共查询到19条相似文献，搜索用时 125 毫秒
1.
北冰洋及其邻近海域极昼期间大气边界层结构特征试验研究 总被引：17，自引：1，他引：16
1年7-月中国"雪龙"号破冰船首航北极科学考察期间,利用TMT(系留式气象塔)大气边界层探测系统,对北冰洋及其邻近海域不同下垫面进行较长时间的连续多次观测. 观测到的大气边界层廓线,其中包括比湿廓线的多层、逆湿结构(逆湿强度最强为0.7g/(10m·kg));风向、风速廓线的切变结构(风向切变为1.1°/m,风速切变为0.11(m·s-1)/m. 特别是持续数日、厚达几百米、其平均逆温强度有时高达1.4℃/10m的逆温结构,这种北冰洋海域特有的大气边界层结构,与地球气候系统中其他圈层的大气边界层结构有明显差别. 据此,提出了对该海域大气-海冰-海洋间动量、感热和潜热等湍流通量垂直交换以及热量平衡等有重要影响的大气逆温的屏障过程. 这为研究北极地区对全球气候影响、模拟北极地区现代气候和未来气候等提供一条新的思路. 此外,文中还给出该海域不同下垫面稳定大气边界层的高度. 相似文献
2.
随着近10年来北京城市化步伐的加快,城市规模迅速扩大,北京三环以外的地区已由20世纪七、八十年代的城郊非均匀下垫面发展成现在粗糙复杂的城区下垫面,市区建筑物相应增多、增密和增高,导致城区地面动力学粗糙度明显增大.本文统计分析了北京325 m气象塔1994年和1997～2003年夏季平均场观测资料,结果表明:(1)在受下垫面影响最为剧烈的近地层,风向逐年趋于紊乱,现在气象塔周围近地面的流场已经具备了典型城市粗糙下垫面的流场特征;(2)近地面夏季平均风速呈现非常明显的逐年递减的趋势,而且距离地表越近,平均风速逐年递减的趋势也越为显著,这种风速逐年递减的趋势直到63 m左右才不明显,说明现在气象塔47 m以下的观测资料反映的是城市冠层的流场特征,城市冠层厚度约在47～63 m之间;(3)随着北京城市化的发展,城区近地面的平均风速存在逐年递减的趋势,但阵风并不存在相似的递减趋势,表明城市冠层的抬升对阵风的影响并不显著. 相似文献
3.
城市的植被覆盖对城市区域的气象环境有重要影响. 为了探讨利用区域边界层气象模式来研究这种影响的可行性,本文以北京为例,采用北京地区目前的城市规划资料以及拟议中的绿化方案,初步模拟分析了不同绿化带布局对北京市冬夏气象环境的影响,并进行了讨论. 同时对地气相互作用过程中的各种地面通量进行一些定量分析,以研究其对气象环境的影响. 通过本文工作发现,所用区域边界模式能够较细致地模拟出城市规划中绿化布局对区域气象环境的影响. 结果表明：绿化林和绿化草地的增加会导致地面风速减小,一般减小05m/s;在冬天算例中,北部绿化林和绿化草地会造成白天轻微增温,夜间微弱降温,幅度约为05～1℃, 东南面绿化带对市区内气象环境影响不大;在夏天算例中,北部绿化林使气温降低,最大幅度约为2℃,东南面绿化林降低北京市区南部的气温,有利于缓解北京夏季的高温灾害. 相似文献
4.
通过建立一个包含比较详细的地面和水体内物理过程的非静力近似中小尺度数值模式,模拟陆地水体对周围空气比湿影响的空间分布,模拟结果与实际情况比较接近。计算结果表明:水体在冬季和夏季都增加周围空气的比湿;增加的幅度是晴天大于阴天、夜间大于白天、冬季大于夏季;仅在夏季晴天正午时,由于水体强烈降温,近水面大气层结很稳定,水体附近空气比湿略有降低。空气比湿的改变主要发生在气流刚过水面的2—3km范围内;在岸上水体影响接近指数律减小,水体对空气比湿影响消失的距离为:在上风岸不到4km,下风岸可超过20km;水体影响空气比湿的高度为200—400m。 相似文献
5.
