1,705 research outputs found
Effects of Land-Surface-Vegetation on theboreal summer surface climate of a GCM
A land surface model (LSM) has been included in the ECMWF Hamburg version 4 (ECHAM4) atmospheric general circulation model (AGCM). The LSM is an early version of the Organizing Carbon and Hydrology in Dynamic Ecosystems (ORCHIDEE) and it replaces the simple land surface scheme previously included in ECHAM4. The purpose of this paper is to document how a more exhaustive consideration of the land surface–vegetation processes affects the simulated boreal summer surface climate.
To investigate the impacts on the simulated climate, different sets of Atmospheric Model Intercomparison Project (AMIP)-type simulations have been performed with ECHAM4 alone and with the AGCM
coupled with ORCHIDEE. Furthermore, to assess the effects of the increase in horizontal resolution the coupling of ECHAM4 with the LSM has been implemented at different horizontal resolutions.
The analysis reveals that the LSM has large effects on the simulated boreal summer surface climate of the atmospheric model. Considerable impacts are found in the surface energy balance due to changes in the surface latent heat fluxes over tropical and midlatitude areas covered with vegetation. Rainfall and atmospheric circulation are substantially affected by these changes. In particular, increased precipitation is found over evergreen and summergreen vegetated areas.
Because of the socioeconomical relevance, particular attention has been devoted to the Indian summer monsoon (ISM) region. The results of this study indicate that precipitation over the Indian subcontinent is better simulated with the coupled ECHAM4–ORCHIDEE model compared to the atmospheric model alone
Effects of increased CO2 levels on monsoons
Increased atmospheric carbon dioxide concentration provided warmer atmospheric temperature and higher atmospheric water vapor content, but not necessarily more precipitation. A set of experiments performed with a state-of-the-art coupled general circulation model forced with increased atmospheric CO2 concentration (2, 4 and 16 times the present-day mean value) were analyzed and compared with a control experiment to evaluate the effect of increased CO2 levels on monsoons. Generally, the monsoon precipitation responses to CO2 forcing are largest if extreme concentrations of carbon dioxide are used, but they are not necessarly proportional to the forcing applied. In fact, despite a common response in terms of an atmospheric
water vapor increase to the atmospheric warming, two out of the six monsoons studied simulate less or equal summer mean precipitation in the 16xCO2 experiment compared to the intermediate sensitivity experiments. The precipitation differences between CO2 sensitivity experiments and CTRL have been investigated specifying the contribution of thermodynamic and purely dynamic processes. As a general rule, the differences depending on the atmospheric moisture content changes (thermodynamic
component) are large and positive, and they tend to be damped by the dynamic component associated with the changes in the vertical velocity. However, differences are observed among monsoons in terms of the role played by
other terms (like moisture advection and evaporation) in shaping the precipitation changes in warmer climates. The precipitation increase, even if weak, occurs despite a weakening of the mean circulation in the monsoon regions(‘‘precipitation-wind paradox’’). In particular, the tropical east-west Walker circulation is reduced, as found from velocity potential analysis. The meridional component of the monsoon circulation is changed as well, with larger (smaller) meridional (vertical) scales
The synergistic effect between positivity, socio-demographic factors and smoking cessation: results of a cohort study
OBJECTIVE: To examine the extent to which a effect does exist between Positivity (POS), smoking and socio-demographic factors in determining quitting smoking in subjects participating in a Group Counselling Program (GCP) for smoking cessation.METHODS: 481 subjects were contacted through a telephone call. A logistic regression analysis was carried out. Possible interaction between sociodemographic variables and POS level was tested using the Synergism Index (SI).RESULTS: For individuals with a POS level over or equal to 3.4 the odds of being smoker was significantly higher among females (OR = 1.55), who smoked at home (OR = 2.16) and lower if there had children at home (OR = 0.53). For individuals with a POS level under 3.4, the only significant variable associated with smoking was beinga female (OR = 2.58). As far concerns the synergistic effect between the variables considered does exist between POS levels and having children at home (SI=1.13) and female gender (SI = 2.8).CONCLUSIONS: The synergistic effect between POS and sociodemographic factors adds evidence on the use of POS as possible determinants of individual happiness
Solving the Resource Allocation Problem in a Multimodal Container Terminal as a Network Flow Problem
International audienceContinuously increasing global container trade and pressure from a limited number of large shipping companies are enforcing the need for efficient container terminals. By using internal material handling resources efficiently, transfer times and operating costs are reduced. We focus our study on container terminals using straddle carriers for transportation and storage operations. We assume that straddle carriers are shared among maritime and inland transport modes (truck, train, barge). The problem is thus to decide how many resources to allocate to each transport mode in order to minimize vehicle (vessel, truck, train, barge) delays. We present a mixed integer linear programming model, based on a network flow representation, to solve this allocation problem. The modular structure of the model enables us to represent different container terminals, transport modes and service strategies. We present parts of our model and exemplary applications for a terminal at the Grand Port Maritime de Marseille in France
