Monthly Archives: January 2009

A Recent Paper “Effects Of Irrigation And Vegetation Activity On Early Indian” By Lee Et Al 2008

There is an important new paper that provides further peer reviewed evidence on the role of land surface processes in the climate system. It is

 Eungul Lee, Thomas N. Chase,Balaji Rajagopalan, Roger G. Barry, Trent W. Biggs and Peter J. Lawrence: Effects of irrigation and vegetation activity on early Indian summer monsoon variability, 2008:Int. J. Climatol. (2008) Published online in Wiley InterScience (www.interscience.wiley.com) DOI: 10.1002/joc.1721

“We examined the effects of land cover change over the Indian subcontinent during pre-monsoon season (March, April, and May - MAM) on early Indian summer monsoon (ISM) rainfall using observed Normalized Difference Vegetation Index (NDVI) and July precipitation for the period of 1982-2003. MAM NDVI anomalies have increased in the Indian subcontinent and the increases are significantly correlated with increases in the irrigated area, not preceding rainfall. July rainfall significantly decreased in central and southern India, and the decrease is statistically related to the increase in the preceding MAM NDVI anomalies. Decreased July surface temperature in the Indian subcontinent (an expected result of increased evapotranspiration due to irrigation and increased vegetation) leads to a reduced land-sea thermal contrast, which is one of the factors driving the monsoon, and therefore weakens the monsoon circulation. A weak early ISM appears to be at least partially a result of irrigation and the resultant increased vegetation and crop activity prior to the monsoon.”

The numerous paper that continue to be published which document a regional and global effect of land use/land cover change on climate indicate that this aspect of the human role in climate variability and change needs to be elevated in its importance in future climate assessments. Unfortunately, this topic was minimized in its importance in the 2007 IPCC report.

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Follow Up To Henk Tennekes’s Guest Weblog

Follow Up: February 3 2009: Gavin Schmidt has ignored my request to write a guest weblog, or to respond to the science questions that I have raised (e.g. see). I have now accepted that he is not interested in scientific debate, and, thus, will not expend any more time seeking to correct the misinformation regarding the modeling of climate that he is presenting on Real Climate.

In response to today’s weblog Real Climate Suffers from Foggy Perception by Henk Tennekes, Gavin Schmidt and I have e-mailed to each other several times today. He is offended by the weblog and stated that it inaccurately reported on his professional credentials. Thus I invited him to write a response as a guest weblog on Climate Science to refute the claims make in the weblog from earlier today. Hopefully, he will accept.

I also invited him to move beyond this issue. Specifically, I wrote this to him in one of the e-mails;

“Others who read our weblogs will benefit if we move the discussion to a scientific level, and I am prepared to work with you on this. Here is a proposal: what if we both presented a Q&A from you and I on both of our websites (identical presentations)? This would provide readers with an informative set of viewpoints with which everyone would benefit.”

If he accepts this offer, the climate community would significantly benefit by reading where we agree and where we disagree on the science issues. We could start, for example, on which of the three hypotheses reported in Three Climate Change Hypotheses – Only One Of Which Can Be True we conclude have been refuted. He certainly has the professional credentials to contribute significantly to this discussion.

 

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Real Climate Suffers from Foggy Perception by Henk Tennekes

Roger Pielke Sr. has graciously invited me to add my perspective to his discussion with Gavin Schmidt at RealClimate. If this were not such a serious matter, I would have been amused by Gavin’s lack of knowledge of the differences between weather models and climate models. As it stands, I am appalled. Back to graduate school, Gavin!

A weather model deals with the atmosphere. Slow processes in the oceans, the biosphere, and human activities can be ignored or crudely parameterized. This strategy has been very successful. The dominant fraternity in the meteorological modeling community has appropriated this advantage, and made itself the lead community for climate modeling. Backed by an observational system much more advanced than those in oceanography or other parts of the climate system, they have exploited their lead position for all they can. For them, it is a fortunate coincidence that the dominant synoptic systems in the atmosphere have scales on the order of many hundreds of kilometers, so that the shortcomings of the parameterizations and the observation network, including weather satellite coverage, do not prevent skillful predictions several days ahead.

A climate model, however, has to deal with the entire climate system, which does include the world’s oceans. The oceans constitute a crucial slow component of the climate system. Crucial, because this is where most of the accessible heat in the system is stored. Meteorologists tend to forget that just a few meters of water contain as much heat as the entire atmosphere. Also, the oceans are the main source of the water vapor that makes atmospheric dynamics on our planet both interesting and exceedingly complicated. For these and other reasons, an explicit representation of the oceans should be the core of any self-respecting climate model. 