利用WRF模式中5种常用边界层参数化方案(ACM2、YSU、BouLac、MYJ和MYNN2.5)及美国能源部大气辐射观测试验(ARM)寿县综合观测数据(2008年8—12月),对比分析了晴天及阴天条件下,不同参数化方案对典型农田下垫面气象要素及边界层结构的模拟效果,结果表明:(1)模式对于云层状况的模拟,非局地方案ACM2和YSU方案优于局地方案.(2)对于近地层气象要素,晴天和阴天条件下均是ACM2方案对于2 m温度和比湿的模拟效果最好,MYJ方案对于风向风速的模拟效果最好.(3)对于位温及比湿垂直廓线的模拟,晴天和阴天条件下均是非局地方案(ACM2和YSU)对白天的模拟效果优于局地方案;ACM2方案对夜间弱稳定层结和逆湿结构的模拟最优;(4)对于风速垂直廓线的模拟,白天不稳定条件下,晴天条件MYJ方案最优,阴天MYNN2.5方案的模拟效果最好;夜间弱稳定条件下,晴天条件ACM2方案与观测值之间的偏差最小,阴天YSU方案模拟效果最好;(5)总体而言,在对典型农田下垫面进行模拟时,晴天和阴天条件下均是ACM2方案更具优势. 相似文献
6.
为了研究城市化进程对城市边界层结构的影响，通过高分辨率的卫星遥感资料获得土地利用类型,以及地表反照率、植被指数等地表参数，以南京为例，运用数值模拟手段进行了研究，结果显示这是一种可行的手段.数值模拟结果表明，随着城市的发展，城市反照率减小、植被减少、地表湿度减小，蒸发耗热减少，感热通量增加140 W/m2，城市波恩比增加.地表和大气之间热量交换加强，湍流热量通量增大了一倍，湍流交换发展加剧，14：00混合层高度抬高了500 m.地表湍流水汽通量和空气中水汽含量都减小，这也使更多的热量用于加热地表和大气，使地温、气温的日变化幅度增加. 相似文献
7.
大气边界层研究进展 总被引：1，自引：0，他引：1
大气边界层对云和对流的发展、演变有重要作用.本文回顾了在大气边界层高度计算方法,边界层的时空分布特征、结构和发展机理,以及边界层参数化方案等方面的主要研究进展.大气边界层高度计算方法主要分为基于大气廓线观测数据计算和基于模式参数化方案计算两大类;大气边界层高度频率分布形态具有明显的日变化特征,并且稳定、中性和对流边界层高度的频率分布呈现出不同的Gamma分布特征;地面湿度状况对边界层发展影响明显,对于不同的下垫面热力性质和地形状况,大气边界层高度呈现出明显的空间差异,青藏高原边界层高度明显高于一般平原地区;在强烈的地面加热驱动下,对流边界层与残余层通过正反馈机制循环增长可以形成4000 m以上的超高大气边界层;研制大气边界层、浅对流以及云物理方案的统一参数化框架是未来数值预报模式的发展趋势. 相似文献
8.
研究新一代中尺度气象模式WRF中两种大气边界层方案(MYJ,YSU)对沈阳冬季大气边界层结构模拟的影响,重点分析温度层结、低层风场、边界层高度等对污染物扩散有重要影响的气象要素.和观测数据的比对表明WRF基本能够模拟出温度风速的日变化特征,但模拟风速偏大.YSU方案由于模拟的边界层顶卷挟和边界层内混合作用较强,夜间接地逆温强度低于MYJ方案,逆温维持时间比MYJ方案短4小时,同时模拟边界层高度也高于MYJ方案,有利于污染物垂直扩散.边界层高度的3种计算方法中,湍流动能方法计算的边界层高度最高,Richardson数方法次之,位温方法得到的高度最低.Richardson数方法对临界值的选取较敏感. 相似文献
9.
