The relationship between the North Atlantic Oscillation(NAO) and the tropical cyclone frequency over the western North Pacific(WNPTCF) in summer is investigated by use of observation data. It is found that their linka...The relationship between the North Atlantic Oscillation(NAO) and the tropical cyclone frequency over the western North Pacific(WNPTCF) in summer is investigated by use of observation data. It is found that their linkage appears to have an interdecadal change from weak connection to strong connection. During the period of 1948–1977, the NAO was insignificantly correlated to the WNPTCF. However, during the period of 1980–2009, they were significantly correlated with stronger(weaker) NAO corresponding to more(fewer) tropical cyclones in the western North Pacific. The possible reason for such a different relationship between the NAO and the WNPTCF during the former and latter periods is further analyzed from the perspective of large-scale atmospheric circulations. When the NAO was stronger than normal in the latter period, an anomalous cyclonic circulation prevailed in the lower troposphere of the western North Pacific and the monsoon trough was intensified, concurrent with the eastward-shifting western Pacific subtropical high as well as anomalous low-level convergence and high-level divergence over the western North Pacific. These conditions favor the genesis and development of tropical cyclones, and thus more tropical cyclones appeared over the western North Pacific. In contrast, in the former period, the impact of the NAO on the aforementioned atmospheric circulations became insignificant, thereby weakening its linkage to the WNPTCF. Further study shows that the change of the wave activity flux associated with the NAO during the former and latter periods may account for such an interdecadal shift of the NAO–WNPTCF relationship.展开更多
Previous studies have demonstrated that the low-frequency sea surface temperature(SST) variability in the Yellow Sea and East China Sea(YECS) is linked to large-scale climate variability, but explanations on the mecha...Previous studies have demonstrated that the low-frequency sea surface temperature(SST) variability in the Yellow Sea and East China Sea(YECS) is linked to large-scale climate variability, but explanations on the mechanisms vary. This study examines the low-frequency variability and trends of some atmospheric and oceanic variables to discuss their different effects on the YECS warming. The increasing temperature trend is also observed at a hydrographic section transecting the Kuroshio.The increasing rate of ocean temperature decreases with depth, which might result in an increase in vertical stratification and a decrease in vertical mixing, and thus plays a positive role on the YECS warming. The surface net heat flux(downward positive)displays a decreasing trend, which is possibly a result of the YECS warming, and, in turn, inhibits it. Wind speeds show different trends in different datasets, such that its role in the YECS warming is uncertain. The trends in wind stress divergence and curl have large uncertainties, so their effects on SST warming are still unclear. The Kuroshio heat transport calculated in this study,displays no significantly increasing trend, so is an unlikely explanation for the SST warming. Limited by sparse ocean observations,sophisticated assimilative climate models are still needed to unravel the mechanisms behind the YECS warming.展开更多
The riverine sediment flux(SF)is an essential pathway for nutrients and pollutants delivery and considered as an important indicator of land degradation and environment changes.With growing interest in environmental c...The riverine sediment flux(SF)is an essential pathway for nutrients and pollutants delivery and considered as an important indicator of land degradation and environment changes.With growing interest in environmental changes over the Tibetan Plateau(TP),this work investigated the variation of the SF in response to climate change in the headwater of the Yangtze River over the past 30 years.Annual time series of hydro-meteorological variables during 1986–2014 indicate significantly increasing trends of air temperature,precipitation,ground temperature,river discharge,suspended sediment concentration and SF.Stepwise changes were identified with significantly higher values of the above variables in1998–2014 compared with 1986–1997,which could potentially be attributed to the strong 1997 El Ni?o event.Double-mass plots indicated that both meltwater and rainfall contributed to the increased river discharge while the increased SF mostly resulted from enhanced erosive power and transport capacities of the increased discharge.However,it was buffered by a decrease in sediment source due to the shift of maximum monthly rainfall from June/July to July/August during which period a denser vegetation cover prevents soil erosion.Partial least squares structural equation modeling analysis confirmed the dominance of warming on the increase of discharge amplified by increased precipitation.It also confirmed that the increased precipitation drives the increase in suspended sediment concentration.Both processes conspire and equally contribute to the stepwise increase of SF.This study provides important insights into the controlling processes for recent SF changes and gives guidance for water and soil conservation on the TP.展开更多
