Identification of CO2 disposal locations in an ocean general circulation model of the North Pacific

A basinwide ocean general circulation model of the North Pacific is used to identify which location is more efficient for ocean CO2 sequestration in the North Pacific. Four injection depths at each one of fifteen locations are chosen. In terms of effectiveness index (EI) and escape factor (EF), it is clear that the effectiveness increases with increasing latitude at the end of the 50 a injection period. Sitebysite differences in the EI can be over 9% for the 1 000 m injection depth in the western North Pacific at the end of 50 a of continuous injection. The difference is much larger for the 500 m injection. The difference decreases with increasing injection depth. However, the sitebysite difference is small for the injection in the eastern North Pacific. The sequestration is more efficient for the injection in the east than in the west. For the 500 m injection depth, the difference in effectiveness between the west and the east is over 10% at the end of 50 a injection period. The largest concentration of sequestered CO2 increases with increasing injection depth. For the injection in both the western and central North Pacific, the largest exchange flux always appears to be at about 42°N, 150°E, whereas for the injection in the eastern area the large flux appears to be in the equatorial region (120°W).     

A Lagrangian mean theory on coastal sea circulation with inter-tidal transports Ⅱ. Numerical Experiments

The results of the new concept of coastal sea circulation are demonstrated by numerical simulations for the first time. The numerical experiments in three types of rectangular model seas illustrate the dependence of circulation on tidal phases due to the convectively nonlinear effect which is estimated by a newly defined drift dispersion in-dex. Then, the present theory is applied in the Bohai Sea of China. At the Bohai Straits and the Huanghe River mouth area the circulation direction even reverses owing to different initial tidal phases which shows that the the-ory copes with nonlinearity well. The calculated M2 tide-induced residual circulation shows that a clockwise gyre exists in the center of an anticlockwise gyre in the central Bohai Sea due to the topographic features. In the Bo-hai Gulf the tide induced circulation shows a 3D structure with outflow at the surface and the inflow at the bottom which can partly explains the spread of the Huanghe River fresh water out of the Bohai Gulf and the inflow of the sediment from the Huanghe River.     

北赤道流分叉点及南海北部环流的研究进展

介绍了北赤道流分叉点、南海北部环流的一些研究成果,并就黑潮对南海的影响所作的研究进行了回顾.北赤道流分叉点的位置对于北赤道流系水体疏运变化及在黑潮和MC之间水体、热量、盐度输运的分配中起着重要的作用.北赤道流分叉点位置约在14.6°N上,分叉点位置随深度增加而北移.分叉点有明显的季节变化和年际变化,在春、夏季向南移动,而在秋、冬季则向北移动.年际变化与ENSO现象相关紧密,在El Nio事件NEC分叉纬度处于最北端,在La Nio事件处于最南端.对于分叉点位置的定量化研究,仍然需要更多的观测结果进行研究.季风和黑潮是影响南海北部环流的两种主要因素.南海北部上层流场主要由广东沿岸流、黑潮入侵流套、东沙海流、南海暖流和吕宋海流组成.除海盆、次海盆尺度环流外,受季风、黑潮和地形等因素的影响,南海表现出多涡结构.通过近些年的卫星观测和数值模拟的结果,人们对南海中尺度涡的认识大大加深,但要想模拟出风应力形成涡的机制,还需要提高风场和模式的分辨率.由于观测资料的限制,对南海流场的垂直结构、以及春-秋季季风转相时期的流场结构等还研究得较少.吕宋海峡水交换是西太平洋对南海影响的主要途径.黑潮在吕宋海峡附近的形变一直是有争议的热点问题,目前对于黑潮入侵有3种观点:(1) 认为黑潮经过吕宋海峡形成流套结构,并分离出中尺度涡影响南海流场、水团结构;(2) 认为黑潮有一直接分支分离出来进入南海形成黑潮分支;(3) 认为吕宋海峡水交换不属于以上两种情况,西太平洋对南海的水团输送另有机制.北赤道流分叉点在对黑潮的水体、热量、盐度输运的分配中起着重要的作用,黑潮对南海北部环流的影响可能与NEC的分叉点位置有关,但目前对NEC的分叉点位置与南海北部环流相关性的研究甚少.最后提出了对未来加强该方面研究的一些展望.     

