Please inform us if you would like to share a research highlight that is relevant to SOLAS, particularly if it was facilitated by SOLAS in some way. This could for example be as a result of a new international collaboration set up through the SOLAS network.
The following highlights have been extracted from SOLAS National Reports that are produced annually by the National Representatives of the SOLAS Networks.
Tracking the variable North Atlantic sink for atmospheric CO2
An international group of scientists demonstrated how the combination of data gathered by satellites and chemical sensors aboard commercial ships can be used to precisely map the uptake of atmospheric CO2 by the entire North Atlantic Ocean. The results suggest that the CO2 uptake in the North Atlantic varies substantially over periods of several years [1].
Under the EU FP6 Integrated Project CARBOOCEAN (endorsed by SOLAS) novel observing systems of sea surface CO2 fugacity based on VOS lines (VOS = voluntary observing ships) have revealed that the North Atlantic sink for anthropogenic carbon (emitted into the atmosphere from fossil fuel burning, cement manufacturing, and land use change) is much more variable than previously thought. It has been shown that it can vary by 50% within few years between 1995 and 2007 [1]. The fact of quickly changing quasi-basin-wide air-sea CO2 fluxes can be considered as a paradigm shift in global carbon cycle research, where traditionally the ocean sink has been considered as a more or less stable sink when compared to the terrestrial carbon sink. Through the dense network of observations – which needs to be sustained also in future – the basin-wide flux estimates can be made with a higher accuracy (about 10%) than any other large scale air-sea CO2 flux assessment so far. Using advanced data assimilation methods (here neural network methods), the fluxes can be interpolated spatially and also temporarily to at least seasonal resolution [2].
1. Watson, A J, U Schuster, D C E Bakker, N R Bates, A Corbière, M González-Dávila, T Friedrich, J Hauck, C Heinze, T Johannessen, A Körtzinger, N Metzl, J Olafsson, A Olsen, A Oschlies, X A Padin, B Pfeil, J M Santana-Casiano, T Steinhoff, M Telszewski, A F Rios, D W R Wallace, and R Wanninkhof (2009). Tracking the Variable North Atlantic Sink for Atmospheric CO2, Science, 326: 1391-1393
2. Telszewski, M, A Chazottes, U Schuster, A J Watson, C Moulin, D C E Bakker, M González-Dávila, T Johannessen, A Körtzinger, H Lüger, A Olsen, A Omar, X A Padin, A F Ríos, T Steinhoff, M Santana-Casiano, D W R. Wallace, and R Wanninkhof (2009). Estimating the monthly pCO2 distribution in the North Atlantic using a self-organizing neural network, Biogeosciences, 6: 1405–1421.
Results from the Indian 'Integrated Campaign for Aerosols, gases and Radiation Budget' (ICARB)
To characterise the atmospheric diversity over the North Indian Ocean and Indian landmass a major multi-platform field campaign Integrated Campaign for Aerosols, gases and Radiation Budget (ICARB), initiated in the pre-monsoon period of 2006, continued until January 2009. This was the biggest such campaign over this region involving 26 national laboratories and sponsored by the Indian Space Research Organization (ISRO) for studying high-resolution multi-parameter data from concurrent measurements of the optical and physical properties over the oceans. The recent experiments helped in the first-ever precision mapping of spatial distribution of aerosol radiative forcing over the Northern Indian Ocean and brought out contrasting radiative characteristics between the air masses over the Bay of Bengal and Arabian Sea [1]. The study revealed the presence of a convectively mixed layer extending up to about 1 km over the Arabian Sea and Bay of Bengal [2] and a convectively stable layer above, sandwiched between unstable layers above and below, acting as a seat for elevated aerosol layers and as conduit for long-range transport [3].
1. K. Krishna Moorthy, Vijayakumar S Nair, S. Suresh Babu and S. K. Satheesh, Spatial and vertical heterogeneities in aerosol properties over oceanic regions around India: Implications to radiative forcing, Quarterly Journal of the Royal Meteorological Society, doi:10.1002/qj.525, 2009.
2. Satheesh, S. K., K. Krishna Moorthy, S. Suresh Babu, V. Vinoj, V. S. Nair, S. Naseema Beegum, C. B. S. Dutt, D. P. Alappattu, and P. K. Kunhikrishnan, Vertical structure and horizontal gradients of aerosol extinction coefficients over coastal India inferred from airborne lidar measurements during the Integrated Campaign for Aerosol, Gases and Radiation Budget (ICARB) field campaign, Journal of Geophysical Research., 114, D05204, doi: 10.1029/2008JD011033, 2009.
3. Vijayakumar S Nair, K. Krishna Moorthy, S. Suresh Babu and S. K. Satheesh., Optical and physical properties of atmospheric aerosols over the Bay of Bengal during ICARB, Journal of the Atmospheric Science, 66, 2640 - 2658, 2009.