Terrestrial supply to marginal seas is a function of interaction between land and ocean in response to climate changes.Terrestrial flux in sediments,therefore,is potential not only to reflect the paleoceanographic evo...Terrestrial supply to marginal seas is a function of interaction between land and ocean in response to climate changes.Terrestrial flux in sediments,therefore,is potential not only to reflect the paleoceanographic evolution of sedimentary basin,but also to reveal the paleoclimatic changes in source regions.Sediments from the Okinawa Trough were quantitatively partitioned into terrestrial,volcanic and biogenitic end members using constrained least-squares technique for geochemical compositional data.Combined with the density of bulk sediments and sedimentation rate,the terrestrial flux in sediments from the Okinawa Trough since the last 35 000 a was estimated.Based on surface seawater temperature（SST） and sea level changes over the past 35 000 a,the response of terrestrial flux to the climate changes was discussed.It is demonstrated that the terrestrial supply to the Okinawa Trough mainly derived from Chinese landmass via the Changjiang（Yangtze） River and controlled by sea level changes.During the post-glaciation,the terrestrial flux was the lowest in response to the highest sea level stand.During the last glacial maximum（LGM）,the terrestrial flux was not so high as previously expected,indicating the arid climatic condition in source region was responsible for lowering the Changjiang River＇s runoff during that time.During the deglaciation,the terrestrial flux increased in response to a quick rising of the sea level,probably implicating occurrence of down-slope transport.The four events characterized by slight increase in terrestrial flux exactly correspond to the LGM,Heinrich events（H1,H2,H3）,respectively.展开更多
Little is known about the mechanism of climate-vegetation coverage coupled changes in the Tibetan Plateau(TP)region,which is the most climatically sensitive and ecologically fragile region with the highest terrain in ...Little is known about the mechanism of climate-vegetation coverage coupled changes in the Tibetan Plateau(TP)region,which is the most climatically sensitive and ecologically fragile region with the highest terrain in the world.This study,using multisource datasets(including satellite data and meteorological observations and reanalysis data)revealed the mutual feedback mechanisms between changes in climate(temperature and precipitation)and vegetation coverage in recent decades in the Hengduan Mountains Area(HMA)of the southeastern TP and their influences on climate in the downstream region,the Sichuan Basin(SCB).There is mutual facilitation between rising air temperature and increasing vegetation coverage in the HMA,which is most significant during winter,and then during spring,but insignificant during summer and autumn.Rising temperature significantly enhances local vegetation coverage,and vegetation greening in turn heats the atmosphere via enhancing net heat flux from the surface to the atmosphere.The atmospheric heating anomaly over the HMA thickens the atmospheric column and increases upper air pressure.The high pressure anomaly disperses downstream via the westerly flow,expands across the SCB,and eventually increases the SCB temperature.This effect lasts from winter to the following spring,which may cause the maximum increasing trend of the SCB temperature and vegetation coverage in spring.These results are helpful for estimating future trends in climate and eco-environmental variations in the HMA and SCB under warming scenarios,as well as seasonal forecasting based on the connection between the HMA eco-environment and SCB climate.展开更多
