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81.
The basic structure and cloud features of Typhoon Nida
(2016) are simulated using a new microphysics scheme (Liuma)
within the Weather Research and Forecasting (WRF) model. Typhoon
characteristics simulated with the Liuma microphysics scheme are
compared with observations and those simulated with a commonly-
used microphysics scheme (WSM6). Results show that using
different microphysics schemes does not significantly alter the
track of the typhoon but does significantly affect the intensity
and the cloud structure of the typhoon. Results also show that
the vertical distribution of cloud hydrometeors and the
horizontal distribution of peripheral rainband are affected by
the microphysics scheme. The mixing ratios of rain water and
graupel correlate highly with the vertical velocity component
and equivalent potential temperature at the typhoon eye-wall
region. According to the simulation with WSM 6 scheme, it is
likely that the very low typhoon central pressure results from
the positive feedback between hydrometeors and typhoon
intensity. As the ice-phase hydrometeors are mostly graupel in
the Liuma microphysics scheme, further improvement in this
aspect is required. 相似文献
82.
83.
利用MM5、T213和Grapes3种数值模式的降水预报产品和山西省108个标准测站的降水实况资料,采用客观统计检验方法,对2008年7月各模式在山西省的累加降水预报进行了对比检验。结果表明:24h中雨以下预报1、213优于MM5,中雨以上MM5则略优于T213,48h预报各级降水MM5都优于T213,T213和MM5对暴雨都有一定的预报能力。无论哪个预报时效和降水量级,Grapes均无明显优势。Grapes预报降水量级和降水范围都偏小,空报较少,漏报严重,尤其48h和72h10mm以上降水基本都漏报。MM5预报降水量级和预报范围都偏大,10mm以上降水TS评分较其它模式高,但同时空报也比较严重。3种模式TS评分均随降水量级的增大而减小,T213和Grapes的TS评分随预报时效的增加而减小,MM5的TS评分随预报时效的增加变化不大。 相似文献
84.
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86.
Forecasting seasonal to multi-year shoreline change 总被引:1,自引:0,他引:1
This contribution details a simple empirical model for forecasting shoreline positions at seasonal to interannual time-scales. The one-dimensional (1-D) model is a simplification of a 2-D behavioural-template model proposed by Davidson and Turner (2009). The new model is calibrated and tested using five-years of weekly video-derived shoreline data from the Gold Coast, Australia. The modelling approach first utilises a least-squares methodology to calibrate the empirical model coefficients using the first half of the dataset of observed shoreline movement in response to known forcing by waves. The model is then verified by comparison of hindcast shoreline positions to the second half of the observed shoreline dataset. One thousand synthetic time-series of wave height and period are generated that encapsulate the statistical characteristics of the modelled wave field, retaining the observed seasonal variability and sequencing characteristics. The calibrated model is used in conjunction with the simulated wave time-series to perform Monte Carlo forecasting of the resulting shoreline positions. The ensemble-mean of the 1000 individual five-year shoreline simulations is compared to the unseen shoreline time-series. A simple linear trend forecast of the shoreline position was used as a baseline for assessing the performance of the model. The model performance relative to this baseline prediction was quantified by several objective methods, including cross-correlation (r), root mean square (RMS) error analysis and Brier Skill tests. Importantly, these tests involved no prior knowledge of either the wave forcing or shoreline response. The new forecast model was found to significantly improve shoreline predictions relative to the simple linear trend model, capturing well both the trend and seasonal shoreline variabilities observed at this site. Brier Skill Scores (BSS) indicate that the model forecasts based on unseen data were rated as ‘excellent’ (BSS = 0.83), and root mean square errors were less than 7 m (≈ 14% of the observed variability). The standard deviations of the 1000 individual simulations from ensemble-averaged ‘mean’ forecast were found to provide a useful means of predicting the higher-frequency (individual storm) shoreline variability, with 98% of the observed shoreline data falling within two standard deviations of the forecast position. 相似文献
87.
李超 《成都信息工程学院学报》1989,(4)
首先,用1980—1985年的深层地温距平资料做付氏展开,并假定满足热传导方程,得到地温及平均地温的表达式。其次,根据前期地温与后期降水成正相关的事实,提出了两种有实用价值的降水短期气候预报方法。结果表明,对1981—1986年汛期(4—9月)旱涝趋势预报效果很好。最后,提出了陆—气耦合系统中存在两类非绝热慢波,一类是准半年波,另一类是准三年波,这刚好可以解释前面的两类相关场,进而为两类预报方法提供了物理基础。 相似文献
88.
长江下游地区降水50-80d低频分量的次季节预测研究 总被引:1,自引:0,他引:1
用1979-2000年逐日长江下游降水的50-80 d低频分量和全球850 hPa低频纬向风主成分,构建了长江下游降水低频分量的次季节预测的扩展复数自回归模型(ECAR)。这种基于数据驱动建模的气候预测方法,不仅能在复数空间上反映全球环流主要低频主分量和长江下游降水低频分量之间的时滞变化信息,而且能更好地描述气候系统的主要分量在低维空间中的变化规律。对2001-2014年长江下游降水低频分量进行次季节逐日变化回报试验的结果表明,50-80 d时间尺度的长江下游低频降水分量的预测时效可达52 d左右,预报能力明显优于自回归模型(AR),而且6-8月的预报技巧最高。基于全球环流主要50-80 d振荡型的发展和变化以及与长江下游低频降水相关的时间演变,对于提前50-60 d预报长江下游地区持续多(少)雨过程很有帮助(尤其是夏季),其中,东亚经向三极子型(EAT)是影响长江下游地区季节内降水变化的最主要的环流因子之一。 相似文献
89.
超前探测中探地雷达应用与结果的处理分析 总被引:2,自引:0,他引:2
在隧道施工中,由于地质条件的复杂性和勘察工作的局限性,往往造成地质勘查成果与开挖后的情况不一致,这就要求在隧道施工工程中进行超前跟踪探测,确保隧道施工的安全。本文主要介绍SIR-3000探地雷达系统在郴(州)宁(远)高速公路芒头岭隧道超前预报中的应用概况,并采用空间域滤波和希尔伯特变换等方法对探测结果进行处理,根据处理结果对隧道掌子面前方溶洞、裂隙等地质情况进行预测。隧道后期的开挖情况证明了雷达预测结果的正确性,取得了较好的预测效果,同时也说明了采用空间滤波、希尔伯特变换等处理方法对改进实测数据质量方面的有用性。 相似文献
90.