Description: The current behaviour of selected climate proxies in Lake Baikal was assessed by remote sensing analyses of ‘Sea viewing Wide Field of view Sensor’ (SeaWiFS) satellite data. Suitable proxies include optically visible water constituents such as phytoplankton, suspended terrigenous matter and yellow substance. These limnological parameters reflect the present-day climate bioproductivity and the river discharge in the catchment area. A biological and geochemical ground truth data set for Lake Baikal was established with the help of members of the paleoclimate project ‘high-resolution CONTINENTal paleoclimate record in Lake Baikal’ (CONTINENT). For processing the SeaWiFS satellite data, the atmospheric correction was adapted to the case of Lake Baikal. Chlorophyll as a proxy for phytoplankton was quantified using global NASA ocean colour algorithms OC2 and OC4. In cases of no optical interferences by terrigenous input, the calculated chlorophyll concentrations in clear pelagic waters were within ±30% accuracy with the CONTINENT cruise data during the summers of 2001 and 2002. Within this range of accuracy, the SeaWiFS time series will be able to show the seasonal variations of chlorophyll of specified bio-optical provinces of Lake Baikal and of CONTINENT sites. In this study, the suspended matter as a proxy for the terrigenous input was calculated according to an empirical algorithm using ground truth data in the time frame of flooding events in summer 2001. The approach chosen correlates the suspended matter concentration with the remotely sensed parameter of ‘attenuation coefficient’ to account for the organic-rich terrigenous input that originates from the swampy watersheds. Seasonal and spatial information that is provided by the analyses of the SeaWiFS satellite data will assist paleoclimate researchers to interpret the autochthonous and allochthonous influences at the CONTINENT coring sites.

Description: Depending on the landscape type high amounts of shadow can be present in remote sensing images. These areas are usually masked using shadow detection techniques and excluded from further analysis. Although significant research has been conducted on the detection of shadows there is still room for improvements. In this investigation we focus on the development of a new shadow detection algorithm capable to be automatically applied without user knowledge on any hyperspectral VIS-NIR image and thus can be implemented in automated pre-processing chains. The analysis is strictly focussed on the VIS-NIR part of the electromagnetic spectrum due to the growing number of VIS-NIR imaging spectrometers. The developed approach consists of two main steps, the selection of potential shadow pixels and the removal of no-shadow pixels from this mask. In this context the separation between shadow and water is the most challenging task. By analysing different images containing inland and ocean water types we found the slope of the reflectance spectrum of water at specific spectral wavelengths within the VIS-NIR range to be a diagnostic feature for water identification. However, the presence of these features depends on the spectral superimposition of water constituents and bottom coverage. These aspects have been considered in the development of a knowledge-based classifier. First results indicate the great potential of the developed algorithm for urban, rural and coastal scenes of different sensor data (AISA, HyMap).

Description: Web-based Geographical Information Systems (GIS) are excellent tools within interdisciplinary and multi-national geoscience projects to exchange and visualize project data. The web-based GIS presented in this paper was designed for the paleolimnological project ‘High-resolution CONTINENTal paleoclimate record in Lake Baikal’ (CONTINENT) (Lake Baikal, Siberia, Russia) to allow the interactive handling of spatial data. The GIS database combines project data (core positions, sample positions, thematic maps) with auxiliary spatial data sets that were downloaded from freely available data sources on the world wide web. The reliability of the external data was evaluated and suitable new spatial datasets were processed according to the scientific questions of the project. GIS analysis of the data was used to assist studies on sediment provenance in Lake Baikal, or to help answer questions such as whether the visualization of present-day vegetation distribution and pollen distribution supports the conclusions derived from palynological analyses. The refined geodata are returned back to the scientific community by using online data publication portals. Data were made citeable by assigning persistent identifiers (DOI) and were published through the German National Library for Science and Technology (TIB Hannover, Hannover, Germany).