However, the observational systems for the oceans are primitive in comparison with their atmospheric counterparts. Satellites that can keep track of what happens below the surface of the ocean have limited spatial and temporalresolution. Also, the scale of synoptic motions in the ocean is much smaller than that of cyclones in the atmosphere, requiring a spatial resolution in numerical models and in the observation network beyond the capabilities of present observational systems and supercomputers. We cannot observe, for example, the vertical and horizontal structure of temperature, salinity and motion of eddies in the Gulf Stream in real time with sufficient detail, and cannot model them at the detail that is needed because of computer limitations. How, for goodness’ sake, can we then reliably compute their contribution to multi-decadal changes in the meridional transport of heat? Are the crude parameterizations used in practice up to the task of skillfully predicting the physical processes in the ocean several tens of years ahead? I submit they are not.

Since heat storage and heat transport in the oceans are crucial to the dynamics of the climate system, yet cannot be properly observed or modeled, one has to admit that claims about the predictive performance of climate models are built on quicksand. Climate modelers claiming predictive skill decades into the future operate in a fantasy world, where they have to fiddle with the numerous knobs of the parameterizations to produce results that have some semblance of veracity. Firm footing? Forget it!

Gavin Schmidt is not the only meteorologist with an inadequate grasp of the role of the oceans in the climate system. In my weblog of June 24, 2008, I addressed the limited perception that at least one other climate modeler appears to have. A few lines from that essay deserve repeating here. In response to a paper by Tim Palmer of ECMWF, I wrote: “Palmer et al. seem to forget that, though weather forecasting is focused on the rapid succession of atmospheric events, climate forecasting has to focus on the slow evolution of the circulation in the world ocean and slow changes in land use and natural vegetation. In the evolution of the Slow Manifold (to borrow a term coined by Ed Lorenz) the atmosphere acts primarily as stochastic high-frequency noise. If I were still young, I would attempt to build a conceptual climate model based on a deterministic representation of the world ocean and a stochastic representation of synoptic activity in the atmosphere.”

From my perspective it is not a little bit alarming that the current generation of climate models cannot simulate such fundamental phenomena as the Pacific Decadal Oscillation. I will not trust any climate model until and unless it can accurately represent the PDO and other slow features of the world ocean circulation. Even then, I would remain skeptical about the potential predictive skill of such a model many tens of years into the future.

 

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Submitted Paper “Assessment Of Temperature Trends In The Troposphere Deduced From Thermal Winds By Pielke Sr. Et Al

Yesterday, Climate Audit announced the submission of a paper on tropospheric temperature trends (see).

We have also submitted a paper which relates to his study. It is

Pielke Sr., R.A., T.N. Chase, J.R. Christy, B. Herman, and J.J. Hnilo, 2009: Assessment of temperature trends in the troposphere deduced from thermal winds. Int. J. Climatol., submitted

“Recent work has concluded that there has been significant warming in the tropical upper troposphere using the thermal wind equation to diagnose temperature trends from observed winds; a result which diverges from all other observational data. In our paper we examine evidence for this conclusion from a variety of directions and find that evidence for a significant tropical tropospheric warming is weak. In support of this
conclusion we provide evidence that, for the period 1979-2007, except for the highest latitudes in the Northern Hemisphere, both the thermal wind, as estimated by the zonal averaged 200 hPa wind and the tropospheric layer-averaged temperature, are consistent with each other, and show no statistically significant trends.”

Our conclusion reads

“Our paper demonstrates that there are significant uncertainties in using the TWE [thermal wind equation] to diagnose tropical temperature trends. Results using the TWE in the deep tropics are in significant disagreement with all other observational data. We have also provided evidence that the TWE is less robust and subject to higher variability and error than other available data. Use of the TWE is not physically appropriate in deep tropical latitudes and near the tropopause it can be affected by the reversal of temperature gradients should the tropopause be crossed. For these reasons we conclude that the diagnosis of an upper tropospheric warming in the tropics using the thermal wind is not likely to be accurate.”

We weblogged on this issue in response to two Nature articles last year; see

Use Of Winds To Diagnose Long Term Temperature Trends – Two New Papers

Comments On The Science In The Nature Paper By Allen and Sherwood

Wind Changes over Time and Space as a Climate Metric to Diagnose Temperature Trends.

 

 

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New Method For Estimating The Impact Of Heterogeneous Forcing On Atmospheric Circulations by Vukicevic et al. 2009

Our research has shown that the forcing of weather systems from diabatic heating by the human input of aerosols is on the order of 60 times that of the forcing from the diabatic heating due to the human addition of well-mixed greenhouse gases (with the dominate gas being CO2); i.e. see

Matsui, T., and R.A. Pielke Sr., 2006: Measurement-based estimation of the spatial gradient of aerosol radiative forcing. Geophys. Res. Letts., 33, L11813, doi:10.1029/2006GL025974.

