Hadley Centre and National Oceanography Centre Night Marine Air Temperature data set: HadNMAT2
The HadNMAT2 data set is a monthly global field of night marine air temperature (NMAT) on a 5°
latitude by 5° longitude grid from 1880 to 2010. The data have been adjusted to minimise
the effects of changes in the height of the thermometer above the sea surface and for non-standard
thermometer exposure during the Second World War. Uncertainties in the gridded fields and time series
have also been estimated. The data are neither interpolated nor variance adjusted.
The data set runs from 1880 to 2010.
Brief description of the data
The NMAT data are taken from version 2.5 of the International Comprehensive Ocean-Atmosphere Data
Set, ICOADS (external
web page), from 1880 to 2010. HadNMAT2 is produced using in-situ measurements of marine air
temperature made on board ships between one hour after sunset and one hour after sunrise. Measurements
that fail quality checks are rejected and the measurements are converted to anomalies by subtracting
climatological values from the measurements, and calculating a robust average of the resulting anomalies
on a 5° by 5° degree monthly grid. After gridding the anomalies, bias corrections
are applied to reduce the effects of spurious trends caused by changes in deck height on non-standard
thermometer exposure. The uncertainties due to under-sampling and measurement error have been calculated
for the gridded monthly data as have the uncertainties of the bias adjustments following the procedures
described in the paper.
For a detailed description of the dataset and its production process, please read the paper describing
the data set. We recommended you read the paper before using the data.
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Other information
Dataset produced in collaboration with:
