High Resolution Winds (HRW)
Contents:
- Goal of the High Resolution Winds product
- High Resolution Winds algorithm summary
- High Resolution Winds output
Goal of the High Resolution Winds product
This product provides a detailed sets of Atmospheric Motion Vectors (AMVs) and Trajectories.
High Resolution Winds algorithm summary
The hrw algorithm is the same as used in the nwc saf/GEO processing packages, which is developed by AEMET.
The hrw algorithm requires data from two separate satellite passages, and it will only create a product in the overlapping part. The retrieval is performed in four main steps:
- Tracers are calculated with two consecutive methods: Gradient and Tracer characteristics.
- These tracers are tracked through one of two different methods (Euclidean distance or Cross correlation), with the selection of up to three tracking centres for each tracer.
- AMVs and Trajectories are then calculated, considering the displacement between the initial position of each tracer and the position of the corresponding tracking centres.
- The pressure levels of the AMVs and Trajectories are calculated.
The algorithm takes satellite imagery input from the sensors
avhrr,
viirs,
modis,
mersi2, or
slstr.
The calculations can combine scenes from any two of them.
Besides the satellite data, the algorithm uses input from the
nwcsaf/pps
Cloud Type,
CTTH,
and (optionally)
CMIC, and it takes
also the following as input:
- nwp short range forecast data
- 1 km gis (digital elevation model) data
High Resolution Winds output
The output is delivered as netCDF- or BUFR-files (configurable).
There are two main outputs:
- AMV is a horizontal wind calculated through the horizontal displacement between two Earth positions in two different satellite images. The number of AMVs varies between the scenes, due to the conditions. Each AMV is defined as a collection of variables, which together describe all characteristics of the AMV, among them wind speed, wind direction, air pressure, etc.
- Trajectory is a path defining the displacement of a specific tracer throughout several satellite images. One trajectory is defined by the displacement of several consecutive AMVs.