The present study investigates the characteristics of turbulent transfer and the conditions for dust emission and transport using the dust concentration and micrometeorological data obtained during dust events occurri...The present study investigates the characteristics of turbulent transfer and the conditions for dust emission and transport using the dust concentration and micrometeorological data obtained during dust events occurring in the spring of 2004 over the Hunshandake desert area. The turbulent exchange coefficients and turbulent fluxes of momentum and heat are calculated. The relationships between dust flux, friction velocity, and wind speed are also explored. The results show that thermal turbulence is dominant during daytime of non-dusty days. The dynamic turbulence increases obviously and the sensible heat flux reduces by different degrees during dust events. There is an efficient downward transfer of momentum before duststorm occurrence, and both the dynamic turbulence and the thermal turbulence are important in the surface layer. The dynamic turbulence even exceeds the thermal turbulence during severe duststorm events. The values of dust flux vary in the range of -5 5, -30 30, and -200-300 μg m^-2 s^-1 during non-dusty days, blowing dust, and duststorm events, respectively. A slight upward transport of dust is observed during non-dusty days. The dust flux gradually varies from positive to negative during duststorm periods, which indicates the time evolution of dust events from dust rising to stably suspending and then deposition. The dust flux is found to be proportional to u＊^3. The threshold values of wind speed and friction velocity are about 6 and 0.4 m s^-1, respectively.展开更多
The wind is a basic factor in the atmosphere subsystem in the Earth system, and an agent in transferring the mass and energy within the system. The grain size and mass flux of the eolian dust in the Neocene deep-sea s...The wind is a basic factor in the atmosphere subsystem in the Earth system, and an agent in transferring the mass and energy within the system. The grain size and mass flux of the eolian dust in the Neocene deep-sea sediments recorded the intensity of the atmospheric circulation and the aridity in the dust source area. The loess on the Loess Plateau, the dust accumulation after its origin, transportation, deposition, and reworked process, is展开更多
The total dust column and the dry deposition flux were calculated based on the optical properties that were measured by a shipboard sun photometer POM-01 MKⅡ in a cloud-free and nonfrontal dust condition on 24 April ...The total dust column and the dry deposition flux were calculated based on the optical properties that were measured by a shipboard sun photometer POM-01 MKⅡ in a cloud-free and nonfrontal dust condition on 24 April 2006.The total dust column was calculated by using an integration method of the particle size distribution;the mean value was 1.42±0.30 g m 2.A linear correlation between the total dust column and the aerosol optical depth (AOD) with a linear factor of 2.7 g m 2 over the Sahara was applied to calculate the total dust column in this study;the results were lower than these calculated by the integration method.A reasonable factor of 3.2 g m 2 was achieved by minimizing the standard deviation (SD) of the two methods.The two layers model,which includes the deposition processes of turbulent transfer,Brownian diffusion,impaction and gravitational settling over the sea's surface,was used to calculate the dry deposition flux;the mean value was 5.05±2.49 μg m 2 s 1.A correlation among the total dust column,dry deposition flux,AOD,and effective radius was discussed.The correlation between the total dust column and the AOD was better than that between the total dust column and the effective radius;however,the correlation between the dry deposition flux and the effective radius was better than that between the dry deposition flux and the AOD.展开更多
