Search results for "Oceanic climate"
showing 10 items of 11 documents
Coralline alga reveals first marine record of subarctic North Pacific climate change
2007
[1] While recent changes in subarctic North Pacific climate had dramatic effects on ecosystems and fishery yields, past climate dynamics and teleconnection patterns are poorly understood due to the absence of century-long high-resolution marine records. We present the first 117-year long annually resolved marine climate history from the western Bering Sea/Aleutian Island region using information contained in the calcitic skeleton of the long-lived crustose coralline red alga Clathromorphum nereostratum, a previously unused climate archive. The skeletal δ18O-time series indicates significant warming and/or freshening of surface waters after the middle of the 20th century. Furthermore, the ti…
Marine climate and hydrography of the Coralline Crag (early Pliocene, UK): isotopic evidence from 16 benthic invertebrate taxa
2019
The taxonomic composition of the biota of the Coralline Crag Formation (early Pliocene, eastern England) provides conflicting evidence of seawater temperature during deposition, some taxa indicating cool temperate conditions by analogy with modern representatives or relatives, others warm temperate to subtropical/tropical conditions. Previous isotopic (δ18O) evidence of seasonal seafloor temperatures from serial ontogenetic sampling of bivalve mollusk shells indicated cool temperate winter (<10 °C) and/or summer (<20 °C) conditions but was limited to nine profiles from two species, one ranging into and one occurring exclusively in cool temperate settings at present. We supplement these resu…
Growth-increment characteristics and isotopic (delta O-18) temperature record of sub- thermocline Aequipecten opercularis (Mollusca: Bivalvia): evide…
2021
Abstract The shell δ18O of young modern Aequipecten opercularis from the southern North Sea provides an essentially faithful record of seasonal variation in seafloor temperature. In this well-mixed setting, A. opercularis shell δ18O also serves as a proxy for seasonal variation in surface temperature. Individuals from less agitated (e.g. deeper) settings in a warm climate would not be expected to record the full seasonal range in surface temperature because of thermal stratification in summer. Such circumstances have been invoked to explain cool isotopic summer temperatures from early Pliocene A. opercularis of eastern England. Support for a sub-thermocline setting derives from high-amplitu…
ISOTOPIC TEMPERATURES FROM THE EARLY AND MID-PLIOCENE OF THE US MIDDLE ATLANTIC COASTAL PLAIN, AND THEIR IMPLICATIONS FOR THE CAUSE OF REGIONAL MARIN…
2017
Mean seasonal extreme temperatures on the seafloor calculated from the shell d 18 Oofthescallop Placopecten clintonius from the basal part of the early Pliocene Sunken Meadow Member (Yorktown Formation) in Virginia are very similar to those from the same horizon at the latitude of Cape Hatteras in North Carolina ( ~ 210 km to the south). The lowest and highest temperatures calculated from each shell (using d 18 O seawater ¼þ 0.7 % )givemean values for winter and summer of 8.4 6 1.1 8 C( 6 1 r ) and 18.2 6 0.6 8 CinVirginia,and8.6 6 0.4 8 Cand16.5 6 1.1 8 C in North Carolina (respective median temperatures: 13.3 8 C and 12.6 8 C). Patterns of ontogenetic variation in d 18 O, d 13 C and micro…
Coastal Oceanic climate change and variability from 1982 to 2009 around South Africa
2010
Changes and fluctuations in sea surface temperature (SST) around the South African coast are analysed at a monthly scale from 1982 to 2009. There is a statistically significant negative trend of up to 0.5 °C per decade in the southern Benguela from January to August, and a cooling trend of lesser magnitude along the South Coast and in the Port Elizabeth/Port Alfred region from May to August. The cooling is due to an increase in upwelling-favourable south-easterly and easterly winds. There is a positive trend in SST of up to 0.55 °C per decade in most parts of the Agulhas Current system during all months of the year, except for KwaZulu-Natal where warming is in summer. The warming was attri…
Rainfall and Sea-Breeze Circulation over South-Western France
1997
South-western France (Aquitaine region) has an oceanic temperate climate but some climatic peculiarities (irregular patterns in isohyets) are observed along a narrow coastal belt. The spatial distribution of winter and summer precipitation shows a ‘rainy strip’ located around 20 to 40 km inland. Three features allow an explanation of this distribution: synoptic flow, sea-breeze and heterogeneous land roughness (presence of the Foret des Landes). To take into account the impact of these features, numerical simulations are examined using a three-dimensional mesoscale model. The occurrence of the forest increases the possibility of precipitation during irregular patterns in isohyets. © 1997 by…
Interannual to decadal variability of summer sea surface temperature in the Sea of Okhotsk recorded in the shell growth history of Stimpson's hard cl…
2017
Abstract Sclerochronological and shell stable oxygen isotopic analyses were conducted on live-caught specimens of Stimpson's hard clams, Mercenaria stimpsoni , from the southern Sea of Okhotsk, off northern Hokkaido, Japan. In this region, the main growing season of this species during early ontogeny (below the age of 12 years) lasts from mid-spring to mid-fall at sea surface temperatures (SST) between approximately 10 and 22 °C. Growth cessation begins between late fall and early spring at SST, below approximately 6 °C; however, shell growth was largely limited to the summer season later in life. Counting of annual increments indicated that this species had a relatively long life span of u…
Holocene interaction of maritime and continental climate in Central Europe: New speleothem evidence from Central Germany
2019
Central European climate is strongly influenced by North Atlantic (Westerlies) and Siberian High circulation patterns, which govern precipitation and temperature dynamics and induce heterogeneous climatic conditions, with distinct boundaries between climate zones. These climate boundaries are not stationary and shift geographically, depending on long-term atmospheric conditions. So far, little is known about past shifts of these climate boundaries and the local to regional environmental response prior to the instrumental era.\ud \ud High resolution multi-proxy data (stable oxygen and carbon isotope ratios, S/Ca and Sr/Ca) from two Holocene stalagmites from Bleßberg Cave (Thuringia) are used…
A Tropical Archipelago
2017
The tropical maritime climate of the Philippines is marked by high temperature and abundant rainfall. The chapter first examines the major characteristics of the climate, dominated by the seasonal alternation of the Amihan and Habagat monsoons, leading to sharp differences between regions for their patterns of rainy seasons. Typhoons from the western Pacific hit the islands with brutal force, even if some years are more prone than others to the onslaught of tropical storms, depending on the general atmospheric circulation and the strength—or absence—of El Nino or La Nina. Typhoons not directly hitting the Philippines can still generate high levels of rainfall and enhance flooding, due to th…
Leukoma antiqua (Bivalvia) - A high-resolution marine paleoclimate archive for southern South America?
2018
The Patagonian Sea in the SW Atlantic is one of the most productive marine ecosystems worldwide. Besides its economic relevance, this shelf sea serves as a major sink for atmospheric CO2 and thus plays a major role in global climate. Despite that, the marine climate dynamics in that region remain barely known. Instrumental records only cover the last 30 years or so and high-resolution climate archives are currently not available. Here, we explore the possibility to obtain seasonally to inter-annually resolved paleotemperature data from shells of the bivalve mollusk, Leukoma antiqua collected alive from the shallow subtidal zone of the San Jorge Gulf. Results demonstrate that this species gr…