Lake level changes in the Caspian Sea monitored by satellite altimetry and gravimetry

Saskia Esselborn (GFZ German Research Centre for Geosciences, Germany)

CoAuthors

Tilo Schöne (GFZ German Research Centre for Geosciences, Germany); Julia Illigner (GFZ German Research Centre for Geosciences, Germany); Christian Gruber (GFZ German Research Centre for Geosciences, Germany)

Event: 2016 Ocean Surface Topography Science Team Meeting

Session: Science III: Two decades of continental water's survey from satellite altimetry - From nadir low-resolution mode to SAR altimetry, new perspectives for hydrology

Presentation type: Type Oral

The Caspian Sea level (CSL) has been subject to fluctuations of more than 2.5 m during the last 40 years. Since 1993 satellite altimeters have monitored fluctuations of more than 1.5 m – multi-annual fluctuations until 2005 and persistent decreasing lake levels in the order of 10 cm/year afterwards with trends of -11 cm/year in the North and -9 cm/year in the South. According to previous studies on these time scales the CSL is dominated by the balance between river (mainly Volga) discharge and net evaporation over the Caspian Sea. However, to some degree also tectonic forces and subsidence due to oil/gas production might be contributing to observed CSL changes.
Changes of the water amount in the Caspian Sea can also be monitored by gravimetric measurements from the GRACE satellites. Time series of equivalent water heights of the Caspian Sea originating from 5 different processing centers were retrieved from the EGSIEM – Plotter (plot.egsiem.eu) and, in addition, from the JPL-mascon solution. While the annual signal of the altimetric and gravimetric data are very close to each other, the trends from 2005 onwards of the equivalent water heights and the sea level from altimetry disagree. Depending on the solution the gravimetric trends account only for 75-50% of the altimetric trends. The reasons for the discrepancies between the two data sources are further investigated.
 

Oral presentation show times:

RoomStart DateEnd Date
Richelieu Thu, Nov 03 2016,09:00 Thu, Nov 03 2016,09:15
Saskia Esselborn
GFZ German Research Centre for Geosciences
Germany
Saskia.Esselborn@gfz-potsdam.de