Solar greenhouses have been used for producing vegetables in northern China during early spring,late autumn or over-winter.To improve the thermal performance of solar greenhouses,a traditional type and a retrofitted d...Solar greenhouses have been used for producing vegetables in northern China during early spring,late autumn or over-winter.To improve the thermal performance of solar greenhouses,a traditional type and a retrofitted design were comparatively evaluated.In the retrofitted design,three adjustments were incorporated:the material and structure of the walls,south-facing roof angle,and structure of the north-facing back-roof.The results indicated that the thermal and light performance of the retrofitted greenhouse was much better than that of the traditional greenhouse.Specifically,the daily mean temperature,minimum air temperature,and soil temperature inside the greenhouses after retrofit ting were increased by 1.3,2.4,and 1.9℃,respectively,meanwhile,the daily total solar radiation and PAR were increased by 28.2%and 9.2%,respectively.The wall temperature and its daily variation range were reduced with increasing depth and height.The characteristic analysis of heat storage and release indicated that higher locations have longer heat storage,and shorter heat release time in vertical direction,as well as a lower ratio of heat release to storage.In horizontal direction,the western wall has the shortest heat storage time but the highest heat release flux density.Altogether,the heat storage time of the wall is 1.5 h less than that of the soil.The heat storage flux density of the wall is 1.5 times of that of the soil,but the heat release flux is only 61%of the soil’s value.The total wall heat storage is half of that of the soil in the greenhouse;the total wall heat release amount is only a quarter of that of the soil.Therefore,the thermal environment of solar greenhouses can be further improved by improving the thermal insulation properties of the wall.展开更多
With the large latent heat and low cost, the paraffin has been widely used in battery thermal management(BTM) system to improve the efficiency and cycling life of power battery. The numerical model of paraffin melting...With the large latent heat and low cost, the paraffin has been widely used in battery thermal management(BTM) system to improve the efficiency and cycling life of power battery. The numerical model of paraffin melting in a cavity has been established, and the effects on the solid–liquid phase change process have been investigated for the purpose of enhancing the heat transfer performance of paraffin-based BTM system. The results showed that the location of the heating wall had great effects on the melting process. The paraffin in the cavity melted most quickly when the heating wall located at the bottom. Furthermore, the effects of thermal conductivity and the velocity of the slip wall have been considered. The gradient of liquid fraction increased with the increase in thermal conductivity, and the melting process could be accelerated or delayed by the slip wall with different velocity.展开更多
Time-series of chlorophyll-a(CHL),a proxy for phytoplankton biomass,and various satellite-derived climate indicators are compared in a region of the Subantarctic Southern Ocean(40°-60°S,110°-140°E)...Time-series of chlorophyll-a(CHL),a proxy for phytoplankton biomass,and various satellite-derived climate indicators are compared in a region of the Subantarctic Southern Ocean(40°-60°S,110°-140°E)for years 2012-2014.CHL reached a minimum in winter(June)and a maximum in late summer(early February).Zonal mean CHL decreased towards the south.Mean sea surface temperature(SST)ranged between 8℃and 15℃and peaked in late February.CHL and SST were positively correlated from March to June,negatively correlated from July to September.CHL and wind speed(WIND)were negatively correlated with peak WIND occurred in winter.Wind direction(WIRD)was mostly in the southwest to westerly direction.The Antarctic Oscillation index(AAO)and CHL were negatively correlated(R=−0.58),indicating that as synoptic wind systems move southwards,CHL increases,and conversely when wind systems move northwards,CHL decreases.A genetic algorithm is used to calibrate the biogeochemical DMS model’s key parameters.Under 4×CO2(after year 2100)Regional mean SST increases 12%-17%,WIND increases 1.2ms−1,Cloud Cover increases 4.8%and mixed layer depth(MLD)decreases 48m.The annual CHL increases 6.3%.The annual mean DMS flux increase 25.2%,increases 37%from day 1 to day 280 and decrease 3%from day 288 to day 360.The general increase of DMS flux under 4×CO2 conditions indicates the Subantarctic regional climate would be affected by changes in the DMS flux,with the potential for a cooling effect in the austral summer and autumn.展开更多
A series of non-woven fabrics were fabricated by blending S0- 80wt% of thennoregulated fibres containing n-elcosane, n-nonadecane or n-octadecane with 0 - 40wt% PET fibres and 0- 20wt% PP fibres. The phase change prop...A series of non-woven fabrics were fabricated by blending S0- 80wt% of thennoregulated fibres containing n-elcosane, n-nonadecane or n-octadecane with 0 - 40wt% PET fibres and 0- 20wt% PP fibres. The phase change properties, thermal conductivity, thermal resistance, heat flux and inner temperature difference between wool felt and the thermoregulated non-woven fabrics of the non-woven fabrics were measured respectively. The thereto-regulated non-woven fabrics absorb heat at 25- 34℃ and release heat at 10- 25℃. The measured highest enthalpy of the non-woven is approximately 18J/g. During a heating process, heat flux of the non-woven fabrics is composed of three parts, heat absorbed by the cold textile touching the hot plate, heat transmitted from the hot plate to the cold plate, and the heat absorbed by PCM from the hot plate during the phase change process. The measured maximum inner temperature difference in a temperature rising process between the wool felt and the thermo-regulated non-woven fabric is approximately 8℃. The inner temperature difference （Tr-Ts〉0） lasts 16 - 45 min By contrary, the measured maximum inner temperature difference in the temperature decreasing process is approximately - 6. 