• NEANIAS Atmospheric Research Community

Results from the aeroshell-mounted neutral mass spectrometer on Viking I indicate that the upper atmosphere of Mars is composed mainly of CO(2) with trace quantities of N(2), Ar, O, O(2), and CO. The mixing ratios by volume relative to CO(2) for N(2), Ar, and O(2) are about 0.06, 0.015, and 0.003, respectively, at an altitude near 135 kilometers. Molecular oxygen (O(2)(+)) is a major component of the ionosphere according to results from the retarding potential analyzer. The atmosphere between 140 and 200 kilometers has an average temperature of about 180 degrees +/- 20 degrees K. Atmospheric pressure at the landing site for Viking 1 was 7.3 millibars at an air temperature of 241 degrees K. The descent data are consistent with the view that CO(2) should be the major constituent of the lower martian atmosphere.

This review is devoted to problems in the photochemical modeling of atmospheric processes. The physicochemical and mathematical foundations underlying the construction of photochemical models are described, a classification of the atmospheric reactions is presented, and the features of photochemical modeling are considered under various irradiance conditions for various atmospheric layers and geographical regions. Atmospheric processes that are important to photochemical models are discussed. Applications involving photochemical models are outlined. Some results are presented to illustrate the capabilities of photochemical models. Special attention is given to relatively recent directions in photochemical modeling, such as data assimilation and inverse problems. The review can be used by experts in areas related to atmospheric chemistry as a basic source of knowledge on the subject and for the development of photochemical modules for atmospheric models.

Energy and the Atmosphere: A Physical-Chemical Approach. By Ian M. Campbell. Pp. 398. (Wiley: Chichester, Sussex, New York and Sydney, 1977.) Hardback £14.50, $31; paperback £5.95, $12.50.

The earth's thermosphere is that region of the atmosphere above the mesopause (80–90 km) where the neutral gas temperature begins to increase from about 200°K to values as high as 600–2,000°K depending upon solar activity. The dynamics of this region of our atmosphere is primarily governed by solar EUV and UV heating, heat and momentum sources associated with high-latitude auroral processes, upward-propagating tides and waves from the lower atmosphere, and ion drag interactions with the ionosphere. The general properties of the thermosphere and the research on thermospheric dynamics prior to 1979 have been reviewed previously in this IUGG series by Dickinson (1975) and Mayr and Harris (1979). Ionospheric processes and large-scale neutral gas-plasma interactions have been reviewed by Evans (1975), and reviews covering thermospheric composition have been given by Carrignan (1975) and Hedin (1979).

Continuous measurements of total ozone (by Dobson spectrophotometers) across the contiguous United States began in the early 1960s. Here, we analyze temporal and spatial variability and trends in total ozone from the five US sites with long-term records. While similar long-term ozone changes are detected at all five sites, we find differences in the patterns of ozone variability on shorter timescales. In addition to standard evaluation techniques, STL-decomposition methods (Seasonal Trend decomposition of time series based on LOESS (LOcally wEighted Scatterplot Smoothing)) are used to address temporal variability and "fingerprints" of dynamical features in the Dobson data. Methods from statistical extreme value theory (EVT) are used to characterize days with high and low total ozone (termed EHOs and ELOs, respectively) at each station and to analyze temporal changes in the frequency of ozone extremes and their relationship to dynamical features such as the North Atlantic Oscillation (NAO) and El Niño–Southern Oscillation. A comparison of the fingerprints detected in the frequency distribution of the extremes with those for standard metrics (i.e., the mean) shows that more fingerprints are found for the extremes, particularly for the positive phase of the NAO, at all five US monitoring sites. Results from the STL decomposition support the findings of the EVT analysis. Finally, we analyze the relative influence of low- and high-ozone events on seasonal mean column ozone at each station. The results show that the influence of ELOs and EHOs on seasonal mean column ozone can be as much as ±5 %, about as large as the overall long-term decadal ozone trends.

In September 1848 Her Majesty’s ships Enterprize and Investigator entered the harbour of Port Leopold, in latitude 74° N. and longitude 91° W., for the purpose of establishing there a depot, of provisions, and of extending, in boats, the examination of the north, south, and west coasts of North Somerset, in search of the missing expedition under the command of Sir John Franklin.