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51.
基于CERES的宁夏空中云水资源特征及其增雨潜力研究 总被引：1，自引：1，他引：0
利用2009-2014年NASA地球观测系统(EOS)云与地球辐射能量系统(CERES)云资料和气象站降水资料,对宁夏北部引黄灌区、中部干旱带及南部山区3个具有不同地形、地貌、气候特征的地区云水资源及增雨潜力特征进行了对比研究。结果表明:宁夏地区大气可降水量在空间分布上呈现从东南向西北方向递减,从季节变化看表现出随夏秋春冬依次递减的特征。在东亚季风和贺兰山地形的共同影响下,全年总云量和低云量在南部山区最大,北部川区最小。云光学厚度与水云粒子半径及冰云等效直径呈显著的负相关关系,其中中部干旱带相关关系最强是开展人工增雨效果最显著的地区。随着全年四季天气气候变化,宁夏人工增雨主要潜力区会逐渐由春季的贺兰山沿山、中部干旱带地区,移动到夏季的银川以南同心以北和固原西南部地区,秋季缩减到海原、西吉一带。 相似文献
52.
In model-based sensitivity studies, the growth of model error over long-term integrations may lead to serious deviations between the simulated and actual states. To reduce these errors, we have developed a new modeling approach with application of the Newtonian relaxation technique, or nudging. In this approach, an identical artificial Newtonian relaxation term that reflects the difference between the model reference state and its analysis (available in many sensitivity studies) is added to the prognostic equations of the two simulated states, the reference state and the perturbed state (for which observations are nonexistent). We have conducted idealized sensitivity experiments with a shallow-water model to evaluate the benefits and viability of this approach and to test its sensitivity to changes in the nudging period and error in the analysis data. The experimental results confirm that this approach lead to more credible atmospheric responses to modified external forcing if the data error is within a reasonable range. The results also indicate that a 12-hour period is more favorable for nudging than a 24-hour period. 相似文献
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As an important bridge between the underlying surface and the free atmosphere, the atmospheric boundary layer is not only closely related to the development of various weather processes, but also plays a key role in local and regional weather and climate changes. In view of the complexity of the atmospheric boundary layer, the numerical simulation of the atmospheric boundary layer has always been a hotspot and difficulty in the numerical simulation research of the atmosphere. In this paper, the three numerical model development stages of the atmospheric boundary layer in recent decades were summarized and the important advances in arid and semi-arid areas, Tibet Plateau, urban complex underlying surface, and special typhoon boundary layer were reviewed. At present, there are still five scientific problems to be solved urgently, including cloud and boundary layer interaction, boundary layer parameterization, model resolution, boundary layer data assimilation and boundary layer development mechanism. Moreover, it was pointed out that in this field we need to strengthen the understanding of different types of atmospheric boundary layer processes, boundary layer bottom and top interface exchange, boundary layer development mechanism in special regions, improve boundary layer parameterization scheme and give full play to the advantages of LES in boundary layer simulation. 相似文献
55.
高云和气溶胶辐射效应对边界层的影响 总被引：10，自引：4，他引：6
通过WRF(Weather Research and Forecasting) 模式嵌套包含了高云和气溶胶辐射效应的大气边界层模式, 结合激光雷达资料, 进行数值模拟, 定量分析高云和气溶胶辐射效应对城市边界层的影响。模式能很好地模拟出在高云和气溶胶辐射效应下城市边界层的特征。夜间, 气溶胶在低层起到保温作用, 高云使得保温作用得到加强, 地表增温达1.5 K。中高层, 气溶胶降低所在气层温度, 高云使得降温幅度减少, 降温达0.2～0.7 K。白天, 高云和气溶胶减少到达地面的太阳短波辐射, 导致低层温度降低, 地表降温达1.3 K。中高层, 气溶胶加热所在的气层, 高云使得这一增温幅度减少, 在500 m处增温最大, 达0.85 K。无论白天还是夜间, 气溶胶的辐射效应都会抵消一部分形成山谷风的热力条件, 使得中低层的风速减少, 这种影响在白天显得尤为明显。高云的存在使得这种抵消得到少量的补偿。 相似文献
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利用渤海沿岸微波辐射计、风廓线雷达、四分量辐射仪和超声风速仪等多种观测反演资料,并结合常规站点气象资料,卫星云图,浮标气象水文观测和FNL（Final）再分析资料研究了2016年12月17~19日一次环渤海大雾个例产生的天气水文条件以及边界层垂直分层的辐射和湍流特征。研究发现:（1）此次大雾出现在大陆低压前部、入海高压后部的西南低空急流控制区域,与强急流相伴的暖湿平流输送为雾区提供了稳定的逆温和持续的水汽积累,非常有利于大雾天气的形成;（2）水汽通量的分布与低空急流的移动密切相关,近地面比湿的增速与低空急流的强度成正比;（3）由于低空急流的水汽输送增湿了环渤海低层大气,从而增强了大气辐射的衰减效应,导致雾形成前向下短波辐射逐渐减小,向下长波辐射不断增加,净辐射在大雾形成后趋近于零;（4）逆温有效抑制了湍流的发展,近地层湍流动能和摩擦速度微弱。 相似文献
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Minzhong Wang Wenshou Wei Qing He Shigong Wang Quan Ren Yan Geng Ling Zhao 《Meteorology and Atmospheric Physics》2014,125(1-2):63-73
