Self Regulation Of The Climate System By Deep Cumulus Convection

We have published a set of papers that discuss an under recognized climate feedback which constrains how warm and cold the troposphere can become. These papers present a constraint based on the temperatures of the sea surface and the deep cumulus response to these temperatures.

The idea is straightforward and originated in an idea from Ben Herman at the University of Arizona. When cold air masses travel over unfrozen ocean, vertical mixing through deep cumulus convection mixes the air through the troposphere such that temperatures at 500mb, for example, hardly ever becomes colder than -40C to -45C.  These cold values are actually reached in November in the Northern Hemisphere despite several more months of winter.

This limit on tropospheric cooling  is reported on in our paper:

Chase, T.N., B. Herman, R.A. Pielke Sr., X. Zeng, and M. Leuthold, 2002: A proposed mechanism for the regulation of minimum midtropospheric temperatures in the Arctic. J. Geophys. Res., 107(D14), 10.10291/2001JD001425

Tsukernik, M., T.N. Chase, M.C. Serreze, R.G. Barry, R. Pielke Sr., B. Herman, and X. Zeng, 2004: On the regulation of minimum mid-tropospheric temperatures in the Arctic. Geophys. Res. Letts., 31, L06112, doi:10.1029/2003GL018831

Herman, B., M. Barlage, T.N. Chase, and R.A. Pielke Sr., 2008: Update on a proposed mechanism for the regulation of  minimum mid-tropospheric and surface temperatures in the Arctic and Antarctic. J. Geophys. Res.-Atmos., 113, D24101, doi:10.1029/2008JD009799.

Herman, B.M. M.A. Brunke, R.A. Pielke Sr., J.R. Christy, and R.T. McNider, 2010: Global and hemispheric lower tropospheric temperature trends. Remote Sensing, 2, 2561-2570; doi:10.3390/rs2112561.

Since, as discussed in my post

The Westerlies Explain The Recent Extreme Winter Weather, Not “Global Warming”

it is the cold tropospheric air towards the poles and the warmer tropospheric air to the south that drives the westerlies, if the coldest that the troposphere can achieve is -40C to -45C, irrespective of a global average surface temperature trend, this is a self-regulation of the climate system.

Similarly, tropospheric temperatures cannot become warmer that about -5C at 500mb  in the tropics for very long as deep convection over the warmest oceans still results in temperatures at that level of ~-5C.  This deep convection is prevalent over tropical oceans as air travels around the globe.

Only if the high latitude oceans warm to well above freezing almost everywhere (which means most of the Arctic and Antarctic sea ice disappears) and/or the tropical oceans warm substantially above their current values, will this self-regulation of the climate system change.  The role of human climate forcings would have to  be large enough to alter these surface temperatures.

The latest sea surface temperature and temperature anomaly maps show that large enough changes have not yet occurred to alter this self-regulation of the climate system – as illustrated below. The 2007 IPCC, and more recent pronouncements have  ignored assessing the role of this self-regulation of the climate.

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