Back to search

ROMFORSK-Program for romforskning

Remote Sensing of Ocean Circulation and Environmental Mass Changes

Awarded: NOK 4.6 mill.

The REOCIRC project develops methods for using satellite measurement to estimate the strength of ocean currents. The satellite uses an altimeter to measure the distance down to the sea surface, and this is what we use to calculate the ocean current. The ocean works more or less like the atmosphere and it is the pressure difference between high- and low pressures that generates currents. A steep sea surface tilt represents a big pressure difference, which again generates a strong current. To validate the satellite data we have developed a new mooring system where the main task is to measure the ocean bottom pressure (OBP). The OBP sensors are placed at the edges of the ocean current in order to measure the pressure difference across the current. There are two main branches of source water, and the most important one is the West Spitsbergen Current (WSC) that carries warm and saline Atlantic Water (AW) into the Arctic Ocean and the Spitsbergen Polar Current (SPC) that transports fresh and cold Arctic Water (ArW) northwards along the coast. Seasonal spatial hydrographic snapshots combine with longer time series in strategic positions on the West Spitsbergen Shelf (WSS), revealed a new circulation pattern of AW in the troughs indenting the WSS, here named the Spitsbergen Trough Current (STC). A hydrographic database for Svalbard has been developed to characterize the SPC and the WSC, their trends in temperature and salinity and the interannual variation in shelf-freshwater. To capture the SPC, two pressure-moorings have been place north of Hornsund, one as close to the shore as possible and the second as close to the front that separates the ArW mass from the AW. Further north, across the Yermak Plateau (YP), the two moorings closest to the coast also captures the pressure difference across the SPC. The WSC flows parallel to the SPC on the YP and we are able to capture both this current in our mooring section. The REOCIRC time series have revealed Topographically Trapped Waves (TTW) which is responsible for the enhancement of diurnal tidal oscillation, and therefore controlling the variability of the warm Atlantic flow around and across the Yermak Plateau. Moreover, nonlinear transfer of tidal energy has been shown to exist on the Yermak Plateau. This initiate long period current oscillation on the Yermak Plateau that controls in periods the transport of warm Atlantic Water to the Arctic Ocean and thus, the sea ice cover north of Svalbard.

Bidratt til kompetanseheving i Norge innen bruk av fjernmålingsprodukter fra Europa, USA og Canada. Spesielt bruk av fjernmålingsdata sammen med direkte målinger i hav, på sjøis og isbreer. Kunnskapen ved UNIS er blitt implementert i ordinære kurs på bachelor, Master og PhD nivå og UNIS har vært vertskap for det internasjonale brukerforum som ESA arrangerer annethvert år (http://eoscience4society.esa.int/CTC18). Økt internasjonalt forskningssamarbeid med USA, Polen og UK er oppnådd. REOCIRC har ført til økt tverrfaglig samarbeid mellom oseanografer, glasiologer og fjernmålingseksperter ved å sammenstille data på massendringer i hav og på land. Gjennom ekspertisen som er etablert i prosjektperioden på UNIS, er forskningsgruppen nå involvert i større prosjekter som Arven etter Nansen (NFR&KD) og INTAROS (EU Horizon 2020) og mindre nasjonale samarbeidsprosjekter. Resultater fra prosjektet ble viktige bidrag i Miljødirektoratets klimarapport for Svalbard: Climate in Svalbard 2100 (2019).

REOCIRC is a basic natural science research project that will apply state of the art instrumentation and theory to study remote sensed ocean circulation and heat fluxes towards the Arctic Ocean and the corresponding environmental mass changes in response to the estimated heat fluxes. The poorly monitored oceanic heat flux may fundamentally affect the future evolution of the Arctic sea ice cover. By building upon experimental and theoretical strengths in oceanography and remote sensing and earth observatio n methods, combinations and collaborations in these approaches will be addressed in innovative ways. REOCIRC is designed to consist of a field campaign collecting in situ data parallel to a satellite data processing group in order to obtain high precision water level estimates and therefore a more precise ocean circulation pattern in the Fram Strait region towards the Arctic Ocean. The combination of collecting in situ and remote data will reveal ocean mass changes that signalize changes in the water colu mn freshwater content and freshwater discharge from land in the chosen experiment region. The main hypothesis of the project is that changes in the ocean circulation and mass distribution at high latitudes are important elements in climate change. The to tal heat input to the Arctic is delicately balanced. Although the oceanic heat flux is small compared with the atmospheric advective heat flux towards the Arctic, the equilibrium thickness (decadal time scales) of undisturbed sea ice is very sensitive to oceanic heat flux. Taking advantage of advances in satellite altimetry and gravimetry, we seek a better understanding of the variability (seasonal, interannual and decadal) in oceanic volume and heat fluxes towards the Arctic Ocean and a unified understan ding of mass changes in the eastern Fram Strait and in Svalbard. That in turn leads to understanding the role of high-latitudes in global climate.

Funding scheme:

ROMFORSK-Program for romforskning