Using the multi-source observation data from wind-profiling radar, microwave radiometer, Doppler weather radar, etc. during the blizzard event in 19–20 March 2012 in Urumqi, this paper analyzed the detailed characteristics of the atmospheric dynamics, thermodynamics, intensity and water vapor during the process of this blizzard weather. The findings suggest: (1) in the course of the blizzard weather, the near-surface atmosphere is mainly dominated by northwest airflows, the wind speed and relative humidity increase rapidly, temperature drops and air pressure ascends; (2) the blizzard weather this time is accompanied by cold front system whose entering time is about 16:00 BT 19 March; the shear line that develops from low to high is the position height of the frontal zone, and the variation of the high-level frontal zone directly reflects the altitude and layers where cold and warm air masses interact; (3) the radar equivalent reflectivity factor of the snowstorm process changes within the range 8–25 dBZe and its large-value zone is correlated well with the blizzard duration, the height for the formation of rain (snow) particles and the snow intensity; (4) before the occurrence of the blizzard, atmosphere is in the state of high temperature and high humidity, the maximum vapor density is around 6 g m?3, water vapor mainly stays under the height of 5,000 m; affected by cold front system, cold airs gradually lift warm and moist airs so that the vapor condenses and deposits into water drops and snow particles, forming the snowstorm in the end. 相似文献
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The Impacts of Two Types of El Ni（n）o on Global Ozone Variations in the Last Three Decades 总被引：1，自引：0，他引：1
The effects of E1Nifio Modoki events on global ozone concentrations are investigated from 1980 to 2010 E1 Nifio Modoki events cause a stronger Brewer-Dobson （BD） circulation which can transports more ozone-poor air from the troposphere to stratosphere, leading to a decrease of ozone inthe lower-middle stratosphere from 90~S to 90~N. These changes in ozone concentrations reduce stratospheric column ozone. The reduction in stratospheric column ozone during E1 Nifio Modoki events is more pronounced over the tropical eastern Pacific than over other tropical areas because transport of ozone-poor air from middle-high latitudes in both hemispheres to low latitudes is the strongest between 60°W and 120°W. Because of the decrease in stratospheric column ozone during E1 Nifio Modoki events more UV radiation reaches the tropical troposphere leading to significant increases in tropospheric column ozone An empirical orthogonal function （EOF） analysis of the time series from 1980 to 2010 of stratospheric and tropospheric ozone monthly anomalies reveals that： E1 Nifio Modoki events are associated with the primary EOF modes of both time series. We also found that E1 Nifio Modoki events can affect global ozone more significantly than canonical E1 Nifio events. These results imply that E1 Nifio Modoki is a key contributor to variations in global ozone from 1980 to 2010. 相似文献
59.
Fengmei Yang Feng Shi Shuyuan Kang Shigong Wang Ziniu Xiao Takeshi Nakatsuka Jun Shi 《Theoretical and Applied Climatology》2013,114(3-4):553-566
It is not clear how the frequency and amplitude of droughts have varied over the past 500 years in China, as the instrumental record is too short to identify centennial-scale trends. While the Monsoon Asia Drought Atlas (MADA) provides some insights into past drought patterns, its accuracy in eastern China remains uncertain. A comparison of the MADA and Chinese historical documents indicates that the MADA alone cannot effectively represent dryness and wetness in eastern China, so it is not appropriate to use the MADA in this region. 相似文献
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应用了一种新的模式spectral albedo model for dirty snow,简称SAMDS,研究了不同参数对于积雪反照率的影响,结果表明：在天顶角固定为60°的条件下,新雪的粒径从50 μm增大到800 μm,使其宽波段反照率从0.92减小到0.78;相对于非球形的雪粒,球形雪粒的积雪反照率更低;吸光性颗粒物对光谱反照率的影响主要在可见光和紫外波段。此外,雪粒径的增大能使吸光性颗粒物的光吸收效应增强。结合东北地区的实测数据,我们发现SAMDS模拟的积雪宽波段反照率与实测结果较为一致。同时,SAMDS模式模拟结果表明,在东北地区,积雪中0.1~1 μg·g-1的黑碳浓度导致积雪宽波段反照率减少2%~8%,造成的瞬时辐射强迫为9~35 W·m-2。 相似文献