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Meteorological FAQs

  • Created by Helene Blanchonnet, last modified by Helen Setchell on Feb 23, 2023

  • Are the t=0 forecast fields the same as the analysis fields?
  • How are data interpolated/transformed to a lower resolution grid?
  • How are Large Scale precipitation, Convective Precipitation and Snowfall defined in the ECMWF model?
  • How are low, medium and high cloud cover defined?
  • How can evaporation have both positive and negative values?
  • How can the Geopotential height in metres be calculated?
  • How to access the archived forecast data of the 06z and 18z HRES/ENS known as the High Frequency Products?
  • Is the field surface pressure available on both model and pressure levels?
  • Many fields have seconds in their units e.g. precipitation and radiation fields. How can instantaneous values be calculated?
  • Visibility Parameter
  • What are 2D wave spectra?
  • What are the definitions of the radiation fields?
  • What are the units of the fields?
  • What is the 4DVAR analysis procedure?
  • What is the direction convention for fields such as radiation and precipitation?
  • What is the direction convention for the U and V components of winds?
  • What is the direction convention for wave fields?
  • What is the land-sea mask (LSM)?
  • Where can I find the definitions of the Gaussian grids?
  • Why does accumulated precipitation has sometimes negative values?
  • Why does the Ensembles forecast not account for glaciers correctly?

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