Formaldehyde and nitrogen dioxide over the remote western Pacific Ocean: SCIAMACHY and GOME-2 validation using ship-based MAX-DOAS observations
Item
Title (Dublin Core)
Formaldehyde and nitrogen dioxide over the remote western Pacific Ocean: SCIAMACHY and GOME-2 validation using ship-based MAX-DOAS observations
Description (Dublin Core)
In October 2009, shipborne Multi-Axis Differential Optical Absorption Spectroscopy (MAX-DOAS) measurements were performed during the TransBrom campaign over the western Pacific Ocean (≈ 40° N to 20° S). Vertical tropospheric trace gas columns and profiles of nitrogen dioxide (NO<sub>2</sub>) and formaldehyde (HCHO) as well as stratospheric NO<sub>2</sub> columns were retrieved in order to validate corresponding measurements from the GOME-2 and SCIAMACHY satellite instruments and to estimate tropospheric background concentrations of these trace gases. <br><br> All instruments reproduced the same characteristic, latitude-dependent shape of stratospheric NO<sub>2</sub>. SCIAMACHY and GOME-2 data differ by about 1% from each other while yielding lower vertical columns than MAX-DOAS morning values as a consequence of measurement time and stratospheric NO<sub>2</sub> diurnal cycle. Due to this diurnal cycle, an increase of 8.7 ± 0.5 × 10<sup>13</sup> molec cm<sup>−2</sup> h<sup>−1</sup> of stratospheric NO<sub>2</sub> was estimated from MAX-DOAS data at low latitudes during the day. <br><br> Tropospheric NO<sub>2</sub> was above the detection limit only in regions of higher anthropogenic impact (ship traffic, transport of pollution from land). A background column of 1.3 × 10<sup>14</sup> molec cm<sup>−2</sup> (or roughly 50 ppt boundary layer concentration) can be estimated as upper limit for the remote ocean, which is in agreement with GOME-2 monthly mean values. In the marine boundary layer close to the islands of Hokkaido and Honshu, up to 0.8 ppbv were retrieved close to the surface. <br><br> Background HCHO concentrations over the remote ocean exhibit a diurnal cycle with maximum values (depending strongly on weather conditions) of 4 × 10<sup>15</sup> molec cm<sup>−2</sup> for the vertical column at noontime. Corresponding peak concentrations of up to 1.1 ppbv were retrieved in elevated altitudes (≈ 400 m) around noon while maximum concentrations in the evening are close to the ground. An agreement between MAX-DOAS and GOME-2 data was found for typical vertical columns of 3 × 10<sup>15</sup> molec cm<sup>−2</sup> over the remote ocean at the time of overpass.
Creator (Dublin Core)
Peters, E.
Wittrock, F.
Großmann, K.
Frieß, U.
Richter, A.
Burrows, J. P.
Date (Dublin Core)
2018-01-15
Type (Dublin Core)
Text
Format (Dublin Core)
application/pdf
Identifier (Dublin Core)
10.5194/acp-12-11179-2012
https://acp.copernicus.org/articles/12/11179/2012/
Source (Dublin Core)
eISSN: 1680-7324
Language (Dublin Core)
eng
