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ROMFORSK-Program for romforskning

Investigation of Arctic rivers runoff, spread and role in global carbon cycle using the Earth Explorer - SMOS

Awarded: NOK 0.30 mill.

CO2 is the major anthropogenic forcing factor for climate change. Marine CO2 sink depends on CO2 concentration which, in turn is strongly dependent upon the input of organic carbon from land with river discharge. Dissolved fraction of organic carbon (DOC) in riverine waters spreads over vast oceanic tracts. Warming is particularly high at high northern latitudes, where the permafrost retreat and increased precipitation enhance the input of DOC into the Arctic and, eventually, in Atlantic Oceans. Quantitat ive assessment of the actual contribution of Arctic Rivers is relevant for the global carbon cycle. However, data on carbon content from in situ measurements are scarce and discontinuous. Application of optical remote sensing (RS) for DOC retrieval is als o limited by cloud coverage and low sun position during ice-free season. DOC in riverine waters is a conservative admixture and in the vicinity of large river estuaries DOC concentration is proportional to decrease of salinity (S). We propose to use Soil Moisture and Ocean Salinity (SMOS) data on Sea Surface Salinity (SSS) for estimation of DOC surface concentrations and for building high resolution time series of DOC flux from four major Arctic rivers: Ob, Yenisey, Lena and Mackenzie. First, we will tes t sensitivity of the SMOS data to variations of salinity and other environmental factors in the Arctic region: sea surface temperature, sea surface roughness, precipitation, coast vicinity. Second, we will process optical remote sensing data for retrieval of DOC concentrations with already developed and tested case-2 algorithms. Third, we will establish region specific relation between SSS derived from SMOS and DOC derived from ocean color data in the estuaries of the Arctic largest rivers. The developed procedure for synergistic use of optical and microwave remote sensing data will be utilized for processing 14 years time series of SeaWIFS/MODIS data and for calculation of DOC fluxes and SSS spatial distributio

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ROMFORSK-Program for romforskning