A WRF-Chem model including a comprehensive gas-phase nitrogen chemistry module was used to simulate a severe dust event appearing in the eastern China on 19-25 March, 2002. The modeling result well reproduced PM10 con...A WRF-Chem model including a comprehensive gas-phase nitrogen chemistry module was used to simulate a severe dust event appearing in the eastern China on 19-25 March, 2002. The modeling result well reproduced PM10 concentrations in various distances from the dust sources and the transport pathway of the dust strom. The results showed that both the concentrations and the dry deposition fluxes of PM10 increased over the China seas during the dust event following the passage of a cold front system. The maximum fluxes of PM10 in the Yellow Sea and the East China Sea during the dust event were 5.5 and 8.4 times of those before the event, respectively. However, the temporal variations of the dry deposition fluxes of particulate inorganic nitrogen differed over the Yellow Sea from those over the East China Sea. Nitrate and ammonium in the whole northern China rapidly decreased because of the intrusion of dust-loaded air on 19 March. The dust plume arrived in the Yellow Sea on 20 March, decreasing the particulate inorganic nitrogen in mass concentration accordingly. The minimum dry deposition fluxes of nitrate and ammonium in the Yellow Sea were about 3/5 and 1/6 of those before the dust arrival, respectively. In contrast, when the dust plume crossed over the Yangtze Delta area, it became abundant in nitrate and ammonium and increased the concentrations and dry deposition fluxes of particulate inorganic nitrogen over the East China Sea, where the maximum dry deposition fluxes of nitrate and ammonium increased approximately by 4.1 and 2.6 times of those prior to the dust arrival.展开更多
本研究利用WRF-Chem(Weather Research and Forecasting model with online coupled Chemistry)模式对未来中国北方沙尘起沙过程变化进行了模拟预测。为了提高预测结果的准确度,研究综合考虑了气溶胶、温室气体和植被覆盖率等因素对天...本研究利用WRF-Chem(Weather Research and Forecasting model with online coupled Chemistry)模式对未来中国北方沙尘起沙过程变化进行了模拟预测。为了提高预测结果的准确度,研究综合考虑了气溶胶、温室气体和植被覆盖率等因素对天气、气候和起沙过程的影响。预测结果显示,2016~2029年西北部沙尘源地起沙量高于北部沙尘源地,地形和气候的差异是导致两地起沙过程及其季节变化差异的主要原因。两个沙尘源地四季起沙通量呈总体减少而部分季节增加的趋势,西北部沙尘源地起沙通量在春季总体呈上升趋势,在夏、秋和冬季呈下降趋势;北部沙尘源地起沙通量在春、夏和冬季呈下降趋势,在秋季呈微弱上升趋势。两个沙尘源地各季起沙通量的变化趋势由近地面风速主导,植被覆盖率、降水和地面温度等因素对起沙通量的年际波动有着重要影响。展开更多
本文利用DPM(Dust Production Model)模型模拟计算了我国北方沙漠地区不同的土壤微团粒在不同的地表粗糙度和地表摩擦风速下的水平跃移通量、粉尘释放通量、粉尘释放效率以及在特定量中粉尘粒子的质量和数浓度的分布,并对上述计算结果...本文利用DPM(Dust Production Model)模型模拟计算了我国北方沙漠地区不同的土壤微团粒在不同的地表粗糙度和地表摩擦风速下的水平跃移通量、粉尘释放通量、粉尘释放效率以及在特定量中粉尘粒子的质量和数浓度的分布,并对上述计算结果进行了讨论和分析。通过与实际观测结果进行对比的粗糙度和地表摩擦风速下粉尘释放通量后发现二者基本一致,从而证明了DPM模型是可以用来初步模拟中国北方沙漠地区的粉尘释放过程,这将有利于进一步较准确得模拟沙尘的输送、沉降以及气候效应。展开更多
分别在南京的两个钢铁厂收集降尘并采集周边表土,并用ICP-AES和磁化率仪分析得到16种元素含量和表土、地面尘的磁化率。结果表明,两个钢铁工业区的大气降尘的年沉降通量分别为190t km-2a-1和407 t km-2a-1,这可能会影响着周边地区土壤...分别在南京的两个钢铁厂收集降尘并采集周边表土,并用ICP-AES和磁化率仪分析得到16种元素含量和表土、地面尘的磁化率。结果表明,两个钢铁工业区的大气降尘的年沉降通量分别为190t km-2a-1和407 t km-2a-1,这可能会影响着周边地区土壤的形成;Al、K、Na、Ti、V在降尘中的含量显著低于表土,而Ca,Fe,Zn,Mn,Pb,Cu在降尘中含量要显著高于表土;表土的磁化率除水田外均大于100×10-8m3kg-1,并且地面尘的磁化率要远远高于表土的磁化率。研究表明,钢铁工业区降尘对其周边土壤中污染元素的积累有明显影响,突出地表现在土壤表层重金属含量升高,而磁化率可以很好地表征这种表聚的特点。展开更多
基金the National Natural Science Foundation of China under Grant No.40775013"863" Program of China under Grant No.2006AA06A306+1 种基金the Special Commonweal Research Program of the Ministry of Science and Technology under Grant No.2008416018the Research Fund for the Doctoral Program of Higher Education under Grant No.20060001025.
