Slayt 1 - RTC, Regional Training Centre - Turkey

Impacts of Grid Point Physics Calculations inSpectral ModelsNow suppose that convectiveprecipitation is triggered at a singlephysics grid point. The graphicillustrates how the effects are feltwithin the model. The red linerepresents the convectiveparameterization that causes a forcingof magnitude 1.0 at a single grid pointon the physics grid in a spectral model.The yellow line is the spectralrepresentation of this forcing plottedback onto the physics grid. Note thatthe associated warming retained in thespectral representation is reduced byaround 33% at that location and itsinfluence spread throughout a longdistance in an unphysical oscillatingpattern, as illustrated here. As themaximum number of waves in thespectral model is doubled, theoscillation fades faster so the distancescale would read about half of what isshown. This example is for a spectralmodel with a maximum wave numberof 170 and a location along 40°N.