We now have a new paper that presents a quantitative methodology to assess the importance of this type of climate forcing. It is

Vukicevic, T., R. A. Pielke Sr., and A. Beltran-Przekurat, 2009: New Method For Estimating The Impact Of Heterogeneous Forcing On Atmospheric Circulations. J. Geophys. Res., doi:10.1029/2008JD010418, in press.

The abstract reads

“In this study a new method for estimating the impact of heterogeneous forcing on atmospheric circulations is discussed. This new method is similar to the commonly used model-based sensitivity studies in that the impact of forcing is diagnosed by a suitable measure of differences between atmospheric states with and without forcing, but differs in the way the atmospheric states are evaluated: by combining standard atmospheric data analysis, observationally-based estimates of the forcing, atmospheric observations and general circulation model (GCM) ensemble simulations. A new numerical technique, derived from the Ensemble Kalman Filter data assimilation approach, is used for
objective estimation of the atmospheric state not affected by the forcing. Using a tutorial example, numerical experiments were conducted varying an asymmetric thermal forcing as a proxy for the heterogeneous forcing. Results show that the method is capable of producing skilled estimates of the impact of the forcing. Strategies for application of the method with real-world data and GCMs are discussed. This new method is expected to produce more realistic estimates of the forcing impact than the standard model sensitivity approach because of the explicit use of the observationally-based estimates of atmospheric states and forcing.”

The importance of this study is that assessment groups, such as the IPCC, have a new tool with which to broaden their evaluations of the role of humans within the climate system. Climate modeling groups are urged to adopt this tool, or a similar approach, to better quantify the role of spatial variations in human climate forcings on weather and climate.

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Filed under Climate Change Forcings & Feedbacks, Climate Models

New Weblog By Bruce Hall On “Decadal Occurrences Of Maximum Statewide Temperature Records”

A very informative weblog has been posted today by Bruce Hall on the “Decadal Occurrences Of Maximum Statewide Temperature Records“. This is a valuable contribution to the analysis of long term climate extremes.

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A New Paper From Model Based Parameterizations To Lookup Tables: An EOF Approach By Leoncini et al paper 2008

We have a new research paper that has been published. This paper applies a new methodology that we reported on in

Pielke Sr., R.A., T. Matsui, G. Leoncini, T. Nobis, U. Nair, E. Lu, J. Eastman, S. Kumar, C. Peters-Lidard, Y. Tian, and R. Walko, 2006: A new paradigm for parameterizations in numerical weather prediction and other atmospheric models. National Wea. Digest, 30, 93-99.

In that paper, we wrote

“Superparameterization embedded, Multi-Modeling Frameworks (MMF) are ….under development at several institutions, and there are plans to create global cloud libraries which includes detailed mass and energy output from cloud resolving models. With the LUT-based approach, the superparameterization approach could be used much more efficiently since the simulations (e.g., the 3-D cloud model) are integrated oflline, and the results are archived in a database for future retrieval.”

In our new paper, we demonstrate, using a radiation parameterization, that the LUT-based aproach is a computationally efficient method to replace existing parameterization approaches and as an effective alternative to the MMF approach.

Our new 2008 paper also further demonstrates that the answers provided on Real Climate by Gavin Schmidt with respect to parameterizations (see) do not adequately recognize that parameterizations in weather and climate models are engineering code. They are not basic physics.

Our paper is

 Leoncini, G., R.A. Pielke Sr., and P. Gabriel, 2008: From model based parameterizations to Lookup Tables: An EOF approach. Wea. Forecasting, 23, 1127.1145.

The abstract reads

“The goal of this study is to transform the Harrington radiation parameterization into a transfer scheme
or lookup table, which provides essentially the same output (heating rate profile and short- and longwave
fluxes at the surface) at a fraction of the computational cost. The methodology put forth here does not
introduce a new parameterization simply derived from the Harrington scheme but, rather, shows that given
a generic parameterization it is possible to build an algorithm, largely not based on the physics, that mimics
the outcome of the parent parameterization. The core concept is to compute the empiricalorthogonal
functions (EOFs) of all of the input variables of the parent scheme, run the scheme on the EOFs, and
express the output of a generic input sounding exploiting the input–output pairs associated with the EOFs.
The weights are based on the difference between the input and EOFs water vapor mixing ratios. A detailed
overview of the algorithm and the development of a few transfer schemes are also presented. Results show
very good agreement (r > 0.91) between the different transfer schemes and the Harrington radiation
parameterization with a very significant reduction in computational cost (at least 95%).”

The conclusion ends with

“While this study is limited to the Harrington radiation parameterization, it is reasonable to believe that the same methodology can be extended to a cloudy sky and applied to other parameterizations with similar results, as first envisioned in Pielke et al. (2006).”

 

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