This documentation describes the record format for the statewide/regional/national files on /pub/data/cirs/ that have the filename drd964x.cddst.txt drd964x.hddst.txt drd964x.pcpst.txt drd964x.pdsist.txt drd964x.phdist.txt drd964x.pmdist.txt drd964x.tmpst.txt drd964x.zndxst.txt TIME BIAS CORRECTED STATEWIDE-REGIONAL-NATIONAL TEMPERATURE-PRECIPITATION APRIL 2007 THE STATEWIDE, REGIONAL, AND NATIONAL DATA The major parameters in this file are sequential statewide, regional, and national monthly precipitation and monthly "time bias corrected" average temperature. The period of record is 1895 through the latest month available. This file is provided online and is updated monthly. The data in this file are used for historical perspectives in the CLIMATE VARIATIONS BULLETIN (Historical Climatology Series 4-7). The monthly values for the most recent one to two years are based on preliminary data and will change when the final data are analyzed. The statewide values are available for the 48 contiguous States and are computed from the divisional values weighted by area. The regional values are computed from the statewide values weighted by area (as defined by T.R. Karl and W.J. Koss, 1984: Historical Climatology Series 4-3: Regional and National Monthly, Seasonal and Annual Temperature Weighted by Area, 1895-1983). The states and area weights for each region are as follows: Northeast Region: CT, 0.02752; DE, 0.01130; ME, 0.18251; MD, 0.05812; MA, 0.04537; NH, 0.05112; NJ, 0.04306; NY, 0.27242; PA, 0.24910; RI, 0.00667; VT, 0.05280 East North Central Region: IA, 0.22098; MI, 0.22854; MN, 0.33003; WI, 0.22045 Central Region: IL, 0.18169; IN, 0.11691; KY, 0.13013; MO, 0.22449; OH, 0.13279; TN, 0.13609; WV, 0.07790 Southeast Region: AL, 0.17576; FL, 0.19944; GA, 0.20051; NC, 0.17952; SC, 0.10576; VA, 0.13900 West North Central Region: MT, 0.31307; NE, 0.16432; ND, 0.15035; SD, 0.16393; WY, 0.20833 South Region: AR, 0.09335; KS, 0.14461; LA, 0.08530; MS, 0.08388; OK, 0.12291; TX, 0.46995 Southwest Region: AZ, 0.26819; CO, 0.24544; NM, 0.28645; UT, 0.19993 Northwest Region: ID, 0.33593; OR, 0.38990; WA, 0.27416 West Region: CA, 0.58943; NV, 0.41057 National (contiguous U.S.) values are computed from the regional values weighted by area. The regional weights are as follows: Northeast, 0.06021 East North Central, 0.08428 Central, 0.10271 Southeast, 0.09715 West North Central, 0.15551 South, 0.18822 Southwest, 0.14053 Northwest, 0.08230 West, 0.08908 As of December 2012, National Weather Service Regions (NWSR) are included. These regions also delineate the NCDC Regional Climate Services regions. The states and weights the make up the four NWSR's are as follows: Eastern Region: CT, .01347; DE, .00553; ME, .08929; MD, .02843; MA, .02220; NH, .02501; NJ, .02107; NY, .13328; NC, .14171; OH, .11082; PA, .12187; RI, .00326; SC, .08349; VT, .02583; VA, .10973; WV, .06501 Southern Region: AL, .0630; AR, .0648; FL, .0715; GA, .0718; LA, .0592; MS, 0582; NM, .1485; OK, .0853; TN, .0515; TX, .3262 Central Region: CO, .1078; IL, .0583; IN, .0375; IA, .0582; KA, .0851; KY, .0418; MI, .0602; MN, .0869; MO, .0721; NE, .0799; ND, .0731; SD, .0797; WI, .0581; WY, .1013 Western Region: AZ, .1319; CA, .1837; ID, .0967; MT, .1703; NV, .1280; OR, .1123; UT, .0983; WA, .0789 The values in this file may not agree with statewide, regional, and national values published in other NCDC publications due to: (1) differences in the way the regions are defined, (2) the temperature data are adjusted for time of observation bias, and (3) the most recent months are based on preliminary data. Monthly heating and cooling degree day values are also available in this file. The statewide values are available for the 48 contiguous States and are computed from the divisional values weighted by population. The heating and cooling degree day values available at this site are used for operational monitoring purposes and may be different from the heating and cooling degree day values published in official degree day publications. DISCUSSION