RADIATION SYMPOSIUM, LENINGRAD, 1964 By P. G. ABEL and D. R. PICK Clarendon Laboratory, Oxford

HE Third International Symposium on radiation processes was held in T Leningrad from 6 to 12 August 1964, with visits to the Main Geophysical and Main Astronomical Observatories nearby in the following days.

Three hundred and fifty delegates from 30 countries were present, the largest delegations coming from the U.S.S.R. and the U S A . who together provided more than 230 delegates. Over 140 papers were presented but of these half were read by title only so as to give a reasonable time for discussion. The conference was held in the Tauride Palace, an imposing building in central Leningrad dating back to the reign of Catherine I1 and now used permanently as a conference centre.

The diversity of languages presented a formidable problem, but this was adequately handled by the symposium interpreters and particularly the ability of most of the participants to speak English.

The proceedings were divided into six sections. The first, on the theory of radiative transfer in planetary atmospheres, was convened by Professor 2. Sekera (University of California). Infra-red spectroscopy of the atmosphere occupied the second session, and was organized by Dr J. N. Howard (Cambridge Research Laboratory, Lexington, Mass.). Professor M. I. Budyko (Main Geophysical Observatory, Leningrad) convened the third session on radiation climatology. On the fourth day, Professor R. M. Goody (Harvard University) led the discussion on radiation problems as related to atmospheric dynamics and the general circulation. The conveners of the fifth day’s session on surface and network instrumentation were Drs A. J. Drummond (Eppley Laboratory, Newport, R.I.) and Y. D. Yanishevsky. The final meeting discussed experimental investigation of the radiation field in the free atmosphere, and was organized by Drs A. Y. Kondratyev (Leningrad University) and D. Q. Wark.

The symposium was opened by Professor F. Moller who then handed over to Professor Sekera, the convener of the first day’s session on the theory of radiation transfer in planetary atmospheres.

In his paper, Professor Sekera gave a review of recent mathematical theories of radiative transfer. The general solution of any problem in radiative transfer requires two stages, firstly the formulation of the problem in terms of equations in matrix form and secondly the reduction of these equations to a form suitable for numerical computation. The recent advances in these methods have made it computationally feasible to solve such problems as the broadening of absorp-

tion lines due to scattering and the effect of scattering on atmospheric emission. Dr W. S. Benedict started off the section on Infra-red Spectroscopy of the

Atmosphere with a very good review of the present theoretical state of the interpretation of detailed structure of molecular bands in the atmosphere. Dr Benedict pointed out the importance of weak lines, including ‘hot’ vibrational lines, lines from the isotopic species and intervibrational lines (with particular reference to water vapour). He also discussed recent work on Fermi resonance, chiefly in carbon dioxide, and vibrational rotational inter-action in carbon dioxide giving mixing of levels.

Professor Budyko, the Director of the Main Geophysical Observatory, spoke on the study of the solar radiation received at the earth’s surface. The con- siderable expansion of actinometric stations over the earth’s surface during the I.G.Y. resulted in sufficient radiation data for an Atlas of the Heat Balance of the Globe to be compiled by workers a t the observatory. This Atlas contains world annual and monthly mean maps of global short-wave radiation, radiation- balance and other components of the heat balance at the earth’s surface. At the same time, observations have been made of diurnal changes in the radiation regime in different climatic zones. These observations have been used to practical effect in estimating such factors as evaporation from a land surface and the rate of photosynthesis in vegetation.

Later papers included one by Dr Manabe, who gave a comprehensive review of the influence of radiative transfer on the general circulation of the atmosphere, and went on to describe the results of his own numerical computa- tions. Manabe assumed an initial resting isothermal atmosphere, and that the only radiation absorbers were carbon dioxide, water vapour, ozone and water- droplet clouds. Using the annual mean value of the extraterrestial insolation, the form of the temperature and wind distribution after two hundred days was computed. The temperature structure agreed well with that observed, giving both the tropopause and the general form of stratospheric temperature- distribution. The height of the jet stream agreed with that observed, but its velocity was much larger.

