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| Titel |
The Vertical Distribution of BrO and Aerosols in the Arctic: Measurements by Active and Passive DOAS |
| VerfasserIn |
Udo Frieß, Holger Sihler, Rolf Sander, Denis Pöhler, Ulrich Platt |
| Konferenz |
EGU General Assembly 2011
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| Medientyp |
Artikel
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| Sprache |
Englisch
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| Digitales Dokument |
PDF |
| Erschienen |
In: GRA - Volume 13 (2011) |
| Datensatznummer |
250046569
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| Zusammenfassung |
| We present results from Multi-Axis Differential Optical Absorption Spectroscopy
(MAX-DOAS) and Long-Path DOAS (LP-DOAS) measurements performed at the North
Slope of Alaska from February to April 2009 as part of the OASIS Barrow 2009 campaign.
For the first time, vertical profiles of aerosol extinction and BrO concentration in the
boundary layer were retrieved simultaneously from MAX-DOAS measurements using
optimal estimation. Even at very low visibility, retrieved extinction profiles and aerosol
optical thickness are in good agreement with co-located ceilometer and Sun photometer
measurements, respectively. BrO surface concentrations of MAX-DOAS and LP-DOAS
are in very good agreement, and it has been found that useful information on the
vertical distribution of BrO can be retrieved from MAX-DOAS even in cases when
blowing snow strongly affects the light path. The retrieved BrO and extinction
vertical profiles allow for a thorough characterization of the vertical structure of the
boundary layer during numerous ozone depletion events observed during Barrow 2009.
High BrO concentrations are usually present during the onset of ozone depletion
events, and BrO disappears as ozone concentrations approach zero. The finding that
elevated BrO concentrations mainly occur under the presence of high extinction
near the surface strongly suggests that BrO release on airborne aerosols and/or ice
particles at high wind speed plays an important role. Back trajectory calculations
indicate that the particles were transported from the frozen ocean to the measurement
site, and that the release of BrO from sea ice and/or frost flowers occurs when low
temperatures (< 250 K) are present in the regions where reactive bromine is emitted. |
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