Search results for "Latitude"
showing 10 items of 210 documents
Urbanization and stability of a bird community in winter
2009
Abstract: The main objective of this study was to analyze between-winter stability of bird communities along latitudinal (950 km) and urban gradients (from small village to towns) in Finland. Birds were surveyed at the same 30-ha study plots using the same methods in 31 villages and town centres in the winters of 1991–1992 and 1999–2000. Species richness did not differ between the 2 study winters, but variation in total abundance of birds increased with increasing urbanization. However, urbanization reduced variation in wintering bird community structure. Species richness, density of wintering birds, and dissimilarity of wintering bird communities did not vary with latitude. According to ou…
Geographical patterns of species turnover in aquatic plant communities
2001
1. A classic theory in biogeography predicts that high latitude communities are unstable. This may be because of decreased species richness or decreased environmental predictability and productivity towards the poles. 2. We studied latitudinal patterns in long-term community persistence of aquatic vascular plants in 112 Finnish lakes, situated within a 1000-km range from the northernmost to the southernmost lake. 3. Contrary to theoretical predictions, we found that the turnover rate of plant species in 45 years was inversely related to latitude. That is, plant communities in northern lakes were more persistent than communities in southern lakes. When we used multiple regression to find the…
Property loss potentials for European midlatitude storms in a changing climate
2007
[1] Winter storms of the midlatitudes are an important factor for property losses caused by natural hazards over Europe. The storm series in early 1990 and late 1999 led to enormous economic damages and insured claims. Although significant trends in North Atlantic/European storm activity have not been identified for the last few decades, recent studies provide evidence that under anthropogenic climate change the number of extreme storms could increase, whereas the total number of cyclones may be slightly reduced. In this study, loss potentials derived from an ensemble of climate models using a simple storm damage model under climate change conditions are shown. For the United Kingdom and Ge…
European phenological response to climate change matches the warming pattern
2006
Global climate change impacts can already be tracked in many physical and biological systems; in particular, terrestrial ecosystems provide a consistent picture of observed changes. One of the preferred indicators is phenology, the science of natural recurring events, as their recorded dates provide a high-temporal resolution of ongoing changes. Thus, numerous analyses have demonstrated an earlier onset of spring events for mid and higher latitudes and a lengthening of the growing season. However, published single-site or single-species studies are particularly open to suspicion of being biased towards predominantly reporting climate change-induced impacts. No comprehensive study or meta-an…
Validation of a very simple model for computing global solar radiation in the European, African, Asian and North American areas
1990
Abstract In a previous paper Coppolino has proposed a very simple model for predicting the monthly mean daily global solar radiation G (MJm −2 day −1 ) at any Italian location using as input only the sunshine duration s (hours) and the noon altitude of the sun on the 15th of the month h n (degrees). The correlation suggested is G = 7.8 s 0.5 (sin h n ) 1.15 . Herein the validity of this model is verified by extending its application to dat from 24 stations displaced at various latitudes, altitudes above sea level and geographical situations in the European, African, Asian and North American areas. Furthermore the validity of this model to fit the data of the tested stations is compared with…
Global distributions of diazotrophs abundance and biomass - Depth integrated values computed from a collection of source datasets - Contribution to t…
2013
The MAREDAT atlas covers 11 types of plankton, ranging in size from bacteria to jellyfish. Together, these plankton groups determine the health and productivity of the global ocean and play a vital role in the global carbon cycle. Working within a uniform and consistent spatial and depth grid (map) of the global ocean, the researchers compiled thousands and tens of thousands of data points to identify regions of plankton abundance and scarcity as well as areas of data abundance and scarcity. At many of the grid points, the MAREDAT team accomplished the difficult conversion from abundance (numbers of organisms) to biomass (carbon mass of organisms). The MAREDAT atlas provides an unprecedente…
Global distributions of diazotrophs nitrogen fixation rates - Depth integrated values computed from a collection of source datasets - Contribution to…
2013
The MAREDAT atlas covers 11 types of plankton, ranging in size from bacteria to jellyfish. Together, these plankton groups determine the health and productivity of the global ocean and play a vital role in the global carbon cycle. Working within a uniform and consistent spatial and depth grid (map) of the global ocean, the researchers compiled thousands and tens of thousands of data points to identify regions of plankton abundance and scarcity as well as areas of data abundance and scarcity. At many of the grid points, the MAREDAT team accomplished the difficult conversion from abundance (numbers of organisms) to biomass (carbon mass of organisms). The MAREDAT atlas provides an unprecedente…
Growth rates of late Miocene corals from Crete (Greece)
2006
Modern scleractinian corals are classical components of marine shallow warm water ecosystems. Their occurrence and diversity patterns in the geological record have been widely used to infer past climates and environmental conditions. Coral skeletal composition data reflecting the nature of the coral environment are often affected by diagenetic alteration. Ghost structures of annual growth rhythms are, however, often well preserved in the transformed skeleton. We show that these relicts represent a valuable source of information on growth conditions of fossil corals. Annual growth bands were measured in massive hemispherical Porites of late Miocene age from the island of Crete (Greece) that …
On the structure of the extra-tropical transition layer from in-situ observations
2012
Abstract. In-situ observations of atmospheric tracers from multiple measurement campaigns over the period 1994–2007 were combined to investigate the Extra-tropical Transition Layer (ExTL) region and the properties of large scale meridional transport. We used potential temperature, equivalent latitude and distance relative to the local dynamical tropopause as vertical coordinates to highlight the behaviour of trace gases in the tropopause region. Vertical coordinates based on constant PV surfaces allowed us to relate the dynamical definition of the tropopause with trace gases distributions and vertical gradients and hence analyse its latitudinal dependence and seasonal variability. Analysis …
A new model for estimating diffuse solar radiation in Italy from clearness index and minimum air mass
1990
The aim of this study is: (a) to propose a new simple model for estimating the monthly mean daily diffuse radiation D, MJ m−2 day−1, using as input only the clearness index Kt and minimum air mass and (b) to develop a map of diffuse solar radiation incident on a horizontal surface in Italy. The correlation herein suggested is D = 5.6 Kt−0.55 (sin hn)1.58 where hn is the noon altitude of the sun on the 15th of the month, in degrees, and Kt = G/H0; G and H0 are the monthly mean daily global and extraterrestrial solar radiation respectively. This equation is applied to Adrano, Palermo, Macerata and Genova stations, provided with measured data of global and diffuse radiation, and the relative c…