MORPHOLOGY, SEDIMENTARY BEDFORMS AND SAND TRANSPORT ACROSS A RIDGE-AND-RUNNEL BEACH UNDER THE ACTION OF SUMMER WAVES

As part of a collaborative study between the 3rd Institute of Oceanography, Xiamen, and the U-K. Universities of East Anglia and St. Andrews, a 4-day experiment was conducted on a ridge- and -runnel beach of north Norfolk on the North Sea coast- Detailed surveys were made of every low water of an area 10m by 30m and electromagnetic current meters were used to measure wave- induced currents over the ridge and in the runnel- The locations of bedform fields were noted, fluorescent sand was used to follow the sand movement and, at the end of the experiment, lacquer peels were taken of the top 0-2 m of a vertical section through the ridge- and- runnel-During the 4 days 0-75 m3 of sand per metre width of beach accreted in the runnel and a similar volume was eroded from the upper foreshore. The dominant shoreward transport, identified qualitatively by the movement of the fluorescent sand, suggests the ridge- and- runnel system migrated shorewards up the general beach slope of 1 by 2 - 3 m. The wave orbital cur     

青藏高原夏季风和北半球夏季季节内振荡对中国西南地区雨季旱涝的影响及协同作用

中国西南地区旱涝变化受多种天气系统影响,青藏高原夏季风(Qinghai-Tibetan Plateau summer monsoon,QTPSM)和北半球夏季季节内振荡(boreal summer intraseasonal oscillation,BSISO)等次季节系统的强弱都会导致中国西南地区雨季旱涝变化,但目前这2个系统的协同作用机制尚缺乏系统性研究。因此,本文利用1981—2020年美国国家海洋与大气管理局气候预报中心日降水量和美国国家环境预报中心日再分析资料等,采用青藏高原季风指数(QTPM index,QTPMI)和BSISO指数,分析QTPSM和BSISO对中国西南地区雨季旱涝的影响及协同作用机制。结果表明:(1)QTPSM的强度与中国西南地区雨季降水量呈反相关,活跃阶段的QTPSM(active QTPSM,AQ)抑制西南地区降水,抑制阶段的QTPSM(inactive QTPSM,IAQ)促进西南地区降水。(2)在BSISO第一模态的5、6相位和第二模态的3、4相位期间,中国西南地区雨季极端降水发生概率增大;而在BSISO第一模态的2、3相位和第二模态的6、7相位期间,中国西南地区雨季极端降水发生概率减小。(3)在协同作用中,BSISO第二模态的6、7相位和QTPSM组合对中国西南地区雨季旱涝影响最大,降水正距平分布范围最广;当BSISO相位与AQ组合转为与IAQ组合时,中国西南地区雨季降水正距平大值区由北部转为南部。(4)在AQ组合相位中,中国西南地区雨季对流层中层盛行东南风,低层东西两侧均为“一高一低”的环流配置,促使印度洋、西太平洋水汽输送至西南地区北部,形成水汽辐合区;在IAQ组合相位中,中国西南地区雨季对流层中层盛行偏北风,低层受强气旋环流控制,促使印度洋水汽持续输送至西南地区南部,形成水汽辐合带。     

