Airborne multi-axis DOAS measurements of tropospheric SO2 plumes in the Po-valley, Italy

[摘要] During the second FORMAT (FORMaldehyde as A Tracer of oxidation in the troposphere)campaign in 2003 the airborne multi-axis DOAS instrument (AMAXDOAS) performedscattered-light spectroscopic measurements of SO₂ overthe city of Mantovaand the power plant Porto Tolle, both situated in the Po-valley, Northern Italy.The SO₂ vertical columns and emission flux were derived from two days ofmeasurements, 26 and 27 September 2003. The SO₂ emission flux from the powerplant Porto Tolle was calculated to 1.93×10²⁵ molec s^-1 on26 September and in good agreement with official emission data, which quote2.25×10²⁵ molec s^-1. On 27 September the measured flux wasmuch lower (3.77×10²⁴ molec s^-1) if ECMWF wind data are used,but of comparable magnitude (2.4×10²⁵ molec s^-1) if theaircraft on-board wind measurements are utilised. Official emissiondata was 2.07×10²⁵ molec s^-1 indicating only a smallchange from the previous day. Over the city of Mantova,the observed SO₂ vertical columns were 1.1×10¹⁶ molec cm^-2and 1.9×10¹⁶ molec cm^-2 on 26 and 27 September,respectively. This is in good agreement with ground-based measurementsof 5.9 ppbv and 10.0 ppbv which correspond to1.2×10¹⁶ molec cm^-2 and2.2×10¹⁶ molec cm^-2 if awell mixed boundary layer of 500m altitude is assumed.

[学科分类] 大气科学