Radiation Budget in the Shelf Areas of the Laptev Sea Sebastian Hellmann Jens Hölemann, Tilman Dinter, Birgit Heim, Astrid Bracher LenaDNM Workshop, Bremerhaven 07 December 2016

Motivation&Objectives Current results Ideas and Outlook Summary Outline: Motivation, investigation area and Objectives First results Modelling of radiation budgets in Laptev Sea Ideas and Outlook Remote sensing data for multi-annual time series Summary Sebastian Hellmann: Radiation Budget in the Shelf Areas of the Laptev Sea 2/14

Motivation&Objectives Current results Ideas and Outlook Summary Sebastian Hellmann: Radiation Budget in the Shelf Areas of the Laptev Sea 3/14

Motivation&Objectives Current results Ideas and Outlook Summary Siberian Laptev Sea: S02, S06, S22: no riverine influence S16, S19: influenced by river plume Sebastian Hellmann: Radiation Budget in the Shelf Areas of the Laptev Sea 4/14

Motivation&Objectives Current results Ideas and Outlook Summary Motivation to analyse CDOM: Light = limiting factor for biological activities CDOM limits solar radiation into water Radiation  ice cover + development  high CDOM absorption changes radiation budget Why do we use remote sensing data: Remote area, very limited access Remote sensing  broad seasonal measurements Inter- and intra-annual changes Sebastian Hellmann: Radiation Budget in the Shelf Areas of the Laptev Sea 5/14

Motivation&Objectives Current results Ideas and Outlook Summary Difficulties for remote sensing investigations: ice cover river plume Sebastian Hellmann: Radiation Budget in the Shelf Areas of the Laptev Sea 6/14

Motivation&Objectives Current results Ideas and Outlook Summary Two main objectives: Question I: absorption in which part of the water column?  influences on radiation budget Question II: are there changes in CDOM- absorption over the last decades  climate effects Sebastian Hellmann: Radiation Budget in the Shelf Areas of the Laptev Sea 7/14

Motivation&Objectives Current results Ideas and Outlook Summary Solar irradiance (up+downwelling) into water Radiative Transfer Model SCIATRAN: developed at Uni Bremen, free to use, but registration required highly resolved solar spectrum (3nm convolved, 250-1050 nm) consider Chl, CDOM, SPM in water Consider aerosols and gaseous absorption in atmosphere SZA between 54° and 80° hourly values for a clear and cloud covered summer day stations in river plume stations on shelf outside river plume --- cloudcovered sky clear sky Sebastian Hellmann: Radiation Budget in the Shelf Areas of the Laptev Sea 8/14

Motivation&Objectives Current results Ideas and Outlook Summary Solar irradiance (up+downwelling) into water Solar irradiance (up+downwelling) into water stations in river plume stations on shelf outside river plume --- cloudcovered sky clear sky Sebastian Hellmann: Radiation Budget in the Shelf Areas of the Laptev Sea 8/14

Motivation&Objectives Current results Ideas and Outlook Summary True colour satellite image ESA-MERIS (L1b), 20 Sept 2010 Sebastian Hellmann: Radiation Budget in the Shelf Areas of the Laptev Sea 9/14

Motivation&Objectives Current results Ideas and Outlook Summary Image of CDOM-absorption (L2) POLYMER-Algorithm, 20 Sept 2010 CDOM-Abs. aCDOM (443nm) [m-1] Sebastian Hellmann: Radiation Budget in the Shelf Areas of the Laptev Sea 10/14

Motivation&Objectives Current results Ideas and Outlook Summary Image of CDOM-absorption (L2) POLYMER-Algorithm, 20 Sept 2010 aRS [m-1] ain-situ [m-1] CDOM-Abs. aCDOM (443nm) [m-1] Sebastian Hellmann: Radiation Budget in the Shelf Areas of the Laptev Sea 10/14

Motivation&Objectives Current results Ideas and Outlook Summary Image of CDOM-absorption (L2) C2X-Algorithm, 20 Sept 2010 CDOM-Abs. aCDOM (443nm) [m-1] Sebastian Hellmann: Radiation Budget in the Shelf Areas of the Laptev Sea 11/14

Motivation&Objectives Current results Ideas and Outlook Summary Image of CDOM-absorption (L2) POLYMER-Algorithm, 20 Sept 2010 aRS [m-1] ain-situ [m-1] CDOM-Abs. aCDOM (443nm) [m-1] Sebastian Hellmann: Radiation Budget in the Shelf Areas of the Laptev Sea 11/14

Challenges to obtain high quality CDOM distribution: Investigation Area Motivation Current results Ideas and Outlook Summary Challenges to obtain high quality CDOM distribution: relationship between CDOM and Chlorophyll Laptev Sea riverine influenced case-2 water global relationships not valid in this shelf sea frequent cloud cover inhibits continuous time series and Comparison with sparse in-situ measurements Sebastian Hellmann: Radiation Budget in the Shelf Areas of the Laptev Sea 12/14

Challenges to obtain high quality CDOM distribution: Investigation Area Motivation Current results Ideas and Outlook Summary Challenges to obtain high quality CDOM distribution: relationship between CDOM and Chlorophyll Laptev Sea riverine influenced case-2 water global relationships not valid in this shelf sea frequent cloud cover inhibits continuous time series and Comparison with sparse in-situ measurements resuspension occurs often in shallow parts of the sea penetration depth very low However: Remote sensing data are the only continuous data Sebastian Hellmann: Radiation Budget in the Shelf Areas of the Laptev Sea 12/14

Investigation Area Motivation Current results Ideas and Outlook Summary Summary and Outlook: Question I: Energy transfer is limited by CDOM but also by solar elevation Question II: Developing an adapted retrieval algorithm to avoid underestimation of CDOM Question II: Using this algorithms to generate a time series and analyse potential feedback to climate changes Sebastian Hellmann: Radiation Budget in the Shelf Areas of the Laptev Sea 13/14

Investigation Area Motivation Current results Ideas and Outlook Summary Sebastian Hellmann: Radiation Budget in the Shelf Areas of the Laptev Sea 14/14

Motivation&Objectives Current results Ideas and Outlook Summary True colour satellite image ESA-MERIS (L1b), 01 Sept 2011 Sebastian Hellmann: Radiation Budget in the Shelf Areas of the Laptev Sea 10/14

Motivation&Objectives Current results Ideas and Outlook Summary What is “CDOM”? Chromophoric or coloured dissolved organic matter Compounds of organic carbon, smaller than 0.2 µm Absorbs light predominantly in UV-blue range  colour of water changes to yellow  gelbstoff Laptev Sea: CDOM mainly transported by Lena river from Mid-Siberian mountain region Distinction between marine and terrestrial origin possible (slope ratio, FDOM analysis) Sebastian Hellmann: Radiation Budget in the Shelf Areas of the Laptev Sea 3/14

Motivation&Objectives Current results Ideas and Outlook Summary Image of CDOM-absorption (L2b) ESA-MERIS-C2R, 01 Sept 2011 CDOM-Absorption aCDOM (=443 nm) [m-1] Sebastian Hellmann: Radiation Budget in the Shelf Areas of the Laptev Sea 11/14