Open AccessDistribution of hydrogen peroxide and methylhydroperoxide over the Pacific and South Atlantic Oceans
Author(s) -
O'Sullivan D. W.,
Heikes B. G.,
Lee M.,
Chang W.,
Gregory G. L.,
Blake D. R.,
Sachse G. W.
Publication year - 1999
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 - 10.1029/98jd01250
Subject(s) - equator , latitude , troposphere , northern hemisphere , altitude (triangle) , atmospheric sciences , mixing ratio , environmental science , southern hemisphere , climatology , oceanography , geology , geometry , mathematics , geodesy
The gas phase hydrogen peroxide and methylhydroperoxide concentrations were measured in the troposphere over the tropical Pacific Ocean as a component of NASA's Global Tropospheric Experiment/Pacific Exploratory Mission‐Tropics A field campaign. Flights on two aircraft covered the Pacific from 70°S to 60°N and 110°E to 80°W and South Atlantic from 40°S to 15°N and 45°W to 70°E, and extending from 76 to 13,000 m altitude. H 2 O 2 and CH 3 OOH have the highest concentrations at a given altitude at the equator and decrease with increasing latitude in both the northern and southern hemispheres. Above 4 km the gradient is substantially reduced for both H 2 O 2 and CH 3 OOH with latitude, and at altitudes in excess of 8 km there is no latitudinal dependence. H 2 O 2 and CH 3 OOH exhibit maximum mixing ratios between 1 and 2 km at all latitudes. The mean mixing ratio of H 2 O 2 at the equator was 1600±600 parts per trillion by volume (pptv) decreasing to 500±250 pptv at latitudes greater than 55° north and south between 1 and 2 km altitude. CH 3 OOH at the equator was 1400±250 pptv, decreasing to 330±200 pptv at high latitudes at altitudes between 1 and 2 km. The concentration of peroxides at high latitudes in the northern hemisphere was generally a factor of 2 higher than at corresponding latitudes in the southern hemisphere. The ratio of H 2 O 2 to CH 3 OOH was between 1 and 2 from 45°S to 35°N at altitudes below 4 km. Between 5° to 15°N the ratio is less than 1, due to preferential removal of H 2 O 2 in the Intertropical Convergence Zone.