2020—2021年国家自然科学基金大气科学代码调整后立项情况透视

2019年,国家自然科学基金地学部以大气科学为试点,调整基金申请代码,从而实现优化大气学科资助布局、推进地学整体代码改进的目标.2020年和2021年的资助项目,大气科学(D05)被划分为3个板块和16个方向:即大气科学的分支学科(D0501～D0508)、支撑技术(D0509～D0512)和发展领域(D0513～D0...     

东北地区一次短时大暴雨β中尺度对流系统分析

为了探寻东北短历时暴雨的预报线索,利用自动站、卫星和常规气象观测资料相结合的方法,研究2006年8月10日最大1 h雨量达到90.8 mm(泰来,其中,后半小时降水82 mm)的东北中西部百年一遇短历时特大暴雨中尺度对流系统(MCS)发展过程,及其发生的天气尺度背景和中尺度环境与触发机制.通过红外卫星云图和高分辨率的可见光云图,分析MCS如何从一个γ中尺度发展为α中尺度对流复合体(MCC)的过程.分析表明,与6个市(县)半小时雨量超过33 mm相关联的MβCS分别发生在2个阶段,第1阶段在MCC形成之前,MβCS主要向东移动(最后合并成MCC),第2阶段,在MCC成熟阶段.MpCS出现在MCC的西南边缘,而且最强短历时暴雨就发生在这里.从分辨率更高的可见光云图上可以发现,有北、西两条积云线,它们交汇的地方MβCS强烈发展并产生暴雨.分析MCS加强和产生暴雨的原因表明:(1)暴雨发生前夕暴雨区域具有高温、高湿和对流性不稳定层结,并存在明显的对流有效位能增加、抬升凝结高度及自由对流高度降低的现象,有利于暴雨发生;(2)β中尺度云团之间的合并,使MCS迅速发展,产生暴雨;(3)北、西两条积云线分别与地面风场中的两条辐合线相对应,在它们交汇处的较强辐合导致β中尺度云团强烈发展产生暴雨.分析MCS在MCC西南方向传播的原因表明,两条辐合线的移动方向和速度决定了暴雨MCS的传播方向.另外,偏北气流的出现和新老云团的新陈代谢过程是触发暴雨的关键因素.上述分析结果也为短历时暴雨的预报提供了有用的线索.     

滇西北高原机场一次暴雨过程的水汽输送特征分析

利用丽江机场自动观测站资料、NCEP再分析资料,引入HYSPLIT轨迹模式,对丽江机场2019年8月8~9日出现的暴雨过程水汽输送特征进行分析。结果表明,丽江机场此次暴雨天气过程是由孟湾低压和南海台风提供充沛的暖湿水汽,与青藏高压引导南下的冷平流形成不稳定层结,低层辐合、高层辐散和强烈的垂直上升运动是暴雨发生的动力因素。此次暴雨过程水汽输送通道主要有三条,其中两条是由孟湾低压及南海台风带来洋面上的西南水汽输送和东北水汽输送,第三条是来自云南中部的云南本地水汽输送。三支通道中,来自洋面上的两支通道对暴雨的水汽贡献最大,分别为46%和30%,本地通道水汽贡献率最小;在500hPa高度层上,3条通道的水汽贡献率基本相当,600hPa高度层上西南通道和东北通道水汽贡献率均比较大,而700hPa高度层上西南通道水汽贡献率占主导地位。      

用分层增益法做干旱预报

测天谚语是制作天气预报的一条重要线索。在多年实际工作中,我们感到“冬暖年要荒”这条谚语客观效果较好。“冬暖”往往导致来年的灾荒。据资料普查,这里所指的年荒,主要是指春、夏旱。 我县地处大山区,水利条件差,干旱经常发生,对农业生产危害很大。我们以“冬暖年要荒”这条谚语为线索,以反映冬暖的物理意义清楚的要素为因子,尽量避免用物理意义不明确的因子,来制作我县的春旱、夏旱预报。其步骤是:     

改进短期冰雹预报模式的体会

冰雹是临夏地区主要灾害性天气之一,在六一八月夏田成熟季节危害很大。为了作好这一时段的冰雹预报,我们总结了过去制作冰雹预报曲线模式的经验教训。从一九六五年至一九七○年我们先后制作了十几套冰雹预报模式,但实践证明准确率不够高,“空炮”比较多,主要原因是缺乏经验线索和物理依据。从七二年开始,我们     

