README FILE FOR NOAA'S 1981-2010 CLIMATE NORMALS
OUTLINE
I. CONTENTS
II. FILENAMING
III. FILE FORMATS
IV. UNITS
V. SPECIAL VALUES
VI. FLAGS
I. CONTENTS
readme.txt - this file
status.txt - describes the latest status of the 1981-2010 Normals
Below are descriptions of the five directories at this level. Note that
directories A-D describe the most popular elements of the 1981-2010 Normals
products. This includes daily/monthly/seasonal/annual normals of temperature,
precipitation, snowfall, and snow depth; various additional parameters based on
these variables such as heating and cooling degree days, threshold exceedances,
and others; and hourly normals of a number of different variables. Additional
normals products are found in E - the supplemental directory - which contains its
own readme and status files. See E below for additional details.
A. products directory
The 1981-2010 Normals are located in the products directory. Within
products, there are four subdirectories:
1. hourly - contains all normals derived from hourly data, including
temperature, dew point temperature, heat index, wind chill, wind,
cloudiness, heating and cooling degree hours, and pressure normals.
2. precipitation - contains all precipitation, snowfall, and snow depth
normals files including percentiles, frequencies, and averages.
3. temperature - contains all temperature-related normals files, including
maximum and minimum temperature normals, heating and cooling degree
day normals, and others.
4. auxiliary - contains free-formatted files in two subdirectories:
a. station - contains all daily, monthly, seasonal, and annual normals
found in the below temperature and precipitation directories, but
organized as one file per station. Users wanting to visually inspect
normals for just one or a few stations should use the files in this
subdirectory.
b. high-precision-degree-days - contains daily heating and cooling
degree days at various bases. Values are reported to the hundredths
place as opposed to whole degrees. These files are intended for users
that need extra precision for ensuring consistency between daily
heating and cooling degree day normals and their associated monthly,
seasonal, and annual totals.
B. station-inventories directory
This directory contains station inventories for each product class. These
inventories include the GHCN-Daily ID, latitude, longitude, state, and
station names. The temperature and precipitation inventories also specify
whether the station is a pseudonormal station.
1. allstations.txt contains all stations in the most recent Normals release
2. hly-inventory.txt contains all stations used in the hourly analysis
3. prcp-inventory.txt contains all stations used in the precipitation analysis
4. snow-inventory.txt contains all stations used in the snowfall analysis
5. snwd-inventory.txt contains all stations used in the snow depth analysis
6. temp-inventory.txt contains all stations used in the temperature analysis
7. zipcodes-normals-stations.txt contains zip codes and post office names for
the vast majority of stations listed in allstations.txt
C. documentation directory
The documentation directory contains technical information about how the
normals were computed and other relevant information.
1. 1981-2010-normals-overview.pdf provides an overview of the 1981-2010
Climate Normals products (not including supplemental normals)
2. daily-temperature-normals-methodology.pdf explains the methodology used to
compute daily temperature normals
3. hourly-filenames.txt lists the filenames and descriptions of files
containing the normals derived from hourly data
4. hourly-methodology-addendum-2014.pdf describes minor changes to the hourly
normals methodology and the increase in station count for the 2014 refresh
of the hourly normals
5. hourly-methodology.pdf describes the methodology utilized to compute all
normals calculated from hourly data
6. hourly-normals.pdf provides an overview of the initial release of the
hourly normals
7. monthly-precipitation-normals.pdf provides an overview of the monthly
precipitation, snowfall, and snow depth normals
8. pairwise.pdf describes the pairwise homogeneity adjustment algorithm used
to account for changes in station observing practices (applies to all
temperature normals products, but not to precipitation-related products)
9. precipitation-filenames.txt lists the filenames and descriptions of files
containing the precipitation-related normals
10. precipitation-methodology.pdf describes the methodology utilized to
compute precipitation, snowfall, and snow depth normals
11. temperature-filenames.txt lists the filenames and descriptions of files
containing the temperature-related normals
12. temperature-methodology.pdf describes the methodology utilized to
compute all temperature-related normals
13. tobadj.inventory.txt is an inventory of stations for which a time of
observation (TOB) adjustment was applied
D. source-datasets directory
The source-datasets directory contains source datasets used to compute the
1981-2010 Normals found in this collection. This includes the major source
datasets as well as a few intermediate steps in the processing of the Normals.
