Status Nov 9
The validation of the system has been somewhat time consuming between this post and the previous, and much has happened. At least 20 GMAO staff (or more) spent several weeks interogating the validation experiments each focusing on various Earth system components. On Oct 11, the GMAO held an internal review of the validation experiments. On Nov 7, the summary of these results were presented to our User Review group in a meeting at GSFC. My interpretation of the Review is that the system has more than enough scientific merit to proceed to production phase, weighing the advances and advantages against the limitations and some weaknesses. When any formal writing from the Review are made available for public posting, I'll put it on the blog. This is a significant milestone for the MERRA project and the GMAO.
There were many very positive results that came out of the MERRA validation experiments. Too many to easily synthesize into blog posts. A validation document is under development, but should take some time. Some results will be posted here as time goes on. In the near term, however, validation pointed out a serious flaw in the system. When the CERES science team evaluated the data, they found that Antarctica and glaciers did not have a diurnal cycle of surface temperature. The reason ended up being a thick glacier layer. Some new code, including a thinner layer and revisions to the energy budget code have produced very reasonable results. So, this fix will be added to the MERRA system. (see the Figure)
Figure: Time series of 2m air temperature at two Antarctica stations. The green line indicates GEOS5 Patch 15, Blue is patch 20 (including the fix) and the read is ECMWF operational analysis. Model data are the nearest gridpoint to the stations. Station data is marked with a black box.
So, the spin up of MERRA production runs are on hold until the system is updated. Some testing of convection parameterization coefficients has been going on through this process. A decision is pending on which, if any, will go into MERRA. The issue to be resolved are, updating the system with new glacier surface temperatures, finalizing the MERRA output routines and final evaluation of the convection parameterization. Spinup runs will restart once these issues are resolved.
There were many very positive results that came out of the MERRA validation experiments. Too many to easily synthesize into blog posts. A validation document is under development, but should take some time. Some results will be posted here as time goes on. In the near term, however, validation pointed out a serious flaw in the system. When the CERES science team evaluated the data, they found that Antarctica and glaciers did not have a diurnal cycle of surface temperature. The reason ended up being a thick glacier layer. Some new code, including a thinner layer and revisions to the energy budget code have produced very reasonable results. So, this fix will be added to the MERRA system. (see the Figure)
Figure: Time series of 2m air temperature at two Antarctica stations. The green line indicates GEOS5 Patch 15, Blue is patch 20 (including the fix) and the read is ECMWF operational analysis. Model data are the nearest gridpoint to the stations. Station data is marked with a black box.So, the spin up of MERRA production runs are on hold until the system is updated. Some testing of convection parameterization coefficients has been going on through this process. A decision is pending on which, if any, will go into MERRA. The issue to be resolved are, updating the system with new glacier surface temperatures, finalizing the MERRA output routines and final evaluation of the convection parameterization. Spinup runs will restart once these issues are resolved.
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