Open AccessLatitudinal variations of trace gas concentrations in the free troposphere measured by solar absorption spectroscopy during a ship cruise
Author(s) -
Notholt J.,
Toon G. C.,
Rinsland C. P.,
Pougatchev N. S.,
Jones N. B.,
Connor B. J.,
Weller R.,
Gautrois M.,
Schrems O.
Publication year - 2000
Publication title -
journal of geophysical research: atmospheres
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.67
H-Index - 298
eISSN - 2156-2202
pISSN - 0148-0227
DOI - 10.1029/1999jd900940
Subject(s) - troposphere , trace gas , mixing ratio , tropics , atmospheric sciences , southern hemisphere , northern hemisphere , atmosphere (unit) , environmental science , climatology , geology , meteorology , physics , fishery , biology
The latitudinal variations of atmospheric trace gas column abundances have been measured during a ship cruise between 57°N and 45°S on the central Atlantic. The measurements were performed in October 1996 using high‐resolution solar absorption spectroscopy in the infrared. The analysis method employed permits the retrieval of the total column densities of 20 different trace gases and for a few compounds the vertical mixing ratio profiles. For CH 4 an interhemispheric difference of 3% was observed. The total columns of the shorter‐lived trace gases CO and C 2 H 6 , analyzed between 57°N and 45°S, reveal a slight maximum in the tropics and a substantial increase north of 45°N. The total columns of C 2 H 2 and HCN, detectable between 30°N and 30°S, reveal a maximum in the tropics of the Southern Hemisphere. For CH 2 O, studied between 57°N and 45°S, a well‐pronounced maximum is observed in the tropics. The profile retrieval gives high mixing ratios for CO, C 2 H 6 , and O 3 north of 40°N in the lower troposphere. In the tropics high concentrations are found for all three compounds in the entire troposphere, even above 12 km. The measurements have been used to estimate averaged mixing ratios of the trace gases for the free troposphere between 0 and 12 km. In the tropics the data give high values: for example, more than 200 pptv for HCN, 750 pptv for CH 2 O, 100 ppbv for CO and 100 pptv for C 2 H 2 . These values are comparable to or higher than what has been observed at midlatitudes, indicating the importance of biomass burning emissions on the tropospheric composition.