Met Office Hadley Centre observations datasets
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HadAT2 Data: Download

Data description

HadAT2 is the recommended version of our gridded radiosonde temperature product. It is a monthly timeseries available on a 10 degree longitude by 5 degree latitude basis. Data are available on nine seperate pressure levels (850, 700, 500, 300, 200, 150, 100, 50, and 30hPa). All values are anomalies relative to the monthly 1966-95 climatology. To create zonal averages we have simply averaged all available gridbox values in each 5 degree latitude band. Large scale mean timeseries for the globe and the tropics (defined here as 20N to 20S) are simply cos(lat) weighted zonal mean field values. This reduces the spatial sampling bias towards Northern Hemisphere mid-latitudes. Other plausible large-scale averaging techniques would impact the timeseries values calculated.

Netcdf files are CF compliant (external link). ASCII files contain formatting information in their headers.


Data are updated every quarter (not every month as implied in the report on the updating of HadAT in near real-time (PDF file)) with, typically, a one month lag so that, for example, December data are typically available by the end of January. This should be suitable for the majority of users. However, in the event that a user particularly requires updated data prior to a quarterly update (otherwise performed in January, April, July and October) then please contact Holly Titchner and we will endeavour to update the data as soon as possible.

Data usage

The data is free for use for non-commercial applications: please read the terms and conditions.
We request that if they haven't already done so users please register with the website here. You do not have to register, but registering and providing information on the applications that the dataset is being put to will help us in improving the science.

More information and diagnostics

Some typically used diagrams are available on our Frequently used plots and graphics page, which may be sufficient for many users requirements. Please note that copyright restrictions apply to the use of these images for commercial purposes. More details on the construction of the dataset are given in the audit page. Details of our uncertainty analysis (at present applied only to seasonal timeseries and frozen to 2001) are available on our uncertainty estimates page. MSU equivalent measures and a discussion of their derivation are available on our MSU equivalents page.

Data files

Monthly station timeseries Netcdf file (13.8 Mb) ASCII file (compressed, 8.1 Mb)
Monthly gridded timeseries Netcdf file (52.7 Mb) ASCII file (compressed, 4.7 Mb)
Monthly zonal, tropical and global timeseries Netcdf file (0.8 Mb) Zonal ASCII file (compressed)

Tropical ASCII file (47 Kb)

Global ASCII file (47 Kb)

HadAT2 is currently updated to: December 2012

The next update is due in: April 2013
It will then be updated to: March 2013

Commercial and media enquiries

You can access the Met Office Customer Centre, any time of the day or night by phone, fax or e-mail. Trained staff will help you find the information or products that are right for you.
Contact the Met Office Customer Centre