Guest opinion: Dr. Tim Ball
On WUWT, Bob Tisdale recently examined the disparity of results between IPCC models in “No Consensus: Earth’s Top of Atmosphere Energy Imbalance in CMIP5-Archived (IPCC AR5) Climate Models” and wrote that
“There are astonishing differences in the modeled estimates of the past, present and future imbalances and the three components that make up the top of the atmosphere (TOA) energy budget.”
There were several earlier studies, but the supposed accuracy improved after satellite data became available. Rossow and Zhang did a study similar to Tisdale in a 1995 article titled, “Calculation of surface and top of atmosphere radiative fluxes from physical quantities based on ISCCP Data sets 2. Validation and first results.”
Our validation studies suggest that the specification of cloud effects is no longer the dominant uncertainty in reconstructing the radiative fluxes at the top of atmosphere and at the surface. Rather cloud property uncertainties are now roughly equal contributors to the flux uncertainty, along with surface and atmospheric properties.
Erhard Raschke did a similar study in 2005 titled, “How well do we compute the insolation at TOA in radiation climatologies and in GCMs.” He found that,
In the spatial and temporal variations of the insolation at TOA as computed by 20 models participating in the AMIP-2 project and for the ISCCP data-set we discover that none of the models reproduced accurately the prescribed TSI value of 1365 Wm−2.
Some of the factors listed as problematic were
Some models ignore leap years. Moreover, leap years are included in different ways either leading to a small increase (0.34 Wm−2) or decrease (0.92 Wm−2) of the annual mean of insolation at TOA.
Most models produce seasonal insolation fields at TOA that deviate from their zonal means. More importantly, the corresponding latitudinal profiles (of zonal averages) differ, as illustrated by deviations to a “reference profile” (here: ISCCP data set). These different latitudinal gradients of insolation are expected to affect the atmospheric circulation in integrations over multiple years. The largest deviations exceed ±5 Wm−2 (in conjunction with extended low sun-elevation times) at high latitudes and polar regions.
Figure 1 is a graph of the latitudinal discrepancies.
These discrepancies compare unfavorably to an absolute accuracy requirement for all radiation quantities at the TOA of 1.5 Wm−2 [Ohring et al., 2004].
Tisdale’s material shows that nobody, including the IPCC, dealt with Raschke’s recommendations.
We recommend that in all climate models and in all “radiation climatologies” the incoming solar radiation at TOA must be identical for any given time period and area on the globe. Modelers should use the real length of the tropical year. Since a similar analysis of IPCC AR4 simulations shows qualitatively the same deficiencies as described here for the AMIP simulations, we think, that there is a need for sensitivity tests that investigate impacts of detected differences in the TOA insolation on circulation structures developing in the model’s climate system.
The Real Problem
Maybe the problem is the same one associated with climate models in general. They are built on inadequate data and inadequate understanding of the structure and mechanisms of the real world. These problems are then exacerbated and aggravated by creating mechanisms to hide, ignore or even falsify the situation. As Raschke notes in a paper titled, “How accurate did GCMs compute the insolation at TOA for AMIP2?”
All models should reproduce the known major state and related fluxes of energy, mass and momentum with high accuracy. But quite large disagreement was found in various quantities, in particular at higher latitudes over both hemispheres [Gates et al., 1999].
Recently other articles (here, here, here and here) discussed the TOA, but they don’t tell you what or where it is. Here is one description that provides an explanation, but as with most climate science measures, it only adds to the confusion.
Technically, there is no absolute dividing line between the Earth’s atmosphere and space, but for scientists studying the balance of incoming and outgoing energy on the Earth, it is conceptually useful to think of the altitude at about 100 kilometers above the Earth as the “top of the atmosphere.” The top of the atmosphere is the bottom line of Earth’s energy budget, the Grand Central Station of radiation. It is the place where solar energy (mostly visible light) enters the Earth system and where both reflected light and invisible, thermal radiation from the Sun-warmed Earth exit. The balance between incoming and outgoing energy at the top of the atmosphere determines the Earth’s average temperature. The ability of greenhouses (sic) gases to change the balance by reducing how much thermal energy exits is what global warming is all about.
