High Resolution MOS Forecasts Based on a Low Resolution Model Dipl.-Met. Klaus Knüpffer, 28.Sep 2009 OUTLINE 1. MOS reduces 50% of the error variance of DMO: Comparison between 1999 and 2009 at Observation Stations 2. How to Extend the Benefit of MOS to the Area? MOS coefficient interpolation 3. Forecast Examples from the Seefeld area 4. Summary and Outlook

High Resolution MOS Forecasts Based on a Low Resolution Model Dipl.-Met. Klaus Knüpffer, 28.Sep MOS reduces 50% of the error variance of the DMO RV(MOS,DMO) = 100% * (MSE_DMO - MSE_MOS) / MSE_DMO MSE: Mean Squared Error = RMSE² MOS (Model Output Statistics) reduces approximately 50% of the error variance of the Direct Model Output (DMO) forecasts of a numerical model – no matter whether high or low resolution – for standard weather elements like temperature, wind and cloud cover.

High Resolution MOS Forecasts Based on a Low Resolution Model Dipl.-Met. Klaus Knüpffer, 28.Sep MOS reduces 50% of the error variance of the DMO Diagram: Reduction of Variance of MOS as compared to DMO 1999: RV(EM-MOS,EM-DMO) 2009: RV(MOS-Mix,GME-DMO) EM : Europa-Modell (DWD) MOS-Mix: Mix of GME-MOS(00 UTC) and ECMWF-MOS(T-12h)

High Resolution MOS Forecasts Based on a Low Resolution Model Dipl.-Met. Klaus Knüpffer, 28.Sep 2009

2. How to Extend the Benefit of MOS to the Area? MOS forecasts are usually only provided at the very places where the observation locations are situated. A technology is outlined which allows MOS forecasts for any location between the observation locations.

High Resolution MOS Forecasts Based on a Low Resolution Model Dipl.-Met. Klaus Knüpffer, 28.Sep How to Extend the Benefit of MOS to the Area? Meteo Service has introduced a technology which relies on the Interpolation of MOS coefficients - not MOS forecasts. This technology is based on orographic descriptors and has already been in use with the German National Weather Service (DWD) since These orographic descriptors refer to latitude, longitude, elevation and the difference between the elevation of the smoothed model orography, and the real elevation.

High Resolution MOS Forecasts Based on a Low Resolution Model Dipl.-Met. Klaus Knüpffer, 28.Sep How to Extend the Benefit of MOS to the Area? Nowadays high resolution orography information is available, and more orographic descriptors can be used. NOAA/NGDC orographic data is available in a resolution of approximately 1 x 1 km and allows for the definition of the following orographic descriptors with different spatial smoothing: - elevation - slope: = first derivative of elevation) - valley/hill:= second derivative of elevation).

High Resolution MOS Forecasts Based on a Low Resolution Model Dipl.-Met. Klaus Knüpffer, 28.Sep How to Extend the Benefit of MOS to the Area? A difference between the weighted orography descriptors is used to define the representativeness between interpolation points and observation locations. This representativeness is the norm of a multi-dimensional vector with the number of dimensions being equal to the number of orography descriptors.

High Resolution MOS Forecasts Based on a Low Resolution Model Dipl.-Met. Klaus Knüpffer, 28.Sep How to Extend the Benefit of MOS to the Area? A procedure to search for the most informative set of representative oberservation stations for a given interpolation point is applied and shown below. Interpolation weights are calculated for the selected oberservation locations based on the representativeness.

High Resolution MOS Forecasts Based on a Low Resolution Model Dipl.-Met. Klaus Knüpffer, 28.Sep How to Extend the Benefit of MOS to the Area? Simple example with usage of only two orography descriptors: - Latitude - Longitude Abbreviations: IS : Interpolation Station OS: Observing Station C : Center point of weighted Observing Stations IC : Interpolation Centre (for searching next observing station)

High Resolution MOS Forecasts Based on a Low Resolution Model Dipl.-Met. Klaus Knüpffer, 28.Sep 2009

weight OS 1: 100%

High Resolution MOS Forecasts Based on a Low Resolution Model Dipl.-Met. Klaus Knüpffer, 28.Sep 2009 weight OS 1: 100%

High Resolution MOS Forecasts Based on a Low Resolution Model Dipl.-Met. Klaus Knüpffer, 28.Sep 2009 weight OS 1: 65% OS 2: 35%

High Resolution MOS Forecasts Based on a Low Resolution Model Dipl.-Met. Klaus Knüpffer, 28.Sep 2009 weight OS 1: 65% OS 2: 35%

