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COSMO General Meeting, Rome, Italy, 5-9 September 2011 Status of the implementation of the tile approach into the COSMO model COLOBOC meeting 5 September.

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Presentation on theme: "COSMO General Meeting, Rome, Italy, 5-9 September 2011 Status of the implementation of the tile approach into the COSMO model COLOBOC meeting 5 September."— Presentation transcript:

1 COSMO General Meeting, Rome, Italy, 5-9 September 2011 Status of the implementation of the tile approach into the COSMO model COLOBOC meeting 5 September 2011 Ekaterina Machulskaya German Weather Service, Offenbach am Main, Germany

2 COSMO General Meeting, Rome, Italy, 5-9 September 2011 Tile and mosaic approaches (recall) Tiled surface scheme within full-fledged COSMO model: implementation, set up of experiments Some results Conclusions and outlook Outline

3 Tile and mosaic approaches from (Ament, …)

4 Tiled Surface Scheme within the 3d COSMO model Mosaic approach implemented by Felix Ament into the COSMO version 4.7 either mosaic or tile approach in the version 4.16, with a user-specified number of tiles or sub-grid mosaic pixels surface type 1 surface type 2 surface type 3 surface type 4 snow- free snow ns_snow ns_stat User-defined parameters: ns_stat: number of static surface types ns_snow: number of those static surface types which can have snow as a separate tile derived parameter nsubs (total number of tiles/pixels): nsubs = (ns_stat - ns_snow) · 1 + ns_snow · 2

5 Tiled Surface Scheme within the 3d COSMO model Examples of set up: Mosaic: without snow tiles with snow tiles Without sub-grid refinement: ns_stat = 0, ns_snow = 0 ns_stat = N, ns_snow = 0 ns_stat = N, ns_snow = N Tiles: only two tiles snow/no snow general case ns_stat = 1, ns_snow = 1 ns_stat = N, ns_snow = M N

6 Tiled Surface Scheme within the 3d COSMO model Details of the realization of the tiles structure should be encapsulated! TYPE tile { LOGICAL :: snow_tile ! is it a snow tile? LOGICAL :: snowfree_tile ! is it a snow-free tile (a counterpart to a snow tile)? INTEGER :: conjunct ! = index of the counterpart (if it is a snow or snow- free tile)} TYPE (tile), ALLOCATABLE :: ctile(:) ! vector of nsubs tiles Example of the code: IF(ctile(n)% snow_tile) THEN … ELSEIF(ctile(n)% snowfree_tile) THEN … ELSE … END IF Extension of the attribute list is possible and easy

7 Tiled Surface Scheme within the 3d COSMO model Number of tiles should not be large (computational efficiency!) Surface types with the largest difference of thermal inertia should be chosen, now: lake/land Grid-scale lakes (lake fraction > 0.5) are already treated within the COSMO with FLake model; there are, however, numerous subgrid-scale water bodies (lake fraction < 0.5) which are ignored: lake fraction

8 Tiled Surface Scheme within the 3d COSMO model: set up Parallel experiment 8330 is set up (COSMO-EU domain, V4_16, running since ) (The information about lake fraction is available within the COSMO model – no additional software to generate external parameters is needed, thanks to Uli Schaettler for this idea!) For sub-grid lakes (lake fraction < 0.5) lake depth is set to 10 m on the zero time step, the cold start is performed: lake surface temperature = MAX( land surface temperature, freezing point ) lake bottom temperature = +4°C (temperature of maximal water density) mixing depth = 8 m ice depth = 0 m shape factor C_T = 0.5 (default) with 2 tiles: lake/land (ns_stat = 2, ns_snow = 0)

9 Tiled Surface Scheme within the 3d COSMO model: results Difference in surface temperature between lake tile and land tile night, UTC day, UTC

10 Tiled Surface Scheme within the 3d COSMO model: results Difference in surface temperature between experiment with tile approach (mean over two tiles) and control experiment night, UTC day, UTC

11 Tiled Surface Scheme within the 3d COSMO model: results

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13 COSMO General Meeting, Rome, Italy, 5-9 September … Experiment is set up, results are monitored Conclusions

14 COSMO General Meeting, Rome, Italy, 5-9 September Thanks to Jochen Förstner, Thomas Hanisch, Jürgen Helmert, Dmitrii Mironov and Bodo Ritter! Thank you for your attention!

15 Tiled Surface Scheme within the 3d COSMO model: results Routine COSMO-EU and COSMO-DE April 2011 May 2011


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