干旱区陆面过程和大气边界层研究进展

干旱区陆面过程和大气边界层不仅与气候、生态、水资源密切相关,而且影响我国气候格局和东亚大气环流,是一个十分重要的研究领域,近20多年已取得了比较系统的研究进展.从干旱区陆面热力和水分过程特征、干旱区大气边界层结构特征、干旱区陆面过程参数及其参数化公式、非均匀下垫面大气边界层理论、干旱城市大气边界层特征与污染机理等方面归纳总结了干旱区陆面过程和大气边界层领域取得的部分研究进展.并且,认为科学试验的代表性、复杂下垫面的影响、尺度转化、地表能量不平衡、极端天气过程的相互作用、水分过程的复杂性等问题是干旱区陆面过程和大气边界层研究领域的突出问题和未来研究重点.     

Research Progress on Physical Parameterization Schemes in Numerical Weather Prediction Models

Atmospheric physics in numerical weather prediction model which predominantly determines the evolution of atmospheric processes is mainly described by physical parameterization. As a result, the development of physical parameterization has been a hot research issue in the area of numerical prediction for a long time. In this regard, the theoretical background and history of physical parameterization schemes for convection, microphysics, and planetary boundary layer, were reviewed in this study. It is suggested that the advance of physical parameterization for the model with high-resolution grid spaces should be considered as a principle issue for numerical model development in the future. Although the gird spaces in current operational numerical models generally decrease toward 10 km owing to the rapid development of high-performance computation, yet most of these schemes are designed for coarse grid spaces. Because of this kind of deficiency, the theoretical basis of these schemes inevitably faces controversy. Directions for development of physical parameterization were also suggested according to the trends of research in numerical prediction.     

A Study on the Impact of Parameterization of Physical Processes on Prediction of Tropical Cyclones over the Bay of Bengal With NCAR/PSU Mesoscale Model

Prediction of the track and intensity of tropical cyclones is one of the most challenging problems in numerical weather prediction (NWP). The chief objective of this study is to investigate the performance of different cumulus convection and planetary boundary layer (PBL) parameterization schemes in the simulation of tropical cyclones over the Bay of Bengal. For this purpose, two severe cyclonic storms are simulated with two PBL and four convection schemes using non-hydrostatic version of MM5 modeling system. Several important model simulated fields including sea level pressure, horizontal wind and precipitation are compared with the corresponding verification analysis/observation. The track of the cyclones in the simulation and analysis are compared with the best-fit track provided by India Meteorological Department (IMD). The Hong-Pan PBL scheme (as implemented in NCAR Medium Range Forecast (MRF) model) in combination with Grell (or Betts-Miller) cumulus convection scheme is found to perform better than the other combinations of schemes used in this study. Though it is expected that radiative processes may not have pronounced effect in short-range forecasts, an attempt is made to calibrate the model with respect to the two radiation parameterization schemes used in the study. And the results indicate that radiation parameterization has noticeable impact on the simulation of tropical cyclones.     

陆面水文过程研究综述

在简单介绍陆面过程模式发展的基础上，从裸土蒸发、植被蒸散、土壤水传输、排水和径流等五个方面详细综述了陆面模式研究中对水文过程的参数化。目前陆面参数化方案中仍存在很大的不确定性，其中陆面水文过程参数化的关键问题包括：土壤分层、土层厚度、根带分布；参数的代表性和移植；观测资料；径流的参数化。分析了径流在陆面模式中的重要性，及目前陆面模式中对径流参数化存在的不足，介绍了部分陆面模式对径流的模拟研究，讨论了未来工作的研究重点。     

Variation of coastal atmospheric boundary layer characteristics with convective activity along the west coast of India during the Arabian Sea Monsoon Experiment (ARMEX) 2002

This paper investigates the characteristic features of the coastal atmospheric boundary layer (CABL) along the west coast of India during the south-west monsoon (SWM) 2002. Extensive surface and upper-air findings were obtained during the same period from the Arabian Sea Monsoon Experiment (ARMEX; 15th June to 15th August 2002) 2002. The operational general circulation model (GCM) of the National Centre for Medium Range Weather Forecasting (NCMRWF) was used in this study to see the spatial variation of the CABL during two specific convective episodes that led to heavy rainfall along the west coast of India. The impact of a non-local closure (NLC) scheme employed in the NCMRWF GCM was carried out in simulating the CABL. The same episodes were also simulated using a similar parameterization scheme employed in the high resolution mesoscale modelling system (MM5). The diurnal variation of CABL is better represented from MM5 simulation. Comparing the MM5 simulation with that of the coarser grid NCMRWF GCM, we observed that the NCMRWF GCM underestimates the values of both latent heat flux (LHF) and the coastal atmospheric boundary layer height (CABLH). Results from MM5 therefore indicate that the best way to move forward in addressing the short-comings of coarse grid-scale GCMs is to provide a parameterization of the diurnal effects associated with convection processes.     

