Journal cover Journal topic
Biogeosciences An interactive open-access journal of the European Geosciences Union
Journal topic
Discussion papers
https://doi.org/10.5194/bg-2019-103
© Author(s) 2019. This work is distributed under
the Creative Commons Attribution 4.0 License.
https://doi.org/10.5194/bg-2019-103
© Author(s) 2019. This work is distributed under
the Creative Commons Attribution 4.0 License.

Submitted as: research article 26 Mar 2019

Submitted as: research article | 26 Mar 2019

Review status
This discussion paper is a preprint. A revision of the manuscript is under review for the journal Biogeosciences (BG).

Air–Sea Fluxes of Greenhouse Gases and Oxygen in the Northern Benguela Current Region During Upwelling Events

Eric J. Morgan1,a, Jost V. Lavric1, Damian L. Arévalo-Martínez2, Hermann W. Bange2, Tobias Steinhoff2, Thomas Seifert1, and Martin Heimann1,3 Eric J. Morgan et al.
  • 1Max Planck Institute for Biogeochemistry, Jena, Germany
  • 2GEOMAR Helmholtz Centre for Ocean Research, Kiel, Germany
  • 3Institute for Atmospheric and Earth System Research (INAR)/Physics, University of Helsinki, Finland
  • anow at: Scripps Institution of Oceanography, La Jolla, CA, USA

Abstract. Ground-based atmospheric observations of CO2, δ(O2/N2), N2O, and CH4 were used to make top-down estimates of the air–sea fluxes of these species from the Lüderitz and Walvis Bay upwelling cells in the northern Benguela region, during upwelling events. Average flux densities (±1σ) were 0.64 ± 0.4 μmol m−2 sec−1 for CO2, −5.1 ± 1.4 μmol m−2 sec−1 for O2 (as APO), 0.57 ± 0.3 nmol m−2 sec−1 for N2O, and 4.3 ± 5.5 nmol m−2 sec−1 for CH4. A comparison of our top-down flux estimates with shipboard-based measurements showed good agreement between both approaches. During the study, upwelling events were sources of CO2, N2O, and CH4 to the atmosphere. N2O fluxes were fairly low, in accordance with previous work suggesting that the evasion of this gas from the Benguela is smaller than for other Eastern Boundary Upwelling Systems (EBUS). Conversely, CH4 release was quite high for the marine environment, a result that supports studies that indicated a large sedimentary source of CH4 in the Walvis Bay area. These results demonstrate the suitability of atmospheric time series for characterizing the temporal variability of upwelling events and their influence on the overall marine GHG emissions from the northern Benguela region.

Eric J. Morgan et al.
Interactive discussion
Status: final response (author comments only)
Status: final response (author comments only)
AC: Author comment | RC: Referee comment | SC: Short comment | EC: Editor comment
Eric J. Morgan et al.
Eric J. Morgan et al.
Viewed  
Total article views: 294 (including HTML, PDF, and XML)
HTML PDF XML Total Supplement BibTeX EndNote
222 71 1 294 16 0 2
  • HTML: 222
  • PDF: 71
  • XML: 1
  • Total: 294
  • Supplement: 16
  • BibTeX: 0
  • EndNote: 2
Views and downloads (calculated since 26 Mar 2019)
Cumulative views and downloads (calculated since 26 Mar 2019)
Viewed (geographical distribution)  
Total article views: 213 (including HTML, PDF, and XML) Thereof 213 with geography defined and 0 with unknown origin.
Country # Views %
  • 1
1
 
 
 
 
Cited  
Saved  
No saved metrics found.
Discussed  
No discussed metrics found.
Latest update: 18 Aug 2019
Publications Copernicus
Download
Short summary
From a two-year atmospheric record of atmospheric oxygen and the greenhouse gases N2O, CO2, and CH4, made at a coastal site in the Namib Desert, we estimated the fluxes of these gases from upwelling events in the northern Benguela current region. We compared these results with flux measurements made on a research vessel in the study area at the same time, and found that the two approaches agreed well. The study region was a source of N2O, CO2, and CH4 to the atmosphere during upwelling events.
From a two-year atmospheric record of atmospheric oxygen and the greenhouse gases N2O, CO2, and...
Citation