In this paper, we use a spectral model for the medium-range numerical weather forecast to discuss the impact of the diurnal variation of solar radiation on the medium-range weather processes. Under the tests of two ty...In this paper, we use a spectral model for the medium-range numerical weather forecast to discuss the impact of the diurnal variation of solar radiation on the medium-range weather processes. Under the tests of two typical winter and summer cases, we find that the influences of the diurnal variation of solar radiation on summer weather are really important, especially on its rainfall, surface heat transport and 500 hPa height field. On winter weather, however, the influences are very weak.展开更多
Heavy rain is a common abnormal weather in China, which is prone to major natural disasters such as floods. By using China National Climate Center’s DERF2.0 (the second-generation product of monthly dynamic extended ...Heavy rain is a common abnormal weather in China, which is prone to major natural disasters such as floods. By using China National Climate Center’s DERF2.0 (the second-generation product of monthly dynamic extended ensemble prediction) models and NCEP (National Centers for Environmental Prediction) data, and using synoptic and dynamic methods and other research methods, the rainfall weather process in most of China from October 3-6, 2021 is analyzed. The results show that: 1) this process had a long duration, large cumulative rainfall and strong extreme. 2) The warm and wet flow and the cold air intersected in the central and western regions of China and Northeast China, which resulted in a regional rainstorm process within ten days. 3) There was a low-level jet moving from Guizhou and Hunan to the south of Northeast China, bringing a lot of water vapor. To sum up, the rainfall process of this round has a certain relationship with the adjustment of atmospheric circulation.展开更多
[Objective] The aim was to study the formation and development of a heavy snow in Benxi area. [Method] Based on conventional meteorological data, the formation and development of a heavy snow in Benxi area from Decemb...[Objective] The aim was to study the formation and development of a heavy snow in Benxi area. [Method] Based on conventional meteorological data, the formation and development of a heavy snow in Benxi area from December 4th to 5th in 2009 were analyzed from the aspects of weather situation evolution and physical quantity field feature. [Result] The heavy snow was caused by upper trough and North China cyclone. In this process, there was upper level divergence and lower level convergence over Benxi area, and it was warm at low attitude and cold at high attitude; southwest jet at low attitude transported water vapor from Bohai Sea to eastern Liaoning, which provided good water vapor condition for snow, but it didn’t reach heavy snow due to inadequate ascending force. The development of Ural Mountains high ridge played an important role in the snow process and the strengthened high ridge moving northward was beneficial to the southward movement of cold air and deepening of upper trough. Analysis on physical quantity field could provide reference for predicting beginning and ending time and strength of heavy snow. [Conclusion] The study could provide basis for the forecast of heavy snow.展开更多
Currently, short horizontal surface wave radiation at the ground surface （GSW） is calculated under the assumption of a This method of estimating the GSW may lead to considerable errors when the model resolution beco...Currently, short horizontal surface wave radiation at the ground surface （GSW） is calculated under the assumption of a This method of estimating the GSW may lead to considerable errors when the model resolution becomes higher and the model terrain becomes steeper. In this paper, to improve the short wave solar radiation simulations, a terrain slope and orientation parameterization has been implemented into the non-hydrostatic mesoscale model GRAPES （Global/Regional Assimilation and Prediction System）. The effects of the terrain slope and orientation on different short range weather processes in China under different model resolutions are simulated and discussed. In the simulations, topography height is taken from NCEP （National Centers for Environmental Prediction） with a resolution of 1 km, and the slope and orientation of terrain are calculated using different staggering schemes and under different weather conditions. The results show that when the model resolution is low （30 and 60 km） and the slope of terrain is not large, the influence of the slope and orientation of terrain on the GSW is not evident; otherwise, however, it is not negligible. Under high model resolutions （3 and 6 km）, the increase （decrease） of simulated precipitation corresponds to the decrease （increase） of the GSW induced by the slope effect, and the variations of precipitation are usually ranged between -5 and 5 ram. Under the high resolution, the surface temperature and heat fluxes are strongly correlated to each other and the high correlation exists mostly in the complex terrain regions. The changes of the GSW, precipitation, surface temperature, and heat fluxes induced by the effects of the terrain slope and orientation are more obvious in mountainous regions, due to the alternations in the atmospheric circulation. It is found as well that under the weather condition of less cloud and less precipitation, the effects of the terrain slope and orientation can be more realistically seen. Therefore, the terrain slope and orientation can usually be neglected in numerical models when the horizontal model resolution is low and the slopes are moderate, but should be taken into account when the model resolution becomes high and the terrain is steep and undulating.展开更多