5℃. The inner temperature difference （Tr-Ts〈0） lasts 16 - 50 min, The temperature regulation properties are obviously observed.展开更多
A quantitative analysis of the total concentrations of Al and Na in the Antarctic ice sheet during the past 340 kyr was performed by applying the acid digestion method to the Dome Fuji ice core. Atmospheric fluxes of ...A quantitative analysis of the total concentrations of Al and Na in the Antarctic ice sheet during the past 340 kyr was performed by applying the acid digestion method to the Dome Fuji ice core. Atmospheric fluxes of mineral and sea-salt aerosol to Dome Fuji were calculated from the total concentration. The average fluxes of mineral aerosol to Dome Fuji in the periods of glacial maximum, 18.6 ± 10.1 mg·m–2·yr–1, were larger than the value in the interglacial periods, 3.77 ± 2.20 mg·m–2·yr–1. Conversely, the fluxes of sea-salt have no significant difference between the average value of glacial maximum, 130 ± 55 mg·m–2·yr–1, and that of interglacial, 111 ± 54 mg·m–2·yr–1. The results obtained in this study suggest that the variation of mineral aerosol flux in Dome Fuji, together with climate change, was much larger than that of sea-salt aerosol flux. This result may have occurred because the variety in the intensity of the source and transport during the glacial-interglacial cycle is more significant for mineral aerosol than that for sea-salt aerosol.展开更多
A global ocean general circulation model, called LASG/IAP Climate system ocean model （LICOM）, is employed to study the influence of climate change on the uptake and storage of anthropogenic CO2 in the global ocean. ...A global ocean general circulation model, called LASG/IAP Climate system ocean model （LICOM）, is employed to study the influence of climate change on the uptake and storage of anthropogenic CO2 in the global ocean. Two simulations were made： the control run （RUN1） with the climatological daily mean forcing data, and the climate change run （RUN2） with the interannually varying daily mean forcing data from the NCEP （National Centers for Environmental Prediction） of the US. The results show that the simulated distributions and storages of anthropogenic dissolved inorganic carbon （anDIC） from both runs are consistent with the data-based results. Compared with the data-based results, the simulations generate higher anDIC concentrations in the upper layer and lower storage amount of anDIC between the subsurface and 1000-m depth, especially in RUN1. A comparison of the two runs shows that the interannually varying forcing can enhance the transport of main water masses, so the rate of interior transport of anDIC is increased. The higher transfer rate of anDIC in RUN2 decreases its high concentration in the upper layer and increases its storage amount below the subsurface, which leads to closer distributions of anDIC in RUN2 to the data-based results than in RUN1. The higher transfer rate in RUN2 also induces larger exchange flux than in RUN1. It is estimated that the global oceanic anthropogenic CO2 uptake was 1.83 and 2.16 Pg C yr-1 in the two runs in 1995, respectively, and as of 1994, the global ocean contained 99 Pg C in RUN1 and 107 Pg C in RUN2 of anDIC, indicating that the model under the interannually varying forcing could take up 8.1% more anthropogenic carbon than the model under the climatological forcing. These values are within the range of other estimates based on observation and model simulation, while the estimates in RUN1 are near the low bound of other works. It is estimated that the variability of root mean square of the global air-sea anthropogenic carbon flux from the simulated 展开更多
基金supported by the Special Fund for Public Welfare Industry(Meteorology)(Grant No.GYHY201306026)the National Natural Science Foundation of China(Grant No.41275078)the National Basic Research Program of China(Grant No.2009CB421407)