OF THE DIVISIONAL VALUES Monthly averages within a climatic division have been calculated by giving equal weight to stations reporting both temperature and precipitation within a division. In the U.S., observers at cooperative stations often take one observation per day, and the ending time of the climatological day at any station can vary from station-to-station as well as year-to-year. Differences of the 24-hour period over which each observer reports his or her maximum and minimum temperature as well as the average temperature [(max + min)/2] affects the calculated monthly mean temperature. Karl, et al. (1986), describe the biases that this introduces. These potential biases were rectified by adjusting for these varying observation times. The model described by Karl, et al. (1986), was used to adjust the climate division averages such that all stations end their climatological day at midnight; i.e., climatological day coincides with calendar day. The time of observation was determined at each station within a climate division during January of the years 1931, 1941, 1951, 1965, 1975, and 1984 for the states of California, Colorado, Illinois, Indiana, New York, North Carolina, and Washington. The fraction of observers recording at various hours of the day was calculated and interpolated for intervening years (extrapolated for subsequent years). For these seven states, the ending time of observation was grouped into three categories: AM, PM, and MD. The AM category included observers who ended their climatological day between 3 AM and 11 AM; the PM category between noon and 9 PM; and the MD category between 10 PM and 2 AM; all local standard time. The fraction of observers in these categories was calculated, and it was assumed the 7 AM observation time best represented the AM category; the 5 PM observation time, the PM category; and midnight for the MD category. The reason for the simplification was to test if a faster method, requiring significantly less bookkeeping and keypunching, could not provide nearly as good results as calculating the fraction of observers at each of the 24 hours of the day. The time of observation bias model was run by using the latitude and longitude of each of the centroids of the climate divisions. The output from the model was the time of observation bias, with respect to a midnight-to- midnight climatological day, for each of the possible ending hours of the climatological day. Each climate division's monthly average was then adjusted by weighting the bias at any given hour by the fraction of stations within the climate division observing at that hour, and subtracting the result for the reported monthly mean temperature. Differences of the biases were small (< 0.3 Deg. F.) for those calculated by categorizing the ending time of observation into three categories compared to those obtained from calculating the fraction of stations with observation times at each of the 24 hours of the day. This is attributed to the preponderance of AM observation times falling between 6 AM and 9 AM, and PM observation times falling between 4 PM and 7 PM. As a result, by assuming 7 AM observation for all AM stations and 5 PM for all PM stations, a good estimate of the median bias is obtained for all AM or PM observations. Furthermore, nearly all the MD stations observed at midnight. It should also be noted that the borders of the climate divisions in 1951 were not consistent with those defined in 1965. Due to the substantial additional effort it would have required locating each station within three or four climate divisions, as defined today, the change in the statewide percentage of AM, PM, and MD observation times was applied in equal proportions to all climate divisions prior to and including 1951. Based on small differences between the two methods of estimating the time of observation bias, the simpler categorical procedure was used for all climate divisions. This should effectively eliminate most of the biases (over 2 Deg.F) in some climate divisions that