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1.
雷达资料在云南一次强降水过程中的三维变分同化试验 总被引：2，自引：0，他引：2
鉴于云南观测信息相对不足、局地强降水突出的现状,利用WRF(Weather Research and Forecasting)模式及其变分同化系统进行雷达反射率因子和反演风场的三维变分同化试验。通过对2012年9月12日00:00—13日00:00发生在云南的一次强降水过程进行数值模拟和对比分析,结果表明,同时同化雷达反演风场和基本反射率因子,对区域模式同化系统中风矢量、相对湿度、位势高度几个基本分析量都有明显影响。雷达资料的同化,有利于区域模式初始场中强降水区域的上游中低层空气湿度增加、水汽输送增强和强降水发生区域的风场辐合加强,从而改善区域模式对强降水落区、强度的预报质量。对于切变线等天气尺度系统影响下的强降水过程,雷达资料的同化持续时间选取3 h、同化间隔为1 h较适宜。另外,雷达反演风场和基本反射率因子的同化均对降水预报改善有明显贡献,且多种资料的同化效果好于单一资料同化。 相似文献
2.
为了将雷达风场资料更好地应用到数值预报模式中, 使用VAD方法反演多普勒雷达风廓线并处理成标准的探空资料进行变分同化试验。结果表明: VAD方法反演的风廓线与探空实况对应较好, 验证了用VAD技术反演风廓线的可行性。用GRAPES-Meso模式的三维变分同化系统对雷达风廓线资料进行同化后, 风场的初始场明显改善, 降水强度和落区预报也有不同程度的改善。其中, 对6 h降水预报的改善明显优于对24 h的预报改善。另外, 在短时强降水预报中, 雷达风场资料的同化频率和同化窗口的不同, 对降水预报的改善情况也有所差异。在个例研究中, 同化间隔为1 h的方案6 h降水预报要优于同化间隔为3 h和6 h的方案, 同化窗口为3 h的试验方案6 h降水预报要好于同化窗口为6 h的试验方案。 相似文献
3.
多普勒雷达估算降水和反演风在不同初值方案下对降水预报影响的数值研究 总被引：7，自引：6，他引：7
基于有限区域中尺度暴雨预报模式AREM,利用常德、荆州、宜昌3部多普勒雷达及武汉数字化天气雷达联合反演的1h降水量资料和宜昌、荆州多普勒雷达反演的水平风场资料,采用3种不同的初值方案:Grapes-3DVAR同化方案、Barnes客观分析法及Barnes-3DVAR同化方案,对2002年7月22日20:00—23日20:00发生在长江流域的一次大暴雨过程进行了多普勒雷达估算降水和反演风场在不同初值方案下对降水预报影响的数值试验,结果表明:(1)采用相同资料源(探空 T213L31分析场),3种初值方案降水模拟效果差别显著。整体而言,融合了Barnes和3DVAR两种方案的Barnes-3DVAR初值方案降水模拟效果最好:雨带模拟完整,位置与实况完全一致;降水中心中尺度结构清晰,位置、强度与实况接近。(2)Barnes-3DVAR同化方案与Grapes-3DVAR同化方案都能同化雷达降水和风场资料,但两者降水预报结果相差很大。Barnes-3DVAR方案下的降水模拟结果明显好于Grapes-3DVAR同化方案。(3)Grapes-3DVAR同化方案下,在控制试验的基础上增加雷达降水资料的同化,24h降水模拟效果有所改善;增加雷达风场资料的同化,仅部分改善模拟效果,某些地方效果反而变差;同时增加雷达降水和风场资料的同化,降水模拟效果反而明显变差。Barnes-3DVAR同化方案则不然,无论雷达降水资料和风场资料单独同化还是两种资料同时同化,降水模拟效果都有不同程度的改进,特别是对雷达降水和风场资料同时同化的模拟结果是各种试验中效果最好的。(4)融合Barnes客观分析方法和Grapes-3DVAR同化方案的Barnes-3DVAR同化方案,是同化雷达降水和风场资料的一种新的、有效的初值方案。 相似文献
4.