本文基于1987—2017年南极点的无线电探空数据，研究了地面至30 km海拔高度的气温、风向和风速的垂直分布及变化趋势.多年平均的逐月数据表明，气温在各高度上均具有显著的季节变化，南半球夏季（冬季）对流层低层温度最高达-25℃（最低达-60℃），分别出现于1月（7月）地面以上约500 m（近地面）.近30年来，年平均地面气温呈0.3℃/10a的增加趋势，增温趋势总体上随高度增加而减缓，至对流层上层的气温变化趋势为负，约为-0.25℃/10a.对于对流层整层平均气温，秋季上升趋势在四季中最为明显，达0.55℃/10a，而年平均气温的趋势约为0.3℃/10a.近地面全年盛行东北风，风速大多在2~10 m·s-1范围内；对流层的低层（高层）为西北风（西南风），在海拔6~9 km处，对流层急流可达25 m·s-1；而平流层低层（高层）为南风（东南风），最大风速可超过30 m·s-1.风速和温度梯度变化特征在地面至10 km（10~30 km）高度段表现为负相关（正相关）.近30年近地面呈现北风增加东风减少的趋势，而高空南风减少，东风和北风增多.对流层整层平均风速显示，各季节平均风速均呈增加趋势，并且与温度类似，秋季的增加趋势最显著，达0.59 m·s-1/10a，而春季趋势最为平缓，仅0.05 m·s-1/10a.对流层整层年平均风速的线性趋势为0.24 m·s-1/10a，地面年平均风速呈0.05 m·s-1/10a的增加趋势. 相似文献
10.
利用京津冀城市群地区6个观测站风廓线雷达夏季一个月同步观测资料,对其进行了风功率谱和小波分析.越接近地面,测站之间风的周期变化特征差异越明显,离地面越远,差异不显著.各站大于1天周期的频谱特征差异小,而小于1天周期的频谱特征差异大.各站频谱在几百米高度有明显日变化.不同位置的测站其日变化周期信号随高度分布表现为不同程度的地形影响效应.部分测站1km高度以下风功率谱在大于1天高频区近似满足-5/3幂分布规律.降水过程风频谱在低层普遍有小于1天的高频周期,这与降水过程高低空风速起伏和变化密切相关.各站平均风矢量日变化在5∶00—6∶00、20∶00—21∶00有明显风速变化和风向转换,1500m以下风向变化差异显著,偏南风出现时间及影响高度与该地区的山谷风和海陆风相联系.各站之间风速相关系数随高度分布呈现出低层低、上层高的特点.最后还给出了风廓线雷达布网建议. 相似文献
11.
Sensitivity of Mesoscale Model Forecast During a Satellite Launch to Different Cumulus Parameterization Schemes in MM5 总被引：1，自引：0，他引：1
The identification of the model discrepancy and skill is crucial when a forecast is issued. The characterization of the model
errors for different cumulus parameterization schemes (CPSs) provides more confidence on the model outputs and qualifies which
CPSs are to be used for better forecasts. Cases of good/bad skill scores can be isolated and clustered into weather systems
to identify the atmospheric structures that cause difficulties to the forecasts. The objective of this work is to study the
sensitivity of weather forecast, produced using the PSU-NCAR Mesoscale Model version 5 (MM5) during the launch of an Indian
satellite on 5th May, 2005, to the way in which convective processes are parameterized in the model. The real-time MM5 simulations
were made for providing the weather conditions near the launch station Sriharikota (SHAR). A total of 10 simulations (each
of 48 h) for the period 25th April to 04th May, 2005 over the Indian region and surrounding oceans were made using different
CPSs. The 24 h and 48 h model predicted wind, temperature and moisture fields for different CPSs, namely the Kuo, Grell, Kain-Fritsch
and Betts-Miller, are statistically evaluated by calculating parameters such as mean bias, root-mean-squares error (RMSE),
and correlation coefficients by comparison with radiosonde observation. The performance of the different CPSs, in simulating
the area of rainfall is evaluated by calculating bias scores (BSs) and equitable threat scores (ETSs). In order to compute
BSs and ETSs the model predicted rainfall is compared with Tropical Rainfall Measuring Mission (TRMM) observed rainfall. It
was observed that model simulated wind and temperature fields by all the CPSs are in reasonable agreement with that of radiosonde
observation. The RMSE of wind speed, temperature and relative humidity do not show significant differences among the four
CPSs. Temperature and relative humidity were overestimated by all the CPSs, while wind speed is underestimated, except in
the upper levels. The model predicted moisture fields by all CPSs show substantial disagreement when compared with observation.
