Potential of the Radar Altimetry for Estimation of the River Input to the Arctic Ocean

Since already ten years, the radar altimetry have been successfully used for estimation of water discharge of large rivers. The arctic rivers are the most challenging objects from methodological point of view as 1) they are covered by ice during the most part of the year and 2) significant part of the water flow passes after the snow melt during only several weeks. In the framework of the ESA ArcFlux project, aiming an estimation of the fresh water fluxes in the Arctic Ocean, a performance of the radar altimetry for precise estimation of the water flux
for different types of the arctic rivers was studied. The test was performed for two large rivers: the Ob River (regular gentle flooding regime) and the Lena River (rapid and sharp spring and summer floods) and for one middle size river Pur (Western Siberia). We investigated different approaches to retrieve water level from different altimetric missions starting from 2002 (singlemission/ single-track, single-mission/multi-tracks, multimissions) and investigated two different methods of discharge estimation (stage-discharge rating curves and Manning solution). The results show very high potential for multi-mission and multi-tracks approaches. The Manning solution, which can be used for discharge estimation for ungauged rivers, also provides very good results. The accuracy of the annual water flow estimates for middle size river is of 17%, while for large rivers it is of 4-7%.