UNITED STATES HISTORICAL CLIMATOLOGY NETWORK (U.S. HCN)
MONTHLY TEMPERATURE AND PRECIPITATION DATA



Contributed by:
David R. Easterling, Thomas R. Karl, Elaine H. Mason, Pamela Y. Hughes
National Oceanic and Atmospheric Administration
National Climatic Data Center
Asheville, North Carolina 28801, U.S.A.

and David P. Bowman
Dyntel Central Zone Program
National Climatic Data Center
Asheville, North Carolina 28801, U.S.A.

Prepared by:
D.P. Kaiser and Linda J. Allison
Carbon Dioxide Information Analysis Center
Environmental Sciences Division

The Carbon Dioxide Information Analysis Center
is a part of the Environmental Sciences Division of the
OAK RIDGE NATIONAL LABORATORY (ORNL)
and is located in Oak Ridge, Tennessee 37831-6335.
The ORNL is managed by UT-Battelle, LLC
for the U.S. DEPARTMENT OF ENERGY
under contract DE-AC05-00OR22725




Contents
Abstract
Keywords
1. Background Information
2. Description of the Database
3. Station Inventory File
4. Station History File
5. Temperature and Precipitation Data Files
6. Data Quality Assessment Files
7. Temperature Files, Adjusted for Urban Effects
8. How to Obtain the Data and Documentation
9. References

Abstract

United States Historical Climatology Network (HCN) Serial Temperature and Precipitation Data (revised 1995)

D. R. Easterling, T. R. Karl, E. H. Mason, P. Y. Hughes, and D. P. Bowman

Extending through 1994, this data base contains monthly total precipitation and temperature data from 1219 stations in the contiguous U.S. To be included in the Historical Climatology Network (HCN), a station had to be currently active (1994), have at least 80 years of monthly temperature and precipitation data, and have experienced few station changes. These data were derived from a variety of sources including the National Climatic Data Center archives, state climatologists, and published literature. The data base contains several hundred variables, including state number; station number; monthly temperatures (minimum, maximum, and mean); total monthly precipitation; and time of observation. This is probably the best monthly temperature and precipitation data set available for the contiguous U.S. because station moves, instrument changes, urbanization effects, and time-of-observation differences have been considered and, where necessary, the data have been corrected.
Keywords : United States, Climate, Monthly climate, precipitation, temperature, climate change


1. Background Information

One of the objectives in establishing the U.S. HCN was to detect temporal changes in regional rather than local climate. Therefore, only stations not influenced to any substantial degree by artificial changes in their local environments were included in the network. Some of the stations in the U.S. HCN are first-order weather stations, but the majority were selected from the ~5,000 stations in the U.S. cooperative weather station network. To be included in the U.S. HCN a station had to be currently active (in 1987), have at least 80 years of mean monthly temperature and total monthly precipitation data, and have experienced relatively few station moves and equipment changes (see INVENT94.ASC) for a complete listing of the stations in the U.S. HCN). An additional criterion used in selecting the 1221 U.S. HCN stations that sometimes compromised the preceding requirement, was the desire to have a uniform distribution of stations across the continental United States.

The U.S. HCN database contains station histories, monthly temperature data {mean, mean minimum, average [i.e., (monthly minimum + monthly maximum) / 2], and mean maximum}, and total monthly precipitation data that were compiled from digital and non-digital data sets archived at the National Climatic Data Center (NCDC). These data sets originated from a variety of sources, including climatological publications, universities, federal agencies, individuals, and data archives. All stations were quality controlled by NCDC through the use of outlier and areal edits. Each station record was then corrected for time-of-observation (TOB) differences, instrument changes, instrument moves, and station moves (Karl and Williams 1987). The effects of urbanization were then removed and four urban temperature files produced (Karl et al. 1988).

A unique feature of these data are that within most temperature and precipitation data files, both original (or estimated) and adjusted data are given along with confidence factors for each adjusted data value. Another unique feature of the database is that in comparison with the long periods of record, only a small portion of the data are represented as missing. In order to make the U.S. HCN record as serially complete as possible, values for stations missing data have been estimated using data from neighboring stations. Since 1900, over 50% of the 1221 stations have data records that are serially complete (i.e., have original, or estimated, and adjusted data).


2. Description of the Database

This NDP provides 27 files:

The format and contents of each data file are described in the following sections.
3. Station Inventory File (invent94.asc)

The station inventory file provides a list of the stations in the U.S. HCN at the time the data set was compiled. The file contains 1221 lines of data and provides essential information about each station. Each record contains the state number; station number; latitude and longitude coordinates; station elevation; station name; two letter state code; beginning year of record in the station history file; ending year of record in the station history file; beginning year of record for the minimum, mean, average, maximum temperatures, and precipitation in the U.S. HCN files; and the beginning year of record for minimum, mean, average, and maximum temperatures in the urban files. This file has no missing values. The file may be read by the following FORTRAN code (invent94.for):


    10    READ (5,100,END=999) STACOD, LAT, LONG, ELEV,
     1    STANAME, STATE, BYRSHF, EYRSHF, HCNMN, HCNAVG,
     1    HCNAV2, HCNMX, HCNPCP, URMN, URAVG, URAV2, URMX
          GOTO 10
C
   100    FORMAT(1I6,2F8.2,1I6,1X,1A30,1A2,11(1X,1I4))

Stated in tabular form, the format of the station history files is as follows:

Table 1. Variable formats for invent94.asc
Name Type Width Start End
STACOD Integer 6 1 6
LAT Real 8 7 14
LONG Real 8 15 22
ELEV Integer 6 23 28
STANAME Character 30 30 59
STATE Character 2 60 61
BYRSHF Integer 4 63 66
EYRSHF Integer 4 68 71
HCNMN Integer 4 73 76
HCNAVG Integer 4 78 81
HCNAV2 Integer 4 83 86
HCNMX Integer 4 88 91
HCNPCP Integer 4 93 96
URMN Integer 4 98 101
URAVG Integer 4 103 106
URAV2 Integer 4 108 111
URMX Integer 4 113 116

Where:

STACOD the unique station code formed by combining the two-digit state number [state numbers range from 1 to 48 (e.g., 01 = Alabama, 02 = Arizona, . . . 48 = Wyoming)] and the four-digit station number (values range from 0008 to 9933)
LAT the station latitude in decimal degrees
LONG is the station longitude in decimal degrees
ELEV the ground elevation at the station, expressed in whole feet above or below mean sea level (values range from -194 to 9065)
STATION the full name of the cooperative station as of 1994
STATE a two-letter state abbreviation (e.g., AL = Alabama, AZ = Arizona, etc.)
BYRSHF the beginning year of record in the station history file
EYRSHF the ending year of record in the station history file (9999 indicates the station is still in operation)
HCNMN the beginning year of record for a station in the minimum temperature data file
HCNAVG the beginning year of record for a station in the mean temperature data file
HCNAV2 the beginning year of record for a station in which both the maximum and minimum temperature data are available
HCNMX the beginning year of record for a station in the maximum temperature data file
HCNPCP the beginning year of record for a station in the precipitation temperature data file
URMN the beginning year of record for a station in the minimum temperature, urban heat island effect data file
URAVG the beginning year of record for a station in the mean temperature, urban heat island effect data file
URAV2 the beginning year of record for a station in which both the maximum and minimum urban heat island effect temperature data are available
URMX the beginning year of record for a station in the maximum temperature, urban heat island effect data file