have become part of the divisional averages. These biases affect both trends and actual estimates of divisional averages. Reference: Karl, et al. (1986): "A model to estimate the time of observation bias associated with monthly mean maximum, minimum, and mean temperatures for the United States" (Thomas R. Karl, Claude N. Williams, Jr., and Pamela J. Young, National Climatic Data Center, and Wayne M. Wendland, Illinois State Water Survey, Journal of Climate and Applied Meteorology, January 1986, vol. 25, pp. 145-160, American Meteorological Society, Boston, MA). The divisional degree day values are derived from the unadjusted temperatures using a statistical algorithm. STATE CODE TABLE: Range of values for the states, regions, and nation is 001-110. 001 Alabama 030 New York 002 Arizona 031 North Carolina 003 Arkansas 032 North Dakota 004 California 033 Ohio 005 Colorado 034 Oklahoma 006 Connecticut 035 Oregon 007 Delaware 036 Pennsylvania 008 Florida 037 Rhode Island 009 Georgia 038 South Carolina 010 Idaho 039 South Dakota 011 Illinois 040 Tennessee 012 Indiana 041 Texas 013 Iowa 042 Utah 014 Kansas 043 Vermont 015 Kentucky 044 Virginia 016 Louisiana 045 Washington 017 Maine 046 West Virginia 018 Maryland 047 Wisconsin 019 Massachusetts 048 Wyoming 020 Michigan 101 Northeast Region 021 Minnesota 102 East North Central Region 022 Mississippi 103 Central Region 023 Missouri 104 Southeast Region 024 Montana 105 West North Central Region 025 Nebraska 106 South Region 026 Nevada 107 Southwest Region 027 New Hampshire 108 Northwest Region 028 New Jersey 109 West Region 029 New Mexico 110 National (contiguous 48 States) The following are the range of code values for the National Weather Service Regions, river basins, and agricultural regions. 111 Great Plains 115 Southern Plains and Gulf Coast 120 US Rockies and Westward 121 Eastern Region 122 Southern Region 123 Central Region 124 Western Region 201 Pacific Northwest Basin 202 California River Basin 203 Great Basin 204 Lower Colorado River Basin 205 Upper Colorado River Basin 206 Rio Grande River Basin 207 Texas Gulf Coast River Basin 208 Arkansas-White-Red Basin 209 Lower Mississippi River Basin 210 Missouri River Basin 211 Souris-Red-Rainy Basin 212 Upper Mississippi River Basin 213 Great Lakes Basin 214 Tennessee River Basin 215 Ohio River Basin 216 South Atlantic-Gulf Basin 217 Mid-Atlantic Basin 218 New England Basin 220 Mississippi River Basin & Tributaties (N. of Memphis, TN) (below codes are weighted by area) 250 Spring Wheat Belt 255 Primary Hard Red Winter Wheat Belt 256 Winter Wheat Belt 260 Primary Corn and Soybean Belt 261 Corn Belt 262 Soybean Belt 265 Cotton Belt (below codes are weighted by productivity) 350 Spring Wheat Belt 356 Winter Wheat Belt 361 Corn Belt 362 Soybean Belt 365 Cotton Belt (below codes are for percent productivity in the Palmer Z Index categories) 450 Spring Wheat Belt 456 Winter Wheat Belt 461 Corn Belt 462 Soybean Belt 465 Cotton Belt FILE FORMAT: Element Record Name Position Element Description STATE-CODE 1-3 STATE-CODE as indicated in State Code Table above. Range of values is 001-110. DIVISION-NUMBER 4 DIVISION NUMBER. Value is 0 which indicates an area- averaged element. ELEMENT-CODE 5-6 01 = Precipitation 02 = Temperature (adjusted for time of observation bias) 03 = Heating Degree Days 04 = Cooling Degree Days 05 = PDSI 06 = PHDI 07 = ZNDX 08 = PMDI YEAR 7-10 This is the year of record. Range is 1895 to current year processed. JAN-VALUE 11-17 Monthly Temperature format: Range of values b-50.00 to b140.00 degrees Fahrenheit. Decimals retain a position in the 7-character field. Missing values in the latest year are indicated by b-99.90. Monthly Precipitation format: Range of values 00.00 to 99.99. Decimal point retains a position in the 7-character field. Missing values in the latest year are indicated by bb-9.99. FEB-VALUE 18-24 MAR-VALUE 25-31 APR-VALUE 32-38 MAY-VALUE 39-45 JUNE-VALUE 46-52 JULY-VALUE 53-59 AUG-VALUE 60-66 SEPT-VALUE 67-73 OCT-VALUE 74-80 NOV-VALUE 81-87 DEC-VALUE 88-94