FGOALS-g3模拟的南亚夏季风:气候态和年际变率

南亚夏季风的变化决定着印度半岛的旱涝状况,气候系统模式则是研究南亚夏季风变化规律的重要工具。本文基于观测和JRA55再分析资料,系统评估了FGOALS-g3模式模拟的南亚夏季风气候态和年际变率,并重点关注FGOALS-g3与FGOALS-g2以及是否考虑海气相互作用的模拟差异。结果表明,由于局地海温模拟的变化,相比于FGOALS-g2,FGOALS-g3模拟的南亚夏季风在气候态热带印度洋信风和El Ni?o期间沃克环流下沉支上有明显改进。同时,由于对流层系统性冷偏差持续存在并且中心位于副热带300 hPa附近,造成气候态上经向温度梯度减弱,使季风环流减弱,导致FGOALS-g3中陆地季风槽的水汽辐散偏差和降水干偏差仍然存在;在年际变率上,FGOALS-g3模拟的El Ni?o期间赤道西太平洋海温冷异常偏弱,印度洋偶极子偏强,导致印度半岛下沉运动减弱,FGOALS-g3中ENSO—印度降水负相关关系也依然偏弱。研究表明,耦合过程导致的气候态海温偏差通过改变环流和水汽输送,有效补偿了大气模式中印度半岛中部和中南半岛的降水湿偏差;在年际变率上,耦合模式由于考虑了海温—降水—云短波辐射的负反馈过程,能够减小大气模式模拟偏差的强度,但印太暖池区海温模拟偏差导致沃克环流下沉支偏西,使得印度半岛的降水响应出现更大的湿偏差。     

A COUPLED INTERANNUAL OSCILLATION SYSTEM

ＩＮＴＲＯＤＵＣＴＩＯＮＥｌＮｉ ｎｏ ＳｏｕｔｈｅｒｎＯｓｃｉｌｌａｔｉｏｎ (ＥＮＳＯ)ｉｓｔｈｅｉｎｔｅｒａｎｎｕａｌｉｎｔｅｒａｃｔｉｏｎｏｆｏｃｅａｎ ａｔｍｏｓｐｈｅｒｅｉｎｔｈｅｔｒｏｐｉｃａｌ(ｅｓｐｅｃｉａｌｌｙｅｑｕａｔｏｒｉａｌ)Ｐａｃｉｆｉｃ .Ｉｔｉｓａｌｓｏｒｅｃｏｇｎｉｚｅｄａｓｂｅｉｎｇｔｈｅｄｏｍｉｎａｎｔｍｅｃｈａｎｉｓｍｏｆｔｈｅｅａｒｔｈ’ｓｉｎｔｅｒａｎｎｕａｌｃｌｉｍａｔｅｃｈａｎｇｅ.Ｓｅｖｅｒａｌｃｏｎｃｅｐｔｕａｌ (ｓｉｍｐｌｅ)ｍｏｄｅｌｓｗｅｒｅｐｒｏｐ…     

The Flexible Global Ocean-Atmosphere-Land system model, Spectral Version 2: FGOALS-s2

The Flexible Global Ocean-Atmosphere-Land System model, Spectral Version 2 (FGOALS-s2) was used to simulate realistic climates and to study anthropogenic influences on climate change. Specifically, the FGOALS-s2 was integrated with Coupled Model Intercomparison Project Phase 5 (CMIP5) to conduct coordinated experiments that will provide valuable scientific information to climate research communities. The performances of FGOALS-s2 were assessed in simulating major climate phenomena, and documented both the strengths and weaknesses of the model. The results indicate that FGOALS-s2 successfully overcomes climate drift, and realistically models global and regional climate characteristics, including SST, precipitation, and atmospheric circulation. In particular, the model accurately captures annual and semi-annual SST cycles in the equatorial Pacific Ocean, and the main characteristic features of the Asian summer monsoon, which include a low-level southwestern jet and five monsoon rainfall centers. The simulated climate variability was further examined in terms of teleconnections, leading modes of global SST (namely, ENSO), Pacific Decadal Oscillations (PDO), and changes in 19th–20th century climate. The analysis demonstrates that FGOALS-s2 realistically simulates extra-tropical teleconnection patterns of large-scale climate, and irregular ENSO periods. The model gives fairly reasonable reconstructions of spatial patterns of PDO and global monsoon changes in the 20th century. However, because the indirect effects of aerosols are not included in the model, the simulated global temperature change during the period 1850–2005 is greater than the observed warming, by 0.6°C. Some other shortcomings of the model are also noted.     

