Hugh W. Ellsaesser

A CLIMATOLOGY OF EPSILON (ATMOSPHERIC DISSIPATION)

Abstract Kolmogorovs structure functions for the longitudinal and transverse components of locally homogeneous isotropic turbulence are combined vectorially to obtain an expression which permits the evaluation of ϵ (atmospheric dissipation rate) from climatological data. This is used to derive climatological patterns of ϵ in the free atmosphere from Crutchers upper wind statistics of the Northern Hemisphere. The latter are combined with Kungs boundary-layer values to estimate the distribution of total atmospheric dissipation over the Northern Hemisphere.

Should we trust models or observations

Abstract Scientists and laymen alike already trust observational data more than theories—this is made explicit in all formalizations of the scientific method. It was demonstrated again during the Supersonic Transport (SST) controversy by the continued efforts to reconcile the computed effect of the 1961–1962 nuclear test series on the ozone layer with the observational record. Scientists, caught in the focus of the political limelight, sometimes, demonstrated their faith in the primacy of observations by studiously ignoring or dismissing as erroneous data at variance with the prevailing theoretical consensus- thereby stalling the theoretical modifications required to accomodate the observations.

Case Study of Feedbacks and Synergisms in a Doubled CO2 Experiment

Abstract A method is described for analyzing the feedback and synergistic contributions of temperature, water vapor, cloud cover, surface albedo and CO2 to the change in the radiation balance at the top of the atmosphere due to a perturbation in an annual-averaged zonal atmospheric climate model. The method is illustrated through analysis of a doubled CO2 experiment with the Lawrence Livermore. National Laboratory Statistical Dynamical Model (LLNL SDM). The method provides insight into the sensitivity of the model to feedback changes in individual parameters and how each parameter influences the effects of the others.

Cyclic Trends in Los Angeles Fine Participates

Noontime visibilities in downtown Los Angeles, averaged over the smog season of June through November, show two cycles of general deterioration and improvement. The improvement since 1962 is confirmed by available high volume filter data and conditions in 1974/75 are at least as good as at anytime since observations were begun in 1933. The decrease in frequency of “rule 57” days suggests that the improvement of the last decade and perhaps the cyclic variation of the past 40 years has been primarily of meteorological origin.

Long path optical extinction and meteorology in the San Francisco Bay area

Abstract Comparison of night-time long path extinction (25 km) across San Francisco Bay and local meteorological measurements at Oakland Airport revealed a dominant role of boundary layer mixing on visibility. Inversion depth and inversion depth multiplied by wind speed were both strongly inversely correlated with night-time atmospheric extinction. Oakland Airport wind speed and humidity showed little correlation with the extinction measurements. Stellar extinction was also found to be sensitive to mixing depth. This is important as visibility and turbidity trend studies rarely include mixing depth measurements. These results indicate the importance of developing instruments to use the same light source for remote sensing of atmospheric constituents, wind and humidity.

WIND VARIABILITY AS A FUNCTION OF TIME

Abstract Kolmogorovs structure functions for longitudinal and transverse components of isotropic turbulence when combined vectorially provide a prediction that vector time variability of the horizontal wind should vary as the cube root of the lag period. Published wind variability data are examined and found to be generally consistent with this prediction for time periods of up to 4 to 6 hr and, when representative of the hemispheric mean excluding the tropical stratosphere, may be consistent with such a prediction for periods of up to 24 to 36 hr.

Understanding why models agree (or disagree)

A number of attempts have been made to model the climatic impact of increasing atmospheric CO/sub 2/. All of the models indicate that warming will result from a doubling of atmospheric CO/sub 2/. The range of results is rather wide, however, with some indicating a global warming of the earths surface by as much as 3.9/sup 0/C and others by as little as 0.3/sup 0/C. Some of the differences in the modeling approaches are discussed. An overall summary of model characteristics and sensitivities to increased atmosphere CO/sub 2/ is presented in table form. This table describes the main features of the various models and their responses, in terms of the increase in surface air temperature, to a doubling of the present day CO/sub 2/ concentration.

Decomposition of radiational effects of model feedbacks

Three separate doubled CO2 experiments with the LLNL SDM (statistical dynamic model) are used to illustrate our efforts to study the climate dynamics, feedbacks and interrelationships of meteorological parameters by decomposing and isolating their individual effects on radiation transport.

Ozone destruction by catalysis: Credibility of the threat

Abstract In an effort to assess the credibility of predictions concerning the O3 layer and to pinpoint avenues for improving current stratospheric models, a review was undertaken of observational data believed to have a bearing on the validity of destruction of stratospheric O3 by catalysis. Aside from short period responses of O3 above 20 km to PCAs and changes in solar flux, no data were found to confirm catalytic destruction both qualitatively and quantitatively. Predicted changes following such perturbations as nuclear tests, solar cycle modulation of cosmic rays, PCAs and volcanic eruptions cannot be clearly identified in the total O3 observations. Observed variations in total O3 appear to have been controlled by processes not included in current stratospheric models. As a minimum, it is concluded that predictions regarding stratospheric O3 do not, at present, warrant the confidence implied by CIAP.