In this paper,the data chosen from measurements by supersonic anemometers in Tongxian County of Beijing in 1990 are used to study characteristics of turbulence spectra in precipitation weather.Some turbulence paramete...In this paper,the data chosen from measurements by supersonic anemometers in Tongxian County of Beijing in 1990 are used to study characteristics of turbulence spectra in precipitation weather.Some turbulence parameters such as turbulence intensity,heat and momentum fluxes,friction velocity,M-O length and stability parameter are calculated and their dependence on turbulence spectra in different stability conditions are analyzed.Some encouraging results are obtained and compared with others' results.展开更多
By employing the T42L9 spectral model introduced flom ECMWF and utilizing the FGGE-III_b data covering the period from 14 June to 19 June 1979,the effects of the Qinghai-Xizang Plateau on the medium- range weather pro...By employing the T42L9 spectral model introduced flom ECMWF and utilizing the FGGE-III_b data covering the period from 14 June to 19 June 1979,the effects of the Qinghai-Xizang Plateau on the medium- range weather processes of the rain during the onset period of the summer monsoon in Eastern Asia in 1979 were studied numerically.According to the initial field of 12GMT 14 June 1979,five-day numerical experiments with or without the orographic effects were carried out respectively.The results show that the Plateau can influence the precipitation significantly during the summer monsoon season.Although the summer monsoon is the result of the seasonal variations of the global circulation and the heating difference between land and sea,it is influenced evidently by the Plateau in medium-range processes.There are very complex interactions between the mountain and diabatic heating effects so that both of them should be considered correctly in the general circulation models in order to describe the nature of the atmosphere reliably.展开更多
Petrographical and geochemical methods were combined to investigate the provenance, geodynamic and weathering history of the Shurijeh sandstones, Kopet-Dagh Basin. The point-counting method and XRF technique are used ...Petrographical and geochemical methods were combined to investigate the provenance, geodynamic and weathering history of the Shurijeh sandstones, Kopet-Dagh Basin. The point-counting method and XRF technique are used for modal and geochemical analyses. Based on petrographical examinations, it seems that the Shurijeh sandstones are mainly deposited in the craton interior and recycled orogen belts. In addition to petrographical investigation, geochemical analyses （major oxides and trace elements） of Late Jurassic-Early Cretaceous rocks reveal that the sedimentation processes are performed in a passive continental margin. Such interpretation is supported with geodynamic and paleogeographical studies of the Kopeh-Dagh basin during this time. The geochemical investigations suggested that the composition of probable source rocks mostly was acidic-intermediate with minor mafic igneous rocks. Based on the above, Paleo-Tethys remnants and their collision-related granitoids, in the south and west of Mashhad, may have been the source area for these rocks. CIA values, which range from 63.8 to 94.9 in samples, are suggesting a moderate to relatively high degree of alteration （weathering） in the source area. Therefore, petrographical and paleogeographical studies of siliciclastic rocks can be used for the provenance, tectonic setting and paleoweathering studies in the source area.展开更多
In order to intensify the leaching process of rare earth（RE） and reduce the impurities in the leachate, ammonium chloride（NH4Cl） and ammonium nitrate（NH4NO3） were mixed as a compound leaching agent to treat the ...In order to intensify the leaching process of rare earth（RE） and reduce the impurities in the leachate, ammonium chloride（NH4Cl） and ammonium nitrate（NH4NO3） were mixed as a compound leaching agent to treat the weathered crust elution-deposited RE ore. Effects of molar ratio of NH~＋_4Cl and NH_4NO_3, ammonium（NH_4） concentration, leaching agent pH and flow rate on the leaching process of RE were studied and evaluated by the chromatographic plate theory. Leaching process of the main impurity aluminium（Al） was also discussed in detail. Results showed that a higher initial ammonium concentration in a certain range could enhance the mass transfer process of RE and Al by providing a driving force to overcome the resistance of diffusion. pH almost had no effects on the mass transfer efficiency of RE and Al in the range of 4 to 8. The relationship between the flow rate and height equivalent to a theoretical plate（HETP） could fit well with the Van Deemter equation, and the flow rate at the lowest HETP was determined. The optimum conditions of column leaching for RE and Al were 1：1（molar ratio） of NH_4Cl and NH_4NO_3, 0.2 mol/L of ammonium concentration, pH 4–8 of leaching agent and 0.5 mL /min of flow rate. Under this condition, the mass transfer efficiency of RE was improved, but no change was observed for Al compared with the most widely used ammonium sulfate. Moreover, the significant difference value（around 20 mL） of retention volume at the peak concentration between RE and Al provided a possibility for their separation. It suggested the potential application of the novel compound leaching agent（NH_4Cl/NH_4NO_3）. It was found that the relative concentration of RE in the leachate could be easily obtained by monitoring the pH of leachate.展开更多
