This is a brief readme file for Global Historical Climatology Network
(GHCN) Monthly Precipitation Version 4 (GMP4).
Directory and file organization:
doc/
ghcn-m_v4_prcp_inventory.txt
ghcn-m_v4_prcp_readme.txt (this file)
access/
Over 100,000 individual CSV files
archive/
A single tar/gzipped file containing the data files
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The ghcn-m_v4_prcp_inventory.txt file contains the most recent location and
name associated with each GHCN ID. These locations may vary within the
individual CSV files as source metadata changes.
Field Column Contents
1 1-11 GHCN identifier (see below for decoding)
2 13-20 Latitude
3 22-30 Longitude
4 32-37 Elevation (meters)
5 39-40 State/province, if available.
6 42-79 Station name
7 81-85 WMO ID, if available. 99999=missing
8 87-90 First year in record
9 92-95 Last year in record
The comma separated value data file for each location is also fixed width.
Fields, column ranges, and their contents are as follows:
Field Column Contents
1 1-11 GHCN identifier (see below for decoding)
2 13-52 Station name
3 54-62 Latitude
4 64-73 Longitude
5 75-82 Elevation (meters)
6 84-89 4 digit year and 2 digit month
7 91-96 Precipitation value (tenths of a millimeter). Trace value is -1.
8 98 Measurement flag
9 100 Quality control flag
10 102 Source flag
11 104-109 Source index
Measurement flags used here only indicate the number of days missing from a
monthly total derived from daily values. A blank flag may indicate that
either no values were missing, or that the data came from a monthly source
and no information about missing days is available. Flag values
A-E correspond to 1-5 days missing from the month.
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Quality Control Flags
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Flag Definition
D The monthly value is part of a sequence of 6 or more values duplicated
in another portion of this record.
K The monthly value is part of a streak of constant values. This streak
may be from one month to the next, or a constant value in a particular
month from one year to the next.
L No other values exist within 18 months of this value.
O The value is a statistical outlier.
R The value exceeds a known world record, includes negative values except -1.
S For GHCN daily sourced records only, the number of nonzero precipitation
days is grossly inconsistent with the number at neighboring stations
T The value at this location is either much smaller or much larger than
neighboring values.
W Within this country, at over half of the locations, this month and an
adjacent month have identical values.
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Source Flags
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Flag Definition
D All sources within GHCN daily except Global Summary of the Day
H US Historical Climatological Network (USHCN)
M Monthly Climatic Data for the World (MCDW)
R International Collection
S Global Summary of the Day (GSOD)
W World Weather Records (WWR)
Z Datzilla fix
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GHCN Identifier
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Characters 1-2 : Country code as in https://www.ncei.noaa.gov/data/ghcnm/v4/doc/ghcnm-countries.txt
with the following additions: MN-Monaco, NN-St. Maarten, UC-Curacao,
VI-British Virgin Islands, XX-Unassigned.
Character 3 : Network code as in Section IV of https://ncei.noaa.gov/pub/data/ghcn/daily/readme.txt
Currently network codes is X if not provided
Characters 4-11 : Varies depending on network code. If characters 3-5 are XLP the
number that follows is an internal index. If characters 3-5 are
MLP, an asserted but unofficial WMO number is used.
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Contact Information
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Please e-mail questions, suggestions, or other feedback to ncei.ghcnm.precipitation@noaa.gov.