*Please note there is also code available for reading this data into SAS (invent94.sas).
4. Station History File (shf94.asc.Z)

The station history file provides valuable information concerning each station in the U.S. HCN. This file documents station moves and instrument changes, lists station observers and observation times, and identifies suspect fields. When this file is used in conjunction with the station inventory file and quality assessment files the user may accurately assess the quality and suitability of each station's data for long-term climate analyses. The file may be read by the following FORTRAN code (shr94.for):

  10    READ (5,100) STACOD, STATE, DIVISION, STANAME,
     1    COUNTY, XREF
  20    READ (5,110,END=999) STACOD2
        BACKSPACE 5
        IF (STACOD .NE. STACOD2) GOTO 10
        READ (5,115) STACOD2, MOBEG, DAYBEG, YRBEG,
     1    MOEND, DAYEND, YREND, (SUSP(I),I=1,15), LATDEG, LATMIN,
     1    LONGDEG, LONGMIN, DISTANCE, DPLUNIT, DIRECT,
     1    ELEV, DISTPO, DPOUNIT, DIRECTPO, NAME, QUALIF,
     1    (INSTRU(I),I=1,36), PCPOT, TMPOT, PCPHT, TMPHT,
     1    (PUB(I),I=1,16), OBSNAME, NUMOBS
C
  100   FORMAT(1I6,1X,1A2,1X,1I2,1X,1A30,1X,1A16,1X,1A25)
  110   FORMAT(1I6)
  115   FORMAT(1I6,2(2(1X,1I2),1X,1I4),1X,15A1,1X,1I3,1X,1I2,1X,
     1    1I4,1X,1I2,1X,1I3,1A1,1A3,1X,1I5,1X,1I4,1A1,
     1    1A3,1X,1A28,1X,1A10,1X,36A1,2(1X,2A2),1X,16A1,1X,
     1    1A46,1X,1I2)

Stated in tabular form, the format of the station history file is as follows:

Table 2. Variable formats for SHF94.ASC


Name Type Width Start End
STACOD Integer 6 1 6
STATE Character 2 8 9
DIVISION Integer 2 11 12
STANAME Character 30 14 43
COUNTY Character 16 45 60
XREF Character 25 62 86
STACOD2 Integer 6 1 6
MOBEG Integer 2 8 9
DAYBEG Integer 2 11 12
YRBEG Integer 4 14 17
MOEND Integer 2 19 20
DAYEND Integer 2 22 23
YREND Integer 4 25 28
SUSPLAT Character 1 30
SUSPLONG Character 1 31
SUSPLOC Character 1 32
SUSPELEV Character 1 33
SUSPPO Character 1 34
SUSPNAME Character 1 35
SUSPQUAL Character 1 36
SUSPINST Character 1 37
SUSPTIME Character 1 38
SUSPHTS Character 1 39
SUSPPUBS Character 1 40
SUSPBEG Character 1 41
SUSPEND Character 1 42
SUSPOBS Character 1 43
SUSPOTHR Character 1 44
LATDEG Integer 3 46 48
LATMIN Integer 2 50 51
LONGDEG Integer 4 53 56
LONGMIN Integer 2 58 59
DISTANCE Integer 3 61 63
DPLUNIT Character 1 64
DIRECT Character 3 65 67
ELEV Integer 5 69 73
DISTPO Integer 4 75 78
DPOUNIT Character 1 79
DIRECTPO Character 3 80 82
NAME Character 28 84 111
QUALIF Character 10 113 122
AI Character 1 124  
CRS Character 1 125  
DT Character 1 126  
EVA Character 1 127  
FP Character 1 128  
HYTHG Character 1 129  
MN Character 1 130  
MX Character 1 131  
NRIG Character 1 132  
NSRG Character 1 133  
NSS Character 1 134  
RRIG Character 1 135  
RRNG Character 1 136  
SDE Character 1 137  
SG Character 1 138  
SRG Character 1 139  
SS Character 1 140  
TG Character 1 141  
DGT Character 1 142  
TB Character 1 143  
EVO Character 1 144  
MMTS Character 1 145  
TELSY Character 1 146  
HYGRO Character 1 147  
HY6 Character 1 148  
HY8 Character 1 149  
SFP Character 1 150  
SRRNG Character 1 151  
SSG Character 1 152  
SSRG Character 1 153  
STB Character 1 154  
AMOS Character 1 155  
AUTOB Character 1 156  
PSY Character 1 157  
PCPOT Character 2 161 162
TMPOT Character 2 163 164
PCPHT Character 2 166 167
TMPHT Character 2 168 169
BULLETW Character 1 171  
COMBBUL Character 1 172  
CLIMDATA Character 1 173  
RIVSTAGE Character 1 174  
HYDROBUL Character 1 175  
PRECDATA Character 1 176  
SNOWBULL Character 1 177  
NOTPUB Character 1 178  
CWB Character 1 179  
MONTHREV Character 1 180  
STATEPUB Character 1 181  
LCD Character 1 182  
BQ Character 1 183  
SGPD Character 1 184  
WWR Character 1 185  
MYB Character 1 186  
OBSNAME Character 46 188 233
NUMOBS Character 2 235 236

Where:
STACOD the unique station code formed by combining the two-digit state number [state numbers range from 1 to 48 (e.g., 01 = Alabama, 02 = Arizona, . . . 48 = Wyoming)] and the four-digit station number (values range from 0008 to 9933)
STATE the two-letter state abbreviation (e.g., AL = Alabama)
DIVISION the state U.S. climatological subdivision number [e.g., Vermont (STACOD = 43) has three climatological subdivisions (01 = Northeastern, 02 = Western, and 03 = Southeastern)]
STANAME the most current station name
COUNTY the county in which the station is presently located
XREF a station cross-reference, representing the cooperative station number of the station or the county name that the current station moved to or from
STACOD2 the unique station code formed by combining the two-digit state number [state numbers range from 1 to 48 (e.g., 01 = Alabama, 02 = Arizona, . . . 48 = Wyoming)] and the four-digit station number (values range from 0008 to 9933)
MOBEG the month the data record started (values range from 01 to 12, and missing values are represented by 99)
DAYBEG the day the data record started (values range from 01 to 31, and missing values are represented by 99)
YRBEG the year the data record started (values range from 1738 to 1994)
MOEND the month the data record ended (values range from 01 to 12, and missing values are represented by 99)
DAYEND the day the data record ended (values range from 01 to 31, and missing values are represented by 99)
YREND the year the data record ended (values range from 1759 to 1994, and 9999 indicates that the station is still in operation at this location).

