README FILE FOR THE U.S. HISTORICAL CLIMATOLOGY NETWORK (U.S. HCN) MONTHLY DATA Version 2 -------------------------------------------------------------------------------- -------------------------------------------------------------------------------- I. DOWNLOAD QUICK START Start by downloading "ushcn-stations.txt," which privides a listing of the U.S. HCN Version 2 Stations indexed by U.S. Cooperative Observer Identification Number. Then download the one or more of the following gzipped files: ***"fully adjusted temperature series"*** - "9641C_YYYYMM_F52.max.gz" if you want fully-adjusted monthly mean maximum temperatures (with estimates for missing values); OR - "9641C_YYYYMM_F52.min.gz" if you want fully-adjusted monthly mean minimum temperatures (with estimates for missing values); OR - "9641C_YYYYMM_F52.avg.gz" if you want the average of fully-adjusted monthly mean maximum and minimum temperatures (with estimates for missing values). ***"unadjusted precipiation series (with estimates for missing values)"*** - "9641C_YYYYMM_F52.pcp.gz" if you want total monthly precipitation (that are NOT bias-adjusted, but have estimates for missing values). ***"temperature series adjusted only for the time of observation bias"*** - "9641C_YYYYMM_tob.max.gz" if you want monthly mean maximum temperatures that are adjusted only for the time of observation bias; OR - "9641C_YYYYMM_tob.min.gz" if you want monthly mean minimum temperatures that are adjusted only for the time of observation bias; OR - "9641C_YYYYMM_tob.avg.gz" if you want the average of monthly mean maximum and minimum temperatures that are adjusted only for the time of observation bias. ***"raw (unadjusted) temperature series"*** - "9641C_YYYYMM_raw.max.gz" if you want monthly mean maximum temperatures that are not bias adjusted; OR - "9641C_YYYYMM_raw.min.gz" if you want monthly mean minimum temperatures that are not bias adjusted; OR - "9641C_YYYYMM_raw.avg.gz" if you want the average of monthly mean maximum and minimum temperatures that are not bias adjusted. where YYYY and MM refer to the Year and Month when the files were updated. Then uncompress the gzipped file, e.g., by using the following Linux/UNIX command: gunzip 9641C_YYYYMM_F52.max.gz Windows and other Operating System users are encouraged to consult http://www.gzip.org/ for information regarding uncompressing GZIP files. Please see the "Executables" and "Frequently Asked Questions" sections for information about your particular operating system. -------------------------------------------------------------------------------- -------------------------------------------------------------------------------- II. CONTENTS OF ftp://ftp.ncdc.noaa.gov/pub/data/ushcn/v2/monthly 9641C_YYYYMM_F52.max.gz: GZIP-compressed file of bias-adjusted mean monthly maximum temperatures (with estimates for missing values) 9641C_YYYYMM_F52.min.gz: GZIP-compressed file of bias-adjusted mean monthly minimum temperatures (with estimates for missing values) 9641C_YYYYMM_F52.avg.gz: GZIP-compressed file of the average of bias- adjusted mean monthly maximum and minimum temperatures (with estimates for missing values) 9641C_YYYYMM_F52.pcp.gz: GZIP-compressed file of total monthly precipitation (UNADJUSTED, but with estimates for missing values) 9641C_err_F52.max.gz: GZIP-compressed file of the estimated uncertainty associated with the bias-adjusted mean monthly maximum temperatures (1 standard error) 9641C_err_F52.min.gz: GZIP-compressed file of the estimated uncertainty associated with the bias-adjusted mean monthly minimum temperatures (1 standard error) 9641C_YYYYMM_tob.max.gz: GZIP-compressed file of mean monthly maximum temperatures adjusted only for the time of observation bias 9641C_YYYYMM_tob.min.gz: GZIP-compressed file of mean monthly minimum temperatures adjusted only for the time of observation bias 9641C_YYYYMM_tob.avg.gz: GZIP-compressed file of the average of mean monthly maximum and minimum temperatures adjusted only for the time of observation bias 9641C_YYYYMM_raw.max.gz: GZIP-compressed file of unadjusted mean monthly maximum temperatures 9641C_YYYYMM_raw.min.gz: GZIP-compressed file of unadjusted mean monthly minimum temperatures 9641C_YYYYMM_raw.avg.gz: GZIP-compressed file of the average of un- adjusted mean monthly maximum and minimum temperatures ushcn-v2-stations.txt: List of U.S. HCN stations and their coordinates