USCRN/USRCRN DAILY FILES UPDATED: 2017-07-06 README CONTENTS: 1. GENERAL INFORMATION 2. DATA VERSION / STATUS UPDATES 3. DIRECTORY / FILE ORGANIZATION 4. FILE AND FILENAME FORMATS A. YEARLY B. SNAPSHOTS C. UPDATES 5. DATA FIELDS / FORMATS / IMPORTANT NOTES ******************************************************************************** 1. GENERAL INFORMATION NCDC provides access to daily data from the U.S. Climate Reference Network / U.S. Regional Climate Reference Network (USCRN/USRCRN) via anonymous ftp at: ftp://ftp.ncdc.noaa.gov/pub/data/uscrn/products/daily01 and an identical web interface at: http://www1.ncdc.noaa.gov/pub/data/uscrn/products/daily01 Before using these data, be sure to review this document carefully, as well as any announcements within the main (daily01) directory. ******************************************************************************** 2. DATA VERSION / STATUS UPDATES Status and Version Information for U.S. Climate Reference Network Data ########################## Version change: 2.1 to 2.1.1 Commencement Date: 2017-06-20 Completion Date: 2017-06-30 Variables impacted: Precipitation Effective June 30, 2017, recalculation using the Official Algorithm for Precipitation (OAP) 2.1.1 has been completed. The purpose of this recalculation is described in Appendix A of the OAP 2.1 documentation: https://www1.ncdc.noaa.gov/pub/data/uscrn/documentation/maintenance/2016-05/USCRN_OAP2.1.Description_PrecipChanges.pdf ########################## Status change: Correction Correction Applied: 2017-05-01 Variables impacted: Precipitation for 3 stations From July 2016 until May 1, 2017, the precipitation values for the following stations and time periods were mistakenly missing on the website and in the FTP product files: NC Asheville 8 SSW 2004-05-01 to 2004-11-01 SC McClellanville 7 NE 2005-05-01 to 2005-11-01 CA Stovepipe Wells 1 SW 2004-05-01 to 2005-06-01 Precipitation data for these stations/time periods that were downloaded during the affected time period should be re-acquired. ########################## Version change: 2.0 to 2.1 Commencement Date: 2016-05-12 Completion Date: 2016-06-13 Variables impacted: Precipitation Relative Humidity (RH) Temperatures from RH Sensor Thermometer Shield Aspiration Fan Speeds Air Temperature (when fan speeds are low) Beginning May 12, 2016, USCRN changed the current data set to version 2.1 from v2.0. This version change was retroactively applied to all USCRN/USRCRN stations for their period-of-record 5-minute measurements from 2016-05-12 until 2016-06-13. [Note that during this period of reprocessing, data on the website and in these FTP products contained a mixture of v2.0 and v2.1 values.] Version 2.1 includes minor precipitation algorithm changes and changes/additions to the quality control ranges for acceptable relative humidity (RH) values, temperatures measured with the RH sensors, and for the speed of the fans which are used to aspirate the air temperature sensors. For precipitation, the Official Algorithm for Precipitation (OAP) v2.1 was implemented which addresses a minor correction to v2.0 that guards against overally large (> 0.3 mm) precipitation residuals from one hour being transferred to the next hour. Further information can be found at http://www.ncdc.noaa.gov/crn/documentation.html. ########################## Version change: 1.0 to 2.0 Commencement Date: 2015-08-17 Completion Date: 2015-09-15 Variables impacted: Precipitation The original Official Algorithm for Precipitation (OAP) version 1.0 was operational until August 17, 2015 and used a pairwise comparison and moving reference depth to calculate precipitation. Precipitation data accessed and/or downloaded prior to this date were calculated using OAP v1.0. Beginning August 17, 2015, all precipitation data were calculated using a new processing algorithm, OAP v2.0. In addition, the v2.0 algorithm was retroactively applied to all USCRN/USRCRN stations for their periods of record (PORs) starting when 5-minute data began being collected. The reprocessing took approximately four weeks to recalculate all station's existing values from v1.0 to v2.0 for their PORs and was completed on September 15, 2015. OAP v2.0 marked a fundamental shift in the procedures used to calculate precipitation. The new