Grell scheme outperforms the other CPSs in simulating wind speed, temperature and relative humidity, particularly in the upper
levels, which implies that representing entrainment/detrainment in the cloud column may not necessarily be a beneficial assumption
in tropical atmospheres. It is observed that MM5 overestimates the area of light precipitation, while the area of heavy precipitation
is underestimated. The least predictive skill shown by Kuo for light and moderate precipitation asserts that this scheme is
more suitable for larger grid scale (>30 km). In the predictive skill for the area of light precipitation the Betts-Miller
scheme has a clear edge over the other CPSs. The evaluation of the MM5 model for different CPSs conducted during this study
is only for a particular synoptic situation. More detailed studies however, are required to assess the forecast skill of the
CPSs for different synoptic situations. 相似文献
12.
本文利用1994～2003年北京市11个气象台站的7、8月夏季常规地面观测资料，并结合中国科学院大气物理研究所325m高铁塔观测资料，分析了近10年的城市化进程对北京市夏季城市气候造成的影响. 结果表明，各气象要素变化都突现了城市化进程的影响：(1)城区相对湿度较郊区明显偏小，呈现一“干岛”特征，且相对湿度呈逐年下降趋势；(2)降水方面，近10年来，北京市的夏季降水量逐年下降非常明显；(3)平均日蒸发量和日照时数城区大于郊区；(4)虽然城区能见度明显小于郊区，但总体来讲，1999年以后，北京地区的能见度趋好；(5)地温同样存在城市热岛现象；(6)北京地区35℃以上高温天数基本呈增多趋势，且城区高温天数明显多于郊区；(7)边界层强逆温的存在有利于城市夏季强热岛的出现. 相似文献
13.
Qiang Dai Dawei Han Miguel A. Rico‐Ramirez Lu Zhuo Nergui Nanding Tanvir Islam 《水文研究》2015,29(7):1704-1716
Radar‐based estimates of rainfall are affected by many sources of uncertainties, which would propagate through the hydrological model when radar rainfall estimates are used as input or initial conditions. An elegant solution to quantify these uncertainties is to model the empirical relationship between radar measurements and rain gauge observations (as the ‘ground reference’). However, most current studies only use a fixed and uniform model to represent the uncertainty of radar rainfall, without consideration of its variation under different synoptic regimes. Wind is such a typical weather factor, as it not only induces error in rain gauge measurements but also causes the raindrops observed by weather radar to drift when they reach the ground. For this reason, as a first attempt, this study introduces the wind field into the uncertainty model and designs the radar rainfall uncertainty model under different wind conditions. We separate the original dataset into three subsamples according to wind speed, which are named as WDI (0–2 m/s), WDII (2–4 m/s) and WDIII (>4 m/s). The multivariate distributed ensemble generator is introduced and established for each subsample. Thirty typical events (10 at each wind range) are selected to explore the behaviours of uncertainty under different wind ranges. In each time step, 500 ensemble members are generated, and the values of 5th to 95th percentile values are used to produce the uncertainty bands. Two basic features of uncertainty bands, namely dispersion and ensemble bias, increase significantly with the growth of wind speed, demonstrating that wind speed plays a considerable role in influencing the behaviour of the uncertainty band. On the basis of these pieces of evidence, we conclude that the radar rainfall uncertainty model established under different wind conditions should be more realistic in representing the radar rainfall uncertainty. This study is only a start in incorporating synoptic regimes into rainfall uncertainty analysis, and a great deal of more effort is still needed to build a realistic and comprehensive uncertainty model for radar rainfall data. Copyright © 2014 John Wiley & Sons, Ltd. 相似文献
14.
Observations from two SOund Detection And Ranging (SODAR) units, a 10 m micrometeorological tower and five Automated Surface Observing Stations (ASOS) were examined during several synoptic scale flow regimes over New York City after the World Trade Center disaster on September 11, 2001. An ARPS model numerical simulation was conducted to explore the complex mesoscale boundary layer structure over New York City. The numerical investigation examined the urban heat island, urban roughness effect and sea breeze structure over the New York City region. Estimated roughness lengths varied from 0.7 m with flow from the water to 4 m with flow through Manhattan. A nighttime mixed layer was observed over lower Manhattan, indicating the existence of an urban heat island. The ARPS model simulated a sea-breeze front moving through lower Manhattan during the study period consistent with the observations from the SODARs and the 10-m tower observations. Wind simulations showed a slowing and cyclonic turning of the 10-m air flow as the air moved over New York City from the ocean. Vertical profiles of simulated TKE and wind speeds showed a maximum in TKE over lower Manhattan during nighttime conditions. It appears that this TKE maximum is directly related to the influences of the urban heat island. 相似文献
15.
