USCRN/USRCRN MONTHLY FILES UPDATED: 2017-07-06 README CONTENTS: 1. GENERAL INFORMATION 2. DATA VERSION / STATUS UPDATES 3. DIRECTORY / FILE ORGANIZATION 4. DATA FIELDS / FORMATS / IMPORTANT NOTES ******************************************************************************** 1. GENERAL INFORMATION NCDC provides access to monthly 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/monthly01 and an identical web interface at: http://www1.ncdc.noaa.gov/pub/data/uscrn/products/monthly01 Before using these data, be sure to review this document carefully, as well as any announcements within the main (monthly01) 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 monthly01 directory contains a single ASCII text file for each USCRN/USRCRN station. Files list that station's monthly data for its period of record. Files are typically updated monthly and are named according to the following convention: CRNM01TT-${name}.txt CRNM01 = filename prefix to denote CRN Monthly01 data TT = 2-character file format number (currently 02) ${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 fixed-width formatted fields with a single set of monthly 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 monthly01 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 monthly data are calculated over the station's month in Local Standard Time. Field# Name Units --------------------------------------------- 1 WBANNO XXXXX 2 LST_YRMO YYYYMM 3 CRX_VN_MONTHLY XXXXXX 4 PRECISE_LONGITUDE Decimal_degrees 5 PRECISE_LATITUDE Decimal_degrees 6 T_MONTHLY_MAX Celsius 7 T_MONTHLY_MIN Celsius 8 T_MONTHLY_MEAN Celsius 9 T_MONTHLY_AVG Celsius 10 P_MONTHLY_CALC mm 11 SOLRAD_MONTHLY_AVG MJ/m^2 12 SUR_TEMP_MONTHLY_TYPE X 13 SUR_TEMP_MONTHLY_MAX Celsius 14 SUR_TEMP_MONTHLY_MIN Celsius 15 SUR_TEMP_MONTHLY_AVG Celsius 1 WBANNO [5 chars] cols 1 -- 5 The station WBAN number. 2 LST_YRMO [6 chars] cols 7 -- 12 The Local Standard Time (LST) year/month of the observation. 3 CRX_VN_MONTHLY [6 chars] cols 14 -- 19 The version number of the station datalogger program that was in effect at the end of the month. Note: This field should be treated as text (i.e. string). 4 PRECISE_LONGITUDE [9 chars] cols 21 -- 29 Station longitude, using WGS-84, with a precision of 4 decimal places. 5 PRECISE_LATITUDE [9 chars] cols 31 -- 39 Station latitude, using WGS-84, with a precision of 4 decimal places. 6 T_MONTHLY_MAX [7 chars] cols 41 -- 47 The maximum air temperature, in degrees C. See Note F. 7 T_MONTHLY_MIN [7 chars] cols 49 -- 55 The minimum air temperature, in degrees C. See Note F. 8 T_MONTHLY_MEAN [7 chars] cols 57 -- 63 The mean air temperature, in degrees C, calculated using the typical historical approach of (T_MONTHLY_MAX + T_MONTHLY_MIN) / 2. See Note F. 9 T_MONTHLY_AVG [7 chars] cols 65 -- 71 The average air temperature, in degrees C. See Note F. 10 P_MONTHLY_CALC [7 chars] cols 73 -- 79 The total amount of precipitation, in mm. See Note G. 11 SOLRAD_MONTHLY_AVG [7 chars] cols 81 -- 87 The average daily total solar energy received, in MJ/meter^2. See Note H. 12 SUR_TEMP_MONTHLY_TYPE [1 chars] cols 89 -- 89 Type of infrared surface temperature measurement: 'R' denotes raw (uncorrected), 'C' denotes corrected, and 'U' is unknown/missing. See Note I. 13 SUR_TEMP_MONTHLY_MAX [7 chars] cols 91 -- 97 The maximum infrared surface temperature, in degrees C. See Note J. 14 SUR_TEMP_MONTHLY_MIN [7 chars] cols 99 -- 105 The minimum infrared surface temperature, in degrees C. See Note J. 15 SUR_TEMP_MONTHLY_AVG [7 chars] cols 107 -- 113 The average infrared surface temperature, in degrees C. See Note 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. Monthly data are calculated using the station's Local Standard Time. 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. Monthly maximum/minimum/average temperatures are the average of all available daily max/min/averages. To be considered valid, there must be fewer than 4 consecutive daily values missing, and no more than 5 total values missing. G. For a monthly precipitation value to be considered valid, there must be precipitation records for at least 97% of the hours in the month. H. Monthly solar radiation is calculated as the average of daily total global solar radiation. To be considered valid, there must be fewer than 4 consecutive daily values missing, and no more than 5 total values missing. I. 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 monthly01 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. J. Monthly maximum/minimum/average surface temperatures are the average of all available daily max/min/avg values. To be considered valid, there must be fewer than 4 consecutive values missing, and no more than 5 total values missing. K. USRCRN stations do not measure solar radiation or surface temperature, so those fields are shown as missing data. L. 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. 04131 201901 2.623 -110.7120 43.6615 -5.5 -18.0 -11.7 -11.4 77.3 6.4 C -6.5 -23.7 -14.5 04131 201902 2.623 -110.7120 43.6615 -4.8 -14.3 -9.5 -9.0 164.2 8.2 C -4.9 -18.5 -10.7 04131 201903 2.623 -110.7120 43.6615 1.3 -13.4 -6.1 -6.2 22.5 16.9 C -0.5 -17.0 -8.7