Origin and source regions of PM10 in the Eastern Mediterranean atmosphere
Daily PM10 aerosol filters were collected from a rural site located on the coastline of the Eastern Mediterranean, Erdemli/IMS-METU in Turkey (36 deg 33' 54'' N and 34 deg 15' 18'' E, at about 22 m above sea level and 10 meters from the sea) between April 2001 and April 2002. The Potential Source Contribution Function (PSCF) analysis has been applied to identify potential source areas of PM10 monitored at Erdemli station (IMS-METU). PSCF maps highlighted that the Saharan desert is the main source area for crustal components. Secondary aerosol components could only be associated with the south-eastern Black Sea, whereas Southern Germany, Northern Italy, Eastern France, Central Poland, the former Republic of Yugoslavia and Albania were identified as the main source regions for residual oil [1].
1. Koçak M., Mihalopoulos N., Kubilay N. (2009) Origin and source regions of PM10 in the Eastern Mediterranean atmosphere. Atmospheric Research 92, 464–474.
Historical reconstruction of air-sea CO2 fluxes in the eutrophied North Sea and interaction with ocean acidification: a model study
The coupled river-coastal sea model RIVERSTRAHLER-MIRO-CO2 (R-MIRO-CO2) has been successfully applied in the Channel and Southern North Sea to assess the decadal changes of carbon cycling in the Belgian coastal zone over the period from 1951 to 1998 in response to the increase of atmospheric CO2 and changing nutrient river loads [1]. Results distinguish two major periods on basis of N and P river loads and coastal enrichment: increased eutrophication (1951-1990) when nutrient enrichment is accompanied by a shift from a source to a sink of atmospheric CO2 as well as an increase in pH and saturation state of aragonite (Ωar) and the decreased P loads period (1990-1998) when P limitation leads to a shift of the coastal system to a source of atmospheric CO2 and decrease pH and Ωar. Overall, the results highlight that changes in river nutrient delivery loads due to management regulation policies can modify carbon cycling in the coastal zone, and lead transiently to stronger changes in carbonate chemistry than ocean acidification.
1. Gypens N., A.V. Borges & C. Lancelot (2009) Effect of eutrophication on air-sea CO2 fluxes in the coastal Southern North Sea: a model study of the past 50 years,Global Change Biology, 15(4), 1040-1056
ICON: The impact of coastal upwelling on the air-sea exchange of climatically important gases
The RRS Discovery hosted an impressive international and interdisciplinary team of scientists during the final cruise of the UK SOLAS programme off north-west Africa in April-May 2009. The ICON cruise, led by Carol Robinson (UEA), investigated the influence of coastal/shelf regions (20-200 km offshore) on the air-sea exchange of climatically important biogenic gases (CH4, N2O, CO2, DMS/DMSP). Along the Mauritanian shelf, upwelling can result in high concentrations of these gases – with their air-sea fluxes strongly influenced by spatial and temporal variability in plankton community structure and productivity (stimulated by the high nutrient content of the upwelled water) and light-driven breakdown of both upwelled and recently-produced dissolved organic matter. All these processes were studied on Discovery 338. Successful tracking of upwelled filaments as they moved offshore (real time SF6 tracer tracking and surface drifters) allowed large scale lagrangian studies to be performed, whilst also monitoring filament evolution (nutrients and physical ocean properties). Interestingly, peak chlorophyll concentrations were found not in filament centres but at their edges, where they met older waters containing lower nutrient levels.
Experiments included investigations of the factors affecting biogenic gas production and consumption processes; air-sea transfer rates of gases (SF6/3H dual tracer) and potential surface layer effects on these (e.g. surfactant concentrations). Using a Moving Vessel Profiler, ~1800 CTD undulations were made, more than 4 times the number on any other Discovery cruise! [1].
1. Robinson C. (2009) The impact of coastal upwelling on the air-sea exchange of climatically important gases (ICON), RRS Discovery 338 Cruise Report, www.bodc.ac.uk/data/information_and_inventories/cruise_inventory/report/d338.pdf
The highly productive western East China Sea acts as a CO2 source in autumn
Underway pCO2 surveys showed that the western inner shelf of the highly productive East China Sea served as a moderate or significant sink of atmospheric CO2 in winter, spring and summer, while it turned to a net source in autumn. Associated with the CO2 degassing was a slight DO deficit as compared with the air equilibrium level. Such a seasonal signal in autumn as a source of atmospheric CO2 may be associated to complex physical and biogeochemical processes, such as the low biological productivity in autumn. Alternatively, that the study area became a source to the atmospheric CO2 may also be associated with the collapse of summer stratification and thereby a recovery of bottom hypoxia in autumn. Therefore we contend that the bottom hypoxia was weakened by vertical mixing in October and eventually disappeared in November. As a consequence, the hypoxic and CO2-rich bottom water became mixed and degassed CO2 to the atmosphere in late autumn. This is the first evidence linking shelf air-sea CO2 exchanges to seasonal hypoxia [1].
1. Zhai WD and Dai MH (2009). On the seasonal variation of air - sea CO2 fluxes in the outer Changjiang (Yangtze River) Estuary, East China Sea. Marine Chemistry, 117: 2-10.