Preliminary evaluations of FGOALS-g2 for decadal predictions

The Flexible Global Ocean-Atmosphere-Land System model, Grid-point Version 2 (FGOALS-g2) for decadal predictions, is evaluated preliminarily, based on sets of ensemble 10-year hindcasts that it has produced. The results show that the hindcasts were more accurate in decadal variability of SST and surface air temperature (SAT), particularly in that of Nin o3.4 SST and China regional SAT, than the second sample of the historical runs for 20th-century climate (the control) by the same model. Both the control and the hindcasts represented the global warming well using the same external forcings, but the control overestimated the warming. The hindcasts produced the warming closer to the observations. Performance of FGOALS-g2 in hindcasts benefits from more realistic initial conditions provided by the initialization run and a smaller model bias resulting from the use of a dynamic bias correction scheme newly developed in this study. The initialization consists of a 61-year nudging-based assimilation cycle, which follows on the control run on 01 January 1945 with the incorporation of observation data of upper-ocean temperature and salinity at each integration step in the ocean component model, the LASG IAP Climate System Ocean Model, Version 2 (LICOM2). The dynamic bias correction is implemented at each step of LICOM2 during the hindcasts to reduce the systematic biases existing in upper-ocean temperature and salinity by incorporating multi-year monthly mean increments produced in the assimilation cycle. The effectiveness of the assimilation cycle and the role of the correction scheme were assessed prior to the hindcasts.     

上地幔高导层与内生金属矿产及油气藏的关系

依据大地电磁测深所发现的上地幔高导层顶面深度可以给出大陆岩石圈-软流圈界面(LAB)的空间发育特征,为认识岩石圈结构及壳幔相互作用等提供重要信息.本文在1996年编制的中国大陆上地幔高导层顶面深度图的基础上,补充了1995—2010年大地电磁测深结果和大地热流数据,以1°×1°网度编制了新的中国大陆上地幔高导层顶面深度图.我国上地幔高导层顶面深度变化很大,具有南北分带,东西分块的特征,呈东浅、西深、北浅、南深的格局,从最浅的50~60km到最深的230km,平均深度为100~120km.据上地幔高导层顶面分布形态,全国共可划分出27个隆起区.通过与中国已知内生金属矿产和油气田的分布对比,发现我国大陆80%以上中生代内生金属矿床分布在上地幔高导层隆起带或其梯度带上方.中国大陆东部含油气盆地主体对应上地幔隆起区,油气田多位于隆起区上方或其边部的过渡带上;西部主体位于幔坳区,主要油气田对应盆地中心的幔坳向周边幔隆过渡的梯度带上;中部表现为仅盆地腹地对应幔坳,盆地周边对应规模较大的上地幔隆起带,主要油气田位于隆起带.总的来看内生金属矿床一般分布在上地幔隆起区靠近造山带一侧,而油气田一般分布在上地幔隆起区靠近盆地一侧.软流圈的不断上隆,造成岩石圈减薄、拉张,张性断裂的出现成为地球深部物质和热量向地壳上部运移的有利通道,为内生金属矿产的形成提供了成矿物质和能量保障,也为含油气盆地带来了生烃催化剂、热能和无机成因的石油与天然气.地球深部超临界流体的存在对上地幔高导层的形成、成矿物质运移可能发挥了重要作用.     

