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Tropospheric BrO from GOME measurements


Introduction    Data   Animated Images  References    Links    Contact

Top Introduction:

Ground based observations of ozone in the polar boundary layer have shown frequent episodes of extremely low concentrations in polar spring in both hemispheres. These “low ozone events” are accompanied by strong increases in filterable bromine and also in bromine oxide (BrO). It is assumed, that boundary layer ozone is destroyed by halogen catalysed cycles very similar to those operating in the stratosphere, but with a strong emphasis on bromine compounds and recycling on and in aerosols rather than in the gas phase. How the bromine is released in the atmosphere is not fully understood, but frost flowers forming on new sea ice or aerosol created from wind blown frost flowers are the most probable explanation.

More recently, a link has also been established between low ozone events and the conversion of gaseous to particulate mercury compounds and subsequent deposition on snow/ice. This is an important mechanism of mercury injection into the polar biosphere, and probably is the reason for the enhanced Hg levels observed in the Arctic and also people strongly depending on sea food. 

 

 

With the GOME instrument, it is for the first time possible to map tropospheric BrO on a global scale, even in remote regions and over the ice caps. The measurements show, that bromine activation (and therefore low ozone) in the boundary layer is not an episodic event but rather a regular feature of polar spring in both hemispheres and extends over large areas and several weeks. BrO in the two hemispheres shows systematic differences that are linked to the different sea land distribution. In the North, most BrO is formed along the coast lines of the Arctic sea, over the polar ice cap and also over the Hudson Bay. In the South, a ring like structure of BrO forms over the ice sheet around Antarctica, but little BrO is found over the continent itself. A similar observation can be made in Greenland. This can be understood if sea ice and some open water is necessary in the BrO formation, a condition found along coast lines and over broken ice but not inlands.

Top Data:

Daily images of total BrO columns based on GOME Near Real Time data can be found on the GOME NRT page.

Daily and monthly averages can be downloaded as ASCII files on our data page.

Monthly averages for the two hemispheres can be viewed from the links below:

NH 1996 Jan Feb Mar Apr May Jun Jul Aug Sep Oct Nov Dec
NH 1997 Jan Feb Mar Apr May Jun Jul Aug Sep Oct Nov Dec
NH 1998 Jan Feb Mar Apr May Jun Jul Aug Sep Oct Nov Dec
NH 1999 Jan Feb Mar Apr May Jun Jul Aug Sep Oct Nov Dec
NH 2000 Jan Feb Mar Apr May Jun Jul Aug Sep Oct Nov Dec
NH 2001 Jan Feb Mar Apr May Jun Jul Aug Sep Oct Nov Dec
NH 2002 Jan Feb Mar Apr May Jun Jul Aug Sep Oct Nov Dec
NH 2003 Jan Feb Mar Apr May Jun
SH 1996 Jan Feb Mar Apr May Jun Jul Aug Sep Oct Nov Dec
SH 1997 Jan Feb Mar Apr May Jun Jul Aug Sep Oct Nov Dec
SH 1998 Jan Feb Mar Apr May Jun Jul Aug Sep Oct Nov Dec
SH 1999 Jan Feb Mar Apr May Jun Jul Aug Sep Oct Nov Dec
SH 2000 Jan Feb Mar Apr May Jun Jul Aug Sep Oct Nov Dec
SH 2001 Jan Feb Mar Apr May Jun Jul Aug Sep Oct Nov Dec
SH 2002 Jan Feb Mar Apr May Jun Jul Aug Sep Oct Nov Dec
SH 2003 Jan Feb Mar Apr May Jun

If you have specific requests for plots or data, please contact Andreas Richter.

Top Animated Images:

Below you can view or download animated GIF-files of Arctic and Antarctic BrO as measured by GOME during the spring periods. The files are about 3 MByte each. Please note, that no cloud correction has been performed and therefore some BrO might be hidden below clouds. The images are three day composites, showing the maximum value observed during this time period.  

NH 1997 SH 1997
NH 1998 SH 1998
NH 1999 SH 1999
NH 2000 SH 2000
NH 2001 SH 2001
NH 2002 SH 2002

Top References:

Top Links:

Top Contact:

If you are interested in more information or GOME BrO data, please contact Andreas Richter.