Archive for August, 2008

Stratospheric cooling?

August 27, 2008

One consequence of Earth undergoing greenhouse-caused warming would be a cooling stratosphere.  It i often claimed that the stratosphere, specifically the lower stratosphere, has in fact been cooling, thus confirming the enhanced greenhouse effect hypothesis.  Skeptics refute this claim in two ways: the cooling was caused by ozone depletion; and the cooling has now stopped.

Proponents of the Enhanced Greenhouse Effect theory suggest that the observed stratospheric cooling has been the product of both ozone depletion and a more intense greenhouse effect.

I recognize that the fact that the stratosphere hasn’t cooled for 13 years is an important point to make, especially considering the fact that month-to-month variation in stratospheric temperatures is small and thus trends are easy to extract.  Yet, I’ve never heard the point made that the only time the stratosphere seemed to cool was right after volcanic stratospheric warming episodes.  I’ve used paint to illustrate my point:

During the volcanic eruptions of El Chichon and Mt. Pinatubo, stratospheric temperature jumped and surface temperature fell.  Yet, instead of stratospheric temperatures returning to normal, they appear to have dropped significantly lower than they were before the eruption.  I’m not proposing any physical mechanism that could explain this, nor am I fully backing the idea that the volcanic eruptions caused the observed coooling.  I just thought it was worth noting.

UPDATE

I finally found a graph of global ozone levels (rather than Antarctic ozone levels or the size of the Antarctic ozone hole).  I’ve posted it below.

With this graph (data from here) as context, the trends in lower stratospheric temperature make sense, as caused (at least in part) by changes in ozone.  The graph appears to show diminishing ozone, with either an 11-year solar cycle!!!! or more likely the effects of bromine and chlorine released into the stratosphere by the especially intense eruptions of El Chichon and Mt. Pinatubo.

Predicted Tropospheric Warming Fails to Occur

August 27, 2008

Edward Linacre and Bart Geerts wrote here,

“With regard to the upper troposphere, radiosonde and MSU data do not show any warming trend either. Critics of ‘global warming’ (6) interpret the observed absence of upper-tropospheric warming as evidence that climate models are flawed: GCMs forced by a doubled CO2 concentration show strong warming in the upper troposphere. They argue that the observed lack of warming (or slight cooling) is an indication of a negative water-vapour feedback. However, the results of Hansen et al (5), obtained with a model that has a strong positive water-vapour feedback and is driven by measured radiative forcings, are consistent with observed temperature change and indicate that ozone depletion has reduced tropopause warming. If this interpretation is correct, during the next 5-10 years, as ozone-depletion levels out and perhaps reverses, warming of the upper troposphere by well-mixed greenhouse gases should become apparent. The model results indicate good agreement with the observed strong cooling in the lower stratosphere (see MSU data above), which is a result of the greenhouse gas accumulation and, secondarily, of the decrease in stratospheric ozone.” 

Here’s the catch; they wrote that in 1998.

So, it’s been 10 years and we have a chance to falsify their claims.  I don’t have upper tropospheric temperature data, but if mid-tropospheric temperatures aren’t increasing, then we shouldn’t expect upper-tropospheric temperatures to be increasing either.

No warming since 1979, and no warming over the past ten years.

And where we’d really expect to see the warming – in the tropical mid-troposphere:

What’s left when you take out ENSO?

August 27, 2008

Here’s my own temperature record without ENSO (El Nino & La Nina).  I know that this is done by NASA, but I don’t know where to find the data, nor would I completely trust the data if I did.  I could explain how I did it, and if anyone wants to know (apparently there were 21 of you today), make a comment, and I’ll post an explanation.

Here’s what you get when you subtract ENSO from hemispheric lower tropospheric temperature from UAH.  This is NOT a removal of ENSO, because the effect of ENSO lasts beyond the initial event.  Instead this is an indication of what needs to be explained, and ENSO might provide the solution (or part of it).

ENSO and volcanoes are the two largest phenomena that impact global temperatures on short timescales.  I had no real way to take the effect of volcanoes out, though you can use the following graph of lower stratospheric temperatures to see when volcanoes effected temperature (as shown by large stratospheric warming events).

David Stockwell has posted on the theory (not endorsed) that surface temperatures are determined by temperatures in the stratosphere, and that an inverse correlation between surface temperatures and lower stratospheric temperatures is implied by Miskolszi’s semi-transparent model.  He posted a graph comparing the two temperature trends over the past several decades.  While I only have access to lower stratospheric data, it still might be informative to do the same comparison shown on his post with the effects of ENSO removed. 