The next 15 variables represent suspect fields in the station history file. The values for these variables will be either 0 or 1. Values of 1 represent field(s) flagged as suspect by the pre-key editor. In the FORTRAN program this data is stored in an single-character, 15-element array named SUSP.


1.  SUSPLAT         Latitude
2.  SUSPLONG        Longitude
3.  SUSPLOC         Distance from previous location
4.  SUSPELEV        Elevation
5.  SUSPPO          Distance from Post Office location
6.  SUSPNAME        Station name
7.  SUSPQUAL        Qualifier added to the station name
8.  SUSPINST        Instruments
9.  SUSPTIME        Observation time
10. SUSPHTS         Instrument heights
11. SUSPPUBS        Publications
12. SUSPBEG         Beginning date
13. SUSPEND         Ending date
14. SUSPOBS         Observer
15. SUSPOTHR        Other observers

LATDEG the degree portion of the station latitude (North).
LATMIN the minute portion of the station latitude (North).
LONGDEG the degree portion of the station longitude (West) (Note: negative signs are missing).
LONGMIN the minute portion of the station longitude (West).
DISTANCE the distance in tenths of miles or city blocks from the previous station location (e.g., 015 = 1.5 miles); if DPLUNIT = "B" then this value represents 15 city blocks; unknown directions are represented by 999.
DPLUNIT the units indicator for DISTANCE (i.e., blank = miles, B = city blocks).
DIRECT the direction on a 16-point compass of a station move from the previous location. Location of the temperature instrument defines the official station location. Values may be blank, character, or numeric. Unknown direction is represented by 999. For example
blank = first record of new station or distance and direction unknown
015 NW = station moved 1.5 (variable DISTANCE) miles (variable DPLUNIT) NW from previous location
000 000 = no change in station or instrument location
000 ESE = moved <0.1 mile east-southeast (ESE) from previous location
000 999 = moved <0.1 mile, direction unknown
900 ESE = temperature instrument moved, precipitation instrument did not move or both instruments were moved to the same location
800 000 = precipitation instrument moved but the temperature instrument did not
999 NW = distance unknown, direction NW
ELEV the ground elevation at the station, expressed in whole feet above or below mean sea level (values range from -194 to 9,843 feet).
DISTPO the distance in tenths of miles or city blocks from the nearest Post Office (e.g. 015 = 1.5 miles); if DPOUNIT = "B" then this value represents 15 city blocks, unknown distances are represented by 9999.
DPOUNIT the units indicator for DISTPO (i.e., blank = miles, B = city blocks).
DIRECTPO the direction on a 16-point compass from the nearest Post Office. Values may be either blank, character, or numeric. Unknown directions are represented by 999.9
For example:
blank = distance and direction unknown
0015 NW = 1.5 (variable DISTPO) miles (variable DPOUNIT) NW of post office
0000 NW = <0.1 mile NW from post office
0000 999 = <0.1 mile from post office, direction unknown
0000 000 = at the post office
NAME the full station name.
QUALIF a qualifier or description that is added to the proper name of the station (e.g., Asheville 2N).


The next 36 variables represent the instrumentation of the station and the station's classification. If an instrument was used at a particular station or if a particular classification is appropriate for that station, the variable will have a value of 1; if it was not used, the variable will have a value of 0. In the FORTRAN program this data is stored in an single-character, 36-element array named INSTRU.


1.  AI             Additional instrument (wind, pressure, etc.)
2.  CRS            Cotton region shelter
3.  DT             Dry bulb thermometer
4.  EVA            Class "A" evaporation station
5.  FP             Fisher-Porter gage
6.  HYTHG          Hygrothermograph
7.  MN             Minimum thermometer
8.  MX             Maximum thermometer
9.  NRIG           Nonrecording river gage
10. NSRG           Nonstandard rain gage
11. NSS            Nonstandard shelter
12. RRIG           Recording river gage
13. RRNG           Recording rain gage
14. SDE            Snow density gage
15. SG             Storage gage
16. SRG            Standard rain gage
17. SS             Standard shelter (official)
18. TG             Thermograph
19. DGT            Digital thermometer
20. TB             Tipping bucket gage
21. EVO            Other than class "A" evaporation station
22. MMTS           Maximum/minimum temperature system
23. TELSY          Telemetry system
24. HYGRO          Hygrothermometer (type unknown)
25. HY6            Hygrothermometer, H06X series
26. HY8            Hygrothermometer, H08X series
27. SFP            Shielded Fischer-Porter gage
28. SRRNG          Shielded recording rain gage
29. SSG            Shielded storage gage
30. SSRG           Shielded standard rain gage
31. STB            Shielded tipping bucket gage
32. AMOS           Automated meteorological observing system
33. AUTOB          Automated observing station
34. PSY            Psychrometer (Alaska only)
35.                not assigned at present
36.                not assigned at present

PCPOT* the observation time (rounded to the whole hour) for precipitation.
TMPOT* the observation time (rounded to the whole hour) for temperature.
PCPHT the height of the precipitation instrument aboveground, rounded to the nearest foot.
TMPHT the height of the temperature instrument aboveground, rounded to the nearest foot.Values for PCPHT and TMPHT may be given in either numerals or characters. Numerical values range from 01 to 99. Potential values include the following:
01-97 = actual height
98 = >= 98 feet
99 = missing
RF = roof, height unknown

*Values for PCPOT and TMPOT may be either numeric, character, or alphanumeric. Possible values and their meaning include the following: 01 to 24 = nearest whole hour; 99 = missing; SR = sunrise; SS = sunset; XXHR XX = number of hours observed per day; 9XX9 XX = hours observed, unknown for both temperature and precipitation; TRID = tri-daily observations, Average Temperature = [7 AM + 2 PM + (2 x 9 PM)] / 4; RS = crop season=sunrise (SR) and other months = sunset (SS).

The next 16 variables represent publications. If the data from a particular station appeared in a publication the variable will have a value of 1; if not, the variable will have a value of 0. In the FORTRAN programs, these data are stored in an single-character, 16-element array named PUB. The variables and their corresponding publications are as follows:


1.  BULLETW      Bulletin W
2.  COMBBUL      Combined Bulletin
3.  CLIMDATA     Climatological Data
4.  RIVSTAGE     Daily River Stages
5.  HYDROBUL     Hydrologic Bulletin
6.  PRECDATA     published as hourly precipitation data
7.  SNOWBULL     Snow Bulletin
8.  NOTPUB       not published
9.  CWB          Report to the chief of the U.S. Weather Bureau
10. MONTHREV     Monthly Weather Review
11. STATEPUB     published in state publications
12. LCD          Local Climatological Data
13. BQ           Bulletin Q, 1870-1903.
14. SGPD         Storage Gage Precipitation Data, Western United States
15. WWR          Weekly Weather Review
16. MYB          U.S. Meteorological Yearbook

OBSNAME the observer's name (may include more than one name per record).
NUMOBS the number of additional known observers during the time of record for a station (values range from 0 to 28).