"7·8"特大暴雨过程雷达风场资料的三维变分同化研究 总被引：10，自引：5，他引：5
基于中尺度暴雨预报模式AREM和三维变分同化系统GRAPeS-3dvar对2003年7月8日发生在长江中游的一场特大暴雨过程,进行了武汉、宜昌多普勒雷达风场资料的三维变分同化研究,结果表明:(1)增加了武汉、宜昌多普勒雷达反演风场资料后,模式对湘-鄂交界处特大暴雨区的模拟效果改善非常显著.(2)分别单独增加武汉、宜昌多普勒雷达风场资料的三维变分同化后,降水模拟都有明显改进,但要差于对两部雷达风场资料同时进行变分同化的结果,表明同化的中尺度初始风场信息越多,初始场的质量越高,降水模拟效果越好.(3)雷达风场资料的三维变分同化,改善了分析场中尺度结构的描述,从而减轻了spin-up现象,使得模式在积分初期就能模拟出与实况相近的强降水. 相似文献
5.
一次大暴雨过程的多普勒雷达资料同化的敏感性试验 总被引：3，自引：1，他引：2
利用WRF中尺度模式及WRF-3DVAR变分同化系统和LAPS雷达资料前处理模块建立试验平台,直接同化S波段多普勒雷达反射率和径向速度资料,通过对2008年8月15-16日发生在我国长江中游的一次大暴雨过程的各项预报对比试验研究,初步检验和评估不同种类多普勒雷达观测数据同化对改进数值模式初始场及其数值预报能力的影响及作用.初步结果表明:多普勒雷达资料同化对提高暴雨数值预报能力有重要作用.无论在24 h累计降水还是在逐时降水预报方面,同化多普勒雷达资料均可使降水雨带分布和强降水中心预报的准确性得到较大改善;多普勒雷达反射率资料同化对初始水汽场的改变显著,对初始风场影响较小,而同化径向速度对初始水汽场的改变较小,但可增加初始风场的中小尺度信息,使初始风场产生较大变化.总体上看,虽然雷达反射率和径向速度资料同化均可改进强暴雨的数值预报,但雷达反射率资料同化对降水雨带和中心预报的改进更为显著和重要. 相似文献
6.
基于1 km分辨率的华南区域短临预报模式,利用松弛逼近法Nudging同化由雷达观测反演的风场和水物质,选取两次华南前汛期降水过程进行试验,目的在于研究调整初始风场和调整初始水物质场对于短临模式降水预报的不同影响。首先对反演结果进行了初步验证,结果表明试验中反演结果是基本合理的。进而将雷达反演结果 Nudging同化到模式预报中,和控制试验(test-ctl)进行比较可以看出:(1)仅Nudging同化水物质试验(test-qcqr)可以比较有效地改进0～7 h降水预报,特别是对于0～2 h降水偏少的现象改进最为显著。(2)仅Nudging同化风场试验(test-uv)对3～7 h预报有一定的改进,但总体来说改进的幅度很小。(3)同时Nudging同化水物质及风场试验(test-qcqr-uv)的结果最优,它对于0～10 h降水预报都有比较明显的改进。从微物理量的垂直分布来看,前期模式降水主要来源于Nudging同化到初始场中的水物质信息,所以test-qcqr和test-qcqr-uv对前期降水预报的改进都比较明显。Nudging同化雷达反演风场资料可以迅速的调整初始场中低层辐合线存在的偏差,但是它对降水的影响必须配合水物质的调整才能比较明显地体现出来。总的来说,Nudging同化水物质对于短临降水预报影响最为显著,而在此基础上Nudging同化雷达风场对于3 h之后的降水预报会有更好的改进。 相似文献
7.