文摘The relationship between the North Atlantic Oscillation(NAO) and the tropical cyclone frequency over the western North Pacific(WNPTCF) in summer is investigated by use of observation data. It is found that their linkage appears to have an interdecadal change from weak connection to strong connection. During the period of 1948–1977, the NAO was insignificantly correlated to the WNPTCF. However, during the period of 1980–2009, they were significantly correlated with stronger(weaker) NAO corresponding to more(fewer) tropical cyclones in the western North Pacific. The possible reason for such a different relationship between the NAO and the WNPTCF during the former and latter periods is further analyzed from the perspective of large-scale atmospheric circulations. When the NAO was stronger than normal in the latter period, an anomalous cyclonic circulation prevailed in the lower troposphere of the western North Pacific and the monsoon trough was intensified, concurrent with the eastward-shifting western Pacific subtropical high as well as anomalous low-level convergence and high-level divergence over the western North Pacific. These conditions favor the genesis and development of tropical cyclones, and thus more tropical cyclones appeared over the western North Pacific. In contrast, in the former period, the impact of the NAO on the aforementioned atmospheric circulations became insignificant, thereby weakening its linkage to the WNPTCF. Further study shows that the change of the wave activity flux associated with the NAO during the former and latter periods may account for such an interdecadal shift of the NAO–WNPTCF relationship.
基金supported by the the National Natural Science Foundation of China (Grant Nos. 41690120, 41690121, 41621064, 91528304 & 41476021)the National Program on Global Change and Air-Sea Interaction (Grant No. GASI-IPOVAI-04)+1 种基金the National Basic Research Program (Grant No. 2013CB430302)the Scientific Research Fund of the Second Institute of Oceanography (Grant No. JG1501)
文摘Previous studies have demonstrated that the low-frequency sea surface temperature(SST) variability in the Yellow Sea and East China Sea(YECS) is linked to large-scale climate variability, but explanations on the mechanisms vary. This study examines the low-frequency variability and trends of some atmospheric and oceanic variables to discuss their different effects on the YECS warming. The increasing temperature trend is also observed at a hydrographic section transecting the Kuroshio.The increasing rate of ocean temperature decreases with depth, which might result in an increase in vertical stratification and a decrease in vertical mixing, and thus plays a positive role on the YECS warming. The surface net heat flux(downward positive)displays a decreasing trend, which is possibly a result of the YECS warming, and, in turn, inhibits it. Wind speeds show different trends in different datasets, such that its role in the YECS warming is uncertain. The trends in wind stress divergence and curl have large uncertainties, so their effects on SST warming are still unclear. The Kuroshio heat transport calculated in this study,displays no significantly increasing trend, so is an unlikely explanation for the SST warming. Limited by sparse ocean observations,sophisticated assimilative climate models are still needed to unravel the mechanisms behind the YECS warming.
基金supported by the Second Tibetan Plateau Scientific Expedition and Research Program(2019QZKK0203)the Strategic Priority Research Program of the Chinese Academy of Sciences(XDA20060202).
文摘The riverine sediment flux(SF)is an essential pathway for nutrients and pollutants delivery and considered as an important indicator of land degradation and environment changes.With growing interest in environmental changes over the Tibetan Plateau(TP),this work investigated the variation of the SF in response to climate change in the headwater of the Yangtze River over the past 30 years.Annual time series of hydro-meteorological variables during 1986–2014 indicate significantly increasing trends of air temperature,precipitation,ground temperature,river discharge,suspended sediment concentration and SF.Stepwise changes were identified with significantly higher values of the above variables in1998–2014 compared with 1986–1997,which could potentially be attributed to the strong 1997 El Ni?o event.Double-mass plots indicated that both meltwater and rainfall contributed to the increased river discharge while the increased SF mostly resulted from enhanced erosive power and transport capacities of the increased discharge.However,it was buffered by a decrease in sediment source due to the shift of maximum monthly rainfall from June/July to July/August during which period a denser vegetation cover prevents soil erosion.Partial least squares structural equation modeling analysis confirmed the dominance of warming on the increase of discharge amplified by increased precipitation.It also confirmed that the increased precipitation drives the increase in suspended sediment concentration.Both processes conspire and equally contribute to the stepwise increase of SF.This study provides important insights into the controlling processes for recent SF changes and gives guidance for water and soil conservation on the TP.