**Please note there is also code available for reading this data into SAS (shf94.sas).
5. Temperature and Precipitation Data Files  (hcnav2.asc.Z, hcn94max.asc.Z,hcn94mea.asc.Z, hcn94min.asc.Z.

Monthly data have been extracted from digital and nondigital data sets archived at the NCDC. The data are sorted by element: one file each for monthly maximum temperature, mean temperature, average temperature [i.e., (monthly minimum + monthly maximum)/2], minimum temperature, and total precipitation. The total monthly precipitation and temperature data files are revisions of the files distributed with the last revision of this NDP. These updates extend the period of record from 1987 through 1994. Each record of these four files contain 1 year of monthly data for a given station. These monthly data sets come from various sources as defined by the source field in the station history file. At most, each file will contain four lines of data per year for each station. These lines include (1) original measured data; (2) time of observation corrections, (3) data adjusted for station moves, instrument changes, and other factors influencing the homogeneity of the station record; and (4) confidence estimates for these adjusted values. These files have not been adjusted for urbanization effects. If a station moved between 1987 and 1994, then the adjusted and estimated data for the station will differ from the revision 1 and 2 data files for the entire period of record. The precipitation data have been completely revised due to the correction of logical errors in the precipitation adjustment programs.

The average temperature file is new at this revision of the NDP and may contain two data records per year, per station. The "+" record is the TOB mean temperature data calculated from the TOB maximum temperature and TOB minimum temperature data. The "A" record is the FILNET mean temperature data calculated from the "A" rows in the maximum and minimum temperature data files. The files may be read by the following FORTRAN code (hcn94.for):

*Note: All data are expressed in hundredths of degrees Fahrenheit, and missing values are represented by -9999. 
  10    READ (5,100,END=999) STACOD, YEAR, ELEM,
     1    TYPE, (HCNDAT(I),FLAG(I),FLAG2(I),FLAG3(I),
     1    FLAG4(I),I=1,13)
        GOTO 10
C
100     FORMAT(I6,1X,I4,1X,I1,A1,13(I5,4A1))

During a few years original data were not available and only estimated data and confidence factors are included. Stated in tabular form, the format of the data files are as follows.



Table 3. Variable formats for files hcn94max.asc, hcn94mea.asc, hcn94av2.asc, hcn94min.asc
Name Type Width Start End
STACOD Integer 6 1 6
YEAR Integer 4 8 11
ELEM Integer 1 13  
TYPE Character 1 14  
JAN Integer 5 15 19
JANFLAG1 Character 1 20  
JANFLAG2 Character 1 21  
JANFLAG3 Character 1 22  
JANFLAG4 Character 1 23  
FEB Integer 5 24 28
FEBFLAG1 Character 1 29  
FEBFLAG2 Character 1 30  
FEBFLAG3 Character 1 31  
FEBFLAG4 Character 1 32  
MARCH Integer 5 33 37
MARFLAG1 Character 1 38  
MARFLAG2 Character 1 39  
MARFLAG3 Character 1 40  
MARFLAG4 Character 1 41  
APR Integer 5 42 46
APRFLAG1 Character 1 47  
APRFLAG2 Character 1 48  
APRFLAG3 Character 1 49  
APRFLAG4 Character 1 50  
MAY Integer 5 51 55
MAYFLAG1 Character 1 56  
MAYFLAG2 Character 1 57  
MAYFLAG3 Character 1 58  
MAYFLAG4 Character 1 59  
JUN Integer 5 60 64
JUNFLAG1 Character 1 65  
JUNFLAG2 Character 1 66  
JUNFLAG3 Character 1 67  
JUNFLAG4 Character 1 68  
JUL Integer 5 69 73
JULFLAG1 Character 1 74  
JULFLAG2 Character 1 75  
JULFLAG3 Character 1 76  
JULFLAG4 Character 1 77  
AUG Integer 5 78 82
AUGFLAG1 Character 1 83  
AUGFLAG2 Character 1 84  
AUGFLAG3 Character 1 85  
AUGFLAG4 Character 1 86  
SEP Integer 5 87 91
SEPFLAG1 Character 1 92  
SEPFLAG2 Character 1 93  
SEPFLAG3 Character 1 94  
SEPFLAG4 Character 1 95  
OCT Integer 5 96 100
OCTFLAG1 Character 1 101  
OCTFLAG2 Character 1 102  
OCTFLAG3 Character 1 103  
OCTFLAG4 Character 1 102  
NOV Integer 5 105 109
NOVFLAG1 Character 1 110  
NOVFLAG2 Character 1 111  
NOVFLAG3 Character 1 112  
NOVFLAG4 Character 1 113  
DEC Integer 5 114 118
DECFLAG1 Character 1 119  
DECFLAG2 Character 1 120  
DECFLAG3 Character 1 121  
DECFLAG4 Character 1 122  
AAN Integer 5 123 127
ANNFLAG1 Character 1 128  
ANNFLAG2 Character 1 129  
ANNFLAG3 Character 1 130  
ANNFLAG4 Character 1 131  

where:
STACOD the unique six digit station code consisting of a two-digit state number [values range from 01 to 48 (i.e., 01 = Alabama, 02 = Arizona, . . . 48 = Wyoming)] and the cooperative station network number (values range from 0008 to 9933)
YEAR the year of record
ELEM the data element to identify the data file (1 = monthly maximum temperatures, 2 = monthly minimum temperatures, 3 = monthly mean temperatures or monthly average temperatures, and 4 = total monthly precipitation)
TYPE the data type code (blank = original data; + = time of observation adjustments; A = station moves, MMTS corrections, missing data adjustments; and C = confidence factor).

Original data are the manuscript or "sources" data that have been archived at NCDC. These data have been manually corrected as needed when checks, such as the annual total vs monthly sum and the average temperature file [i.e., (monthly maximum + monthly minimum)/2] versus mean temperature file, have indicated suspect data. These data are as "clean" as possible with respect to the source (see FLAG2). Adjusted data, along with the confidence factors, are a product of four major computer programs. The station history data and a network of the best correlated nearby stations are used in all these routines. First, the original data are input into a time-of-observation (TOB) debiasing routine so that the data will be consistent with a midnight-to-midnight observation schedule (Karl et al. 1986). Secondly, the TOB corrected data are input into the MMTS program which debiases the data taken from the new Maximum/Minimum Temperature System (MMTS) (Quayle et al. 1991). Thirdly, the data is then entered into the station history adjustment program (SHAP) which debiases the data with respect to instrument changes (other than the MMTS conversion) that may affect the temperature and precipitation data (Karl et al. 1987). The final routine, FILNET, uses the SHAP data and fills in missing original data (i.e., estimates data values based on highly correlated neighboring stations) and then calculates the adjusted data for periods where station changes occurred too often for the SHAP program to make the corrections needed to debias the data.

In the FORTRAN code, the monthly and annual data variables are stored in a 13-element integer array named HCNDAT.


JAN-DEC are the monthly mean temperature or total monthly precipitation estimates.