Simulations of the East Asian subtropical westerly jet by LASG/IAP AGCMs

Performances of two LASG/IAP(State Key Laboratory of Numerical Modeling for Atmospheric Sci- ences and Geophysical Fluid Dynamics/Institute of Atmospheric Physics)Atmospheric General Circulation Models(AGCMs),namely GAMIL and SAMIL,in simulating the major characteristics of the East Asian subtropical westerly jet(EASWJ)in the upper troposphere are examined in this paper.The mean vertical and horizontal structures and the correspondence of the EASWJ location to the meridional temperature gradient in the upper troposphere are well simulated by two models.However,both models underestimate the EASWJ intensity in winter and summer,and are unable to simulate the bimodal distribution of the ma- jor EASWJ centers in mid-summer,relative to the observation,especially for the SAMIL model.The biases in the simulated EASWJ intensity are found to be associated with the biases of the meridional temperature gradients in the troposphere,and furthermore with the surface sensible heat flux and condensation latent heating.The models capture the major characteristics of the seasonal evolution of the diabatic heating rate averaged between 30°-45°N,and its association with the westerly jet.However,the simulated maximum diabatic heating rate in summer is located westward in comparison with the observed position,with a rela- tively strong diabatic heating intensity,especially in GAMIL.The biases in simulating the diabatic heating fields lead to the biases in simulating the temperature distribution in the upper troposphere,which may further affect the EASWJ simulations.Therefore,it is necessary to improve the simulation of the meridional temperature gradient as well as the diabatic heating field in the troposphere for the improvement of the EASWJ simulation by GAMIL and SAMIL models.     

气候变化的归因与预估模拟研究

本文总结了近五年来中国科学院大气物理研究所在气候变暖的归因模拟与预估研究上的主要进展。研究表明,利用海温、太阳辐射和温室气体等实际强迫因子驱动大气环流模式,能够较为合理地模拟全球平均地表气温在20世纪的演变,但是难以模拟出包括北大西洋涛动／北极涛动和南极涛动在内的高纬度环流的长期变化趋势。利用温室气体和硫酸盐气溶胶等“历史资料”驱动气候系统模式,能够较好地模拟出20世纪后期的全球增暖,但如果要再现20世纪前期(1940年代)的变暖,还需同时考虑太阳辐射等自然外强迫因子。20世纪中国气温演变的耦合模式模拟技巧,较之全球平均情况要低;中国气候在1920年代的变暖机理目前尚不清楚。对于近50年中国东部地区“南冷北暖”、“南涝北旱”的气候变化,基于大气环流模式特别是区域气候模式的数值试验表明,夏季硫酸盐气溶胶的负辐射效应超过了温室气体的增暖效应,从而对变冷产生贡献。但现有的数值模拟证据,不足以说明气溶胶增加对“南涝北旱”型降水异常有贡献。20世纪中期以来,青藏高原主体存在明显增温趋势,温室气体浓度的增加对这种增暖有显著贡献。多模式集合预估的未来气候变化表明,21世纪全球平均温度将继续增暖,增温幅度因不同排放情景而异;中国大陆年均表面气温的增暖与全球同步,但增幅在东北、西部和华中地区较大,冬季升温幅度高于夏季、日最低温度升幅要强于日最高温度;全球增暖有可能对我国中东部植被的地理分布产生影响。伴随温室气体增加所导致的夏季平均温度升高,极端温度事件增多;在更暖的气候背景下,中国大部分地区总降水将增多,极端降水强度加大且更频繁发生,极端降水占总降水的比例也将增大。全球增暖有可能令大洋热盐环流减弱,但是减弱的幅度因模式而异。全球增暖可能不是导致北太平洋副热带－热带经圈环流自20世纪70年代以来变弱的原因。文章同时指出了模式预估结果中存在的不确定性。     

基于大型无人机的气象探测系统设计应用

利用高空高速大型无人机自身优势,设计一种基于大型无人机的新型气象探测系统,旨在丰富气象探测技术手段,提高气象探测的准确性。为了实现高空远距气象探测功能,对系统的组成、接口、控制逻辑等进行逐一设计优化,并创新地采用螺旋运转结构,大幅增加气象任务载荷数量,使单个吊舱可装载24枚探空仪。作为一项军民融合的典型应用,本气象探测系统的工程化产品已通过功能试验、力学试验、环境试验等各项试验测试,结果表明系统运行安全有效,满足执行气象探测任务的要求。本气象探测系统的接口设计均遵循通用化、标准化原则,易于推广到现有其他无人机平台,具有广阔的应用前景。