利用中尺度模式WRF(Weather Research and Forecasting Model)及其资料同化系统3DVAR,将国内多普勒天气雷达(CINRAD)反射率因子及径向风资料直接用于中尺度数值模拟;对安徽梅雨期一次暴雨过程进行模拟试验,经过质量控制后,分析同时同化安徽省内六部多普勒天气雷达观测资料对模拟结果的影响。结果表明:(1)经过质量控制后,同化雷达径向风和反射率因子对初始场的风场和湿度场均有较为明显的改善,说明用该雷达资料质量控制方案同化雷达资料是可行的;(2)同化多部雷达径向速度资料能使风场气旋性增强,同化反射率资料能调整初始水汽场,使对流层中下层水汽含量增加;(3)同化多部雷达径向风和反射率因子资料,能提前模拟出强降水回波结构,且其中尺度特征更清晰,降水落区和强度预报更接近实况,同化雷达资料对降水预报能持续影响到12 h,并提高了12 h降水预报准确率。 相似文献
8.
《气象科学进展》2017,(1)
GSI是目前美国NCEP业务上使用的资料分析系统,本文以北京"7·21"特大暴雨为例,通过对雷达资料GSI同化后的模式初始场和强降水预报结果对比分析,检验GSI同化系统对本地雷达资料的融合能力和对强降水的预报效果。通过试验对比可知,经过GSI雷达资料同化后的分析场,可将风场和水汽场进行有效的调整,较好地反映了同时刻大气实际状况,并且水汽增量由加入雷达反射率同化后产生,而雷达径向风的同化只能改变风场结构。对北京"7·21"强降水发生的累积降水预报和逐小时降水预报的不同试验方案对比分析可知,经过GSI雷达资料同化后的初始场对强降水预报有很好的正效应,且同时同化雷达径向风和反射率后预报效果最好,不但对整个雨带位置进行整体调整和改善,而且对强降水中心强度和位置都进行了调整和修正。 相似文献
9.
LAPS同化GPS/PWV资料在暴雨预报中的应用研究 总被引：2，自引：1，他引：1
利用LAPS(Local Analysis and Prediction System)系统同化GPS(Global Positioning System)/PWV(Precipitable Water Vapor)资料,分析GPS/PWV资料对LAPS输出场的影响,并结合WRF模式,将LAPS输出场作为其初始场进行降水预报,进一步考察GPS/PWV资料对降水预报的作用。选取2009年6月28日湖北地区的一次强降水过程,设计三种方案进行试验。结果表明:同化GPS/PWV资料后对LAPS湿度场有显著的改善,而对高度场及风场的作用则不明显;GPS/PWV资料对区域平均可降水量的影响比雷达资料大一个量级;与此同时,利用多种评分方法对6 h累计降水做了检验,分析结果表明同化GPS/PWV资料能够有效地改进WRF模式的初始场,增加丰富的中小尺度信息,并对随后的确定性预报产生正影响。 相似文献
10.
以业务应用为目标,开展雷达反射率三维拼图观测资料在北方区域数值预报系统中的同化应用研究。采用雷达反射率间接同化方法同化北方雷达反射率拼图观测资料,重点关注其对降水、湿度、温度及风的预报能力影响。首先,基于2017年8月雷达拼图观测资料批量同化和对比试验,对雷达拼图资料同化应用效果进行定量评估,结果表明雷达拼图资料同化虽然加大了地面风场预报误差,但在降水预报和湿度、温度预报等方面有明显的改善作用。其次,选择在业务中预报难度较大的强降水个例开展分析研究,分析表明:（1）同化雷达拼图观测资料有效提高了模式降水预报性能,临近降水发生的循环起报时次预报效果更好;（2）对于短时间多次强降水过程发生的预报,循环同化雷达拼图资料可及时弥补模式中由于前次降水导致的水汽、能量等消耗及热/动力条件削弱,持续支持降水系统发展。最后,通过考察雷达反射率的不同同化方案,发现同化反演水凝物或者估计水汽均能改善模式降水预报性能,但是同化估计水汽对降水预报性能的改善更为明显,联合使用两方案能同时对水凝物分布、热力场等进行调整,可提高模式降水预报性能。 相似文献
11.