Effects of increased CO2 levels on monsoons
Increased atmospheric carbon dioxide concentration provided warmer atmospheric temperature and higher atmospheric water vapor content, but not necessarily
more precipitation. A set of experiments performed with a state-of-the-art coupled general circulation model forced with increased atmospheric CO2 concentration (2, 4 and 16 times the present-day mean value) were analyzed and compared with a control experiment to evaluate the effect of increased CO2 levels on monsoons. Generally, the monsoon precipitation responses to CO2 forcing are largest if extreme concentrations of carbon dioxide are used, but they are not necessarly proportional to the forcing applied. In fact, despite a common response in terms of an atmospheric
water vapor increase to the atmospheric warming, two out of the six monsoons studied simulate less or equal summer mean precipitation in the 16xCO2 experiment
compared to the intermediate sensitivity experiments. The precipitation differences between CO2 sensitivity experiments
and CTRL have been investigated specifying the contribution of thermodynamic and purely dynamic processes. As a general rule, the differences depending on the atmospheric moisture content changes (thermodynamic
component) are large and positive, and they tend to be damped by the dynamic component associated with the changes in the vertical velocity. However, differences are observed among monsoons in terms of the role played by
other terms (like moisture advection and evaporation) in shaping the precipitation changes in warmer climates. The precipitation increase, even if weak, occurs despite a weakening of the mean circulation in the monsoon regions (‘‘precipitation-wind paradox’’). In particular, the tropical
east-west Walker circulation is reduced, as found from velocity potential analysis. The meridional component of the monsoon circulation is changed as well, with larger
(smaller) meridional (vertical) scales
Effects of Land-Surface-Vegetation on the boreal summer surface climate of a GCM
A Land Surface Model (LSM) has been included in the ECHAM4 Atmospheric
General Circulation Model (AGCM). The LSM is an early version
of ORCHIDEE (Organizing Carbon and Hydrology In Dynamic EcosystEms)
and it replaces the simple land surface scheme previously included in
ECHAM4. The purpose of this paper is to document how a more exhaustive
consideration of the land-surface-vegetation processes affects the simulated
boreal summer surface climate.
In order to investigate the impacts on the simulated climate, different sets
of AMIP-type simulations have been performed with Echam4 alone and with
the AGCM coupled with ORCHIDEE. Furthermore, to assess the effects of
the increase in horizontal resolution the coupling of Echam4 with the LSM
has been implemented at different horizontal resolutions.
The analysis reveals that the LSM has large effects on the simulated boreal
summer surface climate of the atmospheric model. Considerable impacts
are found in the surface energy balance due to changes in the surface
latent heat fluxes over tropical and mid-latitude areas covered with vegetation.
Rainfall and atmospheric circulation are substantially affected by these
changes. In particular, increased precipitation is found over evergreen and
summergreen vegetated areas.
Due to the socio-economical relevance, particular attention has been devoted
to the Indian Summer Monsoon (ISM) region. Our results indicate that
precipitation over the Indian subcontinent is better simulated with the coupled
Echam4-ORCHIDEE model compared to the atmospheric model alone
Genetic diversity of castanea sativa Mill. accessions from the Tuscan-Emilian Apennines and Emilia Romagna region (italy)
This work investigated the genetic diversity of 134 Castanea sativa Mill. accessions present in the Italian region of Emilia-Romagna. Samples were taken from three collection fields (Granaglione, Zocca and Paloneta) in the Tuscan-Emilian Apennines. The accessions were analyzed by using 16 microsatellite markers (SSR). Genetic distances among accessions, calculated through the DICE coefficient, were used to construct an UPGMA cluster analysis. One major genotype (named "Marroni") was identified across the three investigated collection fields; this variety corresponds to a sweet chestnut cultivar that has been propagated and widely diffused in the Emilia-Romagna region. Other genotypes were represented by different varieties of Italian chestnuts. The results of this study will be used to define and share guidelines for the characterization and varietal certification of the chestnut varieties in the Emilia-Romagna region
Enumerating Abelian Returns to Prefixes of Sturmian Words
We follow the works of Puzynina and Zamboni, and Rigo et al. on abelian
returns in Sturmian words. We determine the cardinality of the set
of abelian returns of all prefixes of a Sturmian word in
terms of the coefficients of the continued fraction of the slope, dependingly
on the intercept. We provide a simple algorithm for finding the set
and we determine it for the characteristic Sturmian words.Comment: 19page
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