algorithm uses a weighted average approach based on each sensor's noise level. It has greatly improved the network's capacity to detect lighter precipitation with greater confidence. For details, see Leeper et. al., 2015, (http://journals.ametsoc.org/doi/abs/10.1175/JTECH-D-14-00185.1) and http://www.ncdc.noaa.gov/crn/documentation.html. ******************************************************************************** 3. DIRECTORY / FILE ORGANIZATION The daily01 directory contains the following subdirectories: - /2000 through the present year -- useful for obtaining the most up-to-date data from one or more stations for a particular year or years (typically updated on a daily basis). - /snapshots -- useful for obtaining data from all stations for all years. The entire dataset (as of the date/time of the filename) can be downloaded in a single compressed file. New snapshot files are created on a regular basis; the most recent file contains the most recent set of data. - /updates -- real-time files broadcast over NOAAPort; stored in yearly subdirectories. These files have the daily values for all stations processed that day. - /obsolete -- files which are now considered to be obsolete and unsuitable for scientific uses but are available as a historical record of work. ******************************************************************************** 4. FILE AND FILENAME FORMATS A. YEARLY Each yearly subdirectory in daily01 contains one file for each USCRN/USRCRN station listing its daily data in ASCII text format. The files are named according to the following convention: CRND01TT-YYYY-${name}.txt CRND01 = filename prefix to denote CRN Daily01 data ** See note below. TT = 2-character file format number (currently 03) YYYY = 4-digit year ${name} = station name (state location vector) (e.g. AZ_Tucson_11_W) ** Filename prefix revision: On April 11, 2011 15:00 UTC, the prefix 'CRNDAILY' was replaced with 'CRND01' and changed retroactively for all years. The 2-character sequence TT indicates the file format number and is updated when the file format is changed. Previous changes were applied retroactively for all years and are outlined below: 1. [Transition from format '01' to '02'] On March 22, 2011 15:00 UTC the format of the Daily product was changed by removing the COOPNO (Cooperative Observer Program Number) column. This had been the second column in the format, starting at character 7 and ending at character 12. With the removal of this column, all following columns were shifted to the left by 7 characters. The contents of the shifted columns remained the same. 2. [Transition from format '02' to '03'] On January 7, 2013 15:00 UTC the format of the Daily product was changed by adding the SUR_TEMP_DAILY_TYPE column. This became the 12th column in the format, starting and ending at character 88. With the addition of this column, all the following columns were shifted to the right by 2 characters. The contents of the shifted columns remained the same. B. SNAPSHOTS The 'snapshots' directory contains a series of compressed (.zip) files. Each file contains the entire data archive of USCRN/USRCRN daily01 data as of the date/time shown on its filename. Once uncompressed, the directory and file structure are identical to the yearly subdirectories (as explained above). Snapshots are created and uploaded at regular intervals, and are named according to the following convention: CRND01TT-YYYYMMDDHHmm.zip CRND01 = filename prefix to denote CRN Daily01 data ** See note below. TT = 2-character file format number (see above) YYYY = 4-digit year files generated MM = 2-digit month files generated (01=Jan, ..., 12=Dec) DD = 2-digit day of month files generated HH = 2-digit hour of day files generated mm = 2-digit minute files generated ** Filename prefix revision: Snapshot files created prior to April 11, 2011 15:00 UTC, use the 'CRNDAILY' prefix. Users may obtain the most recent archive of data for all stations and all years by downloading the most recent file in this directory. As improvements to the dataset are made, the snapshot files serve as a historical record of the archive through time. C. UPDATES The 'updates' directory contains a record of the real-time files which are produced daily and broadcast over NOAAPort (SXXX91 CRND01). Each