Progress in Lightning Forecast by Using Numerical Weather Models and Model Outputs

Lightning can threaten human and equipment safety. An indicator of sever convective weather, it plays an important role in atmospheric chemistry. The intensive studies have advanced the lightning forecast in the mesoscale weather models and its application in global climate models. There are three methods to forecast lightning by using numerical weather models: Numerical diagnosis prediction based on synoptic background filed statistical relations; Flash rate parameterization developed with the relationship between dynamical, microphysical and electrification processes, and The numerical weather model coupled with the explicit electrification and lightning parameterization schemes. In this paper, the research progress in lightning forecast with three above-mentioned methods were reviewed, and the future research issues on lightning forecast were also discussed.     

非均匀下垫面边界层研究现状与展望

评述了非均匀下垫面大气边界层研究的现状和当前发展所面临的一些问题,就近年来非均匀下垫面边界层这一大气边界层研究中的难点和热点问题的由来,所使用的研究方法和手段的发展以及目前面临和亟待解决的问题做了系统的归纳,并对未来非均匀边界层研究发展的趋势和研究方法做了展望。     

Atmospheric boundary layer characteristics during the BOBMEX-Pilot experiment

The atmospheric boundary layer characteristics observed during the BOBMEX-Pilot experiment are reported. Surface meteorological data were acquired continuously through an automatic weather monitoring system and manually every three hours. High resolution radiosondes were launched to obtain the vertical thermal structure of the atmosphere. The study area was convectively active, the SSTs were high, surface air was warm and moist, and the surface air moist static energy was among the highest observed over the tropical oceans. The mean sea air temperature difference was about 1.25‡C and the sea skin temperature was cooler than bucket SST by 0.5‡C. The atmospheric mixed layer was shallow, fluctuated in response to synoptic conditions from 100 m to 900 m with a mean around 500 m.     

城市陆面过程与边界层结构研究

通过城市边界层观测、卫星遥感以及城市边界层数值模拟等途径,获取对城市陆面过程特性的认识,研究建立精细城市边界层模式,引入合理城市区陆面过程参数化方案,并进行城市边界层结构影响研究。研究结果表明：①城市下垫面能量平衡过程迥异于自然地表,引入合理的参数化方案是改善数值模拟性能的关键。②高分辨卫星观测信息是认识城市地表参数状况及其变化的有效途径。 ③人为热排放参数化方案的合理引入是准确描述地表能量平衡过程的又一重要课题。需根据实际情况确定人为热排放的引入方案及量值变化。④应从合理描述城市建筑物下垫面对热力输送及大气动力场的影响出发,研究建立了多层城市冠层模式。⑤应建立更完善的多尺度城市边界层模式系统并引入更新的城市效应参数化方案和数据同化处理,以增强并完善城市边界层数值模拟能力。     

陆面过程研究的现状与发展趋势

对目前陆面过程研究的现状及存在的问题进行了总结,并且提出了与边界层研究有关的几个前沿方向:①非均匀下垫面地表湍流通量的参数化及中尺度通量的参数化方法;②边界层理论在复杂地形条件下的应用,以及次网格地形对通量输送的影响;③进一步改进GCM中冠层地表水文参数化;④边界层的层云和层积云的参数化。     

陆面水文过程与大气模式的耦合及其在黑河流域的应用

陆面过程模式对陆面水文过程有比较详尽的描述,然而,目前的陆面水文过程只考虑了垂直方向的水分运移,比较适合平坦地区的模拟,而在地形坡度较大的山区只考虑垂直方向的水分移动是不够的,尤其是目前随着计算机条件提高,分辨率越来越高,地表水以及土壤水的侧向流动成为山区水文过程必须考虑的部分。同时,目前的陆面过程模式中的径流量是作为诊断量处理,不参与运算。针对以上问题,对Noah陆面过程模式进行了改进,增加了地表积水和积水蒸发、坡面汇流方案、次表面流方案,并且将Routing模块通过次网格过程与大气中尺度模式MM5耦合,发展了高分辨率大气—水文耦合模式。运用发展的高分辨率大气—水文耦合模式,对黑河流域中上游2003年6月23~25日降水过程进行了模拟,研究了陆面水循环过程对大气场的影响。结果表明陆面水循环过程对近地层大气影响很大,首先影响了土壤的湿度与蒸发,进而对边界层稳定性,云结构、云水、雨水含量产生影响,对区域降水也有一定影响。     

