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Method for modernization of Brewer and Dobson spectrophotometers

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Method for modernization of Brewer and Dobson spectrophotometers Powered By Docstoc
					                     How to modernize the Brewer and Dobson’s
                      spectrometers to remove the aerosol error
                  Asadov Hikmat Hamid, doctor of technical sciences,
            chief of department of Azerbaijan National Aerospace Agency
                               Hasadzade 2001@yahoo.com
                 Azerbaijan, Baku, AZ1033, Azadlig ave. 159. ANASA


     As it can be seen from proceedings of the late XX Quadrennial Ozone
Symposium one of the main questions arisen before space ozone measurement is to
prove validity of space measurements by carrying out comparison with results of
appropriate ground measurements. In more than 20 papers submitted to above
Symposium it is stated that difference between two said measurements has reached
approximately 1,5 – 2 % and further improvement of space measurements is limited
by non – similarity of results of Dobson and Brewer spectrometers which are used as
a basis for ground measurements.
     Henceforth, further improvement of space measurements of total content of
ozone is useless till development of new methods, which should substitude obsolete
Dobson’s method and its modifications. One of such methods was proposed by
ourselves [1, 2, 3]. It should be noted, that proposed three – waves method is
designated for ground ozone total content measurements and can be realized in two
modifications:
   1. Spectrometer with full compensation of aerosol error.
   2. Spectrometer with full mutual compensation of aerosol error and error due to
       Reyleigh scattering.
     The algorithm of the method may be described as secuence of following steps:
     1. To carry out measurements of solar flux in wavelengths 1 , 2 , 3 , where
1  2  3 , (may be 1  300 nm; 2  312 ,5 nm and 3  315 nm ). As a result we
obtain relevant values of solar flux S1 , S 2 and S 3 .
     2. To carry out following calculations
                                                      S1  S 3
                                          S rel  2                             (1)
                                                        S2
     3. To change the value of 2 till meeting of following conditions:
     a) in the first modification of proposed method the aerosol error should be
decreased down to zero by relevant selection of 2 .
     b) in the second modification of proposed method the aerosol error should be
compensated with error due to Reileigh scattering by appropriate selection of 2 .
     Mathematical grounding of above is based on well – known Beer’s Law
                                 S    S0  10  X  m   m1                                             (2)
Where all used indices are well known and there is no necessity to describe them.
     Taking into account formulas (1) and (2) we have
                                       1   3                    3             1   3          
               S   S     X 
                                                       2   m  1
                                                                                2   
                                                                                                         2   
                                                                                                                  
       S rel  0 1 0 3 10                                                                                  
                                           2                            2                        2                 
                                                                                                                        (3)
                 S0 2 
It is obvious, that the first condition of above algorithm is met if
                                            1   3
                                                                 2                                                   (4)
                                                      2
It is also obvious, that the second condition of above algorithm is met if
                                   1   3              1   3
                                                                          2   2                                  (5)
                                      2                        2
     As a result we obtain main conditions making it possible to construct accurate
three waves type spectrometers, where continual adjustment of wavelength 2 allow
us to remove error components.
                                         References:
1. Patent of Azerbaijan Rebublic No. a20030134 dated 23.06.03. Three waves
ozonometer. Authors: Asadov H.H., Isayev A.A.
2. Asadov H.H., Aliyev M.M., Isayev A.A.The universal theory of the three – waves
ozonometric measurements “Physics” Journal of AzNAS Institute of Physics, V.X.,
2004, p. 50.
3. Three waves method for measurement of total content of ozone. Full compensation
of measurements error. Asadov H.H., Isayev A.A. Procedings XX Quadrennial
Ozone Symposium, 1-8 June 2004, Kos, Greece, v.1, p. 477.

				
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Description: The new method for ozone total content in atmosphere is suggested