Recent attention has been put into recurring slope lineae (RSL), after the discovery that water is present in them. It is assumed that RSL are due to flowing water. However, even though that might be the case, the gen...Recent attention has been put into recurring slope lineae (RSL), after the discovery that water is present in them. It is assumed that RSL are due to flowing water. However, even though that might be the case, the general characteristics of RSL as well as their seasonal and spatial distribution in Mars, and their occurrence within craters, suggest that RSL correspond to the weathering of frozen aquifers, which coincides with slope stability processes occurring in impact craters and scree slopes from Earth. In this study, we associated RSL with similar weathering processes occurring on impact craters and hydrogeological processes occurring on Earth (including ice, water, and wind erosion and natural aquifer recharge processes). We were able to create a conceptual model on how RSL develop, why are they found mostly in mid latitudes around craters, why are they present in more frequency in one side of crates in high latitudes, and why are there more RSL in the Martian southern hemisphere. Considering the whole hydrogeological processes occurring in craters that experience RSL, we were able to predict where large quantities of liquid water are most likely to be present in the red planet.展开更多
[Objective] The research aimed to analyze a regional rainstorm weather process in north-central Henan Province. [Method] Based on the conventional meteorological observation data and the rainfall data of Henan Meteoro...[Objective] The research aimed to analyze a regional rainstorm weather process in north-central Henan Province. [Method] Based on the conventional meteorological observation data and the rainfall data of Henan Meteorological Station, the diagnostic analysis of atmospheric thermodynamics and dynamics on a rainstorm weather process in north-central Henan Province on July 19, 2010 was carried out. The characteristics of physical quantity field and the evolution of weather situation in north-central Henan Province when the rainstorm happened were studied. [Result] Western Pacific subtropical high strengthened to extend westward. The dynamic uplifting of low vortex at the middle and low layers, the strong water vapor transportation of southwest low-level jet caused the regional rainstorm weather process in north-central Henan Province. The diagnostic results of physical quantity showed that the deep, thick wet layer and the sustained water vapor convergence provided the abundant water vapor for rainstorm generation. The positive vorticity advection center developed and spread from northwest to southeast, which was favorable for the development of vertical movement. The structure maintenance of positive vorticity at the middle and low layers, negative vorticity at the middle and high levels provided the power condition for the regional rainstorm generation. The pumping effect of convergence at the middle and low layers, divergence at the high layer was favorable for the strengthening of vertical ascending motion at the low layer. The uplifting effect of dew point front at the middle and low layers triggered the release of unstable energy. The confrontation of warm and cold air was one of the important reasons for the regional rainstorm. TBB characteristic analysis showed that TBB was from -60 to -50 ℃ in north-central Henan Province in the whole strong precipitation time, and the moving speed was equivalent to that of southwest vortex. The low-value belt of TBB corresponded with the rainstorm occurrence zone in Henan, and the minimum-value center of TBB was basically consistent with the strongest center of precipitation. [Conclusion] The research provided the scientific basis for the short-term forecast of rainstorm.展开更多
The cold wave weather process in Jiujiang in the early spring of February 2020 was analyzed.The results show that the establishment of blocking high near Lake Baikal and the rapid southward of cold air after accumulat...The cold wave weather process in Jiujiang in the early spring of February 2020 was analyzed.The results show that the establishment of blocking high near Lake Baikal and the rapid southward of cold air after accumulation resulted in the cold wave weather accompanied by strong cooling,hale and rain(snow)weather in Jiujiang.Before the cold wave broke out,the ground warmed up significantly,which was also one of thermal conditions for this cold wave weather.Water vapor conditions were abundant at middle and low levels;at 850 hPa,temperature dropped by 12-14℃during February 14-15,and-4℃isotherm appeared in the southern part of central Jiangxi,which is a favorable condition for rain(snow)in most areas of Jiujiang.展开更多
The Tibetan Plateau(TP) is a key area affecting forecasts of weather and climate in China and occurrences of extreme weather and climate events over the world. The China Meteorological Administration, the National Nat...The Tibetan Plateau(TP) is a key area affecting forecasts of weather and climate in China and occurrences of extreme weather and climate events over the world. The China Meteorological Administration, the National Natural Science Foundation of China, and the Chinese Academy of Sciences jointly initiated the Third Tibetan Plateau Atmospheric Science Experiment(TIPEX-Ⅲ) in 2013, with an 8–10-yr implementation plan. Since its preliminary field measurements conducted in 2013, routine automatic sounding systems have been deployed at Shiquanhe, Gaize, and Shenzha stations in western TP, where no routine sounding observations were available previously. The observational networks for soil temperature and soil moisture in the central and western TP have