readme.txt: This file status.txt: Notes on the current status of USHCN Version 2 Monthly Data -------------------------------------------------------------------------------- -------------------------------------------------------------------------------- III. FORMAT OF THE DATA FILES Each data file contains data for all HCN stations for one of the four meteorological variables (also known as data "elements"). Each record (line) in the files contains one year of 12 monthly values plus an annual value (note that the uncertainty estimates have no annual value). The values on each line include the following: ------------------------------ Variable Columns Type ------------------------------ STATION ID 1-6 Character ELEMENT 7-7 Integer YEAR 8-11 Integer VALUE1 13-17 Integer FLAG1 18-18 Character VALUE2 20-24 Integer FLAG2 25-25 Character . . . . . . . . . VALUE13 97-101 Integer FLAG13 102-102 Character ------------------------------ These variables have the following definitions: ID is the station identification code. Please see "ushcn-stations.txt" for a complete list of stations and their metadata. ELEMENT is the element code. There are four values corresponding to the element contained in the file: 1 = mean maximum temperature (in tenths of degrees F) 2 = mean minimum temperature (in tenths of degrees F) 3 = average temperature (in tenths of degrees F) 4 = total precipitation (in hundredths of inches) YEAR is the year of the record. VALUE1 is the value for January in the year of record (missing = -9999). FLAG1 is the flag for January in the year of record. There are five possible values: Blank = no flag is applicable; E = value is an estimate from surrounding values; no original value is available; I = monthly value calculated from incomplete daily data (1 to 9 days were missing); Q = value is an estimate from surrounding values; the original value was flagged by the monthly quality control algorithms; X = value is an estimate from surrounding values; the original was part of block of monthly values that was too short to adjust in the temperature homogenization algorithm. VALUE2 is the value for February in the year of record. FLAG2 is the flag for February in the year of record. . . . VALUE12 is the value for December in the year of record. FLAG12 is the flag for December in the year of record. VALUE13 is the annual value (mean for temperature; total for precipitation) FLAG13 is the flag for the annual value. -------------------------------------------------------------------------------- -------------------------------------------------------------------------------- IV. FORMAT OF "ushcn-v2-stations.txt" ------------------------------ Variable Columns Type ------------------------------ COOP ID 1-6 Character LATITUDE 8-15 Real LONGITUDE 17-25 Real ELEVATION 27-32 Real STATE 34-35 Character NAME 37-66 Character COMPONENT 1 68-73 Character COMPONENT 2 75-80 Character COMPONENT 3 82-87 Character UTC OFFSET 89-90 Integer ------------------------------ These variables have the following definitions: COOP ID is the U.S. Cooperative Observer Network station identification code. Note that the first two digits in the Coop Id correspond to the state. LATITUDE is latitude of the station (in decimal degrees). LONGITUDE is the longitude of the station (in decimal degrees). ELEVATION is the elevation of the station (in meters, missing = -999.9). STATE is the U.S. postal code for the state. NAME is the name of the station location. COMPONENT 1 is the Coop Id for the first station (in chronologic order) whose records were joined with those of the HCN site to form a longer time series. "------" indicates "not applicable". COMPONENT 2 is the Coop Id for the second station (if applicable) whose records were joined with those of the HCN site to form a longer time series. COMPONENT 3 is the Coop Id for the third station (if applicable) whose records were joined with those of the HCN site to form a longer time series. UTC OFFSET is the time difference between Coordinated Universal Time (UTC) and local standard time at the station (i.e., the number of hours that must be added to local standard time to match UTC). -------------------------------------------------------------------------------- -------------------------------------------------------------------------------- For additional information, please send an e-mail to ncdc.ushcn@noaa.gov.