8 research outputs found
Characterisation and quantification of regional diurnal SST cycles from SEVIRI
Hourly SST (sea surface temperature) fields from the geostationary Spinning Enhanced Visible
and Infrared Imager (SEVIRI) offer a unique opportunity for the
characterisation and quantification of the diurnal cycle of SST in
the Atlantic Ocean, the Mediterranean Sea and the northern European
shelf seas. Six years of SST fields from SEVIRI are
validated against the Advanced Along-Track Scanning Radiometer (AATSR)
Reprocessed for Climate (ARC) data set. The overall SEVIRIâAATSR bias is
â0.07 K, and the standard deviation is 0.51 K,
based on more than 53 Ă 106 match-ups.
Identification of the diurnal signal requires an SST foundation
temperature field representative of well-mixed conditions which
typically occur at night-time or under moderate and strong winds.
Such fields are generated from the SEVIRI archive and are validated
against pre-dawn SEVIRI SSTs and night-time SSTs from drifting buoys.
The different methodologies tested for the foundation temperature
fields reveal variability introduced by averaging night-time SSTs
over many days compared to single-day, pre-dawn values. Diurnal
warming is most pronounced in the Mediterranean and Baltic seas
while weaker diurnal signals are found in the tropics. Longer
diurnal warming duration is identified in the high latitudes
compared to the tropics. The maximum monthly mean diurnal signal
can be up to 0.5 K in specific regions
Near-coastal satellite altimetry: Sea surface height variability in the North Sea - Baltic Sea area
Quantitative reconstruction of Holocene sea ice and sea surface temperature off West Greenland from the first regional diatom data set
Holocene oceanographic conditions in Disko Bay, West Greenland, were reconstructed from high-resolution diatom records derived from two marine sediment cores. A modern data set composed of 35 dated surface sediment samples collected along the West Greenland coast accompanied by remote sensing data was used to develop a diatom transfer function to reconstruct April sea ice concentration (SIC) supported by July sea surface temperature (SST) in the area. Our quantitative reconstruction shows that oceanographic changes recorded throughout the last ~11,000âyears reflect seasonal interplay between spring (April SIC) and summer (July SST) conditions. Our records show clear correlation with climate patterns identified from ice core data from GISP2 and Agassiz-Renland for the early to middle Holocene. The early Holocene deglaciation of western Greenland Ice Sheet was characterized in Disko Bay by initial strong centennial-scale fluctuations in April SIC with amplitude of over 40%, followed by high April SIC and July SST. These conditions correspond to a general warming of the climate in the Northern Hemisphere. A decrease in April SIC and July SST was recorded during the Holocene Thermal Optimum reflecting more stable spring-summer conditions in Disko Bay. During the late Holocene, high April SIC characterized the Medieval Climate Anomaly, while high July SST prevailed during the Little Ice Age, supporting previously identified antiphase relationship between surface waters in West Greenland and climate in NW Europe. This antiphase pattern might reflect seasonal variations in regional oceanographic conditions and large-scale fluctuations within the North Atlantic Oscillation and Atlantic Meridional Overturning Circulation