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HadISDH.marine: gridded global monthly ocean surface humidity data version

Update Frequency: Not Planned
Status: Completed
Online Status: ONLINE
Publication State: Preview
Publication Date:


This is the HadISDH.marine version of the Met Office Hadley Centre Integrated Surface Dataset of Humidity (HadISDH). HadISDH.marine is a near-global gridded monthly mean marine surface humidity climate monitoring product. It is created from in situ observations of air temperature and dew point temperature from ships. The observations have been quality controlled and bias-adjusted. Uncertainty estimates for observation issues and gridbox sampling are provided (see data quality statement section below). The data are provided by the Met Office Hadley Centre and this version spans 1/1/1973 to 31/12/2022.

The data are monthly gridded (5 degree by 5 degree) fields. Products are available for temperature and six humidity variables: specific humidity (q), relative humidity (RH), dew point temperature (Td), wet bulb temperature (Tw), vapour pressure (e), dew point depression (DPD).

This version extends the previous version to the end of 2022. Users are advised to read the update document in the Docs section for full details on all changes from the previous release.

To keep informed about updates, news and announcements follow the HadOBS team on twitter @metofficeHadOBS.

For more detailed information e.g bug fixes, routine updates and other exploratory analysis, see the HadISDH blog:


When using the dataset in a paper please cite the following papers (see Docs for link
to the publications) and this dataset (using the "citable as" reference):

Willett, K. M., Dunn, R. J. H., Kennedy, J. J. and Berry, D. I., 2020: Development of
the HadISDH marine humidity climate monitoring dataset. Earth System Sciences Data,
12, 2853-2880,

Freeman, E., Woodruff, S. D., Worley, S. J., Lubker, S. J., Kent, E. C., Angel, W. E.,
Berry, D. I., Brohan, P., Eastman, R., Gates, L., Gloeden, W., Ji, Z., Lawrimore, J.,
Rayner, N. A., Rosenhagen, G. and Smith, S. R., ICOADS Release 3.0: A major update to
the historical marine climate record. International Journal of Climatology.

Citable as:  [ PROVISIONAL ] Willett, K.M.; Dunn, R.J.H.; Kennedy, J.J.; Berry, D.I. (9999): HadISDH.marine: gridded global monthly ocean surface humidity data version NERC EDS Centre for Environmental Data Analysis, date of citation.
Abbreviation: Not defined
Keywords: HadISDH, humidity, surface, marine, gridded, station, specific humidity, temperature, dew point temperature, wet bulb temperature, dew point temperature, vapour pressure, in-situ


Previous Info:
No news update for this record
Previously used record identifiers:
No related previous identifiers.
Access rules:
Public data: access to these data is available to both registered and non-registered users.
Use of these data is covered by the following licence: When using these data you must cite them correctly using the citation given on the CEDA Data Catalogue record.
Data lineage:

HadISDH.marine is a global ocean surface (~10 m) humidity dataset and is produced by the Met Office Hadley Centre in collaboration with NOC. It is based on the sub-daily ship observations from ICOADS. It is passed to CEDA for archiving and distribution.

Data Quality:
Uncertainty estimates are provided as part of the dataset both at the station and gridbox level, this includes information covering station uncertainty (climatological, homogenisation and measurement uncertainty), gridbox spatial and temporal sampling uncertainty and combined station and sampling uncertainty. See dataset associated documentation for full details.
File Format:
Data are NetCDF formatted

Process overview

This dataset was generated by the computation detailed below.

HadISDH.marine: gridded global ocean surface (~10 m) humidity dataset produced by the Met Office Hadley Centre


HadISDH utilises simultaneous sub-daily temperature and dew point temperature data from ICOADS ship data. All humidity variables are calculated at hourly resolution. Quality control, buddy checking and bias adjustment is applied at hourly resolution to adjust all observations to an observing height of 10 m, accounting for changing ship heights over time, and to adjust all non-ventilated instruments to mitigate the moist bias. Gridded monthly means, monthly mean anomalies and 1981 to 2010 climatologies are created.

See Docs 'HadISDH.marine process diagram'. Observation measurement, climatological, whole number presence and bias adjustment uncertainties are estimated for each observation and then gridded. 5° by 5° gridboxes are centred on -177.5°W and -87.5°S to 177.5°E and 87.5°N. Given the uneven distribution of observations over time and space, sampling uncertainty is estimated for each gridbox month.

For greater detail please see:

Willett, K. M., Dunn, R. J. H., Kennedy, J. J. and Berry, D. I.: Development of the HadISDH marine humidity climate monitoring dataset. Earth System Sciences Data, in review, doi:XX.XXXX/essd-XX-XXXX-2020, 2020.

Docs contains links to this publication.

Input Description


Output Description


Software Reference


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