Original and adjusted or estimated temperature data are expressed in units of hundredths of degrees Fahrenheit but are only measured to the nearest tenth of a degree. Precipitation is in hundredths of inches. For adjusted data, one-half the maximum plus one-half the minimum do not necessarily exactly equal the mean. The mean temperature is adjusted independently of the adjustments of the maximum and minimum values (Karl et al. 1986). A -9999 value indicates that data were not available or adjustments were not made for a given data variable.

Confidence factors for temperature are in units of hundredths of degrees Fahrenheit. For precipitation, a dimensionless multiplication factor in hundredths is provided for calculation of confidence intervals. A -9999 indicates that no confidence factors were calculated.

Temperature confidence intervals are calculated by subtracting the temperature confidence factor from the adjusted value to obtain the lower end of the confidence interval (16%, -1 standard deviation). The upper end of the confidence interval (84%, +1 standard deviation) is obtained by adding the confidence factor to the adjusted data. For the precipitation confidence intervals, the lower end of the confidence interval (16%) is obtained by dividing the adjusted value by its confidence factor, and the upper end of the confidence interval (84%) is obtained by multiplying the adjusted value by its confidence factor.


ANN the annual mean of the monthly temperature or total annual precipitation estimates. Original and adjusted temperature data are expressed in units of hundredths of degrees Fahrenheit or hundredths of inches (all 12 months must have data for this variable to be calculated).

In the FORTRAN code the following variables are stored in four, 4-element, single-character arrays named FLAG, FLAG2, FLAG3, and FLAG4 (in the SAS code the data variables are named FLAG1, FLAG2, FLAG3, and FLAG4).


FLAG CODES FOR THE BLANK ROW, THE ORIGINAL DATA
(JAN-DEC)FLAG1 is the code for the number of daily values not available in computing the monthly value (flag values are Blank = 0, A = 1, B = 2, C = 3, . . . I = 9; "." = data is estimated). If the source code flag (FLAG2 -see below) equals 0 or 1, then FLAG1 = I indicates that 1 to 9 days of data are missing.
(JAN-DEC)FLAG2 is the data source code. The codes and their meaning are as follows:
0 = NCDC Tape Deck 3200, Summary-of-the-Day Element Digital File;
1 = NCDC Tape Deck 3220, Summary-of-the-Month Element Digital File;
2 = Means Book Smithsonian Institute, C. A. Schott (1876, 1881, up to 1931);
3 = Manuscript -Original National Climatic Data Records;
4 = CD Climatological Data, published monthly by NCDC;
5 = Climate Record Book for a description, see History of Climatological Record Books, U.S. Department of Commerce, Weather Bureau, U.S.G.P.O., 1960;
6 = Bulletin W Summary of the Climatological Data for the United States by Section by F. H. Bigelow, U.S. Weather Bureau, 1912; and Summary of the Climatological Data for the United States, (Bulletin W - 2nd ed.);
7 = LCD Local Climatological Data, published monthly by NCDC; 8 = State climatologists various sources;
B = Professor Raymond Bradley see Climatic Fluctuations of the Western United States During the Period of Instrumental Records by Bradley, Barry, and Kiladis, Contribution No. 42, Department of Geography and Geology, University of Massachusetts, 1982;
D = Dr. Henry Diaz A compilation of data from Bulletin W, LCD and NCDC Tape Deck 3220 (1983);
G = Professor John Griffith -primarily from Climatological Data;
Blank = computed value from two of three temperature elements.
(JAN-DEC)FLAG3 is a precipitation indicator for trace precipitation (T = Trace). This flag is not used in the temperature files and is blank.
(JAN-DEC)FLAG4 is a code for outliers. The codes and their meaning are as follows:
S = data are outliers, but NCDC did not have enough confidence to invalidate the observation [the data in question are between 3.5 and 5.0 standard deviations from their mean offset with respect to its nearest neighbors (Karl et al. 1986)];
X = data are outliers and are represented as missing (>5.0 standard deviations from their mean offset with respect to the station's nearest neighbors);
Blank = data are not outliers.
ANNFLAG1 is an indicator that daily values were not available when the annual value was computed. The codes and their meaning are as follows:
Blank = indicates that data were not missing;
I = indicates that 1 to 9 days of data are missing in at least 1 month of the year.
ANNFLAG2 is the same source code used for the original data.
ANNFLAG3 is used as an indicator for trace precipitation (T = Trace).
ANNFLAG4 is not used.

FLAG CODES FOR ROW "+," THE TIME-OF-OBSERVATION ADJUSTED DATA
(JAN-DEC)FLAG1 the same as the code used for the original data in FLAG1
In the average temperature file (HCN94AV2.ASC), a code of "." means that the maximum or minimum data had a code of "."; otherwise, the code is the code of the maximum/minimum data with the greatest number of missing days.
(JAN-DEC)FLAG2 the same source code used for the original data
In the average temperature file, this flag is not used and is blank
(JAN-DEC)FLAG3 a precipitation indicator for trace precipitation (T = Trace)
For temperature data, this flag is an indicator of the quality of the available observation times for a given station. The temperature codes and their meanings are as follows:
F = information concerning the observation times for the station during the year was suspect or "flaky" (the temperature data provided when this flag code appears should be used with caution)
G = information concerning the observation times for the station during the year was "good," and the information was judged to be accurate
Blank = observation times were not available for the station during that year
In the average temperature file, this flag represents the worst code for the maximum and minimum data files: blank indicates that the maximum and/or minimum flags were blank; "F" indicates that the maximum and/or minimum flags were "F"; and "G" indicates that the maximum and minimum flags were "G"
(JAN-DEC)FLAG4 the same code as used for FLAG4 in the original data In the average temperature file, this flag represents the worst code for the maximum and minimum data files: "S" indicates that the maximum and/or minimum flags were "S"; and "X" indicates that the maximum and/or minimum flags were "X"; and blank indicates that the minimum and maximum data were not outliers
ANNFLAG1, ANNFLAG2, and ANNFLAG4 not used
ANNFLAG3 used as an indicator for trace precipitation (T = Trace)

FLAG CODES FOR ROW "A," THE ADJUSTED DATA
(JAN-DEC)FLAG1 the same code as used for FLAG1 in the original data
(JAN-DEC)FLAG2 the same code as used for FLAG2 in the original data
(JAN-DEC)FLAG3 an indicator for the station move bias correction (added by the SHAP program). This flag is set to blank in the precipitation data file. The indicators and their meaning are:
Blank = no temperature data adjusted -treated as a station move
O = temperature data adjusted
(JAN-DEC)FLAG4 indicates outliers and missing data estimates. The codes and their meanings are as follows:
Blank = original data do not have outliers
S = original data have outliers, but NCDC did not have enough confidence to invalidate the observation
M = no original data are available, but an estimate is provided that is consistent with the data adjusted by using the nearest neighboring stations; or, the data were in excess of 5.0 standard deviations from their mean offset with respect to the station's nearest neighbors
E = original data are available, but data were estimated by using nearest neighbors because
(1) the data were between 3.5 and 5.0 standard deviations from their mean offset and 1 or more days in the month were missing
(2) adjustments of original data were inappropriate (< 5 years between potential inhomogeneities), so nearest neighbors were used to estimate the data consistent with its 1994, or last known, location.

