Status of Modeling the Planetary Boundary Layer in Climate Models
Abstract
The advent of global satellite data about 35-years ago yielded a significantly different picture of global oceanic surface winds, surface pressure magnitudes and distribution, and consequently global ocean surface stress and heat flux than was found in the global climate record, which is still the basis of most numerical climate modeling. Initially, satellite model functions were established by curve-fitting radar backscatter to buoy and ship data. These data, particularly in the Northern Hemisphere, correlated fairly well with the climate record. This was evidently due to the fact that both were derived from the same surface observations --- land stations, ships and buoys. However, in the So. Hemisphere there was much more discrepancy. It was assumed that this was most likely due to the paucity of buoys and ship data in this region. There was considerable delay in using this revolutionary new data in the numerical weather & climate models. In another departure from 'The way we have always done it', we have used a nonlinear PBL analytical Organized Large Eddy model to include the advective flux contribution of these organized eddies that occupy the entire PBL (Brown, 1970). Compared to the usual linear approximation for the PBL solution (Ekman, 1905) and the use of a 'diffusion coefficient' K to model the fluxes in the PBL with a diffusion equation, the nonlinear model leads to higher winds, different pressure and flux fields and better agreement with observations (Patoux et al, 2003). This was established using both pressure fields (a linear and a nonlinear PBL model) in an NCEP prognosis model and comparing results. Given the assumptions made in the 1970 nonlinear solution producing the coherent structures in the PBL, I was not entirely convinced of its generality --- beyond explaining observed cloud-street characteristics --- so I anticipated some data might appear that disproved the theory. It has been over 40-years now, and no such data has appeared. And considerable observations have substantiated the nonlinear aspects of the theory. So I'm wondering why the numerical models haven't made the effort (admittedly significant) to apply the nonlinear theory in their models. It would help in warding off the many global warming critics who accuse the models of being 'inaccurate'.
- Publication:
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AGU Fall Meeting Abstracts
- Pub Date:
- December 2013
- Bibcode:
- 2013AGUFMNG43A1678B
- Keywords:
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- 0399 ATMOSPHERIC COMPOSITION AND STRUCTURE General or miscellaneous;
- 0545 COMPUTATIONAL GEOPHYSICS Modeling;
- 5739 PLANETARY SCIENCES: FLUID PLANETS Meteorology;
- 1620 GLOBAL CHANGE Climate dynamics