165 lines
7.4 KiB
Text
165 lines
7.4 KiB
Text
This documentation describes the record format for the county files on
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/pub/data/cirs/climdiv that have the filenames:
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climdiv-pcpncy-vx.y.z-YYYYMMDD
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climdiv-tmaxcy-vx.y.z-YYYYMMDD
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climdiv-tmincy-vx.y.z-YYYYMMDD
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climdiv-tmpccy-vx.y.z-YYYYMMDD
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nClimDiv
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COUNTY
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TEMPERATURE-PRECIPITATION
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OCTOBER 2018
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The major parameters in this file are sequential climatic county monthly
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maximum, minimum and average temperature (deg. F. to 10ths) and precipitation (inches to 100ths).
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Period of record is 1895 through latest month available, updated
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monthly.
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Values from the most recent two calendar years will be updated on a monthly
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basis. Period of record updates will occur when the underlying data set
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undergoes a version change.
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METHODOLOGY:
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County values in nClimDiv were derived from area-weighted averages of
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grid-point estimates interpolated from station data. A nominal grid resolution
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of 5 km was used to ensure that all divisions had sufficient spatial sampling
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(only four small divisions had less than 100 points) and because the impact of
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elevation on precipitation is minimal below 5 km. Station data were gridded
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via climatologically aided interpolation to minimize biases from topographic
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and network variability.
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The Global Historical Climatology Network (GHCN) Daily dataset is the source
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of station data for nClimDiv. GHCN-Daily contains several major observing
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networks in North America, five of which are used here. The primary network
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is the National Weather Service (NWS) Cooperative Observing (COOP) program,
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which consists of stations operated by volunteers as well as by agencies such
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as the Federal Aviation Administration. To improve coverage in western states
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and along international borders, nClimDiv also includes the National
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Interagency Fire Center (NIFC) Remote Automatic Weather Station (RAWS) network,
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the USDA Snow Telemetry (SNOTEL) network, the Environment Canada (EC)
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network (south of 52<35>N), and part of Mexicos Servicio Meteorologico Nacional
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(SMN) network (north of 24<32>N). Note that nClimDiv does not incorporate
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precipitation data from RAWS because that networks tipping-bucket gauges are
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unheated, leading to suspect cold-weather data.
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All GHCN-Daily stations are routinely processed through a suite of logical,
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serial, and spatial quality assurance reviews to identify erroneous
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observations. For nClimDiv, all such data were set to missing before
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computing monthly values, which in turn were subjected to additional serial
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and spatial checks to eliminate residual outliers. Stations having at least
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10 years of valid monthly data since 1950 were used in nClimDiv.
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For temperature, bias adjustments were computed to account for historical
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changes in observation time, station location, temperature instrumentation,
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and siting conditions. Changes in observation time are only problematic for
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the COOP network whereas changes in station location and instrumentation occur
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in almost all surface networks. As in the U.S. Historical Climatology Network
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version 2.5, the method of Karl et al. (1986) was applied to remove the
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observation time bias from the COOP network, and the pairwise method of Menne
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and Williams (2009) was used to address changes in station location and
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instrumentation in all networks. Because the pairwise method also largely
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accounts for local, unrepresentative trends that arise from changes in siting
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conditions, nClimDiv contains no separate adjustment in that regard.
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For additional information on how nClimDiv is constructed, please see:
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http://journals.ametsoc.org/doi/abs/10.1175/JAMC-D-13-0248.1
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STATE CODE TABLE:
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Range of values of 01-50.
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01 Alabama 28 New Jersey
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02 Arizona 29 New Mexico
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03 Arkansas 30 New York
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04 California 31 North Carolina
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05 Colorado 32 North Dakota
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06 Connecticut 33 Ohio
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07 Delaware 34 Oklahoma
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08 Florida 35 Oregon
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09 Georgia 36 Pennsylvania
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10 Idaho 37 Rhode Island
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11 Illinois 38 South Carolina
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12 Indiana 39 South Dakota
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13 Iowa 40 Tennessee
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14 Kansas 41 Texas
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15 Kentucky 42 Utah
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16 Louisiana 43 Vermont
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17 Maine 44 Virginia
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18 Maryland 45 Washington
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19 Massachusetts 46 West Virginia
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20 Michigan 47 Wisconsin
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21 Minnesota 48 Wyoming
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22 Mississippi 50 Alaska
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23 Missouri
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24 Montana
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25 Nebraska
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26 Nevada
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27 New Hampshire
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FILE FORMAT:
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IMPORTANT NOTE:
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The format of the county data is slightly different than the other data files. To accomadate
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the 2 digit state code and the 3 digit county FIPS code, the first field contains 11 columns.
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The other data files still contain 10 columns.
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Element Record
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Name Position Element Description
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STATE-CODE 1-2 STATE-CODE as indicated in State Code Table as
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described in FILE 1. Range of values is 01-48.
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DIVISION-NUMBER 3-5 COUNTY FIPS - Range of values 001-999.
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ELEMENT CODE 6-7 01 = Precipitation
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02 = Average Temperature
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27 = Maximum Temperature
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28 = Minimum Temperature
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YEAR 8-11 This is the year of record. Range is 1895 to
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current year processed.
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(all data values are right justified):
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JAN-VALUE 12-18
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Monthly Divisional Temperature format (f7.2)
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Range of values -50.00 to 140.00 degrees Fahrenheit.
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Decimals retain a position in the 7-character
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field. Missing values in the latest year are
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indicated by -99.99.
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Monthly Divisional Precipitation format (f7.2)
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Range of values 00.00 to 99.99. Decimal point
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retains a position in the 7-character field.
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Missing values in the latest year are indicated
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by -9.99.
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FEB-VALUE 19-25
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MAR-VALUE 26-32
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APR-VALUE 33-39
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MAY-VALUE 40-46
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JUNE-VALUE 47-53
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JULY-VALUE 54-60
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AUG-VALUE 61-67
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SEPT-VALUE 68-74
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OCT-VALUE 75-81
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NOV-VALUE 82-88
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DEC-VALUE 89-95
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