Description: The mineralogical composition of Late Quaternary sediments was investigated in three piston cores recovered on elevated plateaus in Lake Baikal: on Continent Ridge, a northern extension of Academician Ridge in the North Basin; on the Posolsky Bank near the Selenga Delta; and on the Vydrino Shoulder in the South Basin. The sediments are alternating biogenic diatom-rich muds and terrigenous silty clays, with sandy layers occurring in the southern (Vydrino) core. Core stratigraphy is based on AMS 14C dates on pollen, diatom zonation, and magnetic record correlation: the 6–10 m long cores cover the last ∼40 kyr in Vydrino, ∼60 kyr in Posolsky and ∼185 kyr in Continent Ridge. The bulk, clay (〈2 μm) and sand (63–200 μm) mineral signatures are compared with the mineralogical assemblages identified in river sediments and rocks sampled in the Selenga watershed and surface sediments collected in the various sub-basins. Spatial variability in the bulk mineral signature mainly reflects the sediment location relative to the lake margin. The complex clay mineral assemblages are more distinctive in terms of source-area. The clay signature of Vydrino core differs from the two other sites, in its high illite content. The Posolsky assemblage is consistent with the Selenga River clay mineral signature. The Continent Ridge clay assemblage is highly variable, reflecting mixing of several sources including a more proximal contribution than the Barguzin or even the Selenga tributaries. The similar hornblende-dominated heavy mineral compositions of the Continent Ridge and Posolsky Bank sediments reflect the homogenous granitoid signature of the watersheds of the eastern side of Lake Baikal. In contrast, in the Southern Basin, the sediments from Vydrino Shoulder are micadominated, recording local sedimentary and metamorphic detritus supplies by numerous small rivers. Besides the control of sediment supply by the Selenga River, our data emphasize the significant influences of the Lake Baikal coastal margins in South and North Basin.

Description: The CHRIS sensor, mounted on the PROBA satellite, is one of the first space-borne hyperspectral sensors offering high spatial resolution (18 m x 18 m). This, combined with the possibilty of multi-temporal coverage, makes CHRIS-PROBA exceptionally well suited for lake water monitoring. The concept of the project MEMAMON is to monitor the water quality of lakes in the Mecklenburg (Germany) and Mazurian (Poland) lake districts. Both test sites contain a large number of lakes with high variability and different trophic states. This paper presents a study, which aims to determine the trophic parameter chlorophyll-a using hyperspectral CHRIS-PROBA data. To investigate the seasonal dynamics of lakes, CHRIS-PROBA data were acquired in spring, summer and autumn 2002, 2003 and 2004. A first analysis of the data showed that CHRIS radiance data have strong artefacts in along track direction. Standard destriping techniques were not sufficient to correct the data. Therefore, a novel iterative destriping technique was developed and successfully applied to CHRIS-PROBA data. During the CHRIS-PROBA data recording, spectral field measurements and acquisition of in-situ data took place at several test sites. Using these data, chlorophyll algorithms were developed and optimised to the spectral characteristics of the CHRIS sensor. On the basis of simulated CHRIS-PROBA spectra in mode 2 and mode 3, the effect on the cholorphyll estimation will be discussed.

Description: Within the paleoclimate project CONTINENT we use Sea viewing Wide Field of view Sensor (SeaWiFS) data to assess information on the current behaviour of selected climate proxies in Lake Baikal, Siberia. Suitable proxies include optically-visible water constituents such as algae biomass and suspended terrigenous matter, whose dynamics reflect the present-day climate bioproductivity and the river discharge in the catchment area. Lake Baikal represents a specific bio-optical water type with high local concentrations of organic matter and low algae biomass concentrations. Field data show a remarkable influence of coloured dissolved organic matter (CDOM) on the optical properties of Lake Baikal's surface waters. For this case 2 water type, the SeaWiFS Data Analysis System’s (SeaDAS) standard atmospheric correction methods result in a considerable overestimation of pigment concentration. Here we describe how we adapted the SeaDAS software and developed techniques for a regional study on Lake Baikal. The optically interacting water constituents are decorrelated with a Maximum Noise Fraction (MNF) analysis that is a modified Principal Component Analyses (PCA). The resultant SeaWiFS PC maps of terrigenous input and phytoplankton distribution reveal the autochthonous and allochthonous influences on the CONTINENT coring sites.