国家自然科学基金大气科学学科二级申请代码下设研究方向与关键词解读：D0503古气候模拟与动力学

为了深入推进新时代自然科学基金改革,2019年大气科学学科率先对2008年版的申请代码进行了优化调整,形成了“分支学科”“支撑技术”和“发展领域”三大有序板块。特别是,2020年新版申请代码设置了“古气候模拟与动力学（D0503）”,实现了大气科学从“分钟、小时直至地史”时间尺度的全覆盖。本文从D0503代码的增设背景、学科内涵、研究方向、关键词、未来发展等方面进行解读和展望,并对近三年该代码下“面青地”项目的申请和资助情况进行了分析。希望本文能够帮助科研人员充分理解D0503研究方向与关键词的内涵和逻辑关系,及时把握该代码的发展趋势,服务古气候研究方向的基金项目申请和评审。     

数值模式中的回溯时间积分研究

本研究提出并发展了大气记忆动力学,基本观点是考虑大气有记忆能力,在引进记忆函数后将制约大气运动的微分方程变换为一个差分积分方程。这样可以由多个时次的初始场而不仅是一个时次的初始场来求得大气运动的数值解。回溯时间差分格式是基于自忆性原理提出的一种新格式,与传统的格式很不一样,可以包含3个以上不同的时间层次,可以从过去的多时次场中得到更多的信息,以期提高预报准确率。该格式在数值计算中还能自动起过滤作用,可以平滑预报场中的虚假值。回溯格式的基本形式（p阶,p≥2）为:     

山西秋季一次极端暴雨过程的异常特征分析

利用山西省109个国家站1960—2019年逐日降水量、2019年9月逐时降水量以及1980—2019年欧洲中期天气预报中心1°×1°逐6 h再分析(ERA5)资料,对2019年9月10—11日山西中南部区域性极端暴雨过程的异常特征及其成因进行分析。结果表明:(1)此次降水过程影响范围大、持续时间长,46站发生极端日降水事件,其中11站日降水量突破9月历史极值。(2)对流层中低层水汽、热力、动力条件均优于1980年以来山西中南部区域性暴雨过程的平均态,不同物理量的标准化距平绝对值(|N|)均达到2.5以上,超过历史相关统计值的上四分位值,尤其是水汽和热力条件表现出一定的极端性。(3)副高位置异常偏西、偏北且强度异常偏强导致中低层水汽和能量输送异常充足,山西中南部地区西边界和南边界的水汽输入对极端降水的发生发展起到重要作用。(4)倾斜上升的西南暖湿气流中存在位势不稳定层,700 hPa暖式切变线和地面冷锋触发对流,回波持续通过暴雨区产生"列车效应";稳定的切变线与异常的低层冷垫提供持续的动力条件,长时间维持异常充沛的水汽和水汽辐合是区域性极端暴雨的主要成因;大范围物理量场异常是导致此次极端降水事件发生的主要因素。     

CAST-LSTM：一种用于雷达回波外推的时空LSTM模型

基于循环神经网络的雷达回波外推算法的预报结果随时间逐渐模糊失真，同时难以预报强回波区域。针对上述问题，提出一种上下文融合和注意力机制的时空长短期记忆网络模型。该方法通过上下文融合模块充分提取雷达图像不同尺度的短期上下文信息；通过注意力模块拓宽预测单元的时间感受域，使模型感知更多的时间动态。以2019—2021年4—9月江苏省气象雷达数据为样本，通过试验对比分析，基于上下文融合和注意力机制的时空长短期记忆网络取得了更好的预测性能。在外推60min，阈值为10、20、40 dBz的条件下，临界成功指数和HSS分别达到0.7611、0.5326、0.2369和0.7335、0.5735、0.3075，有效提高了预测精度。     

