US EPA

1718362 

Journal Article 

Relative optical mass functions for air, water vapour, ozone and nitrogen dioxide in atmospheric models presenting different latitudinal and seasonal conditions 

Tomasi, C; Vitale, V; De Santis, LV 

1998 

1 

Meteorology and Atmospheric Physics
ISSN: 0177-7971
EISSN: 1436-5065 

65 

1-2 

11-30 

WOS:000072958000002 

A study of the dependence features of the relative optical mass functions for air, water vapour, ozone and nitrogen dioxide on the apparent solar zenith angle theta was performed by calculating these optical parameters by means of the well-known computer code LOWTRAN 7 at several values of theta and for nine atmospheric models characterized by different latitudes and seasons. Moreover, other investigations were performed on the dependence features of (i) the relative optical air mass on the thermal characteristics of the low troposphere, (ii) the relative optical water vapour mass on the vertical distribution characteristics of absolute humidity in the troposphere, and (iii) the relative optical mass function for ozone and nitrogen dioxide on the shape characteristics of the vertical profiles of the two gaseous concentrations and the concentration peak altitudes. The results are compared with the values given by the two simple formulas proposed by Kasten (1966) for air and water vapour and the formulas defined by Young (1969) and Staehelin et al. (1995) for ozone and nitrogen dioxide. From this comparison, a wide set of correction factors were obtained which can be conveniently used in the analysis of multispectral sun-radiometric measurements for calculating, with a very high precision, the values of the four optical mass functions at all the angles theta in the 0 degrees to 87 degrees range, corresponding to the various latitudinal and seasonal conditions described by the nine atmospheric models.