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Highly elevated carbon monoxide concentrations in the upper troposphere and lowermost stratosphere at northern midlatitudes during the STREAM II summer campaign in 1994

1999; Elsevier BV; Volume: 1; Issue: 1-3 Linguagem: Inglês

10.1016/s1465-9972(99)00027-6

1873-6467

A. Waibel, Hubertus Fischer, Frank G. Wienhold, P. Siegmund, Byung-ll Lee, J. Ström, Jos Lelieveld, Paul J. Crutzen,

Atmospheric Ozone and Climate

During the second Stratosphere Troposphere Experiment by Aircraft Measurements (STREAM II) five flights up to 12 km altitude were performed over the North Sea, Great Britain, The Netherlands, and Germany, with a Cessna Citation II twin jet aircraft during the period 20–29 July 1994. Carbon monoxide (CO) concentrations in the lowermost stratosphere, which were measured by tunable diode laser absorption spectroscopy, varied between typical background values around 40 parts per billion by volume (ppbv) and highly elevated levels of up to 300 ppbv. The high CO concentrations were observed before a cold front passed over western Europe. The enhanced CO abundance was most probably caused by boreal fires in Canada in connection with convective mixing and subsequent horizontal advection over the North Atlantic Ocean.