also been established. Meanwhile, the plateau-scale and regional-scale boundary layer observations, cloud–precipitation microphysical observations with multiple radars and aircraft campaigns, and tropospheric–stratospheric air composition observations at multiple sites, were performed. The results so far show that the turbulent heat exchange coefficient and sensible heat flux are remarkably lower than the earlier estimations at grassland, meadow, and bare soil surfaces of the central and western TP. Climatologically, cumulus clouds over the main body of the TP might develop locally instead of originating from the cumulus clouds that propagate northward from South Asia. The TIPEX-Ⅲ observations up to now also reveal diurnal variations, macro-and microphysical characteristics, and water-phase transition mechanisms, of cumulus clouds at Naqu station. Moreover, TIPEX-Ⅲ related studies have proposed a maintenance mechanism responsible for the Asian "atmospheric water tower" and demonstrated the effects of the TP heating anomalies on African, Asian, and North American climates. Additionally, numerical modeling studies show that the Γ distribution of raindrop size is more suitable for depicting the TP raindrop characteristics compared to the M–P distribution, the overestimation of sensible heat flux can be reduced via modifying the heat transfer parameterization over the TP, and considering climatic signals in some key areas of the TP can improve the skill for rainfall forecast in the central and eastern parts of China. Furthermore, the TIPEX-Ⅲ has been promoting the technology in processing surface observations, soundings, and radar observations, improving the quality of satellite retrieved soil moisture and atmospheric water vapor content products as well as high-resolution gauge–radar–satellite merged rainfall products, and facilitating the meteorological monitoring, forecasting, and data sharing operations.展开更多
Two weathering profiles of Yanshanian granites on the southern and northern feet of the Dabie Mountains were investigated. The results showed that, on the southern foot of the Dabie Mountains, the weathering profile o...Two weathering profiles of Yanshanian granites on the southern and northern feet of the Dabie Mountains were investigated. The results showed that, on the southern foot of the Dabie Mountains, the weathering profile of the Sikongshan biotite monzonitic granite was eroded with remarkable loss of alkila, calcium and silicon, and richness of aluminium during hydrolysis process and in acidic mediums. Feldspar and biotite, major rock-forming minerals, were altered to illite→ (vermiculite→ 1.4 nm transition minerals) ar kaolinite→halloysite. However, on the northern foot of the Dabie Mountains, the Hepeng biotite orthogranite weathering profile was stable, without silicon depletion, but with remarkably enriched iron and noncrystalline during oxidizing process and in feebly acidic-neutral mediums. The major rock-forming minerals such as feldspar and biotite in the Hepeng weathering profile were weathered to smectites and halloysite→noncrystalline. The above results reveal that weathering differences of the granites between southern and northern feet of the Dabie Mountains may be related to climatic environments and tectonic movements. The southern foot, in hot and rainy environments, was uplifted by tectonics and was intensively leached. The soils in the southern slope were under acidic conditions. In contrast, the northern foot was slightly leached in hot and droughty environments, and the soils were under feebly acidic-neutral conditions.展开更多
Water samples from twenty one boreholes were collected within University of Lagos and analyzed for physical properties, trace elements and cations using inductively coupled plasma optical emission spectrometry (ICP-OE...Water samples from twenty one boreholes were collected within University of Lagos and analyzed for physical properties, trace elements and cations using inductively coupled plasma optical emission spectrometry (ICP-OES). Physical analysis of the samples shows slight acidity and alkalinity with 78% of the samples exceeded recommended standards. They can be classified as fresh water based on TDS and EC. Chloride concentrations fall within water standards in most samples while Al, Na, Pb and Br exceeded recommended standards in most samples. Gibbs plot, relationship between total cations, Na + K, Ca + Mg and Cl showed that all the groundwater samples fall in the water-rock interaction field which suggests that the weathering of rocks and influence of sea water primarily controls the major chemistry of groundwater in the area. Sodium Absorption Ratio (SAR) for all the water samples was less than 10 and excellent for irrigation purpose. Only 33% of water samples were suitable for irrigation based on Soluble Sodium Percentage (SSP) and Magnesium Adsorption Ratio (MAR), whereas based on Kellys Ratios (KR) all the water samples were not good for irrigation purpose having KR greater than 1. Fifty percent of the water samples showed pollution index (PI) above 1 with highest contribution (37.8%) from lead (Pb). Mn, Al, Ni, Fe and As contributed 29.3%, 19.13%, 8.66%, 4.25% and 0.82% respectively.展开更多
文摘In this paper, we use a spectral model for the medium-range numerical weather forecast to discuss the impact of the diurnal variation of solar radiation on the medium-range weather processes. Under the tests of two typical winter and summer cases, we find that the influences of the diurnal variation of solar radiation on summer weather are really important, especially on its rainfall, surface heat transport and 500 hPa height field. On winter weather, however, the influences are very weak.
