选取广东省53个国家基本站,对2019年10月-2020年3月Grapes_1 km模式输出的10 m风场进行检验,发现Grapes_1 km预报与实况整体趋势较一致,但预报10 m风极大值的峰值略有提前;相关性检验方面,相关性比较好的地区是湛江沿海地区、江门沿海、汕头沿海,相关性较差的地区分别是茂名沿海、云浮地区、汕尾沿海;预报命中率随着风速的加大呈明显下降的趋势,且沿海站点的命中率略好于内陆站点;随着风速的增大,预报值相对实况有偏小的趋势.

利用台风最佳路径数据集、1950-2016年厄尔尼诺和拉尼娜事件、赤道太平洋海温关键区海温和行星冲日等资料,运用统计方法研究了西北太平洋台风频数和ENSO的相互关系变化与行星运动的关系.结果 发现:西北太平洋台风频数与ENSO之间相互关系的变化无论长周期还是短周期都与行星位置变化密切相关.从年代际变化来看,两者相互关系在1990年代初期(1993年前后)发生明显改变,在1993年之前,两者为显著的负相关关系,1950-1992年相关系数高达-0.439,检验通过了99％的置信水平,而且,台风频数的极多(少)年大多数与拉尼娜(厄尔尼诺)现象相对应,但在1993年之后两者变为明显的正相关关系.这一改变恰好发生在1993年7月12日出现太阳、地球、天王星、海王星四星一线的特殊星象,而在此前后的数年间,天王星、海王星两大行星同时都保持在6-7月冲日,对地球形成持续作用的引潮力迭加.从年际变化来看,两者的相关系数变化与火星、木星和土星的位置也存在明显的联系:相关系数的谷值与三大行星在夏至前后冲日相对应,其中与火星在夏至附近冲日(此时视赤纬具有负极值)对应的谷值最明显.通过谐波分析发现,相关系数变化的显著周期恰好与三大行星运动周期一致.

利用观测资料及模式结果探讨了EP/CP El Ni(n)o事件对华南前汛期(4-6月)降水异常的影响.结果 发现,EP和CP型相关的华南前汛期降水异常分布之间存在明显月际差异,表现为4、5月EP(CP)型相关的降水异常以偏多(少)为主;6月则相反,EP(CP)型的降水呈负(正)异常分布.分析表明,EP型相关的4、5月偏强的副热带高压与850 hPa上西北太平洋反气旋异常相配合,有利于水汽从海洋向陆地输送,且两广地区水汽辐合,降水异常偏多;而6月相关的500 hPa异常场上对应偏强的东亚大槽,不利于水汽输送,且广东地区处于水汽辐散区,对应降水偏少.CP型相关的4、5月对应500 hPa上东亚大槽偏强,不利于水汽往陆地输送,且华南为水汽辐散,降水偏少;6月的500 hPa上呈现“+-+”的东亚-太平洋遥相关波列(EAP)型,华南地区为明显的水汽辐合,降水偏多.GFDL模式较好地再现了EP/CP型的4、5月降水异常分布及大气环流形势,但是对6月的模拟存在一定偏差.

The Weather Research and Forecasting model version 3.2.1 with the Lin microphysics scheme was used herein to simulate super typhoon Usagi, which occurred in 2013. To investigate the effect of the concentration of cloud condensation nuclei (CCN) on the development of typhoon Usagi, a control simulation was performed with a CCN concentration of 100 cm−3, together with two sensitivity tests: C10 and C1000, having CCN concentrations of 10 cm−3 and 1000 cm−3, respectively. The path, intensity, precipitation, microphysical processes, and the release of latent heat resulting from the typhoon in all three simulations were analyzed to show that an increase in CCN concentration leads to decreases in intensity and precipitation, an increase of the cloudless area in the eye of the typhoon, a more disordered cloud system, and less latent heat released through microphysical processes, especially the automatic conversion of cloud water into rainwater. Overall, an increase in CCN concentration reduces the total latent heat released during the typhoon suggesting that typhoon modification by aerosol injection may be optimized using numerical simulations to ensure the strongest release of latent heat within the typhoon.

利用NCEP再分析资料(1°×1°),使用WRF模式对1604号台风“妮妲”进行了数值模拟,分析了该次台风暴雨形成的环流形势、动力、热力等条件,并探讨台风外围环流触发强对流天气过程的各云微物理量分布特征,结果表明:(1)“妮妲”是在副高偏强且稳定的环流背景下发生的,台风路径为稳定西北向,降水分布南多北少;(2)整个过程可分为台风本体降水和台风外围雨带降水,相对于本体降水,台风外围雨带产生的降水更具有短时强降水的特点;(3)对台风外围环流强降水的预报,能否准确判断冷空气的位置成为预报准确与否的关键;(4)该次台风过程外围环流引发的强降水天气、雪和霰的大值区分别位于雨水大值区的下游和上游方向,结合雷达产品,可能对降水大值区有一定的指示作用.

利用MERRA-2再分析气溶胶光学厚度及气象观测资料,在剔除人为排放长期变化产生的气溶胶光学厚度扰动的基础上,从气候学角度探讨了两类厄尔尼诺事件对中国东部冬季气溶胶的影响.结果表明,东部型厄尔尼诺事件使绝大部分区域气溶胶光学厚度呈正异常分布,尤其对华北至东北的气溶胶污染加剧作用显著;而中部型厄尔尼诺事件使气溶胶光学厚度异常由南至北呈显著的"+-"双极型分布.进一步成因分析发现,虽然两类厄尔尼诺事件都具有削弱冬季风从而减弱北方气溶胶向南传输的作用,但中部型对水平流场的削弱作用不显著,尤其是东北地区没有通过90％的显著性检验.同时二者对北方大气垂直扰动和气溶胶的湿清除作用相反,其中东部型表现为大气垂直扰动和对流有效位能减弱,降水减少,湿清除减弱;而中部型则表现为垂直扰动和对流有效位能增强,降水增多,湿清除增强.对于南方,强东部型事件引发的强降水可能是产生该区域气溶胶污染影响不稳定的主因,而中部型则主要通过气流削弱作用加剧长江中下游地区气溶胶的局地污染.

Observation and research of forest fuel are important for the prediction of fire danger class, with the data of 8 stations in Changbai Mountain (6 measuring points per station), the variations of fuel moisture were analyzed. It was found that the average fuel moisture in Changbai Mountain under forest was 40%, and in most observation dates, it was not easy to burn for the fuel moisture there. Highly flammable condition appeared only one station, easy-to-burn days occupied 12% of the total days. The fuel moisture of the whole Changbai Mountain under forest and the fuel moisture of the same measuring point and of different stations had a good consistency in variation. Analysis of fuel moisture and meteorological element data showed that there was an obvious link between fuel moisture and daily maximum temperature, evaporation capacity, sunshine duration. And there was good correlation between fuel moisture and cumulative precipitation 3 days before observation.

Relationships between forest fuel moisture and meteorological factors were analyzed according to the observation data of forest fuels in six observation points of Tonghua City.Results showed that moisture content had good correlations with maximum temperature,three-day cumulative precipitation,evaporation,and sunshine hours.Linear and multinomial models of moisture content were established according to the results of correlation analysis of moisture contents in different measuring points.At the same confidence level in reliability testing,the relationship predicted by the multinomial model had a higher correlation with the actual situation compared with the linear model.Adjusted coefficient of multiple determination increased by 0.1937 averagely,and the absolute error was reduced by 30.368%.Therefore,the multinomial model is more reasonable than the linear model in describing the relationship between meteorological elements and forest fuel moisture content.