM m^3/m^3
8 VALID_5_CM fraction
9 MEAN_10_CM m^3/m^3
10 MEDIAN_10_CM m^3/m^3
11 IQR_10_CM m^3/m^3
12 VALID_10_CM fraction
13 MEAN_20_CM m^3/m^3
14 MEDIAN_20_CM m^3/m^3
15 IQR_20_CM m^3/m^3
16 VALID_20_CM fraction
17 MEAN_50_CM m^3/m^3
18 MEDIAN_50_CM m^3/m^3
19 IQR_50_CM m^3/m^3
20 VALID_50_CM fraction
21 MEAN_100_CM m^3/m^3
22 MEDIAN_100_CM m^3/m^3
23 IQR_100_CM m^3/m^3
24 VALID_100_CM fraction
25 MEAN_TOP m^3/m^3
26 MEDIAN_TOP m^3/m^3
27 IQR_TOP m^3/m^3
28 VALID_TOP fraction
29 MEAN_COLUMN m^3/m^3
30 MEDIAN_COLUMN m^3/m^3
31 IQR_COLUMN m^3/m^3
32 VALID_COLUMN fraction
1 WBANNO
The station WBAN number.
2 MONTH
Month of year.
3 DAY
Day of month.
4 HOUR
Hour of day.
5 MEAN_5_CM
Soil Moisture Mean at 5 cm depth
6 MEDIAN_5_CM
Soil Moisture Median at 5 cm depth
7 IQR_5_CM
Soil Moisture Interquartile Range at 5 cm depth
8 VALID_5_CM
Fraction of Possible Observations that are Valid at 5 cm depth
9 MEAN_10_CM
Soil Moisture Mean at 10 cm depth
10 MEDIAN_10_CM
Soil Moisture Median at 10 cm depth
11 IQR_10_CM
Soil Moisture Interquartile Range at 10 cm depth
12 VALID_10_CM
Fraction of Possible Observations that are Valid at 10 cm depth
13 MEAN_20_CM
Soil Moisture Mean at 20 cm depth
14 MEDIAN_20_CM
Soil Moisture Median at 20 cm depth
15 IQR_20_CM
Soil Moisture Interquartile Range at 20 cm depth
16 VALID_20_CM
Fraction of Possible Observations that are Valid at 20 cm depth
17 MEAN_50_CM
Soil Moisture Mean at 50 cm depth
18 MEDIAN_50_CM
Soil Moisture Median at 50 cm depth
19 IQR_50_CM
Soil Moisture Interquartile Range at 50 cm depth
20 VALID_50_CM
Fraction of Possible Observations that are Valid at 50 cm depth
21 MEAN_100_CM
Soil Moisture Mean at 100 cm depth
22 MEDIAN_100_CM
Soil Moisture Median at 100 cm depth
23 IQR_100_CM
Soil Moisture Interquartile Range at 100 cm depth
24 VALID_100_CM
Fraction of Possible Observations that are Valid at 100 cm depth
25 MEAN_TOP
Soil Moisture Mean at 5 to 10 cm depth
26 MEDIAN_TOP
Soil Moisture Median at 5 to 10 cm depth
27 IQR_TOP
Soil Moisture Interquartile Range at 5 to 10 cm depth
28 VALID_TOP
Fraction of Possible Observations that are Valid at 5 to 10 cm depth
29 MEAN_COLUMN
Soil Moisture Mean at 5 to 100 cm depth
30 MEDIAN_COLUMN
Soil Moisture Median at 5 to 100 cm depth
31 IQR_COLUMN
Soil Moisture Interquartile Range at 5 to 100 cm depth
32 VALID_COLUMN
Fraction of Possible Observations that are Valid at 5 to 100 cm depth