采用WRFV2.2中尺度数值模式对鄱阳湖地区200 km×200 km范围内,2009年11月5日00∶00至2009年11月6日12∶00不同高度的气象要素进行了数值模拟,得到了水平分辨率为1 km的鄱阳湖地区大气边界层风、温、湿度场和廓线分布的大气边界层物理特征.模拟结果发现:白天鄱阳湖面上空存在着冷岛效应并伴随湖风,而夜间湖面上空存在着热岛效应并伴随陆风,湖面与陆地之间最大温差可达6 ℃;同时地形以及下垫面类型对鄱阳湖区风场的分布具有很大影响,夜间存在一条东北西南走向的低空辐合带,白天逐渐消失;此外受风场和地形作用湖面上空的湿度分布也不均匀,白天湿度层厚度低而夜晚湿度层厚度高,湖中心右侧湿度值大于左侧湿度值.模拟结果能较好地反映鄱阳湖的大气边界层物理特征,有助于了解鄱阳湖地区区域气候的特点,以及由于地形、地理环境、地表特征所形成的不同高度上的风、温、湿的分布规律和大气边界层物理特征,为鄱阳湖地区局地天气预报、风能资源开发、环境保护等提供了科学依据. 相似文献
16.
Summertime Characteristics of the Atmospheric Boundary Layer and Relationships to Ozone Levels over the Eastern United States 总被引：1，自引：0，他引：1
— This paper examines the spatial and temporal distributions of the mixing height, ventilation coefficient (defined as the product of mixing height and surface wind speed), and cloud cover over the eastern United States during the summer of 1995, using the high-resolution meteorological data generated by MM5 (Version 1), a mesoscale model widely used in air quality studies. The ability of MM5 to simulate the key temporal and spatial features embedded in the time series of observations of temperature, wind speed, and moisture is assessed using spectral decomposition methods. Also, mixing heights estimated from the MM5 outputs are compared with those derived from observations at a few locations where data with high temporal resolution are available in the Northeast. In addition, the uncertainties associated with the estimation of the evolution of the boundary layer during the morning time are examined. The results indicate that nighttime mixing heights averaged <200?m, rising to 1 km by 10 EST, and to about 2.5?km in the afternoon. Ventilation coefficients followed a similar diurnal pattern, increasing from 500?m2/s at night?to 15,000?m2/s in the afternoon; the increase due to the growing mixing height and increasing surface wind speeds. Spatial variability of these parameters was relatively small (coefficient of variation=0.25) at?night and in the afternoon when conditions were quasi-stationary, but increased (to 0.5) during morning?and evening hours when mixing heights and wind speeds were changing rapidly. Analyses of surface ozone observations from about 400 sites throughout the eastern United States indicate that days with numerous stations reporting surface ozone concentrations in excess of 80 ppb (i.e., “high ozone” days) generally had less daytime cloud cover, lower surface wind speeds, higher mixing heights, and lower ventilation coefficients than did comparable “low ozone” days. Such meteorological features are consistent with a synoptic anticyclone centered over the mid-south region (Kentucky, Tennessee). Low ozone days were characterized by more disturbed weather conditions (low pressure systems, fronts, greater cloud cover, and precipitation events). Ozone observations at two elevated platforms (～400?m agl) in Garner, NC, and Chicago, IL, indicated that ozone concentrations aloft were about 40% larger on “high ozone” days than on “low ozone” days. On average, high levels of ozone persist aloft for about 2 to 3 days. Strong vertical mixing in the daytime can bring this pool of upper-level ozone downward to augment surface ozone production. Since ozone can be transported downwind several hundred kilometers from its source region over this time scale, depending on upper-level winds, effective ozone control strategies must take into consideration spatial scales ranging from local to regional, and time scales of the order of several days. 相似文献
17.