Observed daily precipitation data from the National Meteorological Observatory in Hainan province and daily data from the National Centers for Environmental Prediction/National Center for Atmospheric Research (NCEP/NCAR) reanalysis-2 dataset from 1981 to 2014 are used to analyze the relationship between Hainan extreme heavy rainfall processes in autumn (referred to as EHRPs) and 10–30 d low-frequency circulation. Based on the key low-frequency signals and the NCEP Climate Forecast System Version 2 (CFSv2) model forecasting products, a dynamical-statistical method is established for the extended-range forecast of EHRPs. The results suggest that EHRPs have a close relationship with the 10–30 d low-frequency oscillation of 850 hPa zonal wind over Hainan Island and to its north, and that they basically occur during the trough phase of the low-frequency oscillation of zonal wind. The latitudinal propagation of the low-frequency wave train in the middle-high latitudes and the meridional propagation of the low-frequency wave train along the coast of East Asia contribute to the ‘north high (cold), south low (warm)’ pattern near Hainan Island, which results in the zonal wind over Hainan Island and to its north reaching its trough, consequently leading to EHRPs. Considering the link between low-frequency circulation and EHRPs, a low-frequency wave train index (LWTI) is defined and adopted to forecast EHRPs by using NCEP CFSv2 forecasting products. EHRPs are predicted to occur during peak phases of LWTI with value larger than 1 for three or more consecutive forecast days. Hindcast experiments for EHRPs in 2015–2016 indicate that EHRPs can be predicted 8–24 d in advance, with an average period of validity of 16.7 d. 相似文献
12.
Based on the measurements obtained at 64 national meteorological stations in the Beijing–Tianjin–Hebei (BTH) region between 1970 and 2013, the potential evapotranspiration (ET0) in this region was estimated using the Penman–Monteith equation and its sensitivity to maximum temperature (Tmax), minimum temperature (Tmin), wind speed (Vw), net radiation (Rn) and water vapor pressure (Pwv) was analyzed, respectively. The results are shown as follows. (1) The climatic elements in the BTH region underwent significant changes in the study period. Vw and Rn decreased significantly, whereas Tmin, Tmax and Pwv increased considerably. (2) In the BTH region, ET0 also exhibited a significant decreasing trend, and the sensitivity of ET0 to the climatic elements exhibited seasonal characteristics. Of all the climatic elements, ET0 was most sensitive to Pwv in the fall and winter and Rn in the spring and summer. On the annual scale, ET0 was most sensitive to Pwv, followed by Rn, Vw, Tmax and Tmin. In addition, the sensitivity coefficient of ET0 with respect to Pwv had a negative value for all the areas, indicating that increases in Pwv can prevent ET0 from increasing. (3) The sensitivity of ET0 to Tmin and Tmax was significantly lower than its sensitivity to other climatic elements. However, increases in temperature can lead to changes in Pwv and Rn. The temperature should be considered the key intrinsic climatic element that has caused the "evaporation paradox" phenomenon in the BTH region. 相似文献
13.
Storms that occur at the Bay of Bengal (BoB) are of a bimodal pattern, which is different from that of the other sea areas. By using the NCEP, SST and JTWC data, the causes of the bimodal pattern storm activity of the BoB are diagnosed and analyzed in this paper. The result shows that the seasonal variation of general atmosphere circulation in East Asia has a regulating and controlling impact on the BoB storm activity, and the “bimodal period” of the storm activity corresponds exactly to the seasonal conversion period of atmospheric circulation. The minor wind speed of shear spring and autumn contributed to the storm, which was a crucial factor for the generation and occurrence of the “bimodal pattern” storm activity in the BoB. The analysis on sea surface temperature (SST) shows that the SSTs of all the year around in the BoB area meet the conditions required for the generation of tropical cyclones (TCs). However, the SSTs in the central area of the bay are higher than that of the surrounding areas in spring and autumn, which facilitates the occurrence of a “two-peak” storm activity pattern. The genesis potential index (GPI) quantifies and reflects the environmental conditions for the generation of the BoB storms. For GPI, the intense low-level vortex disturbance in the troposphere and high-humidity atmosphere are the sufficient conditions for storms, while large maximum wind velocity of the ground vortex radius and small vertical wind shear are the necessary conditions of storms. 相似文献
14.