国家自然科学基金大气科学学科二级申请代码下设研究方向与关键词解读:D0509大气观测、遥感和探测技术与方法

为顺应新一轮科技发展革命,国家自然科学基金委员会积极开展了以“优化学科布局”为主要任务之一的改革工作,学科申请代码的调整是该任务的重要组成部分和切入点。从2019年到2022年,国家自然科学基金委大气科学学科对二级申请代码进行了调整,将与大气探测相关的研究归并至“D0509大气观测、遥感和探测技术与方法”,并将其定义为“支撑技术”板块,以区别于“分支学科”和“发展领域”。本文对D0509二级代码的修订过程进行了介绍,并从大气观测、遥感和探测技术与方法的重要性、内涵与外延、发展趋势等视角,对相关的研究方向和关键词进行了解读。特别是从学科基础层面和具体应用层面两个维度,对D0509下设的六大研究方向,以及各方向的关键词进行分析,有助于申请人和评审专家根据自己的学术背景准确挑选关键词,以利于申请书的精准评审。本文可以为科研人员在基金申请过程中关键词的选择提供参考。     

Transformation of a vortex ring,initiated by a downburst,into a horseshoe vortex in the boundary layer

The oblique interaction of a vortex ring with a boundary in shear flow is considered by the method of three-dimensional vortex singularities (vortons). It is demonstrated how a vortex ring transforms into a horseshoe vortex. The results are in agreement with laboratory observations. The possible application of this approach to the problem of aircraft accidents, caused by downbursts in the atmospheric boundary layer, is briefly discussed.     

Quantitative reconstruction of precipitation and runoff during MIS 5a,MIS 3a,and Holocene,arid China

Marine oxygen isotope stage 5a (MIS 5a), MIS 3a, and Holocene were highlighted periods in paleoclimate studies. Many scientists have published a great number of studies in this regard, but they paid more attention to qualitative research, and there was often a lack of quantitative data. In this paper, based on chronological evidence from a paleolake in arid China, MIS 5a, MIS 3a, and Holocene lake area, the precipitation of the drainage area and the runoff of the inflowing rivers of the lake were reconstructed with ArcGIS spatial analysis software and the improved water and energy balance model which was calibrated by modern meteorological and hydrological data in the Shiyang River drainage basin. The results showed that the paleolake areas were 1824, 1124, and 628 km² for MIS 5a, MIS 3a, and Holocene; meanwhile, the paleoprecipitation and runoff were 293.992–297.433, 271.105–274.294, and 249.431–252.373 mm and 29.103 × 10⁸–29.496 × 10⁸, 18.810 × 10⁸–18.959 × 10⁸, and 10.637 × 10⁸–10.777 × 10⁸ mm, respectively. The quantitative data can help us not only strengthen the understanding of paleoclimatic characteristics but also recognize the complexity and diversity of the climate system.     

高点起步 系统设计 因地制宜 整体推进

气象现代化建设起点要高：尽量采用先进技术和设备，力争五年不落后，按照系统工程原理，统一设计和规划，在实施过程中必须因地制宜，挖潜改造，有本地特色。开发的成果要认真投入业务应用，并努力把它转化为商品，再进一步推动气象现代化建设。     

Global climatic change,hurricanes, and a tropical forest

Most, if not all forests in the Caribbean are subject to occasional disturbances from hurricanes. If current general circulation model (GCM) predictions are correct, with doubled atmospheric CO₂ (2 × CO₂), the tropical Atlantic will be between 1 °C and 4 °C warmer than it is today. With such a warming, more than twice as many hurricanes per year could be expected in the Caribbean. Furthermore, Emanuael (1987) indicates that in a warmed world the destructive potential of Atlantic hurricanes could be increased by 40% to 60%. While speculative, these increases would dramatically change the disturbance regimes affecting tropical forests in the region and might alter forest structure and composition. Global warming impacts through increased hurricane damage on Caribbean forests are presented.An individual tree, gap dynamics forest ecosystem model was used to simulate the range of possible hurricane disturbance regimes which could affect the Luquillo Experimental Forest in Puerto Rico. Model storm frequency ranged from no storms at all up to one storm per year; model storm intensity varied from no damage up to 100% mortality of trees. The model does not consider the effects of changing temperature and rainfall patterns on the forest. Simulation results indicate that with the different hurricane regimes a range of forest types are possible, ranging from mature forest with large trees, to an area in which forest trees are never allowed to reach maturity.     

