vsoweb-override.ini

The vsoweb-override.ini configuration file contains setting for managing the MVF (motion vector field) product and advection used in nowcasting.

Vaisala has carefully chosen good defaults for the nowcasting configuration.

The raster product, such as PPI, CAPPI, of any intensity parameters like Z, R, KDP, or rhoHV that is used as an input for MVF generation should have:

  • As little as possible of ground clutter and the near-radar clear air or particulates (such as dust) returns
  • The bounding box not smaller than any other raster product produced from this site's data

Because the two conditions are contradictory, the easiest way to satisfy first condition is to use a true (not pseudo) CAPPI product with a height of 1.5 ... 2km , but the longest range (biggest bounding box) product is a raster product generated from the survey scans, which usually consist of just one PPI scan and cannot be used to generate true CAPPI products. You must balance these two conditions.

If there are not enough valid products to generate an MVF request, the iteration is skipped and the system waits for the next product to arrive from IRIS.

Basic settings

nowcast.mvf.run defines if MVF generation is enabled in IRIS Focus. By default, MVF generation is enabled (true). 

[NOWCAST]
nowcast.mvf.run = true

The nowcast server URL dentifies where the nowcast HTTP server runs. The default value is for a fully local installation, which is the default installation configuration.

nowcast.http.server.url = http://localhost:31000/focus-nowcast/api/v2/mvf/

The netCDF directory stores MVF generation requests and responses to the Nowcast HTTP Server in netCDF format as well as internal representations of MVF serialized to disk. This directory is cleaned periodically by default.

nowcast.netcdf.dir = /srv/vaisala/radarsw/product/nowcast/

The nowcast.ui.mvf.reference.products and nowcast.ui.mvf.reference.datatypes parameters define the products and data types available for calculating MVF. If set incorrectly or omitted, the system will fall back to the default settings:

nowcast.ui.mvf.reference.products = CAPPI,VIL,PPI,SRI,MAX,LAYER,ECHO,TOPS
nowcast.ui.mvf.reference.datatypes = zdr,reflectivity,rain_rate

Advanced settings

nowcast.mvf.request.num.rasters defines the number of products sent to the nowcast server for generating the MVF. Default is 2. 

nowcast.mvf.request.num.rasters = 2

nowcast.mvf.product.age.limit.minutes defines the maximum number of minutes (5 ... 1000) the system goes back in time to find valid products (of the type used to define MVF generation for a site) to use in generating the MVF. Default is 100.

nowcast.mvf.product.age.limit.minutes = 100

nowcast.mvf.max.gap.minutes defines the maximum acceptable gap in minutes (1 ... 1000) between products for MVF generation. Default is 30.

MVF is a shift in pixels per time interval between frames of the product which was used to generate MVF. The interval between advected products may be different from the interval between advected frames. For example, if MVF was generated from the product which was available every 5 minutes but the interval between advected frames has to be 10 minutes, the MVF shift should be doubled. That MVF scaling is taken into account by a scaling shift in every iteration. 

nowcast.mvf.max.gap.minutes = 30

nowcast.product.times.age.limit.minutes defines the time range for calculating advected product times (2 ... 2880 mininutes. 2880 is the entire two-day range). Default is 100.

Advected product times must be evenly spaced (due to the calculation). The time is derived by dividing the last number of minutes defined in this property by n products found in that period.

The spacing is used as the time gap between advected products. In most cases, set this value to match the value in nowcast.mvf.product.age.limit.minutes.

nowcast.product.times.age.limit.minutes = 100

nowcast.advection.mvf.age.limit.minutes is the maximum number of minutes to go back in time to find an MVF when generating advected products. If an MVF is not found in the time span given, the iteration is skipped and Focus waits for the next product to arrive from IRIS. Range: 5 ... 1000 minutes. Default is 30.

nowcast.advection.mvf.age.limit.minutes=30

nowcast.advection.time.span.minutes defines the time scale when extending nowcasted products into the future (minutes). The normal range is 60 ... 180 minutes. The default is 120 minutes.

You can raise the time scale to up to 6 hours but this is not recommended as the accuracy decreases as time extends into the future.

nowcast.advection.time.span.minutes=120