文摘Heavy rain is a common abnormal weather in China, which is prone to major natural disasters such as floods. By using China National Climate Center’s DERF2.0 (the second-generation product of monthly dynamic extended ensemble prediction) models and NCEP (National Centers for Environmental Prediction) data, and using synoptic and dynamic methods and other research methods, the rainfall weather process in most of China from October 3-6, 2021 is analyzed. The results show that: 1) this process had a long duration, large cumulative rainfall and strong extreme. 2) The warm and wet flow and the cold air intersected in the central and western regions of China and Northeast China, which resulted in a regional rainstorm process within ten days. 3) There was a low-level jet moving from Guizhou and Hunan to the south of Northeast China, bringing a lot of water vapor. To sum up, the rainfall process of this round has a certain relationship with the adjustment of atmospheric circulation.
文摘[Objective] The aim was to study the formation and development of a heavy snow in Benxi area. [Method] Based on conventional meteorological data, the formation and development of a heavy snow in Benxi area from December 4th to 5th in 2009 were analyzed from the aspects of weather situation evolution and physical quantity field feature. [Result] The heavy snow was caused by upper trough and North China cyclone. In this process, there was upper level divergence and lower level convergence over Benxi area, and it was warm at low attitude and cold at high attitude; southwest jet at low attitude transported water vapor from Bohai Sea to eastern Liaoning, which provided good water vapor condition for snow, but it didn’t reach heavy snow due to inadequate ascending force. The development of Ural Mountains high ridge played an important role in the snow process and the strengthened high ridge moving northward was beneficial to the southward movement of cold air and deepening of upper trough. Analysis on physical quantity field could provide reference for predicting beginning and ending time and strength of heavy snow. [Conclusion] The study could provide basis for the forecast of heavy snow.
基金Supported by the Chinese Academy of Meteorological Sciences"10.5"Key Project under Grant No. 2001BA607Bthe National Key Development Program for Basic Sciences under Project No.2004CB418300the Key Project of the National Natural Science Foundation of China under Grant No.40233037
文摘Currently, short horizontal surface wave radiation at the ground surface （GSW） is calculated under the assumption of a This method of estimating the GSW may lead to considerable errors when the model resolution becomes higher and the model terrain becomes steeper. In this paper, to improve the short wave solar radiation simulations, a terrain slope and orientation parameterization has been implemented into the non-hydrostatic mesoscale model GRAPES （Global/Regional Assimilation and Prediction System）. The effects of the terrain slope and orientation on different short range weather processes in China under different model resolutions are simulated and discussed. In the simulations, topography height is taken from NCEP （National Centers for Environmental Prediction） with a resolution of 1 km, and the slope and orientation of terrain are calculated using different staggering schemes and under different weather conditions. The results show that when the model resolution is low （30 and 60 km） and the slope of terrain is not large, the influence of the slope and orientation of terrain on the GSW is not evident; otherwise, however, it is not negligible. Under high model resolutions （3 and 6 km）, the increase （decrease） of simulated precipitation corresponds to the decrease （increase） of the GSW induced by the slope effect, and the variations of precipitation are usually ranged between -5 and 5 ram. Under the high resolution, the surface temperature and heat fluxes are strongly correlated to each other and the high correlation exists mostly in the complex terrain regions. The changes of the GSW, precipitation, surface temperature, and heat fluxes induced by the effects of the terrain slope and orientation are more obvious in mountainous regions, due to the alternations in the atmospheric circulation. It is found as well that under the weather condition of less cloud and less precipitation, the effects of the terrain slope and orientation can be more realistically seen. Therefore, the terrain slope and orientation can usually be neglected in numerical models when the horizontal model resolution is low and the slopes are moderate, but should be taken into account when the model resolution becomes high and the terrain is steep and undulating.
