51 research outputs found
Montane ecosystem productivity responds more to global circulation patterns than climatic trends
Ajuts: we thank the support of KIT IMK-IFU, the University of Wisconsin sabbatical leave program, and the Helmholtz Society/MICMOR fellowship program. We also thank the DWD for German weather data. Phenology data were provided by the members of the PEP725 project. We are indebted to the providers and funders of the eddy covariance flux tower observations, the FLUXNET program, and its database. The sites in Graswang, Rottenbuch and Fendt belong to the TERENO and ICOS-ecosystems networks, funded by Bundesministerium für Bildung und Forschung(BMBF)and the Helmholtz Association. The modeling study of SOLVEG was partially supported by Grant-in-Aid for Scientific Research, no. 21120512, provided by the Japan Society for the Promotion of Science(JSPS). This study was financially supported by the Austrian National Science Fund(FWF) under contract P26425 to GW.Regional ecosystem productivity is highly sensitive to inter-annual climate variability, both within and outside the primary carbon uptake period. However, Earth system models lack sufficient spatial scales and ecosystem processes to resolve how these processes may change in a warming climate. Here, we show, how for the European Alps, mid-latitude Atlantic ocean winter circulation anomalies drive high-altitude summer forest and grassland productivity, through feedbacks among orographic wind circulation patterns, snowfall, winter and spring temperatures, and vegetation activity. Therefore, to understand future global climate change influence to regional ecosystem productivity, Earth systems models need to focus on improvements towards topographic downscaling of changes in regional atmospheric circulation patterns and to lagged responses in vegetation dynamics to non-growing season climate anomalies
Montane ecosystem productivity responds more to global circulation patterns than climatic trends
Regional ecosystem productivity is highly sensitive to inter-annual climate variability, both within and outside the primary carbon uptake period. However, Earth system models lack sufficient spatial scales and ecosystem processes to resolve how these processes may change in a warming climate. Here, we show, how for the European Alps, mid-latitude Atlantic ocean winter circulation anomalies drive high-altitude summer forest and grassland productivity, through feedbacks among orographic wind circulation patterns, snowfall, winter and spring temperatures, and vegetation activity. Therefore, to understand future global climate change influence to regional ecosystem productivity, Earth systems models need to focus on improvements towards topographic downscaling of changes in regional atmospheric circulation patterns and to lagged responses in vegetation dynamics to non-growing season climate anomalies
Detailed source term estimation of the atmospheric release for the Fukushima Daiichi Nuclear Power Station accident by coupling simulations of an atmospheric dispersion model with an improved deposition scheme and oceanic dispersion model
Temporal variations in the amount of radionuclides released into the
atmosphere during the Fukushima Daiichi Nuclear Power Station (FNPS1)
accident and their atmospheric and marine dispersion are essential to
evaluate the environmental impacts and resultant radiological doses to the
public. In this paper, we estimate the detailed atmospheric releases during
the accident using a reverse estimation method which calculates the release
rates of radionuclides by comparing measurements of air concentration of a
radionuclide or its dose rate in the environment with the ones calculated by
atmospheric and oceanic transport, dispersion and deposition models. The
atmospheric and oceanic models used are WSPEEDI-II (Worldwide version of
System for Prediction of Environmental Emergency Dose Information) and
SEA-GEARN-FDM (Finite difference oceanic dispersion model), both developed by the authors. A sophisticated deposition
scheme, which deals with dry and fog-water depositions, cloud condensation
nuclei (CCN) activation, and subsequent wet scavenging due to mixed-phase
cloud microphysics (in-cloud scavenging) for radioactive iodine gas (I2
and CH3I) and other particles (CsI, Cs, and Te), was incorporated into
WSPEEDI-II to improve the surface deposition calculations. The results
revealed that the major releases of radionuclides due to the FNPS1 accident
occurred in the following periods during March 2011: the afternoon of 12
March due to the wet venting and hydrogen explosion at Unit 1, midnight of
14 March when the SRV (safety relief valve) was opened three times at Unit
2, the morning and night of 15 March, and the morning of 16 March. According
to the simulation results, the highest radioactive contamination areas
around FNPS1 were created from 15 to 16 March by complicated interactions
among rainfall, plume movements, and the temporal variation of release
rates. The simulation by WSPEEDI-II using the new source term reproduced the
local and regional patterns of cumulative surface deposition of total
131I and 137Cs and air dose rate obtained by airborne surveys. The
new source term was also tested using three atmospheric dispersion models
(Modèle Lagrangien de Dispersion de Particules d'ordre zéro: MLDP0, Hybrid Single Particle
Lagrangian Integrated Trajectory Model: HYSPLIT, and Met Office's Numerical
Atmospheric-dispersion Modelling Environment: NAME) for regional and global calculations, and the
calculated results showed good agreement with observed air concentration
and surface deposition of 137Cs in eastern Japan
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