In the average temperature file, this flag represents the worst code for the maximum and minimum data files:
"S" indicates that the maximum and/or minimum flags were "S"
"M" indicates that the maximum and/or minimum flags were "M"
"E" indicates that the maximum and/or minimum flags were "E"
blank indicates that the minimum and maximum data do not have outliers
ANNFLAG1, ANNFLAG2, ANNFLAG3, and ANNFLAG4 not used

FLAG CODES FOR ROW "C," THE CONFIDENCE FACTORS
These numeric flag values are used only in the temperature data files. Other possible values are as follows:
X = algorithm was unable to adjust the data;
U = algorithm was unable to adjust the entire series because of the low station density of the network, but an estimate for the missing data is given by using neighboring stations;
A = precipitation data was adjusted by using annual values;
S = precipitation data was adjusted.

The preceding information is all that is needed to use the data on a first-look basis. The flags and the data may be interpreted as follows: (1) if the adjusted data and confidence factor are present (not equal to -9999), then the data have successfully passed through all the adjustments and fill-ins and may be considered NCDC's "best" estimate, or (2) if the original data and TOB data are present but the adjusted data and confidence factor are missing, the temperature data have passed through only the TOB program (i.e., station history adjustment and the fill-in procedures could not estimate the adjusted data).


**Please note there is also code available for reading this data into SAS (hcn94.sas).
6. Data Quality Assessment Files (qa94mean.asc,qa94mxmn.asc,qa94pcp.asc)

Three data quality assessment files were generated by NCDC to allow the user to identify the stations of the highest quality. The information in these files, along with the information in the station history and data inventory files, enable the user to identify the stations with the longest, most complete records. These files provide information for the HCN temperature and precipitation data files only, not the temperature files that have been adjusted for heat island effects. The statistics in these files were generated for the data through 1994.
Quality assessments of the minimum and maximum temperature data have been combined into one file. The minimum and maximum temperature quality assessment file may be read by using the following FORTRAN code (qa94mxmn.for):


  10    READ (5,100,END=999) STATE, STANAME, STATENUM,
     1    STANUM, STADIV, LAT, LONG, ELEV, BPORDATE, R1,
     1    PERORIG, R2, USCDATE, R3, ASCDATE, R4, PERASCD,
     1    R5, PDBPOR, PDR1, APDMX, PDR2, APDMN, PDR3,
     1    PDASCD, PDR4, APDASCMX, PDR5, APDASCMN, PDR6,
     1    CONFMX, R6, CONFMN, R7, CONS40MX, R8, CONS40MN,
     1    R9, CONSFMX, R10, CONSFMN, R11
        GOTO 10
C
 100    FORMAT(1X,A2,1X,A28,1X,I2,1X,I4,1X,A2,1X,
     1    A6,1X,A7,2X,I6,1X,A7,1X,I1,1X,
     1    F5.1,2(1X,I1,1X,A7),1X,I1,1X,
     1    F6.1,1X,I1,2X,I2,2X,I1,4X,I2,3X,
     1    I1,3X,I3,3X,I1,1X,I3,1X,2(I1,3X,
     1    I3,3X),I1,1X,F5.2,1X,
     1    I1,1X,F5.2,1X,2(I1,3X,I2,3X),
     1    I1,2(4X,I2,4X,I1))

The mean temperature and precipitation quality assessment files may be read with the following FORTRAN code (qa94mean.for):

  10    READ (5,100,END=999) STATE, STANAME, STATENUM,
     1    STANUM, STADIV, LAT, LONG, ELEV, BPORDATE, R1,
     1    PERORIG, R2, USCDATE, R3, ASCDATE, R4, PERASCD,
     1    R5, PDBPOR, PDR1, APDBPOR, PDR2, PDASCD,
     1    PDR3, APDSCD, PDR4, CONF, R6, CONS40,
     1    R7, CONSF, R8
        GOTO 10
C

 100    FORMAT(1X,A2,1X,A28,1X,I2,1X,I4,1X,A2,1X,
     1    A6,1X,A7,2X,I6,1X,A7,1X,I1,1X,
     1    F5.1,2(1X,I1,1X,A7),1X,I1,1X,
     1    F6.1,1X,I1,2X,I2,2X,I1,4X,I2,3X,I1,3X,
     1    I3,3X,I1,3X,I3,3X,I1,1X,F5.2,1X,I1,
     1    2X,I2,2X,I1,2X,I2,2X,I1)



Table 4. Variable formats for file qa94mxmn.asc
Name Type Width Start End
STATE Character 2 2 3
STANAME Character 28 5 32
STATENUM Integer 2 34 35
STANUM Integer 4 37 40
STADIV Character 2 42 43
LAT Character 6 45 50
LONG Character 7 52 58
ELEV Integer 6 61 66
BPORDATE Character 7 68 74
R1 Integer 1 76  
PERORIG Real 5 78 82
R2 Integer 1 84  
USCDATE Character 7 86 92
R3 Integer 1 94  
ASCDATE Character 7 96 102
R4 Integer 1 104  
PERASCD Real 6 106 111
R5 Integer 1 113  
PDBPOR Integer 2 116 117
PDR1 Integer 1 120  
APDMX Integer 2 125 126
PDR2 Integer 1 130  
APDMN Integer 3 134 136
PDR3 Integer 1 140  
PDASCD Integer 3 142 144
PDR4 Integer 1 146  
APDASCMX Integer 3 150 152
PDR5 Integer 1 156  
APDASCMN Integer 3 160 162
PDR6 Integer 1 166  
CONFMX Real 5 168 172
R6 Integer 1 174  
CONFMN Real 5 176 180
R7 Integer 1 182  
CONS40MX Integer 2 186 187
R8 Integer 1 191  
CONS40MN Integer 2 195 196
R9 Integer 1 200  
CONSFMX Integer 2 205 206
R10 Integer 1 211  
CONSFMN Integer 2 216 217
R11 Integer 1 222  