file contains all the USCRN/USRCRN daily data from every station loaded into the database since the last transmission. The yearly subdirectories contain a collection of ASCII files named according to the following convention: CRND01TT-YYYYMMDDHHmm.txt CRND01 = filename prefix to denote CRN Daily01 data ** See note above. TT = 2-character file format number (see above) YYYY = 4-digit local year MM = 2-digit local month (01=Jan, ..., 12=Dec) DD = 2-digit local day of month HH = 2-digit local standard time hour of day (always 23) mm = 2-digit minute (always 59) The 'updates' files are named according to the calendar date of the observations. The daily records for the previous calendar day are generated several times each day to ensure that late arriving data are included. ******************************************************************************** 5. DATA FIELDS / FORMATS Each station file contains fixed-width formatted fields with a single day's data per line. A summary table of the fields and a detailed listing of field definitions/column formats are shown below. Fortran users will find the column widths and counts useful. The file "HEADERS.txt", found in the daily01 directory, is designed to be prepended to the data for use with spreadsheet programs, data extraction tools (e.g. awk) or any other programming language. This file contains the following three lines: 1. Field Number 2. Field Name 3. Unit of Measure Please be sure to refer to the "Important Notes" section below for essential information. All daily data are calculated over the station's 24-hour LST day. Field# Name Units --------------------------------------------- 1 WBANNO XXXXX 2 LST_DATE YYYYMMDD 3 CRX_VN XXXXXX 4 LONGITUDE Decimal_degrees 5 LATITUDE Decimal_degrees 6 T_DAILY_MAX Celsius 7 T_DAILY_MIN Celsius 8 T_DAILY_MEAN Celsius 9 T_DAILY_AVG Celsius 10 P_DAILY_CALC mm 11 SOLARAD_DAILY MJ/m^2 12 SUR_TEMP_DAILY_TYPE X 13 SUR_TEMP_DAILY_MAX Celsius 14 SUR_TEMP_DAILY_MIN Celsius 15 SUR_TEMP_DAILY_AVG Celsius 16 RH_DAILY_MAX % 17 RH_DAILY_MIN % 18 RH_DAILY_AVG % 19 SOIL_MOISTURE_5_DAILY m^3/m^3 20 SOIL_MOISTURE_10_DAILY m^3/m^3 21 SOIL_MOISTURE_20_DAILY m^3/m^3 22 SOIL_MOISTURE_50_DAILY m^3/m^3 23 SOIL_MOISTURE_100_DAILY m^3/m^3 24 SOIL_TEMP_5_DAILY Celsius 25 SOIL_TEMP_10_DAILY Celsius 26 SOIL_TEMP_20_DAILY Celsius 27 SOIL_TEMP_50_DAILY Celsius 28 SOIL_TEMP_100_DAILY Celsius 1 WBANNO [5 chars] cols 1 -- 5 The station WBAN number. 2 LST_DATE [8 chars] cols 7 -- 14 The Local Standard Time (LST) date of the observation. 3 CRX_VN [6 chars] cols 16 -- 21 The version number of the station datalogger program that was in effect at the time of the observation. Note: This field should be treated as text (i.e. string). 4 LONGITUDE [7 chars] cols 23 -- 29 Station longitude, using WGS-84. 5 LATITUDE [7 chars] cols 31 -- 37 Station latitude, using WGS-84. 6 T_DAILY_MAX [7 chars] cols 39 -- 45 Maximum air temperature, in degrees C. See Note F. 7 T_DAILY_MIN [7 chars] cols 47 -- 53 Minimum air temperature, in degrees C. See Note F. 8 T_DAILY_MEAN [7 chars] cols 55 -- 61 Mean air temperature, in degrees C, calculated using the typical historical approach: (T_DAILY_MAX + T_DAILY_MIN) / 2. See Note F. 9 T_DAILY_AVG [7 chars] cols 63 -- 69 Average air temperature, in degrees C. See Note F. 10 P_DAILY_CALC [7 chars] cols 71 -- 77 Total amount of precipitation, in mm. See Note F. 11 SOLARAD_DAILY [8 chars] cols 79 -- 86 Total solar energy, in MJ/meter^2, calculated from the hourly average global solar radiation rates and converted to energy by integrating over time. 12 SUR_TEMP_DAILY_TYPE [1 chars] cols 88 -- 88 Type of infrared surface temperature measurement. 