USCRN/USRCRN HOURLY FILES UPDATED: 2016-06-14 README CONTENTS: 1. GENERAL INFORMATION 2. DATA VERSION / STATUS UPDATES 3. DIRECTORY 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 hourly 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/hourly02 and an identical web interface at: http://www1.ncdc.noaa.gov/pub/data/uscrn/products/hourly02 Before using these data, be sure to review this document carefully, as well as any announcements within the main (hourly02) directory. ******************************************************************************** 2. DATA VERSION / STATUS UPDATES 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 ORGANIZATION The hourly02 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 an hourly 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 contain hourly values for all stations. ******************************************************************************** 4. FILE AND FILENAME FORMATS A. YEARLY Each yearly subdirectory in hourly02 contains one file for each USCRN/USRCRN station listing its hourly data in ASCII text format. The files are named according to the following convention: CRNH02TT-YYYY-${name}.txt CRNH02 = filename prefix to denote CRN hourly02 data TT = 2-character file format number (currently 03) YYYY = 4-digit year ${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. 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 hourly 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 hourly product was changed by adding the SUR_TEMP_TYPE column. This became the 20th column in the format, starting and ending at character 125. 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 hourly02 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: CRNH02TT-YYYYMMDDHHmm.zip CRNH02 = filename prefix to denote CRN hourly02 data 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 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 hourly and broadcast over NOAAPort (SXXX91 CRNH02). The yearly subdirectories contain a collection of ASCII files named according to the following convention: CRNFFH02TT-YYYYMMDDHHmm.txt FF = 2-digit file frequency, in minutes (60) H02 = filename prefix to denote CRN hourly02 data TT = 2-character file format number (see above) YYYY = 4-digit year MM = 2-digit month (01=Jan, ..., 12=Dec) DD = 2-digit day of month HH = 2-digit hour of day mm = 2-digit minute Each file contains all the USCRN/USRCRN hourly data from every station loaded into the database since the last transmission (during the period of time lasting 'FF' minutes and ending at the UTC time YYYYMMDDHHmm). Note that 'updates' files are *not* named according to the observation time. Data from stations generally arrives at NCDC and are loaded into the database steadily throughout the hour, however sometimes an observation is relayed several hours later (due to temporary transmission problems, etc). ******************************************************************************** 5. DATA FIELDS / FORMATS Each station file contains fixed-width formatted fields with a single hour'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 hourly02 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 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 UTC_DATE YYYYMMDD 3 UTC_TIME HHmm 4 LST_DATE YYYYMMDD 5 LST_TIME HHmm 6 CRX_VN XXXXXX 7 LONGITUDE Decimal_degrees 8 LATITUDE Decimal_degrees 9 T_CALC Celsius 10 T_HR_AVG Celsius 11 T_MAX Celsius 12 T_MIN Celsius 13 P_CALC mm 14 SOLARAD W/m^2 15 SOLARAD_FLAG X 16 SOLARAD_MAX W/m^2 17 SOLARAD_MAX_FLAG X 18 SOLARAD_MIN W/m^2 19 SOLARAD_MIN_FLAG X 20 SUR_TEMP_TYPE X 21 SUR_TEMP Celsius 22 SUR_TEMP_FLAG X 23 SUR_TEMP_MAX Celsius 24 SUR_TEMP_MAX_FLAG X 25 SUR_TEMP_MIN Celsius 26 SUR_TEMP_MIN_FLAG X 27 RH_HR_AVG % 28 RH_HR_AVG_FLAG X 29 SOIL_MOISTURE_5 m^3/m^3 30 SOIL_MOISTURE_10 m^3/m^3 31 SOIL_MOISTURE_20 m^3/m^3 32 SOIL_MOISTURE_50 m^3/m^3 33 SOIL_MOISTURE_100 m^3/m^3 34 SOIL_TEMP_5 Celsius 35 SOIL_TEMP_10 Celsius 36 SOIL_TEMP_20 Celsius 37 SOIL_TEMP_50 Celsius 38 SOIL_TEMP_100 Celsius 1 WBANNO [5 chars] cols 1 -- 5 The station WBAN number. 2 UTC_DATE [8 chars] cols 7 -- 14 The UTC date of the observation. 3 UTC_TIME [4 chars] cols 16 -- 19 The UTC time of the observation. Time is the end of the observed hour, so the 0000 hour is actually the last hour of the previous day's observation (starting just after 11:00 PM through midnight). 4 LST_DATE [8 chars] cols 21 -- 28 The Local Standard Time (LST) date of the observation. 5 LST_TIME [4 chars] cols 30 -- 33 The Local Standard Time (LST) time of the observation. Time is the end of the observed hour (see UTC_TIME description). 6 CRX_VN [6 chars] cols 35 -- 40 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). 7 LONGITUDE [7 chars] cols 42 -- 48 Station longitude, using WGS-84. 8 LATITUDE [7 chars] cols 50 -- 56 Station latitude, using WGS-84. 