USCRN/USRCRN SOIL MOISTURE 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 ******************************************************************************** 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 This standardized soil moisture product is derived using the soil moisture climatology from the SMC01 product series (described in a separate README file) in the following manner. The soil moisture volumetric water content (SMVWC) is reported as observed for the layer in question. The soil moisture anomaly (SMANOM) is derived by subtracting the MEDIAN from the SMVWC value and dividing the difference by the interquartile range (IQR) for that hour: SMANOM = (SMVWC - MEDIAN) / (IQR) The soil moisture percentile (SMPERC) is derived by taking all the values that were used to create the empirical cumulative distribution function (ECDF) that yielded the MEDIAN and adding the current observation to the set, recalculating the ECDF, and determining the percentile value of the current observation. Finally, the soil temperature for the individual layers is provided for the dataset user convenience. Soil temperature is not provided for the combined layers. 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, and the standardized soil moisture product recalculated with the updated climatology for the period of record. ******************************************************************************** 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. ******************************************************************************** 3. FILE AND FILENAME FORMATS The soilanom01 directory contains a single CSV text file for the period-of-record time series of standardized soil moisture values for each USCRN station. Files are typically updated multiple times per day and are named according to the following convention: CRNSSM01TT-${name}.csv CRNSSM01 = filename prefix to denote CRN SoilMoisture01 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. ******************************************************************************** 4. DATA FIELDS / FORMATS Each station file contains CSV formatted fields with a single 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 --------------------------------------------- 1 WBAN_NO XXXXX 2 DATE_TIME YYYYMMDDHH 3 LONGITUDE Decimal_degrees 4 LATITUDE Decimal_degrees 5 SMVWC_5_CM m^3/m^3 6 SMANOM_5_CM IQR_deviations 7 SMPERC_5_CM Percentile 8 ST_5_CM Celsius 9 SMVWC_10_CM m^3/m^3 10 SMANOM_10_CM IQR_deviations 11 SMPERC_10_CM Percentile 12 ST_10_CM Celsius 13 SMVWC_20_CM m^3/m^3 14 SMANOM_20_CM IQR_deviations 15 SMPERC_20_CM Percentile 16 ST_20_CM Celsius 17 SMVWC_50_CM m^3/m^3 18 SMANOM_50_CM IQR_deviations 19 SMPERC_50_CM Percentile 20 ST_50_CM Celsius 21 SMVWC_100_CM m^3/m^3 22 SMANOM_100_CM IQR_deviations 23 SMPERC_100_CM Percentile 24 ST_100_CM Celsius 25 SMVWC_TOP m^3/m^3 26 SMANOM_TOP IQR_deviations 27 SMPERC_TOP Percentile 28 SMVWC_COLUMN m^3/m^3 29 SMANOM_COLUMN IQR_deviations 30 SMPERC_COLUMN Percentile 1 WBAN_NO The station WBAN number. 2 DATE_TIME The Universal Coordinated Time (UTC) date and hour of the observation. 3 LONGITUDE Station longitude, using WGS-84. 4 LATITUDE Station latitude, using WGS-84. 5 SMVWC_5_CM Soil Moisture Volumetric Water Content at 5 cm depth 6 SMANOM_5_CM Soil Moisture Anomaly at 5 cm depth 7 SMPERC_5_CM Soil Moisture Percentile at 5 cm depth 8 ST_5_CM Soil Temperature at 5 cm depth 9 SMVWC_10_CM Soil Moisture Volumetric Water Content at 10 cm depth 10 SMANOM_10_CM Soil Moisture Anomaly at 10 cm depth 11 SMPERC_10_CM Soil Moisture Percentile at 10 cm depth 12 ST_10_CM Soil Temperature at 10 cm depth 13 SMVWC_20_CM Soil Moisture Volumetric Water Content at 20 cm depth 14 SMANOM_20_CM Soil Moisture Anomaly at 20 cm depth 15 SMPERC_20_CM Soil Moisture Percentile at 20 cm depth 16 ST_20_CM Soil Temperature at 20 cm depth 17 SMVWC_50_CM Soil Moisture Volumetric Water Content at 50 cm depth 18 SMANOM_50_CM Soil Moisture Anomaly at 50 cm depth 19 SMPERC_50_CM Soil Moisture Percentile at 50 cm depth 20 ST_50_CM Soil Temperature at 50 cm depth 21 SMVWC_100_CM Soil Moisture Volumetric Water Content at 100 cm depth 22 SMANOM_100_CM Soil Moisture Anomaly at 100 cm depth 23 SMPERC_100_CM Soil Moisture Percentile at 100 cm depth 24 ST_100_CM Soil Temperature at 100 cm depth 25 SMVWC_TOP Soil Moisture Volumetric Water Content at 5 to 10 cm depths 26 SMANOM_TOP Soil Moisture Anomaly at 5 to 10 cm depths 27 SMPERC_TOP Soil Moisture Percentile at 5 to 10 cm depths 28 SMVWC_COLUMN Soil Moisture Volumetric Water Content at 5 to 100 cm depths 29 SMANOM_COLUMN Soil Moisture Anomaly at 5 to 100 cm depths 30 SMPERC_COLUMN Soil Moisture Percentile at 5 to 100 cm depths