文摘The present study investigates the characteristics of turbulent transfer and the conditions for dust emission and transport using the dust concentration and micrometeorological data obtained during dust events occurring in the spring of 2004 over the Hunshandake desert area. The turbulent exchange coefficients and turbulent fluxes of momentum and heat are calculated. The relationships between dust flux, friction velocity, and wind speed are also explored. The results show that thermal turbulence is dominant during daytime of non-dusty days. The dynamic turbulence increases obviously and the sensible heat flux reduces by different degrees during dust events. There is an efficient downward transfer of momentum before duststorm occurrence, and both the dynamic turbulence and the thermal turbulence are important in the surface layer. The dynamic turbulence even exceeds the thermal turbulence during severe duststorm events. The values of dust flux vary in the range of -5 5, -30 30, and -200-300 μg m^-2 s^-1 during non-dusty days, blowing dust, and duststorm events, respectively. A slight upward transport of dust is observed during non-dusty days. The dust flux gradually varies from positive to negative during duststorm periods, which indicates the time evolution of dust events from dust rising to stably suspending and then deposition. The dust flux is found to be proportional to u＊^3. The threshold values of wind speed and friction velocity are about 6 and 0.4 m s^-1, respectively.
文摘The wind is a basic factor in the atmosphere subsystem in the Earth system, and an agent in transferring the mass and energy within the system. The grain size and mass flux of the eolian dust in the Neocene deep-sea sediments recorded the intensity of the atmospheric circulation and the aridity in the dust source area. The loess on the Loess Plateau, the dust accumulation after its origin, transportation, deposition, and reworked process, is
基金funded by the National BasicResearch Program of China (Grant No. 2006CB403702)the Public Meteorology Special Foundation of Ministry of Science and Technology (Grant No. GYHY200706036)the National Natural Science Foundation of China (Grant No. 60638020)
文摘The total dust column and the dry deposition flux were calculated based on the optical properties that were measured by a shipboard sun photometer POM-01 MKⅡ in a cloud-free and nonfrontal dust condition on 24 April 2006.The total dust column was calculated by using an integration method of the particle size distribution;the mean value was 1.42±0.30 g m 2.A linear correlation between the total dust column and the aerosol optical depth (AOD) with a linear factor of 2.7 g m 2 over the Sahara was applied to calculate the total dust column in this study;the results were lower than these calculated by the integration method.A reasonable factor of 3.2 g m 2 was achieved by minimizing the standard deviation (SD) of the two methods.The two layers model,which includes the deposition processes of turbulent transfer,Brownian diffusion,impaction and gravitational settling over the sea's surface,was used to calculate the dry deposition flux;the mean value was 5.05±2.49 μg m 2 s 1.A correlation among the total dust column,dry deposition flux,AOD,and effective radius was discussed.The correlation between the total dust column and the AOD was better than that between the total dust column and the effective radius;however,the correlation between the dry deposition flux and the effective radius was better than that between the dry deposition flux and the AOD.
