基于MODIS-EVI数据的神农架林区植被指数变化特征研究   总被引：1，自引：0，他引：1  

黄靖  夏智宏 《气象与环境科学》2013,36(3):39-43

对植被覆盖动态变化监测可以提供生态系统状况有价值的信息,可以检测到人类或气候作用引起的变化.以2003-2012年MODIS的遥感数据为信息源,利用增强型植被指数(EVI),采用最大值合成法,对神农架林区植被覆盖动态变化进行监测,并与同期的气候因子进行相关性分析,结果表明:10 a来神农架林区植被覆盖整体呈增加趋势,且东部地区的EVI增幅大于西部增幅,特别是近5 a(2008-2012年),除2010年外,植被指数均为正距平.说明神农架林区近5 a来植被生长状况较好,生态环境得到了进一步改善.与气候因子进行相关性分析说明,气温是制约神农架植被生长的主要气候因子,而降水和日照是影响该地区植被生长的重要气候因子.  相似文献   

2012年桂西北一次地面人工增雨作业天气条件的分析和捕捉     

何飞  刘丽君  黄晓辉  张正国 《气象研究与应用》2013,34(1):55-59

以百色市田林县一次降雨过程的人工增雨作业天气和作业实况作为研究对象,对相应天气形势和物理量场进行剖析并对增雨效果进行检验。得出:在短波槽、切变线和弱冷空气为主的中低层天气系统影响下,低层水汽充足,上升运动的加剧及弱冷空气的入侵可激发降雨的产生;在降雨初期对液水含量大,冰晶含量偏低的冷云及时进行人工催化作业,可收到明显的增雨效果。  相似文献   

Last Glacial Maximum Sea Surface Temperatures: A Model-Data Comparison          下载免费PDF全文

WANG Tao  LIU Yi  HUANG Wei 《大气和海洋科学快报》2013,6(5):233-239

In this study,the authors investigated changes in Last Glacial Maximum(LGM)sea surface temperature(SST)simulated by the Paleoclimate Modelling Intercomparison Project(PMIP)multimodels and reconstructed by the Multiproxy Approach for the Reconstruction of the Glacial Ocean Surface(MARGO)project,focusing on model-data comparison.The results showed that the PMIP models produced greater ocean cooling in the North Pacific and Tropical Ocean than the MARGO,particularly in the northwestern Pacific,where the modeldata mismatch was larger.All the models failed to capture the anomalous east-west SST gradient in the North Atlantic.In addition,large discrepancies among the models were observed in the mid-latitude ocean,particularly with models in the second phase of the PMIP.Although these models showed better agreement with the MARGO,the latest models in the third phase of the PMIP did not show substantial progresses in simulating LGM ocean surface conditions.That is,improvements in the modeling community are still needed to describe SST for a better understanding of climate during the LGM.  相似文献   

利用气温与云顶亮温差值检测云方法研究     

黄毅梅  郝剑平  杜春丽 《气象与环境科学》2013,36(4):22-28

利用2005年7-12月卫星资料、地面观测资料、探空资料和地形资料,统计分析了无云条件下气温与云顶亮温的差值,结果表明：无云情况下气温与云顶亮温差值平均为5.04℃,且具有较大的日变化性。由此提出了按时次分别求取阈值用以检测云。通过个例对比分析,初步得出该方法检测云具有以下特点：可用于全天候云检测;不受地形地貌等因素的影响;该云检测方法应用于反演计算,不仅反演的中、高云区域与实测的比较一致,而且反演的低云区域与实测结果也比较一致。  相似文献   

Stratospheric radiative feedback limited by the tropospheric influence in global warming     

Wang  Yuwei  Huang  Yi 《Climate Dynamics》2020,55(9-10):2343-2350

Whether the stratospheric radiative feedback amplifies the global warming remains under debate. The stratospheric water vapor (SWV), one of the primary feedbacks in the stratosphere, is argued to be an important contributor to the global warming. On the other hand, the overall stratospheric feedback, which consists of both the SWV feedback and the stratospheric temperature (ST) feedback, does not amount to a significant value. The key to reconciling these seemingly contradictory arguments is to understand the ST change. Here, we develop a method to decompose the ST change and to quantify the decomposed feedbacks. We find that the SWV feedback, which consists of a 0.04 W m⁻² K⁻¹ direct impact on the top-of-the-atmosphere radiation and 0.11 W m⁻² K⁻¹ indirect impact via ST cooling, is offset by a negative ST feedback of − 0.13 W m⁻² K⁻¹ that is radiatively driven by the tropospheric warming. This compensation results in an insignificant overall stratospheric feedback.

