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 ******************************************************************************** 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. ******************************************************************************** 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 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. ******************************************************************************** 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 ----------------------------------------------- 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