Climate Group
New high latitude surface air temperature dataset
A new gridded Surface Air Temperature dataset for the region north of 40°N has been created for the period 1900–2000 using Objective Analysis (OA) methods. The advantage of this data set is its enhanced spatial coverage in high northern latitudes due to the ability of OA to optimize the data when the information is scarce (Kuzmina et al., 2007 – Tellus, in revision)
Arctic sea ice transformation
Several independent analyses have led to the consensus that the annual arctic sea-ice extent decreased ~3% per decade from 1978 up to now. Our estimates based on satellite microwave radiometer data show that over the same period, negative trend in the thick multi-year sea ice extent is at least two times higher.The loss of sea ice is one of the most evident manifestations of a global warming (Johannessen et al., 1999, Science)
Coupled atmosphere–ocean model ECHAM-4 (MPI-M, Hamburg) predicts that winter ice cover may be reduced by ~20% at the end of 21st century in response to CO² doubling, whereas reduction of summer ice cover may be much more dramatic – by ~80%, with arctic marginal seas being ice-free in summer (Johannessen et al., 2004, Tellus)
Greenland Ice Sheet elevation changes
Analysis of Greenland Ice Sheet elevation change from ERS-1/2 (European Remote Sensing satellites) radar altimeter data from 1992 to 2003 has shown that on the average its elevation (excluding some margin areas) was growing at a rate of 5.4±0.2 cm/year. In the interior regions of the ice sheet the elevation growth is observed because of high snow accumulation. Over the marginal areas elevation is decreasing due to intensified summer melting caused by global warming (Johannessen et al., 2005, Science)
Atmosphere–Ocean Interactions Group
Radar Imaging Model (RIM)
RIM model is an advanced powerful tool to simulate SAR (Synthetic Aperture Radar) signatures (both NRCS (Normalized Radar Cross Section) and Doppler shift) of various ocean phenomena: surface currents and fronts, surface and internal waves, near-surface wind field, biogenic and manmade contaminations. RIM had been extensively tested against wellcontrolled field experiments. The method is used for quantitative assessment of the satellite SAR signatures (Kudryavtsev et al., 2005, J. Geophys. Res.; Johannessen et al., 2005, J. Geophys. Res.)
Simulated SAR image is consistent with real one both in terms of the shape and magnitude of the NRCS contrasts field
Oil spills
Radar Imaging Model enables to detect and quantify SAR signatures of oil spills. Currently the model is developed for the case of identification of oil spills in leads (Kudryavtsev et al., 2005, J. Geophys. Res.)
An example of ENVISAT SAR observation of oil spills (black spot)made by a ship in the Novorossiysk bay
Aquatic Ecosystems Group
Synergistic remote sensing of natural waters
Investigation of complex processes in aquatic ecology from space requires a retrieval of ecologyrelated variables, e.g. of phytoplankton chlorophyll, suspended minerals and dissolved organics, and of water surface temperature. This is achieved via both development of relevant sophisticated retrieval algorithms for marine and lake waters and synergistic use of data from satellite sensors operating in the visible, infrared and microwaves (Pozdnyakov et al., 2007, Geophys. Res. Lett.)
suspended minerals (c) in Lake Ladoga in early May from MODIS (a) and SeaWiFS (b, c) satellite data averaged for seven years (1998-2005)
Harmful algal bloom satellite monitoring
Harmful algal blooms (HABs) have become one of the pressing problems of coastal marine ecology. Optical satellite remote sensing can provide both an early warning of HABs and timely detection and monitoring of their development and displacement due to advection by surface currents, which is important for safe-guarding of fish farming, recreation facility, etc. (Pettersson, L.H. and Pozdnyakov D.V. Monitoring of harmful algal blooms. Chichester: Springer-Praxis, 250 pp. – in press)
MetOcean Group