1. coop.52g.20110530.FLs.52g.tar.gz contains standardized monthly temperatures
2. coop.52g.20110530.tad.tar.gz contains TOB adjustments
3. ghcnd-all.tar.gz contains GHCN-Daily
4. ghcnd-stations.txt is a list of stations present in the GHCN-Daily files
5. ghcnd-version.txt contains the specific version of GHCN-Daily used
6. isdlite-normals.tar.gz contains the ISD-Lite hourly data
7. mly-prcp-filled.txt contains filled monthly precipitation values
8. mly-tmax-filled.txt contains filled monthly maximum temperature values
9. mly-tmin-filled.txt contains filled monthly minimum temperature values
The *-filled.txt files are intermediate values used in the computation of the
Normals. Users wishing to utilize these files for another purpose should
contact NCDC for formatting and other information.
E. supplemental directory
The supplemental directory contains NOAA's 1981-2010 Supplemental Normals.
A separate readme and status file describing this product class is found in
the supplemental directory. Supplemental normals include agriculture-related
normals such as frost-freeze dates; air freezing index return periods; and
10-year (2001-2010) hourly normals. A variety of monthly temperature normals
computed using something other than a strict 30-year average; including 5-,
10-, 15-, and 20-year averages, OCN, and Hinge Fit; will be released in the
future.
II. FILENAMING
Except for the auxiliary normals files, all other product files are named
following the form RRR-EEEE-SSSSSS[-CCCCCCC].txt, where the portion in brackets
is only used when necessary. The four components are defined as follows.
A. RRR is the Reporting period, which can take the following values:
ann = annual
djf = December, January, February (winter)
dly = daily
hly = hourly
jja = June, July, August (summer)
mam = March, April, May (spring)
mly = monthly
mtd = month-to-date
rtp = return periods (used for Air Freezing Index)
son = September, October, November (autumn)
ytd = year-to-date
B. EEEE is the meteorological element, which can take the following values:
cldd = cooling degree days
cldh = cooling degree hours
clod = clouds
dewp = dew point temperature
dutr = diurnal temperature range
hidx = heat index
htdd = heating degree days
htdh = heating degree hours
prcp = precipitation
pres = sea level pressure
snow = snowfall
snwd = snow depth
tavg = daily mean temperature (average of tmax and tmin)
temp = temperature
tmax = daily maximum temperature
tmin = daily minimum temperature
wchl = wind chill
wind = wind
C. SSSSSS = Statistic, which can take the following values:
10pctl = Climatological 10th percentile
1stdir = Prevailing Wind Direction
1stpct = Prevailing Wind Percentage
2nddir = Secondary Wind Direction
2ndpct = Secondary Wind Percentage
25pctl = Climatological 25th percentile
50pctl = Climatological 50th percentile
75pctl = Climatological 75th percentile
90pctl = Climatological 90th percentile
avgnds = Average Number of Days (followed by a condition)
avgspd = Average Wind Speed
baseNN = Average of base NN (other than 65F) Heating or Cooling Degree Days
NN can be 40,45,50,55,57,60 for Heating Degree Days
NN can be 45,50,55,57,60,70,72 for Cooling Degree Days
normal = Climatological Average
pctall = Probability of Occurrence (followed by a condition)
pctbkn = Percent Broken (clouds)
pctclm = Percent Calm (winds)
pctclr = Percent Clear (clouds)
pctfew = Percent Few (clouds)
pctovc = Percent Overcast (clouds)
pctsct = Percent Scattered (clouds)
vctdir = Mean Wind Vector Direction
vctspd = Mean Wind Vector Magnitude
D. CCCCCCC = Condition used only in conjunction with average numbers of days per
month and probabilities of occurrence; can take the following values:
geNNNhi = greater than or equal to NNN hundredths of inches
NNN can be 001,010,050,100 (for precipitation)
geNNNti = greater than or equal to NNN tenths of inches
NNN can be 001,010,030,050,100 (for snowfall)
geNNNwi = greater than or equal to NNN whole inches
NNN can be 001,003,005,010 (for snow depth)
grthNNN = greater than or equal to NNN whole degrees Fahrenheit
NNN can be 040,050,060,070,080,090,100
lsthNNN = less than or equal to NNN whole degrees Fahrenheit
NNN can be 000,010,020,032,040,050,060
E. Examples:
1. Long-term averages of monthly precipitation totals:
mly-prcp-normal.txt
2. The average number of days per month with snowfall greater than 1 inch:
mly-snow-avgnds-ge010ti.txt
3. Daily average base-65 heating degree days:
dly-htdd-normal.txt.