ENSO Forecasts

August 25, 2008
We’ve got some predictions.
Erl Happ is predicting the return of La Nina in September.       

“Lack of sunspot pressure and a very quiet solar wind that keeps 200hPa temperatures very low, historically they have never been as low as long as we have kept records. Add to that the fact that the Southern Ocean cools strongly in NH summer and that cold tongue is now pushing up from the South. The positive sea surface temperature anomalies in the NH are vanishing fast. Just check out the amount of cold surface water there is in the Southern Hemisphere and compare the area of the ocean in the southern to the Northern Hemisphere.”

Mr. Happ reminds me: “Remember, my prediction of a La Nina late in the year is conditional on Lack of sunspot pressure and a very quiet solar wind that keeps 200hPa temperatures very low.  The next El Nino will come when Solar Cycle 24 revs up.”

 

David Dilley, a proponent of one of the crazy solar system gravity rules terrestrial climate theories, is predicting El Nino in December.

“Meteorologist and climate researcher David Dilley of Global Weather Oscillations Inc. (GWO) says a recurring gravitational cycle called the “Primary Forcing Mechanism (PFM) for climate”, will act like a magnet and cause the South Pacific high pressure center to be pulled out of its normal location in October and November, setting the stage for a moderate to strong El Niño to form in December.” (http://www.prweb.com/releases/2008/07/prweb1158684.htm)

Both Erl Happ and David Dilley hold theories that are contrary to modern climate change theory, and both projections are based on their theories.  I’m intrigued by Happ’s theory and I’ll be posting on it soon.

RSS minus UAH – A Revealing Analysis

August 13, 2008

The two global radiosonde datasets used widely are RSS and UAH.  While they use essentially the same raw data, they apply different statistical techniques to find the global average temperature.  Because of this, RSS shows a greater global temperature tend (.17 C/decade) than UAH (.13 C/decade).  This difference is mainly due to different tropical temperature records.

Out of curiosity, I graphed RSS minus UAH from 1979 to 2008, and I got something verryyy strange.  I was expecting a linearly upward trend (RSS would become warmer and warmer each year than UAH).  Instead:

There are some things to note.

1. The difference between RSS and UAH swings wildly back and forth from 1979 to 1990.  This may be because the two datasets were still being tinkered with and adjusted.

2. There appears to be a step sometime during 1992 during the course of two months.  Perhaps RSS adjusted upward or UAH adjusted downward.  Or perhaps there was tinkering at all.

3. Around 1995, we begin to see an annual cycle in the difference between the two datasets, and that cycle becomes very well defined post-2002.  This means that for some reason, seasons are impacting the temperature records in one or both datasets, which seems like it wouldn’t be a good thing.

4. Secondly, from 2003 to the present, the two datasets have been converging in a very linear manner aside from the strange season-related cycle.  In fact, the convergance looks so linear and perfect that it seems as if RSS and UAH have reconciled their differences (besides the season-related cycle) and that an adjustment is being done each year on one of the datasets – either warming the UAH record or cooling the RSS record.

This simple analysis of subtracting one dataset from another turned out to be very informative.  When you have two datasets intended to describe the same phenomenon, it is often helpful to graph the difference between the two over time, because most of the actual signal is removed, and the raw differences between the datasets over time are shown.  Then we may be able to attribute causes to the differences, possibly reconciling the datasets and shedding light on possible problems with datasets.

UPDATE 1

I’ve graphed the difference over time between RSS and UAH for the NH, SH, and Tropics now.  The seasonal-cycle is evident in the NH and less so in the SH.  The tropics also contain the seasonal cycle, which is especially confusing.  The recent convergence of the two datasets seems to be mostly due to changes in SH data from one or both of the datasets.  Tropics data has contributed less to the convergance and the NH contributed barely at all.  The clear RSS bias toward warming due to a difference in numerical analysis in the tropics is shown.  This RSS bias toward more warming than UAH, the validity of which I can’t comment on, seems to have stopped since 2003.

UPDATE 2

It appears that the convergence of UAH and RSS might be due to series of corrections made by the UAH team (Spencer and Christy), adjusting the UAH record upward.  Or maybe I’m reading the readme wrong.  Or maybe I don’t understand diurnal drift.  But this may be an explanation for the convergence.