  相似文献   

A new DRP-4DVar-based coupled data assimilation system for decadal predictions using a fast online localization technique     

He  Yujun  Wang  Bin  Huang  Wenyu  Xu  Shiming  Wang  Yong  Liu  Li  Li  Lijuan  Liu  Juanjuan  Yu  Yongqiang  Lin  Yanluan  Huang  Xiaomeng  Peng  Yiran 《Climate Dynamics》2020,54(7):3541-3559

Climate Dynamics - A new coupled data assimilation (CDA) system based on dimension-reduced projection four-dimensional variational data assimilation (DRP-4DVar) for decadal predictions is developed...  相似文献   

Improved methods for estimating equilibrium climate sensitivity from transient warming simulations     

Dai  Aiguo  Huang  Danqing  Rose  Brian E. J.  Zhu  Jian  Tian  Xiangjun 《Climate Dynamics》2020,54(11):4515-4543

Climate Dynamics - Equilibrium climate sensitivity (ECS) refers to the total global warming caused by an instantaneous doubling of atmospheric CO2 from the pre-industrial level in a climate system....  相似文献   

2014年5月8—9日引发珠江口区域强降水的两个长生命史MCS特征分析     

陈涛  张芳华  符娇兰  于超 《气象》2020,46(4):449-461

2014年5月8日上午至9日白天,广东中南部珠江口地区连续受MCS A1、MCS A2两个长生命史中尺度对流系统影响,形成长时间强降水。其中5月8日午后华南内陆地区MCS A1逐步增强,从广西东部向广东珠江口方向移动,陆上活动时间超过11 h; MCS A2从9日凌晨至上午持续影响珠江口沿海地区,维持时间超过9 h,导致珠江口沿海地区出现400 mm 以上单站降水量。过程发生前,8日早上华南南部地区具有弱地面温度梯度,中午MCS A1对流触发与广西南部地面南风增强、华南南部云开大山—云雾山中尺度地形抬升有紧密关系;在弱斜压环境条件下,MCS A1从层云伴随线状对流结构演变为中尺度涡旋组织结构。8日夜间MCS S1入海后,与陆上遗留冷池相关的地面温度边界稳定在珠江口西侧沿海地区;9日凌晨西南低空急流增强后,MCS A2在珠江口沿海残留冷池边界附近开始发展,在向上游迎风方向传播的过程中,逐步形成多条平行β中尺度线状对流组织结构,对流系统整体移动缓慢,造成珠江口沿海地区出现较高的总降水量。计算表明MCS A2冷池边界扩张速度与低层垂直切变相对平衡,有利于形成较为直立的对流单体,增强的边界层水汽输送、更高的对流单体高度有利于产生较高的降水强度。通过总结这两个华南地区长生命史MCS发生发展过程,表明通过分析对流反馈造成的边界层/近地面层热动力特征变化,对于分析MCS发展特征、提高华南前汛期中尺度暴雨预报能力具有重要意义。  相似文献   

雷达资料同化对一次浙江初春罕见飑线过程数值模拟的影响分析     

陈锋  董美莹  苏涛  冀春晓 《气象》2020,46(4):462-477

以2018年3月4日影响浙江的初春罕见飑线过程为例,利用WRF模式与GSI-3DVar同化系统开展了雷达资料同化对重大强对流天气的影响研究,分析了雷达资料同化对此次飑线过程的模拟改进作用和可能影响过程,对比了雷达反射率因子和雷达径向速度的同化效果,探讨了不同数量和位置的雷达资料同化对模拟效果的影响。结果表明:雷达资料(尤其是反射率因子)同化有效改善了飑线边界层特征的模拟,从而改进了模式对飑线过程中组合反射率因子、降水、大风等发展演变的模拟效果。雷达反射率因子同化通过直接调整水凝物质含量,修正风暴中降水模拟及由此引起的蒸发冷却,形成更接近实况的强冷池,进而产生了比雷达径向速度同化更大的正贡献。相对于同化非关键区域的雷达资料,同化飑线过程上游关键区域的雷达观测所包含的重要中小尺度信息,对飑线过程模拟效果提升更为重要。  相似文献   

Duplex equilibria of Ural circulation anomalies     

Dongdong Li  Yongli He  Jianping Huang 《Climate Dynamics》2020,54(3):1425-1452

Atmospheric circulation anomalies over the Ural Mountains are crucial indicators of the anomalous downstream weather and climate over East Asia. Here, we provide a new perspective on the mechanism of Ural circulation anomalies. We use a simple theoretical model to determine that the relationship between the solar forcing and three Ural circulation patterns, namely, neutral type, trough anomaly and ridge anomaly, is a nonlinear relationship following the supercritical pitchfork bifurcation theory. The theory predicts that when the total solar irradiance (TSI) is below a critical value, trough and ridge anomalies represent duplex equilibria and are equally likely to occur at the same TSI. Based on 180 winter months record, we have estimated the bidimensional probability density of TSI and the monthly mean geopotential height at 500 hPa or zonal wind at 850 hPa over the Ural Mountains. Results show that Sc = 1360.9 W m−2 is a critical value of TSI, the neutral type pattern is the single circulation regime when TSI > Sc, whereas trough and ridge anomaly patterns are duplex circulation regimes when TSI < Sc. Besides, when TSI < Sc, during the same TSI range, trough and ridge anomaly events occur at nearly the same frequencies. These results generally agree with the theoretical model. We demonstrate that trough and ridge anomalies, as duplex equilibria, result from the large-scale zonal flow interacting with the Ural Mountains. Low TSI tends to strengthen the large-scale zonal flow over the Ural Mountains, hence inducing either a trough anomaly or ridge anomaly.  相似文献