Search results for "Season"

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…

Atmospheric dust, early cases, and localized meningitis epidemics in the African meningitis belt: an analysis using high spatial resolution data.

2018

8 pages; International audience; Background : Bacterial meningitis causes a high burden of disease in the African meningitis belt, with regular seasonal hyperendemicity and sporadic short, but intense, localized epidemics during the late dry season occurring at a small spatial scale [i.e., below the district level, in individual health centers (HCs)]. In addition, epidemic waves with larger geographic extent occur every 7–10 y. Although atmospheric dust load is thought to be an essential factor for hyperendemicity, its role for localized epidemics remains hypothetic.Objectives : Our goal was to evaluate the association of localized meningitis epidemics in HC catchment areas with the dust lo…

Climate change impact on the West African monsoon from June to October.

2015

Sixteen CMIP5 models are used toanalyse how climate changes over the West African Monsoon region between a “future period”, defined from 2031 to 2070under the rcp4.5 emission scenario, and the “current period”, defined from 1960 to 1999 under the historical emissionscenario. The results show an increase of the September to October rainfall amounts. Circulation anomalies include of anincreases of sea-level pressure over the Mediterranean Sea and Europe that allow a strengthening of the moisture flux fromEuro-Mediterranean regions into the Sahel. These changes are stronger in autumn.

Seasonal Distribution Of Exacerbations In The Poet-COPD; Study

2011

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…

Localization of quantitative trait loci for diapause and other photoperiodically regulated life history traits important in adaptation to seasonally …

2015

Seasonally changing environments at high latitudes present great challenges for the reproduction and survival of insects, and photoperiodic cues play an important role in helping them to synchronize their life cycle with prevalent and forthcoming conditions. We have mapped quantitative trait loci (QTL) responsible for the photoperiodic regulation of four life history traits, female reproductive diapause, cold tolerance, egg-to-eclosion development time and juvenile body weight in Drosophila montana strains from different latitudes in Canada and Finland. The F2 progeny of the cross was reared under a single photoperiod (LD cycle 16:8), which the flies from the Canadian population interpret a…

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 …

Global L-band vegetation volume fraction estimates for modeling vegetation optical depth

2021

The attenuation of microwave emissions through the canopy is quantified by the vegetation optical depth (VOD), which is related to the amount of water, the biomass and the structure of vegetation. To provide microwave-derived plant water estimates, one must account for biomass/structure contributions in order to extract the water component from the VOD. This study uses Aquarius scatterometer data to build an L-band global seasonality of vegetation volume fraction (d), representative of biomass/structure dynamics. The dynamic range of d is adapted for its application in a gravimetric moisture (Mg) retrieval model. Results show that d ranging from 0 to 3.35.10- 4 is needed for modelling physi…

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…