4. Daily average base-50 heating degree days:
dly-htdd-base50.txt
5. Hourly heat index normals:
hly-hidx-normal.txt
Station-based normals file (one file per station) are named following this
format: GGGGGGGGGGG-normals.txt, where GGGGGGGGGGG is the GHCN Daily ID.
III.FILE FORMATS
A. FORMAT OF ANNUAL/SEASONAL FILES
(ann-*.txt, djf-*.txt, mam-*.txt, jja-*.txt, son-*.txt)
Each file contains the annual/seasonal values of one parameter at all
qualifying stations. There is one record (line) per station.
The variables in each record include the following:
Variable Columns Type
----------------------------
STNID 1- 11 Character
VALUE 19- 23 Integer
FLAG 24- 24 Character
----------------------------
These variables have the following definitions:
STNID is the GHCN-Daily station identification code. See the lists in the
station-inventories directory.
VALUE1 is the annual/seasonal value.
FLAG1 is the completeness flag for the annual/seasonal value. See Flags
section below.
B. FORMAT OF MONTHLY FILES
(mly-*.txt)
Each file contains the values of one parameter for each month of the year
at all qualifying stations. There is one record per station.
The variables in each record include the following:
Variable Columns Type
----------------------------
STNID 1- 11 Character
VALUE1 19- 23 Integer
FLAG1 24- 24 Character
- - - - - - - - - - - - - -
VALUE12 96-100 Integer
FLAG12 101-101 Character
----------------------------
These variables have the following definitions:
STNID is the GHCN-Daily station identification code.
VALUE1 is the January value.
FLAG1 is the completeness flag for January. See Flags section below.
- - - -
Value12 is the December value.
Flag12 is the completeness flag for December.
C. FORMAT OF DAILY, MONTH-TO-DATE, AND YEAR-TO-DATE FILES
(dly-*.txt, mtd-*.txt, ytd-*.txt)
Each file contains the values of one parameter for each day of the year
at all qualifying stations. There is one record per station-calendar month.
The variables in each record include the following:
Variable Columns Type
----------------------------
STNID 1- 11 Character
MONTH 13- 14 Integer
VALUE1 19- 23 Integer
FLAG1 24- 24 Character
- - - - - - - - - - - - - -
VALUE31 229-233 Integer
FLAG31 234-234 Character
----------------------------
These variables have the following definitions:
STNID is the GHCN-Daily station identification code.
MONTH is the month in the 30-year period used. 01=January; 12=December
VALUE1 is the value for the first day of the month.
FLAG1 is a completeness flag based on the WMO normals classification, for
the first day of the month. See Flags Section below.
- - - -
Value31 is the value for day 31 of the month.
Flag31 is the completeness flag for day 31 of the month.
D. FORMAT OF HOURLY FILES
(hly-*.txt)
Each file contains the values of one parameter for each hour of the day
at all qualifying stations. There is one record per station-calendar day.
The variables in each record include the following:
Variable Columns Type
----------------------------
STNID 1- 11 Character
MONTH 13- 14 Integer
DAY 16- 17 Integer
VALUE1 19- 23 Integer
FLAG1 24- 24 Character
- - - - - - - - - - - - - -
VALUE24 180-184 Integer
FLAG24 185-185 Character
----------------------------
These variables have the following definitions:
STNID is the GHCN-Daily station identification code
MONTH is the month in the 30-year period used. 01=January; 12=December
DAY is the day in the 30-year period used. Varies from 1 to 31 in each
record.
VALUE1 is the value for the first hour of the day
FLAG1 is a completeness flag based on the WMO normals classification, for
the first hour of the day. See Flags Section below.
- - - -
Value24 is the value for last hour of the month.
Flag24 is the completeness flag for the last hour of the day
E. FORMAT OF STATION INVENTORIES
(*-inventory.txt, allstations.txt)
Each file contains on station per line.
The variables in each record include the following:
------------------------------
Variable Columns Type
------------------------------
ID 1-11 Character
LATITUDE 13-20 Real
LONGITUDE 22-30 Real
ELEVATION 32-37 Real
STATE 39-40 Character
NAME 42-71 Character
GSNFLAG 73-75 Character
HCNFLAG 77-79 Character
WMOID 81-85 Character
METHOD* 87-99 Character
------------------------------
These variables have the following definitions:
ID is the station identification code. Note that the first two
characters denote the FIPS country code, the third character
is a network code that identifies the station numbering system
used, and the remaining eight characters contain the actual
station ID.
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 (for U.S. stations only).
NAME is the name of the station.