Consider the implication that TOA is a line 100km above the surface and equidistant around the Earth. Now look at the known structures of the atmosphere and factors that affect weather and climate.
Most weather occurs in the Troposphere, and that is far from uniform or spherical. There is inadequate horizontal surface data to construct the General Climate Models (GCM) and even less in the vertical. More layers make no difference if you have no data. William Ferrell proposed a three-cell model of circulation within the Troposphere in the 1850s (Figure 2). It is still in many textbooks, with the middle cell named after Ferrell, Figure 2 is from 2012.
Figure 3 is a more recent approximation of what is going on within the Troposphere. Notice the Ferrell cell is now an “Indirect Cell”. There is a debate about whether it exists because the diagram shows an average condition. The Polar Front shifts seasonally, from approximately 38°N in the winter to 65°N in the summer. The Southern Hemisphere range is from 40°S to 65°S because of the land/water ratio difference
The top of the Tropopause also changes seasonally. The height at the Equator ranges between 17 and 18 km while it is 7 to 10 km at the Poles because of the greater seasonal temperature range. As the diagram shows, the Tropopause is a distinctive but not continuous boundary with breaks associated with the Jet Streams. All these factors affect the energy flows between the surface and the TOA. It is like trying to cross a very turbulent, fast flowing, constantly changing river. I suggest it is impossible to model such a complex dynamic system with virtually no data. There are serious limitations with accurate measures at high latitudes from the surface up.
Then there is the problem of the different direction of incoming solar radiation and outgoing irradiation. The Earth is a rotating sphere and that complicates everything. Figure 4 shows that solar energy strikes only half the Earth and varies considerably in the angle of incidence. The outgoing long wave passes through considerably different depths of the atmosphere with constantly varying constituencies including clouds, aerosols and gas levels.
The Ozone layer also lies within the 100 km TOA. Usually, it is dealt with as a homogenous zone but in reality the interaction between ultraviolet radiation and oxygen varies considerably at different levels. It is not unusual for ozone levels to increase at one level while decreasing at another. It also varies considerably spatially as the so-called ozone hole attests.
Another important factor essentially ignored is magnetism and its influence on numerous components of the energy balance. I wrote about one possible relationship in a previous WUWT article. A Danish study by Mads Faurschou Knudsen and Peter Riisager showed a relationship between precipitation patterns and geomagnetism. They attribute the relationship to the same mechanism identified by Svensmark.
Their work, which only looks at Earth’s magnetism, does not include the distortion of the entire atmospheric system from the magnetosphere on down by the pressure of the solar wind. Figure 5 shows the impact on the upwind side and the elongation on the downwind side, but again this is a static image. In reality, the area of maximum pressure is constantly moving as the earth rotates.
In their introduction Mads et al., underline the general problems
It remains difficult to capture the complexity of Earth’s climate system in numerical models. A meaningful discussion of past and future climate variability cannot, therefore, rely solely on mechanistic computer models, but must, at least to some extent, be based on actual climate observations. Because the instrumental records are too short to elucidate several aspects of the climate system, new insights often have to rely on crude comparisons between climate-proxy records and potential climate-forcing factors recorded in geological archives. The controversial role of the Sun as a driver of climate change represents a good example, as geological proxy records are important for our endeavor to understand climate variability.
Tisdale focuses on the modeled oceans as one source of discrepancy in the TOA numbers. As he notes,
We can simply add ocean heat accumulation and TOA energy imbalance to the list of things that climate models do not simulate properly.
A very good indication of the complexity of the problem of creating accurate models for the energy balance at the TOA is the fact Raschke noted a variation in results of plus (0.34 Wm−2) or minus (0.92 Wm−2) or a range of 1.26 Wm−2. Also, he found that
The largest deviations exceed ±5 Wm−2 (in conjunction with extended low sun-elevation times) at high latitudes and polar regions.
To put this in perspective, Lenaert Bengtsson, previously the Director of Research at ECMWF and Director of the Max Planck Institute for Meteorology noted,
…the radiative forcing by greenhouse gases (including methane, nitrogen oxides and fluorocarbons) has increased by 2.5 watts per square meter since the mid-19th century.
As with most climate measures, the supposed impact of all greenhouse gases is less than the error factor in a multitude of the inadequate data sources.