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Every day hundreds of thousands of observations
are made of the atmosphere measuring quantities such as pressure,
wind, temperature and humidity. The nature of the observing systems
vary considerably: single-site measurements on land and sea;
vertical and horizontal profiles in narrow tracks from weather
balloons and aircraft, and over large areas from satellite; radar
rainfall data. Each observation has its own set of characteristics
- the resolution of the measuring instrument, the systematic
and statistical errors of the measurement, the location and time
of observation - which may be either consistent or at odds with
another observation. To use these observations in an operational
weather forecasting system requires us to monitor their availability,
to quality control them, and to process them into a form that
can be used.
The data assimilation team has developed and maintains
software systems which can do all of these tasks for current
operational data sources and which can be readily extended for
new observation systems which we may use in the future.
The following links give expanded descriptions
of our work.
A brief survey of the main observation types received and used operationally by the Met Office.
More about observation types
Maps are produced showing the location of observations received and
used in each
operational run of the model. These maps show that the distribution
of certain types of observations may be rather uneven. For example,
surface data are concentrated on land masses but there still remains
large expanses of land with few observations. The distribution
of radiosonde stations is even more sparse. The reports form
aircraft clearly show the main aviation routes which are concentrated
over Europe and North America. Satellite data are very important
in filling in the holes left by terrestrial-based observing types.
View data coverage
maps
The maps are updated daily. Note, your browser must support javascript
and javascript must be enabled in order to view the maps.
We monitor observations to ensure that quality
is maintained and use statistical methods to identify systematic
errors which may be automatically corrected. This work is also
used to recommend future observation deployment programmes. The
Met Office is designated as the World Meteorological Organization's
official monitor of surface marine observations.
More about observation
monitoring
Before observations are used they need to be carefully quality
controlled to ensure that the data may be used with confidence.
More about quality control
The observation processing system quality controls
the observations and converts them into a form ready
for use in the model.
More about observation
processing
Details of the typical number of observations assimilated
in a 24-hour period, details of changes to the observation
processing system and details of rejection and acceptance
lists.
More about observation usage |
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