GSNFLAG is a flag that indicates whether the station is part of the GCOS
Surface Network (GSN). The flag is assigned by cross-referencing
the number in the WMOID field with the official list of GSN
stations. There are two possible values:
Blank = non-GSN station or WMO Station number not available
GSN = GSN station
HCNFLAG is a flag that indicates whether the station is part of the U.S.
Historical Climatology Network (HCN). There are two possible
values:
Blank = non-HCN station
HCN = HCN station
WMOID is the World Meteorological Organization (WMO) number for the
station. If the station has no WMO number, then the field is blank.
METHOD* is an indication of whether a "traditional" or a "pseudonormals"
approach was utilized for temperature or precipitation. This field
in only found in prcp-inventory.txt and temp-inventory.txt
IV. UNITS
tenths of degrees Fahrenheit for maximum, minimum, average, dew point, heat
index, wind chill, and air temperature normals and standard deviations.
e.g., "703" is 70.3F
tenths of days for the number of days per month above or below certain threshold,
such as days above 90F. e.g., "256" is 25.6 days.
whole degrees Fahrenheit for heating and cooling degree days (except high
precision files while are in hundredths of degrees Fahrenheit).
hundredths of inches for average monthly/seasonal/annual precipitation,
month-to-date/year-to-date precipitation, and percentiles of precipitation.
e.g., "1" is 0.01" and "1486" is 14.86"
tenths of inches for average monthly/seasonal/annual snowfall,
month-to-date/year-to-date snowfall, and percentiles of snowfall.
e.g. "39" is 3.9"
whole inches for percentiles of snow depth.
tenths of percent for probabilities of precipitation, snowfall, or snow
depth exceeding a specific threshold, as well as cloud and wind percentages.
e.g., "207" is 20.7%
tenths of degree hours for heating and cooling degree hours. e.g., "152" is 15.2
tenths of millibars for mean sea level pressure normals.
e.g., "10147" is 1014.7 mb
tenths of percent for prevailing and secondary wind direction percentages.
e.g., "299" is 29.9%
prevailing and secondary wind directions can take on 8 values:
1=N, 2=NE, 3=E, 4=SE, 5=S, 6=SW, 7=W, 8=NW
tenths of mph for wind speeds and vector magnitudes. e.g. "73" is 7.3 mph
whole degrees for mean vector wind directions
V. SPECIAL VALUES
-9999: missing or insufficient data; values cannot be computed
-8888: date not defined (e.g. February 30, September 31) - used in daily files to
achieve fixed-length records
-7777: a non-zero value that would round to zero, for variables bound by zero.
-6666: parameter undefined; used in precipitation/snowfall/snow depth percentiles
when number of nonzero values is insufficient
-5555: parameter not available because it was inconsistent with another parameter
VI. FLAGS
Flags accompany every Normals value and indicate the completeness of the data
record used to compute each value, accounting for methodological differences for
different product classes. There are six flag options described generally below.
Due to methodological differences, the flags are applied somewhat differently
between the temperature-based normals and the precipitation-based and hourly
normals. For the precipitation-based and hourly normals, the following flags were
assigned independently for each normals value reported based on number of years
available for that individual calculation. For temperature-based normals, strong
precedence is given to the monthly normals of maximum and minimum temperature,
and all other temperature-related normals at the daily, monthly, seasonal, and
annual timescales are equivalent to or derived from the flags for these two
variables.
C = complete (all 30 years used)
S = standard (no more than 5 years missing and no more than 3 consecutive
years missing among the sufficiently complete years)
R = representative (observed record utilized incomplete, but value was scaled
or based on filled values to be representative of the full period of record)
P = provisional (at least 10 years used, but not sufficiently complete to be
labeled as standard or representative). Also used for parameter values on
February 29 as well as for interpolated daily precipitation, snowfall, and
snow depth percentiles.
Q = quasi-normal (at least 2 years per month, but not sufficiently complete to
be labeled as provisional or any other higher flag code. The associated
value was computed using a pseudonormals approach or derived from monthly
pseudonormals.
Blank = the data value is reported as a special value such as -9999
Notes: Flags Q and R are not applicable for hourly normals. Flags Q and R also
aren't applicable to average number of days with different precipitation,
snowfall, and snow depth threshold exceedance; precipitation/snowfall/snow
depth probabilities of occurrence; and daily precipitation/snowfall/snow depth
percentiles. Further, Q flags are not applicable for standard deviations. High-
precision degree day values are presented without corresponding flags.