Quote:Also I am not going to waste many more brain cells arguing with you MalabarJag but here are two studies that discuss the tropospheric hotspot.

<a class="bbc_url" href='http://iopscience.iop.org/article/10.1088/1748-9326/10/5/054007;jsessionid=BF2E4FB1F77915ADC6010A9F83D32C01.c2.iopscience.cld.iop.org'>http://iopscience.iop.org/article/10.1088/1748-9326/10/5/054007;jsessionid=BF2E4FB1F77915ADC6010A9F83D32C01.c2.iopscience.cld.iop.org</a>

Abstract

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<span style="font-size:12px;">We present an updated version of the radiosonde dataset homogenized by Iterative Universal Kriging (IUKv2), now extended through February 2013, following the method used in the original version (Sherwood et al 2008 Robust tropospheric warming revealed by iteratively homogenized radiosonde data J. Clim. <a class="bbc_url" href='http://dx.doi.org/10.1175/2008JCLI2320.1'>[font=inherit]21 5336–52</a>). This method, in effect, performs a multiple linear regression of the data onto a structural model that includes both natural variability, trends, and time-changing instrument biases, thereby avoiding estimation biases inherent in traditional homogenization methods. One modification now enables homogenized winds to be provided for the first time. This, and several other small modifications made to the original method sometimes affect results at individual stations, but do not strongly affect broad-scale temperature trends. Temperature trends in the updated data show three noteworthy features. First, tropical warming is equally strong over both the 1959–2012 and 1979–2012 periods, increasing smoothly and almost moist-adiabatically from the surface (where it is roughly 0.14 K/decade) to 300 hPa (where it is about 0.25 K/decade over both periods), a pattern very close to that in climate model predictions. This contradicts suggestions that atmospheric warming has slowed in recent decades or that it has not kept up with that at the surface. Second, as shown in previous studies, tropospheric warming does not reach quite as high in the tropics and subtropics as predicted in typical models. Third, cooling has slackened in the stratosphere such that linear trends since 1979 are about half as strong as reported earlier for shorter periods. Wind trends over the period 1979–2012 confirm a strengthening, lifting and poleward shift of both subtropical westerly jets; the Northern one shows more displacement and the southern more intensification, but these details appear sensitive to the time period analysed. There is also a trend toward more easterly winds in the middle and upper troposphere of the deep tropics.[/font]
The original IUK dataset (Sherwood et al <a class="bbc_url" href='http://iopscience.iop.org/article/10.1088/1748-9326/10/5/054007;jsessionid=BF2E4FB1F77915ADC6010A9F83D32C01.c2.iopscience.cld.iop.org#erl510711bib20'>2008</a>) extended only through 2005. Here we present changes over time from an extension of this dataset through February 2013. These results confirm those of the other newer studies, suggesting that tropospheric warming has indeed proceeded as expected in spite of the problems that earlier studies have had in detecting it.
[font='franklin-gothic-urw-cond']3. Updated trend results[/font]
3.1. Temperature


<span style="font-size:12px;">The chief value of such records is in the more accurate estimation of long-term changes, of which the simplest characterization is the linear trend. The estimated temperature trend versus latitude and height (figure <a class="bbc_url" href='http://iopscience.iop.org/article/10.1088/1748-9326/10/5/054007;jsessionid=BF2E4FB1F77915ADC6010A9F83D32C01.c2.iopscience.cld.iop.org#erl510711f1'>1</a>) is somewhat noisy since each latitude band is based on a different and independent set of stations, but its features are clearer and somewhat stronger than those shown in S08. A maximum can be seen in the tropical upper troposphere in every latitude band from about 30S–20N, centred near 300 hPa. Because the trend reliability varies significantly among stations (with very scattered results in particular for stations in India), we follow S08 in taking the median of stations in latitude bands, although results are not highly sensitive to this choice.
The time evolution of average temperature in the troposphere (from roughly 1.5–14 km) in each of three latitude bands agrees closely with those of the Hadley Centre-Climate Research Unit Temperature Version 4 (HadCRUT4) surface record (Morice et al <a class="bbc_url" href='http://iopscience.iop.org/article/10.1088/1748-9326/10/5/054007;jsessionid=BF2E4FB1F77915ADC6010A9F83D32C01.c2.iopscience.cld.iop.org#erl510711bib13'>2012</a>), both in terms of overall warming trend and year-to-year variation (figure <a class="bbc_url" href='http://iopscience.iop.org/article/10.1088/1748-9326/10/5/054007;jsessionid=BF2E4FB1F77915ADC6010A9F83D32C01.c2.iopscience.cld.iop.org#erl510711f3'>3</a>) supporting the accuracy of the estimates at least on large scales. Atmospheric warming is slightly slower than surface warming in the extratropical bands, but faster in the tropics, as expected. The southern extratropics warmed rapidly from 1960 up until the late 1970s but more slowly after that, while the Northern extratropics warmed only after the mid−1970s; these features are similar in the troposphere and surface data. Interestingly, tropical warming appears steadier in the troposphere than at the surface, and did not slow after 1998 despite slower warming in the surface record. This is the main reason why the trends are now slightly stronger than those shown in S08.
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