基金This study is supported by the National Natural Science Foundation of China.
文摘In this paper,the data chosen from measurements by supersonic anemometers in Tongxian County of Beijing in 1990 are used to study characteristics of turbulence spectra in precipitation weather.Some turbulence parameters such as turbulence intensity,heat and momentum fluxes,friction velocity,M-O length and stability parameter are calculated and their dependence on turbulence spectra in different stability conditions are analyzed.Some encouraging results are obtained and compared with others' results.
文摘By employing the T42L9 spectral model introduced flom ECMWF and utilizing the FGGE-III_b data covering the period from 14 June to 19 June 1979,the effects of the Qinghai-Xizang Plateau on the medium- range weather processes of the rain during the onset period of the summer monsoon in Eastern Asia in 1979 were studied numerically.According to the initial field of 12GMT 14 June 1979,five-day numerical experiments with or without the orographic effects were carried out respectively.The results show that the Plateau can influence the precipitation significantly during the summer monsoon season.Although the summer monsoon is the result of the seasonal variations of the global circulation and the heating difference between land and sea,it is influenced evidently by the Plateau in medium-range processes.There are very complex interactions between the mountain and diabatic heating effects so that both of them should be considered correctly in the general circulation models in order to describe the nature of the atmosphere reliably.
文摘Petrographical and geochemical methods were combined to investigate the provenance, geodynamic and weathering history of the Shurijeh sandstones, Kopet-Dagh Basin. The point-counting method and XRF technique are used for modal and geochemical analyses. Based on petrographical examinations, it seems that the Shurijeh sandstones are mainly deposited in the craton interior and recycled orogen belts. In addition to petrographical investigation, geochemical analyses （major oxides and trace elements） of Late Jurassic-Early Cretaceous rocks reveal that the sedimentation processes are performed in a passive continental margin. Such interpretation is supported with geodynamic and paleogeographical studies of the Kopeh-Dagh basin during this time. The geochemical investigations suggested that the composition of probable source rocks mostly was acidic-intermediate with minor mafic igneous rocks. Based on the above, Paleo-Tethys remnants and their collision-related granitoids, in the south and west of Mashhad, may have been the source area for these rocks. CIA values, which range from 63.8 to 94.9 in samples, are suggesting a moderate to relatively high degree of alteration （weathering） in the source area. Therefore, petrographical and paleogeographical studies of siliciclastic rocks can be used for the provenance, tectonic setting and paleoweathering studies in the source area.
基金Project supported by the National Natural Science Foundation of China(51274152 and 41472071)the Program for Excellent Young Scientific and Technological Innovation Team of Hubei Provincial Department of Education,China(T201506)
文摘In order to intensify the leaching process of rare earth（RE） and reduce the impurities in the leachate, ammonium chloride（NH4Cl） and ammonium nitrate（NH4NO3） were mixed as a compound leaching agent to treat the weathered crust elution-deposited RE ore. Effects of molar ratio of NH~＋_4Cl and NH_4NO_3, ammonium（NH_4） concentration, leaching agent pH and flow rate on the leaching process of RE were studied and evaluated by the chromatographic plate theory. Leaching process of the main impurity aluminium（Al） was also discussed in detail. Results showed that a higher initial ammonium concentration in a certain range could enhance the mass transfer process of RE and Al by providing a driving force to overcome the resistance of diffusion. pH almost had no effects on the mass transfer efficiency of RE and Al in the range of 4 to 8. The relationship between the flow rate and height equivalent to a theoretical plate（HETP） could fit well with the Van Deemter equation, and the flow rate at the lowest HETP was determined. The optimum conditions of column leaching for RE and Al were 1：1（molar ratio） of NH_4Cl and NH_4NO_3, 0.2 mol/L of ammonium concentration, pH 4–8 of leaching agent and 0.5 mL /min of flow rate. Under this condition, the mass transfer efficiency of RE was improved, but no change was observed for Al compared with the most widely used ammonium sulfate. Moreover, the significant difference value（around 20 mL） of retention volume at the peak concentration between RE and Al provided a possibility for their separation. It suggested the potential application of the novel compound leaching agent（NH_4Cl/NH_4NO_3）. It was found that the relative concentration of RE in the leachate could be easily obtained by monitoring the pH of leachate.
