Testing Energy Balance and Budget
In this previous post, I mentioned the energy budget / balance for the Earth’s systems. Specifically, the fundamental hypothesis for AGW is that human activities have created an imbalance in the radiative-energy transport budget and that an increase in temperature will be obtained in order to return to some kind of, but practically undefined, equilibrium state. A true state of energy in-come = energy out-go is never attained for the Earth’s systems. The daily and yearly cyclic variations are observed easily by direct experience and instrumental means. Especially, neither the out-going infrared energy or the in-coming ultra-violet energy are constant, and are not monotonically increasing or decreasing.
As I noted in that post, many of the important phenomena and processes that can change the amounts of energy in-coming to and out-going from the Earth’s systems are independent of the radiative-energy states of the systems. There are no inherent natural physical phenomena and processes acting so as to maintain a state of radiative-energy balance for the Earth’s systems. Natural events, both external from and internal to, the Earth’s systems are free to cause changes in the state of the systems such that either an increase or a decrease in the amount of energy results; in-come. Natural events can also act to both increase or decrease the amount of energy leaving the systems; out-go. Very likely, the grand-time-and-space-average albedo is changing all the time and thus changing the in-coming energy. So are the mechanisms that effect loss of infrared energy and changes in the out-going energy.
The occurrence of the natural events, and the outcome relative to the associated radiative-energy transport properties, cannot be known until after the fact. Many human activities including CO2 emissions can also change conditions that affect the radiative-energy transport properties of the Earth’s systems. The perturbations due to human activities on the radiative-energy balance are reported to be small; a few W/m^2.
Testing the Models and Methods
Additional consideration of this situation has led me to think about how testing of GCM model results might better be reported. It seems to me that models and methods are better tested if results of calculations are compared with information more nearly directly related to the basic premise of a problem and its investigations. If the temperature is changing, there should be corresponding changes in the outgoing long-wave radiative energy. The interactions between water vapor in the atmosphere for both UV and IR radiative transport are of first-order importance.
Because it results in an amplification of the effects of increasing concentrations of CO2, an increase in the water-vapor content of the atmosphere has been determined to be an important consequence of an increasing temperature at the Earth’s surface. The physical phenomena and processes that are critical parts of this interaction are tightly coupled to the temperature distribution, primarily in the vertical direction, in the atmosphere. Accurate calculation of the response will require accurate calculation of the temperature distribution.
The several radiative-energy transport aspects of clouds, almost all represented by parameterizations, are critically important. Clouds are the primary contributor to the numerical value of the albedo. Water vapor is not transparent to radiative-energy transport for infrared energy. Such mundane aspects as representation of the variation of the vapor pressure of water with respect to temperature are also importance. Let’s ignore other aspects of the solid and liquid phases of water in the atmosphere and all the other suspended particulate matter.
None of these critically important first-order phenomena and processes can be calculated from first principles and instead are handled with empirical data and / or parameterizations.
As these are the critical aspects of the AGW hypotheses, calculated results should be compared with data measured for the these phenomena and processes. While the data might not be of the highest quality due to the enormous temporal and spatial scales for the problem, comparisons with these directly related aspects are preferable over comparisons with the usual much more indirect aspects. To note the direct relationship to the AGW hypotheses, if the temperature is increasing, the OLR must be increasing as a reflection of the increasing temperature.
WGI SPM Contribution
I have looked at the WGI contribution to the SPM. I don’t see any discussions of these aspects of the problem and I don’t find comparisons of calculations with data for these processes. I consider this to be an important shortcoming. Direct testing of hypotheses is critical to increasing confidence in both the hypotheses and the models and methods developed to investigate these.
Energy Balance and Budget and Models
There are other important related issues relative to the models and calculations. What level of accuracy in the basically empirical models of the first-order interactions described above will be necessary to accurately resolve the relatively small changes in the radiative-energy balance. Specifically, can the temporal-averge, whole-Earth albedo be determined to the required degree of fidelity. Can the effects of water vapor and clouds, on both ultra-violet and infrared energy, be determined to the required degree of fidelity. Can the estimated change in the Earth’s response due to increasing CO2 concentrations even be detected in the measured data?
The calculations with GCMs are known to use a relatively course spatial resolution. Has the spatial resolution that is necessary to accurately resolve the temperature distribution and its associated effects through water vapor and clouds, of the radiative-energy balance been determined.
The estimates of the magnitude of the perturbations in the energy balance of the Earth’s systems due to all the changes in the systems made by humans is small; a few ( maybe 5 ) Watts per square meter. I think the documentation that is available in the open literature for the GCMs is not sufficiently detailed to determine the degree to which accurate accounting of the mass and energy equations is attained. Additionally, the fidelity of the model is equally affected by the treatment of the model’s equations beyond the continuous-equation stage.
The calculated initial energy content of the Earth’s systems, for example, will be a function of the spatial resolution used at run time. Conservation of that initial energy, plus accurate accounting for the gains and losses, especially in the inter-systems transfer of sensible energy and the inter-phase transfer for those processes that involve phase change, is critically dependent on the several aspects of the numerical solution methods. Ensuring that the discrete approximations conserve energy and careful attention to the time-level at which the various terms are evaluated are critically important. Different time levels for the temperatures of materials that exchange sensible energy, for example, introduces numerical non-conservation of energy. As do the time levels for processes associated with phase change. As do the time levels for all discrete approximations that model driving gradients.