Data

The data within GHCNM v3 for the time being consist of monthly average temperature, and maximum and minimum temperature, for the 7280 stations contained within GHCNM v2. Several new sources have been added to v3, and a new "3 flag" format has been introduced, similar to that used within the Global Historical Climatology Network-Daily (GHCND).

Variable definitions:

ID: 11 digit identifier, digits 1-3=Country Code, digits 4-8 represent the WMO id if the station is a WMO station.It is a WMO station if digits 9-11="000".

YEAR: 4 digit year of the station record.

ELEMENT: element type, monthly mean temperature="TAVG"

monthly maximum temperature="TMAX"

monthly minimum temperature="TMIN"

VALUE: monthly value (MISSING=-9999).Temperature values are in hundredths of a degree Celsius, but are expressed as whole integers (e.g. divide by 100.0 to get whole degrees Celsius).

DMFLAG: data measurement flag, nine possible values:

blank = no measurement information applicable

a-i = number of days missing in calculation of monthly mean

temperature (currently only applies to the 1218 USHCN

V2 stations included within GHCNM)

QCFLAG: quality control flag, seven possibilities within quality controlled unadjusted (qcu) dataset, and 2 possibilities within the quality controlled adjusted (qca) dataset.

Quality Controlled Unadjusted (QCU) QC Flags:

BLANK = no failure of quality control check or could not be evaluated.

D = monthly value is part of an annual series of values that are exactly the same (e.g. duplicated) within another year in the station's record.

I = checks for internal consistency between TMAX and TMIN.  Flag is set when TMIN > TMAX for a given month.

L = monthly value is isolated in time within the station record, and this is defined by having no immediate non-missing values 18 months on either side of the value.

M = Manually flagged as erroneous.

O = monthly value that is >= 5 bi-weight standard deviations from the bi-weight mean.Bi-weight statistics are calculated from a series of all non-missing values in the station's record for that particular month.

S = monthly value has failed spatial consistency check. Any value found to be between 2.5 and 5.0 bi-weight standard deviations from the bi-weight mean, is more closely scrutinized by exmaining the 5 closest neighbors (not to exceed 500.0 km) and determine their associated distribution of respective z-scores.At least one of the neighbor stations must have a z score with the same sign as the target and its z-score must be greater than or equal to the z-score listed in column B (below), where column B is expressed as a function of the target z-score ranges (column A).

W = monthly value is duplicated from the previous month, based upon regional and spatial criteria and is only applied from the year 2000 to the present.

Quality Controlled Adjusted (QCA) QC Flags:

A = alternative method of adjustment used.

M = values with a non-blank quality control flag in the "qcu" dataset are set to missing the adjusted dataset and given an "M" quality control flag.

X = pairwise algorithm removed the value because of too many inhomogeneities.

SFLAG: data source flag for monthly value, 18 possibilities:

C = Monthly Climatic Data of the World (MCDW) QC completed but value is not yet published

G = GHCNM v2 station, that was not a v2 station that had multiple time series (for the same element).

J = Colonial Era Archive Data

K = received by the UK Met Office

M = Final (Published) Monthly Climatic Data of the World (MCDW)

N = Netherlands, KNMI (Royal Netherlans Meteorological Institute)

P = CLIMAT (Data transmitted over the GTS, not yet fully processed for the MCDW)

U = USHCN v2

W = World Weather Records (WWR), 9th series 1991 through 2000

Z = Datzilla (Manual/Expert Assessment)

0 to 9 = For any station originating from GHCNM v2 that had multiple time series for the same element, this flag represents the 12th digit in the ID from GHCNM v2. See the next section, "Stations with Multiple Time Series," for more information.

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