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nwp_measurements

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Measurements used in Numerical Weather Prediction (NWP)

Here, we provide a little survey about some classical and remote sensing measurements used in atmospheric analysis for operational Numerical Weather Prediction. The following images have been prepared by Alexander Cress, DWD, and R. Potthast, DWD/Uni Reading.

In addition to the “standard” data below, a wide range of further data and instruments is in development or already in use, for example GPS/GNSS data, Radar doppler winds and Radar reflectivities, SEVIRI Infrared measurements, lidar measurements.

Land and Ship Stations

We first show the measurement stations on lands and ships. The numbers here reflect the actual number of stations which were used for one three-hour assimilation period. Note that these measurements are only surface measurements, they do not necessarily reflect the atmospheric variables away from the earth's surface.

Buoys

The coverage and number of buoys is shown in the following figure.

Radiosondes measure a full profile of the atmosphere from the ground to about 10 or even 5hPa. Here, we show the number of radiosonde launches for the 00UTC date.

Airplane Measurements

Airplane measurements are provided by AMDAR and various other reporting mechanisms. Here, we do not count the number of airplanes, but the number of reports which have been used. One airplane will issue a report every several minutes along its flight path. The number of records will vary strongly during the day, here over Europe it has been night and only a few planes have been transmitting.

In general, various instruments measuring infrared and microwave radiation within atmospheric columns are used for operational numerical weather prediction systems. Here, the image displays microwave radiation data, where each point indicates a “field of view”, an atmospheric columns for which different frequencies are measured and processed.

Atmospheric Motion Vectors

Here, we show atmospheric motion vectors as they can be obtained from satellite bourne imagers and sounders. The number given here count the data records, i.e. every atmospheric motion wind measurement is counted separately.

Early Transmission Service Image

Satellite data are only transmitted every 90minutes. To use them in weather prediction, early transmission services have been established. We show a typical image of such an early transmitted and thus incomplete data set.

Scatterometers

Scatterometers are active instruments which determine wind speed on the ocean surface. Here, we count data records, i.e. measurement points during the 3h assimilation window.

Pilots and Wind Profiler

Pilots are radiosondes with reduced measurement types. Wind profiler are active instruments which determine the wind speed in a column of the atmosphere. The numbers here count the number of such columns which are measured, with many data points in each column.