'R' denotes raw measurements, 'C' denotes corrected measurements, and 'U' indicates unknown/missing. See Note G. 13 SUR_TEMP_DAILY_MAX [7 chars] cols 90 -- 96 Maximum infrared surface temperature, in degrees C. 14 SUR_TEMP_DAILY_MIN [7 chars] cols 98 -- 104 Minimum infrared surface temperature, in degrees C. 15 SUR_TEMP_DAILY_AVG [7 chars] cols 106 -- 112 Average infrared surface temperature, in degrees C. 16 RH_DAILY_MAX [7 chars] cols 114 -- 120 Maximum relative humidity, in %. See Notes H and I. 17 RH_DAILY_MIN [7 chars] cols 122 -- 128 Minimum relative humidity, in %. See Notes H and I. 18 RH_DAILY_AVG [7 chars] cols 130 -- 136 Average relative humidity, in %. See Notes H and I. 19 SOIL_MOISTURE_5_DAILY [7 chars] cols 138 -- 144 Average soil moisture, in fractional volumetric water content (m^3/m^3), at 5 cm below the surface. See Notes I and J. 20 SOIL_MOISTURE_10_DAILY [7 chars] cols 146 -- 152 Average soil moisture, in fractional volumetric water content (m^3/m^3), at 10 cm below the surface. See Notes I and J. 21 SOIL_MOISTURE_20_DAILY [7 chars] cols 154 -- 160 Average soil moisture, in fractional volumetric water content (m^3/m^3), at 20 cm below the surface. See Notes I and J. 22 SOIL_MOISTURE_50_DAILY [7 chars] cols 162 -- 168 Average soil moisture, in fractional volumetric water content (m^3/m^3), at 50 cm below the surface. See Notes I and J. 23 SOIL_MOISTURE_100_DAILY [7 chars] cols 170 -- 176 Average soil moisture, in fractional volumetric water content (m^3/m^3), at 100 cm below the surface. See Notes I and J. 24 SOIL_TEMP_5_DAILY [7 chars] cols 178 -- 184 Average soil temperature, in degrees C, at 5 cm below the surface. See Notes I and J. 25 SOIL_TEMP_10_DAILY [7 chars] cols 186 -- 192 Average soil temperature, in degrees C, at 10 cm below the surface. See Notes I and J. 26 SOIL_TEMP_20_DAILY [7 chars] cols 194 -- 200 Average soil temperature, in degrees C, at 20 cm below the surface. See Notes I and J. 27 SOIL_TEMP_50_DAILY [7 chars] cols 202 -- 208 Average soil temperature, in degrees C, at 50 cm below the surface. See Notes I and J. 28 SOIL_TEMP_100_DAILY [7 chars] cols 210 -- 216 Average soil temperature, in degrees C, at 100 cm below the surface. See Notes I and J. IMPORTANT NOTES: A. All fields are separated from adjacent fields by at least one space. B. Leading zeros are omitted. C. Missing data are indicated by the lowest possible integer for a given column format, such as -9999.0 for 7-character fields with one decimal place or -99.000 for 7-character fields with three decimal places. D. Daily data are calculated using the station's local day. E. There are no quality flags for these derived quantities. When the raw data are flagged as erroneous, these derived values are not calculated, and are instead reported as missing. Therefore, these fields may be assumed to always be good (unflagged) data, except when they are reported as missing. F. The daily values reported in this dataset are calculated using multiple independent measurements for temperature and precipitation. USCRN/USRCRN stations have multiple co-located temperature sensors that make 10-second independent measurements which are used to produce max/min/avg temperature values at 5-minute intervals. The precipitation gauge is equipped with multiple load cell sensors to provide independent measurements of depth change at 5-minute intervals. G. On 2013-01-07 at 1500 UTC, USCRN began reporting corrected surface temperature measurements for some stations. These changes impact previous users of the data because the corrected values differ from uncorrected values. To distinguish between uncorrected (raw) and corrected surface temperature measurements, a surface temperature type field was added to the daily01 product. The possible values of the this field are "R" to denote raw surface temperature measurements, "C" to denote corrected surface temperature measurements, and "U" for unknown/missing. H. Relative humidity is computed from 5-minute values in almost all cases. All USCRN stations now report 5-minute averages, however the two Asheville, NC stations reported only hourly RH values until 2007-02-22. I. USRCRN stations do not measure solar radiation, surface temperature, relative humidity or soil variables, so those fields are shown as missing data. J. USCRN stations have multiple co-located soil sensors that record independent measurements. The soil values reported in this dataset are an average of the day's hourly soil measurements which are calculated from the multiple independent measurements. Soil moisture is the ratio of water volume over sample volume (m^3 water/m^3 soil). K. In accordance with Service Change Notice 14-25 from the National Weather Service, NCDC stopped providing data from the 72 Southwest Regional Climate Reference Network (USRCRN) stations on June 1, 2014. The historical data for these stations remain available.