where:
STATE the two-letter state abbreviation (e.g., AL = Alabama);
STANAME the full name of the cooperative station;
STATENUM the state code (e.g., 01 = Alabama, 02 = Arizona, . . . 48 = Wyoming);
STANUM the cooperative station number (the unique station code, STACOD, used in the other data files is formed by combining the two-digit state number and the four-digit station number);
STADIV the division number [the cooperative station number and division number are separated by a hyphen (e.g., 1084-07)];
LAT the latitude, expressed in degrees and minutes (e.g., 31-04);
LONG the longitude (West), expressed in degrees and minutes (e.g., 91-17);
ELEV the station elevation, expressed in feet above or below mean sea level;
BPORDATE the first month and year that data became available for a station (e.g., 12/1891);
R1 a decile ranking to judge the length of the period of record (BPORDATE) for a particular station in relation to the rest of the network [values range from 0 to 9, with the lowest deciles given to the longest records (i.e., 0 implies the lower 10 percentile, 1 implies 10-20 percentile, and 9 implies 90-100 percentile)];
PERORIG is the percentage of original data available from the beginning period of record (BPORDATE) through 1994 for a given station (a useful indicator of the amount of missing and estimated data for a given station);
R2 a decile ranking to compare the percentage of original data available for one station with the percentage of original data available for the other stations in the network [values range from 0 to 9, with the lowest deciles assigned to stations having the greatest percentage of original data available (i.e., 0 implies the 1-10 percentile, 1 implies the 10-20 percentile, and 9 implies the 90-100 percentile)];
USCDATE the date the original data become serially complete, or the date from which there are no missing data in the record for a particular station (99/9999 indicates that the original data never became serially complete and no data exist for 12/1994);
R3 a decile ranking to compare the length of the serially complete original data in relation to the rest of the network [values range from 0 to 9 with the lowest deciles assigned to the stations with the fewest estimated adjusted data (i.e., 0 implies the 1-10 percentile, 1 implies 10-20 percentile, and 9 implies 90-100 percentile)];
ASCDATE the date at which the adjusted data become serially complete (99/9999 indicates that the adjusted data never became serially complete and no data exist for 12/1994);
R4 a decile ranking to compare the length of the serially complete adjusted data record with other stations in the network [values range from 0 to 9 with the lowest deciles assigned to the stations with the fewest estimated data values (i.e., 0 implies the 1-10 percentile, 1 implies 10-20 percentile, and 9 implies 90-100 percentile)];
PERASCD the percentage of adjusted data that were estimated since the adjusted serially complete date (ASCDATE); if ASCDATE = 99/9999, then PERASCD = -999.90;
R5 a decile ranking to judge the percentage of the estimated data since the adjusted serial complete date (ASCDATE) [values range from 0 to 9, with the lowest deciles assigned to the stations with the lowest percentages of estimated data (i.e., 0 implies the 1-10 percentile, 1 implies 10-20 percentile, and 9 implies 90-100 percentile)];
PDBPOR the number of potential discontinuities counted from BPORDATE (from the station history file);
PDR1 a decile ranking to judge the number of potential discontinuities in the record [values range from 0 to 9, with the lowest deciles assigned to the stations with the fewest discontinuities (i.e., 0 implies the 1-10 percentile, 1 implies 10-20 percentile, and 9 implies 90-100 percentile)];
APDMX the number of potential discontinuity adjustments since BPORDATE for the maximum temperature record;
PDR2 a decile ranking to judge the number of potential discontinuities adjusted for in the maximum temperature record since BPORDATE;
APDMN the number of potential discontinuity adjustments for since BPORDATE for the minimum temperature record;
PDR3 a decile ranking to judge the number of potential discontinuities adjusted for in the minimum temperature record since BPORDATE;
PDASCD the number of potential discontinuities counted from ASCDATE (from station history file), if ASCDATE = 99/9999, then PDASCD = -99.00;
PDR4 a decile ranking to judge the number of potential discontinuities since ASCDATE;
APDASCMX the number of potential discontinuity adjustments made since ASCDATE in the maximum temperature record, if ASCDATE = 99/9999, then APDASCMX = -99.00;
PDR5 a decile ranking to judge the number of potential discontinuity adjustments made since ASCDATE in the maximum temperature record;
APDASCMN the number of potential discontinuity adjustments made since ASCDATE in the minimum temperature record, if ASCDATE = 99/9999, then APDASCMN = -99.00;
PDR6 a decile ranking to judge the number of potential discontinuity adjustments made since ASCDATE in the minimum temperature record;
CONFMX the average confidence interval from ASCDATE for the maximum temperature record, if ASCDATE = 99/9999, then CONFMX = -9.99;
R6 a decile ranking to judge the average confidence interval from ASCDATE for the maximum temperature record;
CONFMN the average confidence interval from ASCDATE for the minimum temperature record, if ASCDATE = 99/9999, then CONFMN = -9.99;
R7 a decile ranking to judge the average confidence interval from ASCDATE for the minimum temperature record;
CONS40MX the consistency of the adjusted maximum temperature data for each station compared with the 20 most highly correlated of the station's 40 nearest neighbors over the past 40 years;
R8 a decile ranking to judge the consistency of the adjusted maximum temperature data for each station with respect to the 20 most highly correlated of the station's 40 nearest neighbors;
CONS40MN the consistency of the adjusted minimum temperature data for each station compared with the 20 most highly correlated of the station's 40 nearest neighbors over the past 40 years;
R9 a decile ranking to judge the consistency of the adjusted minimum temperature data for each station with respect to the 20 most highly correlated of the station's 40 nearest neighbors;
CONSFMX the consistency of the adjusted maximum temperature data for each station with respect to the 20 most highly correlated of the station's 40 nearest neighbors over the full period of record (since BPORDATE);
R10 a decile ranking to judge the consistency of the adjusted maximum temperature data since BPORDATE for each station with respect to the 20 most highly correlated of the station's 40 nearest neighbors;
CONSFMN the consistency of the adjusted minimum temperature data for each station with respect to the 20 most highly correlated of the station's 40 nearest neighbors over the full period of record (since BPORDATE);
R11 a decile ranking to judge the consistency of the adjusted minimum temperature data since BPORDATE for each station with respect to the 20 most highly correlated of the station's 40 nearest neighbors.


CONS40MX, CONS40MN, CONSFMX and CONSFMN were assessed by calculating the trend of the difference (or log ratio) series of a station with each of its 20 nearest neighbors. If the station is consistent with its neighbors, no overwhelming trend of sign between the 20 trend values should be found. The number of station pairs with positive trends, minus negative trends, is given. A value above 12 has about a 1% chance of occurrence (if the station is consistent with its neighbors over time). A large value, 14 or more, may imply there is an undocumented move or local modifications of the local environment (i.e., heat island effects, growth of trees, etc.).

**Please note there is also code available for reading this data into SAS (qa94mxmn.sas).

Table 5. Variable formats for files qa94mean.asc and qa94pcp.asc
Name Type Width Start End
STATE Character 2 2 3
STANAME Character 28 5 32
STATENUM Integer 2 34 35
STANUM Integer 4 37 40
STADIV Character 2 42 43
LAT Character 6 45 50
LONG Character 7 52 58
ELEV Integer 6 61 66
BPORDATE Character 7 68 74
R1 Integer 1 76  
PERORIG Real 5 78 82
R2 Integer 1 84  
USCDATE Character 7 86 92
R3 Integer 1 94  
ASCDATE Character 7 96 102
R4 Integer 1 104  
PERASCD Real 6 106 111
R5 Integer 1 113  
PDBPOR Integer 2 116 117
PDR1 Integer 1 120  
APDBPOR Integer 2 125 126
PDR2 Integer 1 130  
PDASCD Integer 3 134 136
PDR3 Integer 1 140  
APDSCD Integer 3 144 146
PDR4 Integer 1 150  
CONF Real 5 152 156
R6 Integer 1 158  
CONS40 Integer 2 161 162
R7 Integer 1 165  
CONSF Integer 2 168 169
R8 Integer 1 172  

