Climate & Water Balance Changes in the Caspian Region – Astrakhan – 19-20 Oct 2010

SATELLITE ALTIMETRY TO SUPPORT STUDIES OF SEA LEVEL CHANGE IN THE

CASPIAN SEA

Presented by

Ramiz MamedovRamiz Mamedov

Institute of Geography,Center for the Problems of the Caspian Sea

Baku, Azerbaijan

Contributors:

Cretaux J.F., Testut L., F. Lyard (Laboratoire d'Etude en Géophysique et Océanographie Spatiales, France),Calmant S. (Institut de Recherche pour le Développement , France) Vignudelli S. (Consiglio Nazionale delle Ricerche, Italy)Calzas M. (Institut National des Sciences de l’Univers, France)Kostianoy A. (PP Shirshov Institute of Oceanology, Russia)

Climate & Water Balance Changes in the Caspian Region – Astrakhan – 19-20 Oct 2010

� A space borne tide gauge� To monitor sea level changes� 18 yrs multi-mission archive� A success story in open ocean� Now working to get more and

better data in inland seas� Caspian Sea proposed as

laboratory for calibration/validation � Progresses in technology promise

better resolution capability � Developing capacity in inland sea

altimetry in Caspian countries is a priority

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Satellite altimetry in few wordsSatellite altimetry in few words

Coastal Zone

Climate & Water Balance Changes in the Caspian Region – Astrakhan – 19-20 Oct 2010 3

Caspian Sea Caspian Sea –– In situ sea level infrastructureIn situ sea level infrastructure

�Source:Caspian Env Programme

1999

� Concerns:� Where are data located? � In what quantity? � Of what quality?� Who owns data? � How to access?

� What we have seen:� Different sampling� Manual recording� Often gappy or collection stopped� Just tables (no metadata)� Language differences

� Jiloy, Zhiloy, Chilov – same station!!!

�BUT ….the quality and usability of the altimeter-derived observations is dependent upon good calibration/validation of

the satellite sensors with in situ observations.

Climate & Water Balance Changes in the Caspian Region – Astrakhan – 19-20 Oct 2010 4

Caspian Sea Caspian Sea –– Water level variability from in situ dataWater level variability from in situ data

Baku

Will the Caspian sea level rise again?

� Longest record at Baku (since 1837)� Shows a rising of more than 2 metres between 1977 and 1995 � Now stabilized near the −27 m level� Understanding variability at all scales – a complicated puzzle� Combination of factors: climatic (atmospheric variations),

anthropogenic (e.g. river drainage and water use, especially Volga), geologic (e.g. subsidence)

Climate & Water Balance Changes in the Caspian Region – Astrakhan – 19-20 Oct 2010 5

� Based on 1 Hz data� Referred to Baltic Sea level reference frame� Shows seasonal variations probably due to climatological (evaporation &

precipitation) and hydrological (river runoff, discharge to Kara Bogaz Gol) cycle

� Inter-annual tendencies might be interpreted in the light of decadal climate variability and amplification of irrigation in the Volga river basin

Caspian Sea Caspian Sea –– Water level variability from multiWater level variability from multi--

mission altimetrymission altimetry

Climate & Water Balance Changes in the Caspian Region – Astrakhan – 19-20 Oct 2010 6

� Agree well with “ground truth” at basin scale, but still some local « mysteries » (e.g. 70 mm in 1995)

� Errors in altimetry ~15 mm/yr� Possible uncertainty in the global lake level deduced from

in situ stations

�-27,2

�-27,1

�-27

�-26,9

�-26,8

�-26,7

�-26,6

�-26,5

�1992 �1993 �1994 �1995 �1996 �1997 �1998 �1999 �2000 �2001 �2002

�Time (year)

�Sea level (m

) �?

Caspian Sea Caspian Sea –– Comparison of TOPEX/Poseidon Comparison of TOPEX/Poseidon

altimetry (red) and in situ stations (black)altimetry (red) and in situ stations (black)

�Need of a permanent Cal/Val site for satellite altimetry

Climate & Water Balance Changes in the Caspian Region – Astrakhan – 19-20 Oct 2010 7

Sea level pilot station operating at Absheron Port (Baku)Sea level pilot station operating at Absheron Port (Baku)

��Satellite altimetry ground tracks Satellite altimetry ground tracks ��Jason (red), Envisat (white), GFO Jason (red), Envisat (white), GFO (green), T/P 2002(green), T/P 2002--2005 (yellow)2005 (yellow)

Climate & Water Balance Changes in the Caspian Region – Astrakhan – 19-20 Oct 2010 8

� Started to collect data in June 2008 and still ongoing� Processed the first year� Work in progress …..

Some pictures about field work in June 2008Some pictures about field work in June 2008

Climate & Water Balance Changes in the Caspian Region – Astrakhan – 19-20 Oct 2010 9

Sea level variability at Absheron PortSea level variability at Absheron Port

� During the observational period, the sea level at Port Absheron exhibits a large high frequency variability apparently more pronounced during summer time as well as an annual cycle.

� There are also other oscillations superimposed that need careful investigation

� The spectrum analysis shows the existence of a little tidal contribution to the sea level

� The large contribution is observed in the 3-30 day band, possibly linked to the meteorological forcing

Climate & Water Balance Changes in the Caspian Region – Astrakhan – 19-20 Oct 2010

� To be filled at end

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SummarySummary

Bottom-up message