文摘Recent attention has been put into recurring slope lineae (RSL), after the discovery that water is present in them. It is assumed that RSL are due to flowing water. However, even though that might be the case, the general characteristics of RSL as well as their seasonal and spatial distribution in Mars, and their occurrence within craters, suggest that RSL correspond to the weathering of frozen aquifers, which coincides with slope stability processes occurring in impact craters and scree slopes from Earth. In this study, we associated RSL with similar weathering processes occurring on impact craters and hydrogeological processes occurring on Earth (including ice, water, and wind erosion and natural aquifer recharge processes). We were able to create a conceptual model on how RSL develop, why are they found mostly in mid latitudes around craters, why are they present in more frequency in one side of crates in high latitudes, and why are there more RSL in the Martian southern hemisphere. Considering the whole hydrogeological processes occurring in craters that experience RSL, we were able to predict where large quantities of liquid water are most likely to be present in the red planet.
文摘[Objective] The research aimed to analyze a regional rainstorm weather process in north-central Henan Province. [Method] Based on the conventional meteorological observation data and the rainfall data of Henan Meteorological Station, the diagnostic analysis of atmospheric thermodynamics and dynamics on a rainstorm weather process in north-central Henan Province on July 19, 2010 was carried out. The characteristics of physical quantity field and the evolution of weather situation in north-central Henan Province when the rainstorm happened were studied. [Result] Western Pacific subtropical high strengthened to extend westward. The dynamic uplifting of low vortex at the middle and low layers, the strong water vapor transportation of southwest low-level jet caused the regional rainstorm weather process in north-central Henan Province. The diagnostic results of physical quantity showed that the deep, thick wet layer and the sustained water vapor convergence provided the abundant water vapor for rainstorm generation. The positive vorticity advection center developed and spread from northwest to southeast, which was favorable for the development of vertical movement. The structure maintenance of positive vorticity at the middle and low layers, negative vorticity at the middle and high levels provided the power condition for the regional rainstorm generation. The pumping effect of convergence at the middle and low layers, divergence at the high layer was favorable for the strengthening of vertical ascending motion at the low layer. The uplifting effect of dew point front at the middle and low layers triggered the release of unstable energy. The confrontation of warm and cold air was one of the important reasons for the regional rainstorm. TBB characteristic analysis showed that TBB was from -60 to -50 ℃ in north-central Henan Province in the whole strong precipitation time, and the moving speed was equivalent to that of southwest vortex. The low-value belt of TBB corresponded with the rainstorm occurrence zone in Henan, and the minimum-value center of TBB was basically consistent with the strongest center of precipitation. [Conclusion] The research provided the scientific basis for the short-term forecast of rainstorm.
文摘The cold wave weather process in Jiujiang in the early spring of February 2020 was analyzed.The results show that the establishment of blocking high near Lake Baikal and the rapid southward of cold air after accumulation resulted in the cold wave weather accompanied by strong cooling,hale and rain(snow)weather in Jiujiang.Before the cold wave broke out,the ground warmed up significantly,which was also one of thermal conditions for this cold wave weather.Water vapor conditions were abundant at middle and low levels;at 850 hPa,temperature dropped by 12-14℃during February 14-15,and-4℃isotherm appeared in the southern part of central Jiangxi,which is a favorable condition for rain(snow)in most areas of Jiujiang.