High Resolution MOS Forecasts Based on a Low Resolution Model Dipl.-Met. Klaus Knüpffer, 28.Sep 2009

weight OS 1: 41% OS 2: 22% OS 3: 37 %

High Resolution MOS Forecasts Based on a Low Resolution Model Dipl.-Met. Klaus Knüpffer, 28.Sep 2009 weight OS 1: 41% OS 2: 22% OS 3: 37 %

High Resolution MOS Forecasts Based on a Low Resolution Model Dipl.-Met. Klaus Knüpffer, 28.Sep 2009

2. How to Extend the Benefit of MOS to the Area? 3-dimensional example in more complex orography - Latitide - Longitude - Elevation Interpolation Point: Seefeld (between Innsbruck and Zugspitze) Elevation: m

High Resolution MOS Forecasts Based on a Low Resolution Model Dipl.-Met. Klaus Knüpffer, 28.Sep 2009

weight OS 1: 100%

High Resolution MOS Forecasts Based on a Low Resolution Model Dipl.-Met. Klaus Knüpffer, 28.Sep 2009 weight OS 1: 100%

High Resolution MOS Forecasts Based on a Low Resolution Model Dipl.-Met. Klaus Knüpffer, 28.Sep 2009 weight OS 1: 63% OS 2: 37%

High Resolution MOS Forecasts Based on a Low Resolution Model Dipl.-Met. Klaus Knüpffer, 28.Sep 2009 weight OS 1: 63% OS 2: 37%

High Resolution MOS Forecasts Based on a Low Resolution Model Dipl.-Met. Klaus Knüpffer, 28.Sep 2009

weight OS 1: 49% OS 2: 29% OS 3: 22%

High Resolution MOS Forecasts Based on a Low Resolution Model Dipl.-Met. Klaus Knüpffer, 28.Sep 2009 weight OS 1: 49% OS 2: 29% OS 3: 22%

High Resolution MOS Forecasts Based on a Low Resolution Model Dipl.-Met. Klaus Knüpffer, 28.Sep 2009

weight OS 1: 39% OS 2: 24% OS 3: 17% OS 4: 20%

High Resolution MOS Forecasts Based on a Low Resolution Model Dipl.-Met. Klaus Knüpffer, 28.Sep 2009 weight OS 1: 39% OS 2: 24% OS 3: 17% OS 4: 20%

High Resolution MOS Forecasts Based on a Low Resolution Model Dipl.-Met. Klaus Knüpffer, 28.Sep 2009

weight OS 1: 35% OS 2: 21% OS 3: 16% OS 4: 18% OS 5: 10%

High Resolution MOS Forecasts Based on a Low Resolution Model Dipl.-Met. Klaus Knüpffer, 28.Sep 2009 weight OS 1: 35% OS 2: 21% OS 3: 16% OS 4: 18% OS 5: 10%

High Resolution MOS Forecasts Based on a Low Resolution Model Dipl.-Met. Klaus Knüpffer, 28.Sep 2009

2. How to Extend the Benefit of MOS to the Area? Consideration of all 18 orography descriptors -Longitude, Latitude -Elevation in 4 scales: 1, 10, 100, 1000 km -Gradient_U(Elevation) in 4 scales -Gradient_V(Elevation) in 4 scales -Rotor (=La-Placian=2nd derivative) of Elevation in 4 Scales for valley/hill distinction

High Resolution MOS Forecasts Based on a Low Resolution Model Dipl.-Met. Klaus Knüpffer, 28.Sep 2009 weight OS 1: 37% OS 2: 14% OS 3: 22% OS 4: 27%

High Resolution MOS Forecasts Based on a Low Resolution Model Dipl.-Met. Klaus Knüpffer, 28.Sep Forecast Examples from the Seefeld area Interpolated MOS forecasts for , 13 UTC based on the concept of coefficient interpolation outlined above are presented with special emphasis on alpine orography are shown with horizontal resolutions of approximately 70 km 7 km and 2 km..

High Resolution MOS Forecasts Based on a Low Resolution Model Dipl.-Met. Klaus Knüpffer, 28.Sep Forecast Examples from the Seefeld area Forecast examples for , 13 UTC Synoptic Situation: High pressure in the NNW and Low pressure in the SE, northern flow with precipitation in the northern alps. Snowfall above ~1.000 m, rain below.

High Resolution MOS Forecasts Based on a Low Resolution Model Dipl.-Met. Klaus Knüpffer, 28.Sep 2009

4. Summary and Outlook Systematical verifications of the new coefficient interpolatoin procedure are not present yet but good experiences of -DWD for 15 years with the old, verified coefficient interpolation scheme -Customers in Switzerland who like these forecasts -The Geophysical Information Service of the German Defense Forces who apply this scheme in a worldwide Auto-TAF application. Thank you.