基金supported by the National Science Foundation of China (No.40976063)International Cooperative Projects of MOST (No.2010DFA91350)
文摘A WRF-Chem model including a comprehensive gas-phase nitrogen chemistry module was used to simulate a severe dust event appearing in the eastern China on 19-25 March, 2002. The modeling result well reproduced PM10 concentrations in various distances from the dust sources and the transport pathway of the dust strom. The results showed that both the concentrations and the dry deposition fluxes of PM10 increased over the China seas during the dust event following the passage of a cold front system. The maximum fluxes of PM10 in the Yellow Sea and the East China Sea during the dust event were 5.5 and 8.4 times of those before the event, respectively. However, the temporal variations of the dry deposition fluxes of particulate inorganic nitrogen differed over the Yellow Sea from those over the East China Sea. Nitrate and ammonium in the whole northern China rapidly decreased because of the intrusion of dust-loaded air on 19 March. The dust plume arrived in the Yellow Sea on 20 March, decreasing the particulate inorganic nitrogen in mass concentration accordingly. The minimum dry deposition fluxes of nitrate and ammonium in the Yellow Sea were about 3/5 and 1/6 of those before the dust arrival, respectively. In contrast, when the dust plume crossed over the Yangtze Delta area, it became abundant in nitrate and ammonium and increased the concentrations and dry deposition fluxes of particulate inorganic nitrogen over the East China Sea, where the maximum dry deposition fluxes of nitrate and ammonium increased approximately by 4.1 and 2.6 times of those prior to the dust arrival.
文摘本研究利用WRF-Chem(Weather Research and Forecasting model with online coupled Chemistry)模式对未来中国北方沙尘起沙过程变化进行了模拟预测。为了提高预测结果的准确度,研究综合考虑了气溶胶、温室气体和植被覆盖率等因素对天气、气候和起沙过程的影响。预测结果显示,2016~2029年西北部沙尘源地起沙量高于北部沙尘源地,地形和气候的差异是导致两地起沙过程及其季节变化差异的主要原因。两个沙尘源地四季起沙通量呈总体减少而部分季节增加的趋势,西北部沙尘源地起沙通量在春季总体呈上升趋势,在夏、秋和冬季呈下降趋势;北部沙尘源地起沙通量在春、夏和冬季呈下降趋势,在秋季呈微弱上升趋势。两个沙尘源地各季起沙通量的变化趋势由近地面风速主导,植被覆盖率、降水和地面温度等因素对起沙通量的年际波动有着重要影响。
文摘本文利用DPM(Dust Production Model)模型模拟计算了我国北方沙漠地区不同的土壤微团粒在不同的地表粗糙度和地表摩擦风速下的水平跃移通量、粉尘释放通量、粉尘释放效率以及在特定量中粉尘粒子的质量和数浓度的分布,并对上述计算结果进行了讨论和分析。通过与实际观测结果进行对比的粗糙度和地表摩擦风速下粉尘释放通量后发现二者基本一致,从而证明了DPM模型是可以用来初步模拟中国北方沙漠地区的粉尘释放过程,这将有利于进一步较准确得模拟沙尘的输送、沉降以及气候效应。
文摘分别在南京的两个钢铁厂收集降尘并采集周边表土,并用ICP-AES和磁化率仪分析得到16种元素含量和表土、地面尘的磁化率。结果表明,两个钢铁工业区的大气降尘的年沉降通量分别为190t km-2a-1和407 t km-2a-1,这可能会影响着周边地区土壤的形成;Al、K、Na、Ti、V在降尘中的含量显著低于表土,而Ca,Fe,Zn,Mn,Pb,Cu在降尘中含量要显著高于表土;表土的磁化率除水田外均大于100×10-8m3kg-1,并且地面尘的磁化率要远远高于表土的磁化率。研究表明,钢铁工业区降尘对其周边土壤中污染元素的积累有明显影响,突出地表现在土壤表层重金属含量升高,而磁化率可以很好地表征这种表聚的特点。