河套干旱地区夏季边界层结构特征观测分析

利用2013年夏季7月爱尔达K/LLX802J型机动式边界层风廓线雷达获取的三维风场资料和银川站高空气象探测资料,对河套干旱地区夏季边界层日变化特征进行了分析.结果表明:爱尔达K/LLX802J型机动式风廓线雷达能较好的反映并分辨出夏季河套干旱地区边界层内大气湍流和风场的演变过程.夏季7月河套干旱地区边界层高度白天平均为2127.2 m,夜间平均为1760.7 m,白天边界层高度比夜间平均高366.5 m.河套干旱区夏季地表非绝热加热对边界层的影响主要集中在800 m以下,800~2000 m高度边界层则主要受昼夜交替和大尺度天气系统的影响.夏季7月河套干旱地区边界层风速在300 m以下随高度增加而增大,离地500 m以下边界层易在北京时间07:00-11:00和18:00-21:00时段发生风速切变;300 m以下边界层白天盛行西南偏南风、夜间盛行南风,300~2000 m高度边界层白天和夜间均盛行东南风;离地300 m以下边界层易在夜间21:00-23:00时出现风向切变.夏季7月白天河套干旱地区边界层大气垂直速度在300 m高度以下随高度增加而增大,由0.3 m·s^-1增大到0.6 m·s^-1,夜间边界层大气垂直速度在200 m高度以下随高度增大而增大;300 m高度以上边界层大气垂直速度无论昼夜随高度变化均较小.     

内蒙古半干旱草原土壤植被大气相互作用(IMGRASS)综合研究

为深化对中纬半干旱草原气候生态相互作用过程、机制及其对全球变化的响应与贡献的认识 ,一项名为“内蒙古半干旱草原土壤植被大气相互作用 (IMGRASS)”的基金重大项目于 1997—2 0 0 1年在内蒙古锡林郭勒草原执行。IMGRASS计划在 1998年草原生长季节、在所选定的以典型草原为主 ,包括草甸草原、稀疏沙地草原等在内的中尺度试验区开展了多点、多要素的综合观测。观测内容包括土壤、植被、大气的相关要素和发生于地气界面的潜热、感热通量 ,还包括N2 O ,CH4 ,CO2 等微量气体交换量、辐射与降水分布。除 1998年中尺度观测试验外 ,在 1999— 2 0 0 1年在代表性地点进行了微量气体收支、遥感和沙尘天气相关的专项观测 ,结合草原站已进行的长期监测资料 ,分析气候生态长期相互作用 ,特别是人类活动干预的影响。在分析观测结果的基础上 ,对该地区的气候生态相互作用进行了数值模拟研究。文章作为介绍IMGRASS计划的第一部分 ,对该项研究计划作一全面简要介绍 ,包括科学目标、计划实施实验区背景、中尺度综合观测 ,并对实验所得大气边界层结构、辐射通量、沙地土壤水份状况、地表反射率谱与遥感测量等提供了个例分析 ,并简单介绍IMGRASS数据库。有关与全球变化有关的几个方面的初步研究结果将在本期刊中另文进行     

大气科学发展的回顾与展望

回顾了20世纪大气科学的发展历程和所取得的重要成就。就20世纪这100年中大气探测技术、大气环流与大尺度动力学、数值天气预报和大气环流数值试验、大气物理、中小尺度气象学、大气环境和大气化学、中层大气、气候系统动力学、气候预测和全球变化等方面所取得重要研究进展和学术成就作了系统的回顾；并对21世纪初大气科学研究发展的趋势作了展望。     

Sensitivity of tropical cyclone intensification to boundary layer and convective processes

This study examines the role of the parameterization of convection, planetary boundary layer (PBL) and explicit moisture processes on tropical cyclone intensification. A high-resolution mesoscale model, National Center for Atmospheric Research (NCAR) model MM5, with two interactive nested domains at resolutions 90 km and 30 km was used to simulate the Orissa Super cyclone, the most intense Indian cyclone of the past century. The initial fields and time-varying boundary variables and sea surface temperatures were taken from the National Centers for Environmental Prediction (NCEP) (FNL) one-degree data set. Three categories of sensitivity experiments were conducted to examine the various schemes of PBL, convection and explicit moisture processes. The results show that the PBL processes play crucial roles in determining the intensity of the cyclone and that the scheme of Mellor-Yamada (MY) produces the strongest cyclone. The combination of the parameterization schemes of MY for planetary boundary layer, Kain-Fritsch2 for convection and Mixed-Phase for explicit moisture produced the best simulation in terms of intensity and track. The simulated cyclone produced a minimum sea level pressure of 930 hPa and a maximum wind of 65 m s⁻¹ as well as all of the characteristics of a mature tropical cyclone with an eye and eye-wall along with a warm core structure. The model-simulated precipitation intensity and distribution were in good agreement with the observations. The ensemble mean of all 12 experiments produced reasonable intensity and the best track.     