基金The National Natural Science Foundation of China under contract Nos 40431002, 40276024 and 40606016
文摘Terrestrial supply to marginal seas is a function of interaction between land and ocean in response to climate changes.Terrestrial flux in sediments,therefore,is potential not only to reflect the paleoceanographic evolution of sedimentary basin,but also to reveal the paleoclimatic changes in source regions.Sediments from the Okinawa Trough were quantitatively partitioned into terrestrial,volcanic and biogenitic end members using constrained least-squares technique for geochemical compositional data.Combined with the density of bulk sediments and sedimentation rate,the terrestrial flux in sediments from the Okinawa Trough since the last 35 000 a was estimated.Based on surface seawater temperature（SST） and sea level changes over the past 35 000 a,the response of terrestrial flux to the climate changes was discussed.It is demonstrated that the terrestrial supply to the Okinawa Trough mainly derived from Chinese landmass via the Changjiang（Yangtze） River and controlled by sea level changes.During the post-glaciation,the terrestrial flux was the lowest in response to the highest sea level stand.During the last glacial maximum（LGM）,the terrestrial flux was not so high as previously expected,indicating the arid climatic condition in source region was responsible for lowering the Changjiang River＇s runoff during that time.During the deglaciation,the terrestrial flux increased in response to a quick rising of the sea level,probably implicating occurrence of down-slope transport.The four events characterized by slight increase in terrestrial flux exactly correspond to the LGM,Heinrich events（H1,H2,H3）,respectively.
基金the National Natural Science Foundation of China(Grant Nos.42205059 and 42005075)the Strategic Priority Research Program of the Chinese Academy of Sciences(Grant Nos.XDA23090303 and XDB40010302)+1 种基金the State Key Laboratory of Cryospheric Science(Grant No.SKLCS-ZZ-2024 and SKLCS-ZZ-2023)the Key Laboratory of Mountain Hazards and Earth Surface Processes.
文摘Little is known about the mechanism of climate-vegetation coverage coupled changes in the Tibetan Plateau(TP)region,which is the most climatically sensitive and ecologically fragile region with the highest terrain in the world.This study,using multisource datasets(including satellite data and meteorological observations and reanalysis data)revealed the mutual feedback mechanisms between changes in climate(temperature and precipitation)and vegetation coverage in recent decades in the Hengduan Mountains Area(HMA)of the southeastern TP and their influences on climate in the downstream region,the Sichuan Basin(SCB).There is mutual facilitation between rising air temperature and increasing vegetation coverage in the HMA,which is most significant during winter,and then during spring,but insignificant during summer and autumn.Rising temperature significantly enhances local vegetation coverage,and vegetation greening in turn heats the atmosphere via enhancing net heat flux from the surface to the atmosphere.The atmospheric heating anomaly over the HMA thickens the atmospheric column and increases upper air pressure.The high pressure anomaly disperses downstream via the westerly flow,expands across the SCB,and eventually increases the SCB temperature.This effect lasts from winter to the following spring,which may cause the maximum increasing trend of the SCB temperature and vegetation coverage in spring.These results are helpful for estimating future trends in climate and eco-environmental variations in the HMA and SCB under warming scenarios,as well as seasonal forecasting based on the connection between the HMA eco-environment and SCB climate.
基金The study was financially supported by the National Natural Science Foundation of China(31601794)International cooperation fund of Beijing Academy of Agriculture and Forestry Sciences(GJHZ2018-04)the project of Facilities Horticulture Innovation Team of Beijing Academy of Agriculture and Forestry Sciences(JNKST201615).