The descriptions for variables STATE through PDR1 are as defined following Table 5. The remaining variables are defined as follows:

APDBPOR the number of potential discontinuity adjustments made since BPORDATE;
PDR2 a decile ranking to judge the number of potential discontinuity adjustments made since BPORDATE;
PDASCD the number of potential discontinuities counted from ASCDATE (from station history file), if ASCDATE = 99/9999, then PDASCD = -99.00;
PDR3 a decile ranking to judge the number of potential discontinuities since ASCDATE;
APDSCD the number of potential discontinuity adjustments made since ASCDATE (from station history file), if ASCDATE = 99/9999, then APDSCD = -99.00;
PDR4 a decile ranking to judge the number of potential discontinuity adjustments ma de since ASCDATE;
CONF the average confidence interval since ASCDATE, if ASCDATE = 99/9999, then CONF = -9.99;
R6 a decile ranking to judge the average confidence interval since ASCDATE;
CONS40 consistency of the adjusted data for each station with respect to the 20 most highly correlated of the station's 40 nearest neighbors over the past 40 years;
R7 a decile ranking to judge the consistency of the adjusted data for each station with respect to the 20 most highly correlated of the station's 40 nearest neighbors over the past 40 years;
CONSF consistency of the adjusted data for each station with respect to the 20 most highly correlated of the station's 40 nearest neighbors over the full period of record;
R8 a decile ranking to judge the consistency of the adjusted data for each station with respect to the 20 most highly correlated of the station's 40 nearest neighbors over the full period of record.

CONS40 and CONSF are assessed by calculating the trend of the difference (or log ratio) series of the station of interest with each of its 20 nearest neighbors. If the station is consistent with its neighbors, no overwhelming number of trend in sign should be found. The number of station pairs with positive trends, minus negative trends, is given. A value above 12 has about a 1% chance of occurrence (if the stations are truly consistent with their neighbors over time). A large value, 14 or more, may imply there is an undocumented moves or modifications of the local environment have occurred.



**Please note there is also code available for reading this data into SAS (qa94mean.sas).
7. Temperature Files Adjusted for Urbanization Effects (ur94av2.asc.Z,ur94max.asc.Z,ur94mean.asc.Z,ur94min.asc.Z)

This document provides four additional temperature files {minimum, mean, average [i.e., (monthly maximum + monthly minimum)/2], and maximum} adjusted for the same biases mentioned in the other temperature files (i.e., station moves, instrument changes, time-of-observation biases, etc.) and also for urbanization effects. The urbanization biases have been removed by using the techniques of Karl et al. (1988). Each station has the same period of record as in the corresponding temperature files (that containing original data, adjusted data, estimated data, and confidence estimates). In these files "urban" only adjusted data are given. No original data or confidence factors are provided. All data are expressed in degrees Fahrenheit, and missing values are represented by -99.99.

All four files are formatted in the same manner and may be read by using the following FORTRAN code (urban94.for):



 10    READ (5,100,END=999) STACOD, YEAR, (MONTH(I),
     1    I=1,12),WIN, SPR, SUM, FAL, ANN
        GOTO 10
C
100     FORMAT(I6,1X,I4,17(1X,F6.2))


Table 6. Variable formats for files ur84max.asc, ur94mean.asc, ur94av2.asc, and ur94min.asc
Name Type Width Start End
STACOD Integer 6 1 6
YEAR Integer 4 8 11
JAN Real 6 13 18
FEB Real 6 20 25
MAR Real 6 27 32
APR Real 6 34 39
MAY Real 6 41 46
JUN Real 6 48 53
JUL Real 6 55 60
AUG Real 6 62 67
SEP Real 6 69 74
OCT Real 6 76 81
NOV Real 6 83 88
DEC Real 6 90 95
WIN Real 6 97 102
SPR Real 6 104 109
SUM Real 6 111 116
FAL Real 6 118 123
ANN Real 6 125 130


where:
STACOD the unique station code formed by combining the two-digit state number [state numbers range from 1 to 48 (e.g., 01 = Alabama, 02 = Arizona, . . . 48 = Wyoming)] and the four-digit station number (values range from 0008 to 9933);
YEAR the year of record;
JAN - DEC are the monthly adjusted temperature estimates expressed in degrees Fahrenheit (missing values are represented by -99.99; estimates have been adjusted for station moves, instrument changes, time-of-observation differences, MMTS, and urbanization effects);
SPR, SUM, FAL, WIN, ANN are the seasonal temperature estimates calculated using the JAN-DEC data, values are expressed in degrees Fahrenheit (missing values are represented by -99.99.).


The seasons are defined as follows:

Winter (WIN) = December of the preceding year and January and February;
Spring (SPR) = March, April, and May;
Summer (SUM) = June, July, and August;
Fall (FAL) = September, October, and November;
Annual (ANN) = January 1 to December 31

**Please note there is also code available for reading this data into SAS (urban94.sas).

8. How to obtain the data

The HCN/M database is available free of charge from CDIAC. The data and a plain text version of the documentation are available from CDIAC's anonymous FTP (file transfer protocol) area via the Internet. Please note: your computer needs to have FTP software loaded on it (this is built in to most modern day operating systems). Commands used to obtain the database are shown below. For additional information, contact CDIAC.


ftp cdiac.esd.ornl.gov or ftp 128.219.24.36
(When the system asks you to login, enter "anonymous")
(When the system asks for your password, enter your e-mail address.)
Change the directory to pub/ndp070 (i.e., "cd pub/ndp070")
Retrieve the file you want (e.g., "get invent.txt")

The data and an HTML version of the documentation may also be obtained from CDIAC's web site at http://cdiac.esd.ornl.gov/.

For non-internet data acquisitions (e.g., 8mm tape, CD-ROM, etc.), users should contact CDIAC directly.


Address:
Carbon Dioxide Information Analysis Center
Oak Ridge National Laboratory
P.O. Box 2008
Oak Ridge, Tennessee 37831-6335, U.S.A.


Telephone:
(423) 574-3645 (Voice)
(423) 574-2232 (Fax)


Electronic mail:
cdiac@ornl.gov

References


Karl, T. R., and C. N. Williams, Jr. 1987. An approach to adjusting climatological time series for discontinuous inhomogeneities. Journal of Climate and Applied Meteorology 26:1744 1763.

Karl, T. R., C. N. Williams, Jr., P. J. Young, and W. M. Wendland. 1986. A model to estimate the time of observation bias associated with monthly mean maximum, minimum and mean temperatures for the United States. Journal of Climate and Applied Meteorology 25:145 160.

Karl, T. R., H. F. Diaz, and G. Kukla. 1988. Urbanization: Its detection and effect in the United States climate record. Journal of Climate 1:1099 1123.

Quayle, R. G., D. R. Easterling, P. Y. Hughes, and T. R. Karl. 1991. Effects of recent thermometer changes in the cooperative network. Bulletin of the American Meteorological Society 72:1718-1724.

 

 

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