Driven by the increase in CO_(2)concentration,climate models reach a consensus that the large-scale circulation of the South Asian summer monsoon(SASM) becomes weakened but with different magnitudes.This study investi...Driven by the increase in CO_(2)concentration,climate models reach a consensus that the large-scale circulation of the South Asian summer monsoon(SASM) becomes weakened but with different magnitudes.This study investigates the major uncertainty sources of the SASM response to an abrupt quadrupling of CO_(2)(abrupt-4×CO_(2))in 18 models of phase 6 of the Coupled Model Intercomparison Project.The projected weakening of the SASM indicated by both zonal and meridional monsoon circulation indices is closely linked to decreases in the meridional gradient of upper-tropospheric temperature between Eurasia and the Indian Ocean(EUTT-IUTT).A climate feedback-response analysis method is applied to linearly decompose the uncertainty of changes in EUTT-IUTT into the partial changes due to external forcing and internal processes of the earth-atmosphere column.Results show that the uncertainty of changes in EUTT-IUTT is contributed positively by the dominant atmospheric dynamic process,followed by the cloud shortwave radiative effect,and negatively by the surface latent heat flux and cloud longwave radiative effect.Contributions from CO_(2)forcing and other internal processes including albedo and water vapor feedbacks,oceanic heat storage,and sensible heat flux are found to be minor.展开更多
Composite top- and subsoil samples were collected from the greenhouses in the Al-Balawneh area,Jordan,where intensive greenhouse production system(IGPS) has been practiced since 1998,to study the impact of IGPS on soi...Composite top- and subsoil samples were collected from the greenhouses in the Al-Balawneh area,Jordan,where intensive greenhouse production system(IGPS) has been practiced since 1998,to study the impact of IGPS on soil quality as measured by the chemical and biological properties to develop a sustainable production system.The study showed that IGPS led to higher electrical conductivity in top- and subsoils compared to an uncultivated soil(control).Quality and amount of irrigation water,lack of efficient drainage,and quantity and types of applied fertilizers were major factors resulting in salt buildup.IGPS resulted in lower total N(TN) and NO_3-N in the soil compared to the control.The lower TN was due to crop uptake,microbial immobilization,volatilization,and irregular application of composted animal manure or poultry manure.In contrast,higher residual Olsen-P content was detected in both soil layers of greenhouses than in the control.Residual P was classified as very high in the topsoil layers and sufficient to high in the subsoil layers.Residual available K in the soils of greenhouses was relatively lower than that in the control and it was,however,classified as high to very high.A large increase of Cl and a considerable decrease in the bacterial count were observed in both soil layers of IGPS compared to the control treatment.Economically sustainable soil management practices need to be adopted by farmers to achieve a sustainable and profitable production.This can be accomplished through education,targeted towards the farming community in the central Jordan Valley.展开更多
基金jointly supported by the National Natural Science Foundation of China [grant numbers 4208810141911540470+3 种基金42075028]the Guangdong Major Project of Basic and Applied Basic Research [grant number 2020B0301030004]the Natural Science Foundation of Guangdong Province of China [grant number 2018A0303130268]the Guangdong Province Key Laboratory for Climate Change and Natural Disaster Studies [grant number2020B1212060025]。
文摘Driven by the increase in CO_(2)concentration,climate models reach a consensus that the large-scale circulation of the South Asian summer monsoon(SASM) becomes weakened but with different magnitudes.This study investigates the major uncertainty sources of the SASM response to an abrupt quadrupling of CO_(2)(abrupt-4×CO_(2))in 18 models of phase 6 of the Coupled Model Intercomparison Project.The projected weakening of the SASM indicated by both zonal and meridional monsoon circulation indices is closely linked to decreases in the meridional gradient of upper-tropospheric temperature between Eurasia and the Indian Ocean(EUTT-IUTT).A climate feedback-response analysis method is applied to linearly decompose the uncertainty of changes in EUTT-IUTT into the partial changes due to external forcing and internal processes of the earth-atmosphere column.Results show that the uncertainty of changes in EUTT-IUTT is contributed positively by the dominant atmospheric dynamic process,followed by the cloud shortwave radiative effect,and negatively by the surface latent heat flux and cloud longwave radiative effect.Contributions from CO_(2)forcing and other internal processes including albedo and water vapor feedbacks,oceanic heat storage,and sensible heat flux are found to be minor.
文摘Composite top- and subsoil samples were collected from the greenhouses in the Al-Balawneh area,Jordan,where intensive greenhouse production system(IGPS) has been practiced since 1998,to study the impact of IGPS on soil quality as measured by the chemical and biological properties to develop a sustainable production system.The study showed that IGPS led to higher electrical conductivity in top- and subsoils compared to an uncultivated soil(control).Quality and amount of irrigation water,lack of efficient drainage,and quantity and types of applied fertilizers were major factors resulting in salt buildup.IGPS resulted in lower total N(TN) and NO_3-N in the soil compared to the control.The lower TN was due to crop uptake,microbial immobilization,volatilization,and irregular application of composted animal manure or poultry manure.In contrast,higher residual Olsen-P content was detected in both soil layers of greenhouses than in the control.Residual P was classified as very high in the topsoil layers and sufficient to high in the subsoil layers.Residual available K in the soils of greenhouses was relatively lower than that in the control and it was,however,classified as high to very high.A large increase of Cl and a considerable decrease in the bacterial count were observed in both soil layers of IGPS compared to the control treatment.Economically sustainable soil management practices need to be adopted by farmers to achieve a sustainable and profitable production.This can be accomplished through education,targeted towards the farming community in the central Jordan Valley.