基金Supported by the China Meteorological Administration Special Public Welfare Research Fund for The Third Tibetan Plateau Atmospheric Science Experiment(TIPEX-Ⅲ)—Boundary Layer and Tropospheric Observations(GYHY201406001)
文摘The Tibetan Plateau(TP) is a key area affecting forecasts of weather and climate in China and occurrences of extreme weather and climate events over the world. The China Meteorological Administration, the National Natural Science Foundation of China, and the Chinese Academy of Sciences jointly initiated the Third Tibetan Plateau Atmospheric Science Experiment(TIPEX-Ⅲ) in 2013, with an 8–10-yr implementation plan. Since its preliminary field measurements conducted in 2013, routine automatic sounding systems have been deployed at Shiquanhe, Gaize, and Shenzha stations in western TP, where no routine sounding observations were available previously. The observational networks for soil temperature and soil moisture in the central and western TP have also been established. Meanwhile, the plateau-scale and regional-scale boundary layer observations, cloud–precipitation microphysical observations with multiple radars and aircraft campaigns, and tropospheric–stratospheric air composition observations at multiple sites, were performed. The results so far show that the turbulent heat exchange coefficient and sensible heat flux are remarkably lower than the earlier estimations at grassland, meadow, and bare soil surfaces of the central and western TP. Climatologically, cumulus clouds over the main body of the TP might develop locally instead of originating from the cumulus clouds that propagate northward from South Asia. The TIPEX-Ⅲ observations up to now also reveal diurnal variations, macro-and microphysical characteristics, and water-phase transition mechanisms, of cumulus clouds at Naqu station. Moreover, TIPEX-Ⅲ related studies have proposed a maintenance mechanism responsible for the Asian "atmospheric water tower" and demonstrated the effects of the TP heating anomalies on African, Asian, and North American climates. Additionally, numerical modeling studies show that the Γ distribution of raindrop size is more suitable for depicting the TP raindrop characteristics compared to the M–P distribution, the overestimation of sensible heat flux can be reduced via modifying the heat transfer parameterization over the TP, and considering climatic signals in some key areas of the TP can improve the skill for rainfall forecast in the central and eastern parts of China. Furthermore, the TIPEX-Ⅲ has been promoting the technology in processing surface observations, soundings, and radar observations, improving the quality of satellite retrieved soil moisture and atmospheric water vapor content products as well as high-resolution gauge–radar–satellite merged rainfall products, and facilitating the meteorological monitoring, forecasting, and data sharing operations.
基金This work was supported by the Ministry of Land and Resources,PRC(Grant No.992041)the National Natural Science Foundation of China(Grant No.49972022)China Scholarship Council.
文摘Two weathering profiles of Yanshanian granites on the southern and northern feet of the Dabie Mountains were investigated. The results showed that, on the southern foot of the Dabie Mountains, the weathering profile of the Sikongshan biotite monzonitic granite was eroded with remarkable loss of alkila, calcium and silicon, and richness of aluminium during hydrolysis process and in acidic mediums. Feldspar and biotite, major rock-forming minerals, were altered to illite→ (vermiculite→ 1.4 nm transition minerals) ar kaolinite→halloysite. However, on the northern foot of the Dabie Mountains, the Hepeng biotite orthogranite weathering profile was stable, without silicon depletion, but with remarkably enriched iron and noncrystalline during oxidizing process and in feebly acidic-neutral mediums. The major rock-forming minerals such as feldspar and biotite in the Hepeng weathering profile were weathered to smectites and halloysite→noncrystalline. The above results reveal that weathering differences of the granites between southern and northern feet of the Dabie Mountains may be related to climatic environments and tectonic movements. The southern foot, in hot and rainy environments, was uplifted by tectonics and was intensively leached. The soils in the southern slope were under acidic conditions. In contrast, the northern foot was slightly leached in hot and droughty environments, and the soils were under feebly acidic-neutral conditions.
文摘Water samples from twenty one boreholes were collected within University of Lagos and analyzed for physical properties, trace elements and cations using inductively coupled plasma optical emission spectrometry (ICP-OES). Physical analysis of the samples shows slight acidity and alkalinity with 78% of the samples exceeded recommended standards. They can be classified as fresh water based on TDS and EC. Chloride concentrations fall within water standards in most samples while Al, Na, Pb and Br exceeded recommended standards in most samples. Gibbs plot, relationship between total cations, Na + K, Ca + Mg and Cl showed that all the groundwater samples fall in the water-rock interaction field which suggests that the weathering of rocks and influence of sea water primarily controls the major chemistry of groundwater in the area. Sodium Absorption Ratio (SAR) for all the water samples was less than 10 and excellent for irrigation purpose. Only 33% of water samples were suitable for irrigation based on Soluble Sodium Percentage (SSP) and Magnesium Adsorption Ratio (MAR), whereas based on Kellys Ratios (KR) all the water samples were not good for irrigation purpose having KR greater than 1. Fifty percent of the water samples showed pollution index (PI) above 1 with highest contribution (37.8%) from lead (Pb). Mn, Al, Ni, Fe and As contributed 29.3%, 19.13%, 8.66%, 4.25% and 0.82% respectively.
