Search results for " season"
showing 10 items of 340 documents
Predicting dengue fever outbreaks in French Guiana using climate indicators
2016
Background Dengue fever epidemic dynamics are driven by complex interactions between hosts, vectors and viruses. Associations between climate and dengue have been studied around the world, but the results have shown that the impact of the climate can vary widely from one study site to another. In French Guiana, climate-based models are not available to assist in developing an early warning system. This study aims to evaluate the potential of using oceanic and atmospheric conditions to help predict dengue fever outbreaks in French Guiana. Methodology/Principal Findings Lagged correlations and composite analyses were performed to identify the climatic conditions that characterized a typical e…
Comparison of global ultraviolet (290–385 nm) and global irradiation measured during the warm season in valencia, spain
1994
This paper studies data of ultraviolet (290–385 nm band) horizontal solar irradiation and global horizontal solar irradiation measured at Valencia (Spain) during the period March 1991 to September 1991. Analysis of error estimations and correlation coefficients show that the 10 minute, hourly, and daily values of ultraviolet (UV) and global irradiation are highly correlated. Improved figures and less dependence on location are achieved by defining a clearness index for the UV 290–385 nm band and relating it to the conventional whole-band clearness index. The novel clearness index obtained from Valencia data is approximately half of the conventional clearness index. Considering solar elevati…
MACC regional multi-model ensemble simulations of birch pollen dispersion in Europe
2015
Abstract. This paper presents the first ensemble modelling experiment in relation to birch pollen in Europe. The seven-model European ensemble of MACC-ENS, tested in trial simulations over the flowering season of 2010, was run through the flowering season of 2013. The simulations have been compared with observations in 11 countries, all members of the European Aeroallergen Network, for both individual models and the ensemble mean and median. It is shown that the models successfully reproduced the timing of the very late season of 2013, generally within a couple of days from the observed start of the season. The end of the season was generally predicted later than observed, by 5 days or more…
Plant colonization of bare peat surface - relative importance of seed availability and soil
1992
A field survey on two former peat harvesting sites of similar successional age revealed a marked difference in species composition and a 30-fold difference in biomass of the established vegetation Based on this observation, a field experiment in which the substrate was changed between sites was conducted to examine whether the differences in revegetation were mainly a consequence of differences in seed supply or in substrate quality After three growing seasons, a many hundred-fold difference in plant biomass existed between the transplanted and control plots with the same substrate, but only a small difference between the plots with a different substrate within the site Biological activity …
Effects of artificial plant cover on plant colonization of a bare peat surface
1992
. This paper describes the effect of artificial plant cover on plant colonization of a bare peat surface, resulting from peat harvesting. Plant species colonization was compared on plots supplied with plastic models simulating Vaccinium vitis-idaea plants and plots without this artificial cover. After two growing seasons, species composition and total biomass of the established plant cover were similar in the two plot types. However, the number of established seedlings in the plots with artificial cover was significantly higher than that in the plots without cover. Out of 13 species observed four differed significantly in their performance on the two plot types. Betula spec. had both higher…
Foliar influences on the vegetative development of grapevine
1997
<p style="text-align: justify;">Various defoliation treatments were applied to grapevine shoots during the whole duration of the growth period: full defoliation of every shoot of vine, defoliations retaining a various number of adult leaves to the base of every shoot and defoliations retaining a various number of young leaves to the top. The effects of these treatments allow to identify the major foliar influences on the vegetative development. Total defoliation induced a lesser intemodal elongation. This result is probably due, in part, to a carbohydrates deficiency consecutive to this drastic treatment. The defoliations with variation of the number of young leaves showed that the le…
Detection and origin of different types of annual laminae in recent stalagmites from Zoolithencave, southern Germany: Evaluation of the potential for…
2016
Abstract. An arrangement of three stalagmites from Zoolithencave (southern Germany) was analysed for different types of annual laminae using both microscopic and geochemical methods. The speleothems show visible laminae (consisting of a clear and a brownish, pigmented layer pair) as well as fluorescent and elemental laminae. The age of the speleothems was constrained to 1800 to 1970 AD by 14C-dating of a charcoal piece below the speleothems, detection of the 14C bomb peak, as well as counting of annual laminae. Dating by the 230Th/U-method was impossible due to detrital contamination. On the annual time-scale, the variability of Mg, Ba, and Sr is controlled by Prior Calcite Precipitation (P…
Diurnal and Seasonal Solar Induced Chlorophyll Fluorescence and Photosynthesis in a Boreal Scots Pine Canopy
2019
Solar induced chlorophyll fluorescence has been shown to be increasingly an useful proxy for the estimation of gross primary productivity (GPP), at a range of spatial scales. Here, we explore the seasonality in a continuous time series of canopy solar induced fluorescence (hereafter SiF) and its relation to canopy gross primary production (GPP), canopy light use efficiency (LUE), and direct estimates of leaf level photochemical efficiency in an evergreen canopy. SiF was calculated using infilling in two bands from the incoming and reflected radiance using a pair of Ocean Optics USB2000+ spectrometers operated in a dual field of view mode, sampling at a 30 min time step using custom written …
Validating an apple dry matter production model with whole canopy gas exchange measurements in the field
1999
The simplified apple dry matter production model developed by Lakso and Johnson (1990) was modified by inputing tree-specific parameters from a study of seasonal growth and gas exchange of 4-year-old Empire/M.9 apple trees, and light and temperature response curves developed for Empire apple organs. Measurements of the seasonal trend of diurnal net C02 and canopy water vapor exchange were made at intervals on three four-year-old 'Empire'/M.9 slender spindle apple trees in the orchard from 10 days after bloom until 25 days after harvest. The tree canopies were enclosed in clear plastic "balloon- type" chambers (similar to Corelli and Magnanini, 1993) that was monitored continuously for more …
Modelling surface energy fluxes over maize using a two-source patch model and radiometric soil and canopy temperature observations
2008
Abstract Models estimating surface energy fluxes over partial canopy cover with thermal remote sensing must account for significant differences between the radiometric temperatures and turbulent exchange rates associated with the soil and canopy components of the thermal pixel scene. Recent progress in separating soil and canopy temperatures from dual angle composite radiometric temperature measurements has encouraged the development of two-source (soil and canopy) approaches to estimating surface energy fluxes given observations of component soil and canopy temperatures. A Simplified Two-Source Energy Balance (STSEB) model has been developed using a “patch” treatment of the surface flux so…