Wind-driven, double-gyre, ocean circulation in a reduced-gravity, 2.5-layer, lattice boltzmann model

A coupled lattice Boltzmann （LB） model with second-order accuracy is applied to the reduced-gravity, shallow water, 2.5-layer model for wind-driven double-gyre ocean circulation. By introducing the secondorder integral approximation for the collision operator, the model becomes fully explicit. The Coriolis force and other external forces are included in the model with second-order accuracy, which is consistent with the discretization accuracy of the LB equation. The feature of the multiple equilibria solutions is found in the numerical experiments under different Reynolds numbers based on this LB scheme. With the Reynolds number increasing from 3000 to 4000, the solution of this model is destabilized from the anti-symmetric double-gyre solution to the subtropic gyre solution and then to the subpolar gyre solution. The transitions between these equilibria states are also found in some parameter ranges. The time-dependent variability of the circulation based on this LB simulation is also discussed for varying viscosity regimes. The flow of this model exhibits oscillations with different timescales varying from subannual to interannual. The corresponding statistical oscillation modes are obtained by spectral analysis. By analyzing the spatiotemporal structures of these modes, it is found that the subannual oscillation with a 9-month period originates from the barotropic Rossby basin mode, and the interarmual oscillations with periods ranging from 1.5 years to 4.6 years originate from the recirculation gyre modes, which include the barotropic and the baroclinic recirculation gyre modes.     

A fast response,open path,infrared hygrometer,using a semiconductor source

Investigations were carried out as to the feasibility of using a semiconductor source in the design of a new rapid response, open-path hygrometer. A single-beam instrument was constructed employing an infrared light emitting diode (LED) as a source instead of the usual high energy, wideband filament. The spectral emission envelope encompassed the 1.87 m water absorption band. Electronic modulation and thermoelectrical cooling of the diode eliminated the conventional chopper wheel and stabilized the peak wavelength emission. Path length was 200 mm. Over a water vapour concentration range of 0–16 g m^–3, absorption varied by 2% in a linear fashion. At 10 Hz, the noise level was 0.1 g m^–3 rms. Hygrometer resolution and stability are constrained by the detector noise level, the small source emission in the absorption band and low frequency drift in the optical filter. Despite these problems, the new instrument showed comparable performance characteristics to a commercial Lyman- hygrometer. Latent heat fluxes measured with both instruments and a Kaijo-Denki, 3-D sonic anemometer agreed to within 4% over a range 0–350 W m^–2. Further improvements in performance can be anticipated with advances in detector and LED technology.     

非绝热二维滞弹性流体的动力稳定性

采用滞弹性近似下的二维滞流体动力学方程组，讨论了中尺度对称扰动的动力稳定性，得到其绝热情况下对称不稳定的判据条件。研究结果表明，相对于浅对流的情况而言，深对流情况下对称不稳定的条件更为苛刻一些。在考虑非绝热加热时，扰动增长率随其波长的变化会产生间断现象，中低层加热明显对中－β尺度扰动具有激发增长的作用，并且促使扰动向暖区传播，而中高层加热则具有一定的差异性。     

Measurements in a turbulent patch in a rotating,linearly-stratified fluid

A series of experiments is described in which a turbulent patch is generated locally by an oscillating grid positioned at one end and mid-depth of a rotating channel filled initially with a linearly-stratified fluid. Measurements have been made of vertical density profiles through the patch both during sustained oscillations and following cessation of grid forcing. Temporal variations in patch size and structure, Thorpe scales, mixedness parameter and available potential energy are deduced from these measurements, and the effects thereon of varying the background rotation rate, initial buoyancy frequency and grid action are investigated. For the growth phase of the patch, previous results obtained by other workers are confirmed and extended. Because the rapid turbulent motions implied a large Rossby number, rotation was not important during this phase. During the decay phase, rotational effects are shown to become important, and the presence of rotation is found to retard the decay of both the mixedness and the Thorpe scales of the density overturns within the patch. The work is novel in that measurements of the patch parameters listed above have not previously been carried out in the presence of rotation. The results are relevant to studies of such patches that have been observed in the ocean and atmosphere.     

Results from a high-power, high-frequency sodar

A multifrequency bistatic Doppler sodar has been used to document the mixing effect associated with thermal plumes. The convergence effect has been studied. It has been shown values of convergence associated with plumes near .001 s⁻¹ .