9 T_CALC [7 chars] cols 58 -- 64 Average air temperature, in degrees C, during the last 5 minutes of the hour. See Note F. 10 T_HR_AVG [7 chars] cols 66 -- 72 Average air temperature, in degrees C, for the entire hour. See Note F. 11 T_MAX [7 chars] cols 74 -- 80 Maximum air temperature, in degrees C, during the hour. See Note F. 12 T_MIN [7 chars] cols 82 -- 88 Minimum air temperature, in degrees C, during the hour. See Note F. 13 P_CALC [7 chars] cols 90 -- 96 Total amount of precipitation, in mm, recorded during the hour. See Note F. 14 SOLARAD [6 chars] cols 98 -- 103 Average global solar radiation, in watts/meter^2. 15 SOLARAD_FLAG [1 chars] cols 105 -- 105 QC flag for average global solar radiation. See Note G. 16 SOLARAD_MAX [6 chars] cols 107 -- 112 Maximum global solar radiation, in watts/meter^2. 17 SOLARAD_MAX_FLAG [1 chars] cols 114 -- 114 QC flag for maximum global solar radiation. See Note G. 18 SOLARAD_MIN [6 chars] cols 116 -- 121 Minimum global solar radiation, in watts/meter^2. 19 SOLARAD_MIN_FLAG [1 chars] cols 123 -- 123 QC flag for minimum global solar radiation. See Note G. 20 SUR_TEMP_TYPE [1 chars] cols 125 -- 125 Type of infrared surface temperature measurement: 'R' denotes raw (uncorrected), 'C' denotes corrected, and 'U' when unknown/missing. See Note H. 21 SUR_TEMP [7 chars] cols 127 -- 133 Average infrared surface temperature, in degrees C. See Note H. 22 SUR_TEMP_FLAG [1 chars] cols 135 -- 135 QC flag for infrared surface temperature. See Note G. 23 SUR_TEMP_MAX [7 chars] cols 137 -- 143 Maximum infrared surface temperature, in degrees C. 24 SUR_TEMP_MAX_FLAG [1 chars] cols 145 -- 145 QC flag for infrared surface temperature maximum. See Note G. 25 SUR_TEMP_MIN [7 chars] cols 147 -- 153 Minimum infrared surface temperature, in degrees C. 26 SUR_TEMP_MIN_FLAG [1 chars] cols 155 -- 155 QC flag for infrared surface temperature minimum. See Note G. 27 RH_HR_AVG [5 chars] cols 157 -- 161 RH average for hour, in percentage. See Note I. 28 RH_HR_AVG_FLAG [1 chars] cols 163 -- 163 QC flag for RH average. See Note G. 29 SOIL_MOISTURE_5 [7 chars] cols 165 -- 171 Average soil moisture at 5 cm below the surface, in m^3/m^3. See Note K. 30 SOIL_MOISTURE_10 [7 chars] cols 173 -- 179 Average soil moisture at 10 cm below the surface, in m^3/m^3. See Note K. 31 SOIL_MOISTURE_20 [7 chars] cols 181 -- 187 Average soil moisture at 20 cm below the surface, in m^3/m^3. See Note K. 32 SOIL_MOISTURE_50 [7 chars] cols 189 -- 195 Average soil moisture at 50 cm below the surface, in m^3/m^3. See Note K. 33 SOIL_MOISTURE_100 [7 chars] cols 197 -- 203 Average soil moisture at 100 cm below the surface, in m^3/m^3. See Note K. 34 SOIL_TEMP_5 [7 chars] cols 205 -- 211 Average soil temperature at 5 cm below the surface, in degrees C. See Note K. 35 SOIL_TEMP_10 [7 chars] cols 213 -- 219 Average soil temperature at 10 cm below the surface, in degrees C. See Note K. 36 SOIL_TEMP_20 [7 chars] cols 221 -- 227 Average soil temperature at 20 cm below the surface, in degrees C. See Note K. 37 SOIL_TEMP_50 [7 chars] cols 229 -- 235 Average soil temperature at 50 cm below the surface, in degrees C. See Note K. 38 SOIL_TEMP_100 [7 chars] cols 237 -- 243 Average soil temperature at 100 cm below the surface, in degrees C. See Note K. 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. Hourly data are calculated over the 60-minute period *ending* at the time shown. E. Calculated fields, such as T_CALC and P_CALC, do not have quality flags associated with them because these are derived quantities from raw data. When the raw data used in the calculation are flagged as erroneous, the 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 hourly 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. Quality control flags indicate the following: 0 denotes good data and 3 denotes erroneous data. H. 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 data 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. I. Hourly relative humidity is computed from 5-minute averages in almost all cases, however the two Asheville, NC stations reported only hourly RH values until 2007-02-22. J. USRCRN stations do not measure solar radiation, surface temperature, relative humidity or soil variables, so those fields are shown as missing data. K. USCRN stations have multiple co-located soil sensors that record independent measurements at 5-minute intervals. The hourly soil values reported in this dataset are calculated from these multiple independent measurements. Average soil moisture (volumetric water content) is the ratio of water volume over sample volume (m^3 water/m^3 soil). 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. M. This product supersedes the hourly01 files. It contains all of the variables from the earlier product, plus additional ones.