"Our planet is a comfortable spaceship with a perfectly adjusted system of life support, reliably protecting all the living matter from harmful influence of surrounding outer space." So begins the article "Astrophysicists Study the Earth Atmosphere" by Boris Somov, Dr. Sc. (Phys. & Math.), and Anatoly Khlystov, Cand. Sc. (Phys. & Math.) from the P. K. Shternberg State Astronomy Institute (GAISh) of Moscow State University, published in the magazine Earth and the Universe.
They have reminded us that magnetic field and oxygen-azotic atmosphere are the basis for earth system of life support. Water steam, carbonic acid and ozone, which occupy only 1 percent of the planet aerosphere, actively affect its characteristics. Therefore, when studying them, one should, first of all, recourse to astrophysical methods.
Referring, first and foremost, to the problems of climate changes*, the authors state that if our planet consisted of only azote, oxygen and argon, the average temperature of the planet surface would have been about −3°C due to thermal inertia. However, owning to the greenhouse effect** it reaches approximately +15°C. The matter is that in its cover there are small impurities of fumes of water, carbonic acid, methane, nitric oxide and gases of artificial nature transparent for visible solar radiation and at the same time absorbing infrared radiation. Due to this the latter doesn't go to space environment, which increases the average temperature of the Earth by approximately 18°C as compared to the atmosphere without impurities.
In a word, the main reason for warming which is lately observed is growth in the quantity of greenhouses gases in our aerosphere. The most efficient of them is water steam, though its mass has insignificantly changed for thousands of years compared to carbonic acid the quantity of which increased by 20 percent from 1880 to 1989 alone, 12 percent falling on 1958 - 1989. In case this situation persists, by 2030 its concentration will be doubled, which means climate warming will threaten life existence on the Earth.
By the way, the authors emphasized that the processes relating to creation of climate are extremely complicated and, therefore, quantitative estimations of global warming aren't accurate for the time being. The process of simulation of the atmosphere response to the changes of greenhouse gases concentrations, first of all, carbonic acid, causes the main vagueness in the calculations. Traditional local measuring procedures of CO2, the main component of emissions under the city conditions, do not give reliable average values of its mass for large megalopolis either. That's why GAISh scientists carry out relevant measures in the atmosphere of Moscow using the experience of the Universe exploration.
The work is carried out with the help of stationary facilities, namely, a ground-based telescope. Before entering its tube the light from remote cosmic bodies gets through the whole stratum of the Earth's atmosphere which, naturally, also becomes an object of observation.
To measure celestial bodies' velocities, Doppler effect is widely used*. In so doing, telluric (earth) lines** in spectrum serve as check points with relation to which displacements of spectral lines of stars, the Sun, planets, comets, etc. are defined. The mechanism of telluric lines formation shows physical conditions in the atmospheres of planets. With the help of specially developed techniques of calibration of spectrometric measurements, in the middle of the last century GAISh scientists discovered in Alma-Ata that the content of water steam in the mountains significantly changed.
Later on the scientists used radiation transfer control applied in astrophysics when exploring the space around stars, to calculate profiles of telluric lines of oxygen and water steam in the Earth's atmosphere, and they proved to be subject to seasonal variations. Then they managed to obtain the data relating to the temperature and atmospheric density of our planet. Afterwards, it was used when solving the significant applied problem - to ensure the most favorable conditions for laser emission advancing in the Earth's atmosphere.
The stored knowledge allowed native specialists to engage more closely in systematic measurements of greenhouse gases composition and, first of all, the most dangerous CO2 above Moscow. Thus, by selecting air samples in different districts of the capital, the employees of the RAS Institute of Applied Physics came to conclusion: industrial emissions of the latter above the city create apparent spatial dissimilarities
* See: L. Krasnokutskaya, "Serving the Science of Atmosphere," Science in Russia, No. 5, 2006. - Ed.
** See: Yu. Israel, "Threat of Climatic Catastrophe?", Science in Russia, No. 4, 2004. - Ed.
* Doppler effect is the change in the length of a wave (or in frequency of vibration) resulting from relative motion of the source and the receiver. - Ed.
** Telluric lines are absorption lines in spectra of extraterrestrial sources of radiation emerging when radiation interacts with molecules of azote, oxygen, ozone and water in the Earth's atmosphere. - Ed.
Graphic representation of greenhouse effect. Distribution of radiation energy by wave-lengths for the Sun and the Earth.
at the height of 350 - 500 m. In the substratum (50 m) they reach 10 percent of background value in the unfavorable meteorological situation. The worse situation (up to 15 percent) is observed with diurnal and/or seasonal cycles of serious anthropological emissions. It takes approximately a month to obtain the data characterizing a general situation in one or another district.
Also, the authors mentioned that the GAISh specialists had used lead sulphide cell cooled by carbon-dioxide ice as a radiation detector. They estimated the influence of CO2 variations on registered equivalent width of spectral lines-it shows what share of solar energy one or another line absorbs. The contribution of variation of the atmosphere low stratum (500 m) is calculated based on its medium model: only 9 percent of complete equivalent line width is created in the bottom layer. Taking into account the maximum possible (15 percent of variation) intensity of CO, industrial emissions, uncertainty in the estimations of its content does not exceed 1.5 percent, i. e. it is within the limits of reasonable errors. It turns out that the astrophysical techniques allow to monitor on a real-time basis, which makes it acceptable when solving the problems we are interested in.
Now domestic specialists use a solar telescope of a tower type with a spectrographic camera of high resolution. Owing to this, there was obtained the most accurate data about the spectra of our celestial body atmosphere from the distance of about 150 mln km. It is extremely significant in itself. Moreover, being a powerful projector, this device will light through the whole stratum of our atmosphere.
The records of the article about seasonal content of CO2 in the atmosphere, in particular, above Moscow are of interest. Here we mean the statistical data for 1992 - 1995. It was calculated that in the capital there are about 35 sunny days, and there are no more than 10 completely clear days. Since the distribution of clear days by months is not equal in it, the observations made in GAISh during different periods of year proved to be in a common multi-year row. As a result, it was proved that the concentration of CO2 usually reduces to the minimum at the end of summer and increases to the maximum during winter months. This relates to seasonal fluctuation of photosynthesis of plants and increase in industrial emissions of carbonic acid from autumn to spring due to increased fuel consumption for the heating of premises.
In 1991, starting to make regular observations of CO2 infrared lines as per the program of astrophysical researches of atmosphere above the city, GAISh specialists looked through the records of telluric lines of spectrum from the archives made in December 1969. It turned out that for 22 years separating these dates carbonic acid concentration in the air above the capital increased by approximately 48 percent. At the same time its planetary increase (from 1973 to 1991), according to the results of NOAA American laboratory monitoring, amounted to only 8 percent.
In 1998 - 1999, the GAISh obtained new records of spectra of CO2 molecule lines. It became clear that the content of carbon dioxide in Moscow air basin continues to increase. The latest observations in 2003 and 2005 definitely confirmed this conclusion. Scientists make a conclusion that suspension of growth in CO2 concentration content above the capital is the main problem of the day. The means for its solution are known: it is taking numerous production facilities using hydrocarbon fuel out of the city, as well as further autecologization of automobile transport.
B. Somov, A. Khlystov, "Astrophysicists Study the Earth Atmosphere", Earth and the Universe, No. 6, 2006
Prepared by Yaroslav RENKAS
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