In the final session on the experimental investigation of the atmospheric radiation field, the delegates heard of Professor Kondratyev’s work with balloon- mounted apparatus. Using standard instruments, measurements of the values of global, direct solar and reflected radiation, radiation-balance, ozone distribu- tion, temperature, humidity and pressure have been recorded over a wide range of’conditions and altitudes up to 30 km.

The conference ended on a lively note with Dr J. Hampson contributing a paper on chemical instability in the stratosphere. He correlated experimental measurements of ozone in the stratosphere with a photochemical theory. An interesting consequence of his theory was that the stratosphere could have two stable structures, one wet and the other dry, with only a relatively small energy- change for a transition between the two states. The consequence would be a much cooler troposphere, modifying the weather, with the stable system of comparatively high ozone-concentration prevailing in the stratosphere.

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Phofograph by P . G . rlbel and D . R . Pick

Part of the impressive enclosure at Voyeykovo Geophysical Observatory, Leningrad, showing some of the instruments used for measuring radiation

VISITS

The Main Leningrad Geophysical Observatory is situated in Voyeykovo, 30 km from the city, in an isolated area in a range of low hills, and covers a considerable area. Of particular interest to us was the meteorological instru- ment testing area, in which the measurements from various types of instruments were compared and recorded in an elaborate underground control room. Experiments were being made on the effect of altering the height above the ground of rainfall apparatus, and relating the results to the wind profile up to about 2 m.

This observatory also housed an impressive display of meteorological apparatus dating back to the turn of the century, including some very early actinometers. There was also included a set of meteorological sondes from many nations.

Professor Kondratyev's laboratory in Leningrad University was very similar to a laboratory in this country; on an informal visit we were shown some of the balloon apparatus, including a very elegant sun seeker and we heard of work carried out there on the effect of aerosols in the atmosphere.

The final scientific visit was to the Main Astronomical Observatory in Pulkovo.

We are grateful to the Royal Meteorological Society for a grant towards travelling expenses

JET STREAM AND LENTICULAR CIRRUS (Photographs on page 222)

JET-STREAM CIRRUS. This photograph was taken looking north-east from Bracknell, Berkshire, at 1030 GMT, 31 December 1964. It shows both the typical abrupt edge and the banded structure of an extensive system of cirrus and cirrostratus accompanying a jet stream. The jet core lies within the clear air not far from, and parallel to, the cloud edge. On this occasion winds approaching 150 kt were recorded near 30,000 ft.

CIRRUS LENTICULARIS, looking west from Bushey Park, Teddington, Surrey, 1035 GMT, 19 August 1962. A t the time, an occluding depression was moving slowly north-east some 500 miles north-west of Britain, with its front lying north to south along the west coast of Ireland. Winds at cloud level were westerly as the upper ridge ahead of the depression moved slowly east. This photograph shows cirrus in the form of lenticular patches somewhat fused together. The fibrous structure normally so typical of cirrus is here largely absent, suggesting that the clouds are so new (perhaps only 15 minutes old, or even less) that none of the constituent crystals have yet had enough time to grow large and fall out, and so become sorted by gravity into streaks.

NOTES FROM EAST AFRICA, No I

The levels of Lake Victoria since 1899 at Jinja Gauge are shown in Fig. I below. The natural outlet of Lake Victoria at Jinja was closed when the Owens Falls Dam was completed in April 1954, but the dam was so constructed that the natural rate of outflow from the lake could be maintained. There was restricted flow at Jinja during constructional work from January 1950 to Decem- ber 1953.

The recent abrupt rise of water level (see Fig. I) has also been experienced in other East African lakes-Nyasa, Tanganyika, Edward, Albert, Naivasha, Rukwa, etc. Fig. z (opposite) shows rainfall anomaly map of East Africa for the period when the lakes began to rise to their present record levels.

The information in this note is contributed by Mr U. W. Thompson and Dr H. T. MBrth Data for Fig. I were supplied by the of the East African Meteorological Department.

Director, Water Development Department, Entehbe, Uganda.

Fig. I . Levels of Lake Victoria since 1899 at Jinja Gauge (Ft above datum)

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