Satellite-derived SSTs are validated in the northern South China Sea (NSCS) using in situ SSTs from the drifting buoys and well-calibrated sensors installed on Research/Vessel(R/V) Shiyan 3. The satellite SSTs are Advanced Very High Resolution Radiometer (AVHRR) daytime SST, AVHRR nighttime SST, Tropical rainfall Measuring Mission Microwave Imager (TMI) daytime SST and TMI nighttime SST. Availability of satellite SST, which is the ratio that the number of available satellite SST to the total ocean pixels in NSCS is calculated; annual average SST availabilities of AVHRR daytime SST, AVHRR nighttime SST, TMI daytime SST and TMI nighttime SST are 68.42%, 69.99%, 56.57% and 52.80%, respectively. Though the TMI SST availability is nearly constant throughout the year, the variations of the AVHRR SST availability are much larger because of seasonal variations of cloud cover in NSCS. Validation of the satellite-derived SSTs shows that bias±standard deviation (STD) of AVHRR SST is −0.43±0.76 and −0.33±0.79 °C for daytime and nighttime, respectively, and bias±STD of TMI SSTs is 0.07±1.11 and 0.00±0.97 °C for daytime and nighttime, respectively. It is clear that AVHRR SSTs have significant regional biases of about −0.4 °C against the drifting buoy SSTs. Differences between satellite-derived−in situ SSTs are investigated in terms of the diurnal SST cycle. When satellite-derived wind speeds decrease down below 6 m/s, the satellite SSTs become higher than the corresponding in situ SSTs, which means that the SST difference (satellite SST−Buoy SST) is positive. This wind-speed dependence of the SST difference is consistent with the previous results, which have mentioned that low wind speed coupled with clear sky conditions (high surface solar radiation) enhance the diurnal SST amplitude and the bulk-skin temperature difference. 相似文献
18.
《中国科学:地球科学(英文版)》2021,(8)
Despite the prevalence of artificial separation of daytime and nighttime hot extremes, they may actually co-occur or occur sequentially. Considering their potential lead-lag configuration, this study identified an entire heatwave period as consecutive days with either daytime or nighttime hot extremes and investigated the changes of the prevalence and sequence of daytime and nighttime hot extremes during heatwaves over China from 1961 to 2017. It was found that the majority(82%) of heatwaves were compound heatwaves that had both daytime and nighttime hot extremes exceeding the 90 th percentile-based thresholds, while only 7%(11%) were purely daytime(nighttime) heatwaves that contained only daytime(nighttime) hot extremes. During the entire periods of compound heatwaves, daytime hot extremes usually occurred one day or a few days before nighttime hot extremes, which was in accordance with the daily variations in radiation and meteorological conditions, such as the increasing surface humidity and cloud cover, and decreasing solar radiation during the entire heatwave periods. From 1961 to2017, compound heatwave numbers exhibited the sharpest increase with a statistically significant trend of 0.44 times decade-1, in contrast to an insignificant trend of 0.00 times decade-1 for purely daytime heatwaves and a significant trend of 0.09 times decade-1 for purely nighttime heatwaves. Within the compound heatwave periods, hot nights were starting earlier and ending later, and numbers of concurrent daytime-nighttime hot extremes increased significantly at 0.20 days decade-1. In particular,urban area were not only subject to increasingly more frequent and longer compound heatwaves, but also to more occurrences of concurrent daytime-nighttime hot extremes with more serious impact. This study provides instructions for researchers to customize and select appropriate heatwave indices. 相似文献
19.
Zhang Wenguang Meng Jingyi Liu Bo Zhang Shichun Zhang Jing Jiang Ming Lv Xianguo 《水文研究》2017,31(11):1990-1999
Precipitation is usually the primary source of water for the hydrological cycle in a semiarid area. However, dew occurs frequently and affects water circulation dramatically in the west of Jilin Province in China. Measurements of the amount of dew formed and precipitation were carried out from July 2012 to October 2013 in the Momoge Natural Reserve. The results indicated that moisture from primary precipitation in the summer originated from the East Asian monsoon and was affected by the atmospheric circulation in the middle and high latitudes of Eurasia in the winter. The dew amount was approximately 19.44 mm (approximately 5% of the total rainfall amount), consisting of the evapotranspiration in the local area and atmospheric moisture. Dew also supplies nutrients to the local vegetation. The maximum contribution of total nitrogen, total phosphorus, and potassium in unit corn area could reach 288.60, 27.46, and 291.63 mg/m2 in half a month, respectively. The wind speed, relative humidity, and lowest temperature were the primary factors that dramatically affected dew formation and amount. As an additional source of fresh water, dew not only had a positive impact on the ecosystem in arid and semiarid zones but also played an important role in the local water cycle and other ecological processes. This research has important implications for water circulation and land use management. 相似文献