文摘Solar greenhouses have been used for producing vegetables in northern China during early spring,late autumn or over-winter.To improve the thermal performance of solar greenhouses,a traditional type and a retrofitted design were comparatively evaluated.In the retrofitted design,three adjustments were incorporated:the material and structure of the walls,south-facing roof angle,and structure of the north-facing back-roof.The results indicated that the thermal and light performance of the retrofitted greenhouse was much better than that of the traditional greenhouse.Specifically,the daily mean temperature,minimum air temperature,and soil temperature inside the greenhouses after retrofit ting were increased by 1.3,2.4,and 1.9℃,respectively,meanwhile,the daily total solar radiation and PAR were increased by 28.2%and 9.2%,respectively.The wall temperature and its daily variation range were reduced with increasing depth and height.The characteristic analysis of heat storage and release indicated that higher locations have longer heat storage,and shorter heat release time in vertical direction,as well as a lower ratio of heat release to storage.In horizontal direction,the western wall has the shortest heat storage time but the highest heat release flux density.Altogether,the heat storage time of the wall is 1.5 h less than that of the soil.The heat storage flux density of the wall is 1.5 times of that of the soil,but the heat release flux is only 61%of the soil’s value.The total wall heat storage is half of that of the soil in the greenhouse;the total wall heat release amount is only a quarter of that of the soil.Therefore,the thermal environment of solar greenhouses can be further improved by improving the thermal insulation properties of the wall.
基金supported by the National Natural Science Foundation of China(51406223)
文摘With the large latent heat and low cost, the paraffin has been widely used in battery thermal management(BTM) system to improve the efficiency and cycling life of power battery. The numerical model of paraffin melting in a cavity has been established, and the effects on the solid–liquid phase change process have been investigated for the purpose of enhancing the heat transfer performance of paraffin-based BTM system. The results showed that the location of the heating wall had great effects on the melting process. The paraffin in the cavity melted most quickly when the heating wall located at the bottom. Furthermore, the effects of thermal conductivity and the velocity of the slip wall have been considered. The gradient of liquid fraction increased with the increase in thermal conductivity, and the melting process could be accelerated or delayed by the slip wall with different velocity.
基金the National Natural Science Foundation of China (Nos. 41276097 and 11701298) for providing research funding for this project
文摘Time-series of chlorophyll-a(CHL),a proxy for phytoplankton biomass,and various satellite-derived climate indicators are compared in a region of the Subantarctic Southern Ocean(40°-60°S,110°-140°E)for years 2012-2014.CHL reached a minimum in winter(June)and a maximum in late summer(early February).Zonal mean CHL decreased towards the south.Mean sea surface temperature(SST)ranged between 8℃and 15℃and peaked in late February.CHL and SST were positively correlated from March to June,negatively correlated from July to September.CHL and wind speed(WIND)were negatively correlated with peak WIND occurred in winter.Wind direction(WIRD)was mostly in the southwest to westerly direction.The Antarctic Oscillation index(AAO)and CHL were negatively correlated(R=−0.58),indicating that as synoptic wind systems move southwards,CHL increases,and conversely when wind systems move northwards,CHL decreases.A genetic algorithm is used to calibrate the biogeochemical DMS model’s key parameters.Under 4×CO2(after year 2100)Regional mean SST increases 12%-17%,WIND increases 1.2ms−1,Cloud Cover increases 4.8%and mixed layer depth(MLD)decreases 48m.The annual CHL increases 6.3%.The annual mean DMS flux increase 25.2%,increases 37%from day 1 to day 280 and decrease 3%from day 288 to day 360.The general increase of DMS flux under 4×CO2 conditions indicates the Subantarctic regional climate would be affected by changes in the DMS flux,with the potential for a cooling effect in the austral summer and autumn.
基金the financial supports from The Hong Kong Polytechnic University(the Area of Strategic Development Project,No A180) the National Natural Science Foundation of China(No50073015).
