1 / 14

Radiation Calculation on a Coarser Grid - Very First Results With LMK

Radiation Calculation on a Coarser Grid - Very First Results With LMK. Thorsten Reinhardt, Deutscher Wetterdienst Thorsten.Reinhardt@dwd.de. Standard calling frequency of radiation scheme: 1 hr, but more frequent calling would be costly Column assumption at small grid sizes questionable

linda-bates
Download Presentation

Radiation Calculation on a Coarser Grid - Very First Results With LMK

An Image/Link below is provided (as is) to download presentation Download Policy: Content on the Website is provided to you AS IS for your information and personal use and may not be sold / licensed / shared on other websites without getting consent from its author. Content is provided to you AS IS for your information and personal use only. Download presentation by click this link. While downloading, if for some reason you are not able to download a presentation, the publisher may have deleted the file from their server. During download, if you can't get a presentation, the file might be deleted by the publisher.

E N D

Presentation Transcript

  1. Radiation Calculation on a Coarser Grid - Very First Results With LMK Thorsten Reinhardt, Deutscher Wetterdienst Thorsten.Reinhardt@dwd.de

  2. Standard calling frequency of radiation scheme: 1 hr, but more frequent calling would be costly Column assumption at small grid sizes questionable Calling radiation only every hour questionable Motivation

  3. Cloud dx=2.8 km (LMK grid size) assume cloud 7 grid sizes big, moving at v=10.9 m/s

  4. Cloud then the cloud has moved 7 gridpoints after 30 min, if dx=2.8 km assume cloud moving at v=10.9 m/s

  5. actual cloud cloud radiative effect then the cloud has moved 7 gridpoints after 30 min, if dx=2.8 km assume cloud moving at v=10.9 m/s But radiative effect is taken into account still at old position!

  6. Therefore: Calculate radiation scheme on a coarser grid. Call radiation scheme more frequently.

  7. Approach: calculate radiation on a coarser grid LMK grid grid for radiation

  8. 1) Average input variables onto coarser grid 2) Calculate radiation on coarser grid 3) Re-distribute onto LMK grid 4) Smooth output with discrete filter 5) Apply albedo correction Procedure Current implementation: maximal grid size of coarse grid: (nboundlines+1) x LMK grid Averaging (Step 4) and albedo correction (Step 5) can be switched on/off

  9. LMK Testsuite 2.2c for July 2004 • Changes compared to Testsuite 2.2: • Radiation on a coarser (2x2) grid • Call radiation very 15 min instead of every hour

  10. First Results:

  11. First Results: • Overall: nearly neutral impact • • Bottom and top radiative fluxes, averaged: neutral • Verification against 24-h precipitation sums: ok • Eye-inspection of visualized output: ok • Verification against synop data: not yet done • Pointwise, of course, also bigger differences • Outlook: • It might be better to vary continously position of coarse grid vs. fine grid.

More Related