The spatial and temporal variations of daily maximum temperature(Tmax), daily minimum temperature(Tmin), daily maximum precipitation(Pmax) and daily maximum wind speed(WSmax) were examined in China using Mann-Kendall test and linear regression method. The results indicated that for China as a whole, Tmax, Tmin and Pmax had significant increasing trends at rates of 0.15℃ per decade, 0.45℃ per decade and 0.58 mm per decade,respectively, while WSmax had decreased significantly at 1.18 m·s~(-1) per decade during 1959—2014. In all regions of China, Tmin increased and WSmax decreased significantly. Spatially, Tmax increased significantly at most of the stations in South China(SC), northwestern North China(NC), northeastern Northeast China(NEC), eastern Northwest China(NWC) and eastern Southwest China(SWC), and the increasing trends were significant in NC, SC, NWC and SWC on the regional average. Tmin increased significantly at most of the stations in China, with notable increase in NEC, northern and southeastern NC and northwestern and eastern NWC. Pmax showed no significant trend at most of the stations in China, and on the regional average it decreased significantly in NC but increased in SC, NWC and the mid-lower Yangtze River valley(YR). WSmax decreased significantly at the vast majority of stations in China, with remarkable decrease in northern NC, northern and central YR, central and southern SC and in parts of central NEC and western NWC. With global climate change and rapidly economic development, China has become more vulnerable to climatic extremes and meteorological disasters, so more strategies of mitigation and/or adaptation of climatic extremes,such as environmentally-friendly and low-cost energy production systems and the enhancement of engineering defense measures are necessary for government and social publics. 相似文献
15.
《大气和海洋科学快报》2013,(1):67
正AIMS AND SCOPE Atmospheric and Oceanic Science Letters (AOSL) publishes short research letters on all disciplines of the atmosphere sciences and physical oceanography. Contributions from all over the world are welcome.SUBMISSIONAll submitted 相似文献
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17.
<正>With the support of specialized funds for national science institutions,the Guangzhou Institute of Tropical and Marine Meteorology,China Meteorological Administration set up in October 2008 an experiment base for marine meteorology and a number of observation systems for the coastal boundary layer,air-sea flux,marine environmental elements,and basic meteorological elements at Bohe town,Maoming city,Guangdong province,in the northern part of the South China Sea. 相似文献
18.
《大气和海洋科学快报》2014,7(6):F0003-F0003
AIMS AND SCOPE
Atmospheric and Oceanic Science Letters （AOSL） publishes short research letters on all disciplines of the atmosphere sciences and physical oceanography. Contributions from all over the world are welcome. 相似文献
Atmospheric and Oceanic Science Letters （AOSL） publishes short research letters on all disciplines of the atmosphere sciences and physical oceanography. Contributions from all over the world are welcome. 相似文献
19.
《大气和海洋科学快报》2014,(5):F0003-F0003
AIMS AND SCOPE Atmospheric and Oceanic Science Letters （AOSL） pub- lishes short research letters on all disciplines of the atmos- phere sciences and physical oceanography. Contributions from all over the world are welcome. 相似文献
20.
《大气和海洋科学快报》2012,(3):273
正AIMS AND SCOPE Atmospheric and Oceanic Science Letters (AOSL) publishes short research letters on all disciplines of the atmosphere sciences 相似文献