文摘A series of non-woven fabrics were fabricated by blending S0- 80wt% of thennoregulated fibres containing n-elcosane, n-nonadecane or n-octadecane with 0 - 40wt% PET fibres and 0- 20wt% PP fibres. The phase change properties, thermal conductivity, thermal resistance, heat flux and inner temperature difference between wool felt and the thermoregulated non-woven fabrics of the non-woven fabrics were measured respectively. The thereto-regulated non-woven fabrics absorb heat at 25- 34℃ and release heat at 10- 25℃. The measured highest enthalpy of the non-woven is approximately 18J/g. During a heating process, heat flux of the non-woven fabrics is composed of three parts, heat absorbed by the cold textile touching the hot plate, heat transmitted from the hot plate to the cold plate, and the heat absorbed by PCM from the hot plate during the phase change process. The measured maximum inner temperature difference in a temperature rising process between the wool felt and the thermo-regulated non-woven fabric is approximately 8℃. The inner temperature difference （Tr-Ts〉0） lasts 16 - 45 min By contrary, the measured maximum inner temperature difference in the temperature decreasing process is approximately - 6. 5℃. The inner temperature difference （Tr-Ts〈0） lasts 16 - 50 min, The temperature regulation properties are obviously observed.
文摘A quantitative analysis of the total concentrations of Al and Na in the Antarctic ice sheet during the past 340 kyr was performed by applying the acid digestion method to the Dome Fuji ice core. Atmospheric fluxes of mineral and sea-salt aerosol to Dome Fuji were calculated from the total concentration. The average fluxes of mineral aerosol to Dome Fuji in the periods of glacial maximum, 18.6 ± 10.1 mg·m–2·yr–1, were larger than the value in the interglacial periods, 3.77 ± 2.20 mg·m–2·yr–1. Conversely, the fluxes of sea-salt have no significant difference between the average value of glacial maximum, 130 ± 55 mg·m–2·yr–1, and that of interglacial, 111 ± 54 mg·m–2·yr–1. The results obtained in this study suggest that the variation of mineral aerosol flux in Dome Fuji, together with climate change, was much larger than that of sea-salt aerosol flux. This result may have occurred because the variety in the intensity of the source and transport during the glacial-interglacial cycle is more significant for mineral aerosol than that for sea-salt aerosol.
基金Supported by the National Basic Research and Development (973) Program of China (2010CB951802)China Meteorological Adminstration Special Public Welfare Research Fund (GYHY2008416022)National Natural Science Foundation of China (40730106)
文摘A global ocean general circulation model, called LASG/IAP Climate system ocean model （LICOM）, is employed to study the influence of climate change on the uptake and storage of anthropogenic CO2 in the global ocean. Two simulations were made： the control run （RUN1） with the climatological daily mean forcing data, and the climate change run （RUN2） with the interannually varying daily mean forcing data from the NCEP （National Centers for Environmental Prediction） of the US. The results show that the simulated distributions and storages of anthropogenic dissolved inorganic carbon （anDIC） from both runs are consistent with the data-based results. Compared with the data-based results, the simulations generate higher anDIC concentrations in the upper layer and lower storage amount of anDIC between the subsurface and 1000-m depth, especially in RUN1. A comparison of the two runs shows that the interannually varying forcing can enhance the transport of main water masses, so the rate of interior transport of anDIC is increased. The higher transfer rate of anDIC in RUN2 decreases its high concentration in the upper layer and increases its storage amount below the subsurface, which leads to closer distributions of anDIC in RUN2 to the data-based results than in RUN1. The higher transfer rate in RUN2 also induces larger exchange flux than in RUN1. It is estimated that the global oceanic anthropogenic CO2 uptake was 1.83 and 2.16 Pg C yr-1 in the two runs in 1995, respectively, and as of 1994, the global ocean contained 99 Pg C in RUN1 and 107 Pg C in RUN2 of anDIC, indicating that the model under the interannually varying forcing could take up 8.1% more anthropogenic carbon than the model under the climatological forcing. These values are within the range of other estimates based on observation and model simulation, while the estimates in RUN1 are near the low bound of other works. It is estimated that the variability of root mean square of the global air-sea anthropogenic carbon flux from the simulated