Simulation Experiments of Land Surface Physical Processes and Ecological Effect over Different Underlying Surface

Based on the existing Land Surface Physical Process Models(Deardorff, Dickinson, LIU, Noilhan, Seller, ZHAO), a Comprehensive Land Surface Physical Process Model (CLSPPM) is developed by considering the different physical processes of the earth‘s surface-vegetation-atmosphere system more completely. Compared with SiB and BATS, which are famous for their detailed parameterizations of physical variables, this simplified model is more convenient and saves much more computation time. Though simple, the feas...     

Atmospheric mesoscale conditions during the Boothbay meteotsunami: a numerical sensitivity study using a high-resolution mesoscale model

The article aims to test the sensitivity of high-resolution mesoscale atmospheric model to fairly reproduce atmospheric processes that were present during the Boothbay Harbor meteotsunami on 28 October 2008. The simulations were performed by the Weather and Research Forecasting (WRF) model at 1-km horizontal grid spacing by varying initial conditions (ICs) and lateral boundary conditions (LBCs), nesting strategy, simulation lead time and microphysics and convective parameterizations. It seems that the simulations that used higher-resolution IC and LBC were more successful in reproduction of precipitation zone and surface pressure oscillations caused by internal gravity waves observed during the event. The results were very sensitive to the simulation lead time and to the choice of convective parameterization, while the choice of microphysics parameterization and the type of nesting strategy (one-way or two-way) was less important for reproducibility of the event. The success of the WRF model appears limited to very short-range forecasting, most advanced parameterizations, and very high-resolution grid spacing; therefore, the applicability of present atmospheric mesoscale models to future operational meteotsunami warning systems still has a lot of room for improvements.     

陆面过程与天气研究

陆面作为大气运动的下边界,通过动量、热量及物质交换与大气发生复杂的相互作用。陆面过程被认为是影响天气气候的关键过程之一。关于陆面过程对气候的影响已经开展了大量较为深入的研究,相比之下,针对陆面过程对天气的影响研究并没有受到足够的重视。近年来,陆面过程与天气研究也开始受到了越来越多的关注。本文从陆面基本要素、下垫面构成、陆面诱发的局地环流3个方面,回顾了土壤湿度、地形、土地利用、山谷-平原环流等要素和过程对强对流、暴雨、台风、高温热浪等天气事件影响研究的相关进展,以期为今后的研究提供参考。需要指出,尽管此方面的研究已取得了一定进展,但关于陆面过程对天气,尤其是极端(高影响)天气的影响及机制还有待深入研究,进而从陆面过程的角度来理解重要天气形成、发生和发展的机理,从而为数值模式发展和天气预报业务提供更有力的科学支撑。     

大气边界层物理学的研究进展和面临的科学问题

回顾了大气边界层物理学的发展历史，总结了该领域国际上目前所取得的主要研究进展，提出国内外在未来大气边界层物理学研究方面可能面临的一些主要科学问题，还对未来大气边界层物理学的发展方向提出若干建议，同时也指出了大气边界层物理学研究在思想和方法上应该注意的一些相关问题。     

冰川区不同气温估算方法评估 ——以藏东南帕隆4号冰川为例

冰川作为地表特殊的下垫面,冰川区内气温明显低于同高度非冰川区大气温度。如何利用低海拔非冰川区观测资料精确估算高海拔冰川区气温,直接关系着青藏高原冰川消融估算及其水文效应的评估。利用架设在藏东南帕隆藏布4号冰川不同高度带的四台自动气象站资料,分析了冰川区与非冰川区气温的波动特征,评估了迄今为止通用的线性递推模型（DT模型）、分段拟合模型（SM模型）和简化热力学模型（GB模型）三种方法在藏东南冰川区气温估算方面的应用效果。对比研究发现：SM模型在帕隆4号冰川上的模拟效果最为理想且操作相对简单;传统DT模型在消融区存在严重的高估,帕隆4号冰川表面夏季（6-8月）正积温的高估比例接近39%;GB模型由于受到诸如冰川风边界层厚度等不确定性的影响,降低了大范围温度估算的可操作性。