100hPa环流变化与川渝地区旱涝异常分析

应用ＳＶＤ技术,诊断分析了北半球１００ｈＰａ高度场与川渝地区夏季降水的关系。结果表明：高度场与降水场具有密切的时空相关性,第一模态反映了两场间的主要耦合特征;南亚高压活动地区前期１０～１２月、１～４月高度场变化,通过影响未来夏季南亚高压强度、位置,导致川渝地区夏季旱涝异常。高度场与降水场的这种非同步联系,物理意义明确,时空相关显著,是一种有价值的预测川渝地区夏季旱涝异常的强信号。     

2022年7月大气环流和天气分析

2022年7月大气环流主要特征为北半球极涡呈单极型且较常年同期略偏强,中高纬环流呈4波型分布,西太平洋副热带高压较常年同期偏北偏西。7月,全国平均降水量为96.6 mm,较常年同期偏少21%,为1961年以来历史同期第二少;全国平均气温为23.2℃,较常年同期偏高1.0℃,为1961年以来历史同期第二高。月内有6次区域性暴雨天气过程,1—7日强降水过程由于受到台风登陆及减弱后的低压环流与西风带系统相互作用,影响我国中东部大部分地区,5次强降水集中在西北地区东部、华北、黄淮、东北地区。月内共有3个台风生成,较常年同期偏少;经历2次高温天气过程,表现出极端性显著、影响范围广和持续时间长的特点,四川盆地、江南、西北地区东部、新疆的部分地区出现40℃以上高温天气,多站日最高气温突破历史同期极值。     

大西洋经向翻转环流对岁差响应的气候背景依赖性

大西洋经向翻转环流（Atlantic Meridional Overturning Circulation,AMOC）是气候系统重要的组成部分,其强度变化可直接影响南北半球的热量分配,厘清其变化机理对全球变暖背景下的未来预估至关重要。海洋沉积物记录发现,在晚更新世,AMOC的变化与地球岁差周期有紧密联系,但其物理机理尚不清楚。本文利用海洋-大气耦合气候模型—COSMOS(ECHAM5/JSBACH/MPIOM)模型,通过敏感试验,分析在冰盛期冷期和间冰期暖期气候背景下,AMOC对地球岁差变化的响应机理。结果表明：岁差降低引起的北半球夏季太阳辐射增强,会导致间冰期暖期背景下的AMOC显著减弱,但对冰盛期AMOC的影响并不明显。通过进一步分析发现,在间冰期暖期,夏季太阳辐射增强,造成高低纬大西洋海表的升温,同时促进北大西洋高纬度地区的局地降水,两者导致北大西洋表层海水密度降低,共同削弱大西洋深层水生成。而在冰盛期冷期,大西洋高低纬度地区的响应对AMOC的影响反向—副热带升温触发的海盆尺度低压异常,通过其南侧的西风异常削弱大西洋向太平洋的水汽输送,导致净降水增多,海表盐度下降;同时,高纬度升...     

A note on the role of meridional wind stress anomalies and heat flux in ENSO simulations

Four comparative experiments and some supplementary experiments were conducted to examine the role of meridional wind stress anomalies and heat flux variability in ENSO simulations by using a high-resolution Ocean General Circulation Model （OGCM）. The results indicate that changes in the direction and magnitude of meridional wind stress anomalies have little influence on ENSO simulations until meridional wind stress anomalies are unrealistically enlarged by a factor of 5.0. However, evidence of an impact on ENSO simulations due to heat flux variability was found. The simulated Nino-3 index without the effect of heat flux anomalies tended to be around 1.0° lower than the observed, as well as the control run, during the peak months of ENSO events.     

Interdecadal Variability of the East Asian Summer Monsoon and Associated Atmospheric Circulations

Based on the National Centers for Environmental Prediction and National Center for Atmospheric Research （NCEP/NCAR） reanalysis data from 1950-1999, interdecadal variability of the East Asian Summer Monsoon （EASM） and its associated atmospheric circulations are investigated. The EASM exhibits a distinct interdecadal variation, with stronger （weaker） summer monsoon maintained from 1950-1964 （1976-1997）. In the former case, there is an enhanced Walker cell in the eastern Pacific and an anti-Walker cell in the western Pacific. The associated ascending motion resides in the central Pacific, which flows eastward and westward in the upper troposphere, descending in the eastern and western ends of the Pacific basin. At the same time, an anomalous East Asian Hadley Cell （EAHC） is found to connect the low-latitude and mid-latitude systems in East Asia, which strengthens the EASM. The descending branch of the EAHC lies in the west part of the anti-Walker cell, flowing northward in the lower troposphere and then ascending at the south of Lake Baikal （40°-50°N, 95°- 115°E） before returning to low latitudes in the upper troposphere, thus strengthening the EASM. The relationship between the EASM and SST in the eastern tropical Pacific is also discussed. A possible mechanism is proposed to link interdecadal variation of the EASM with the eastern tropical Pacific SST. A warmer sea surface temperature anomaly （SSTA） therein induces anomalous ascending motion in the eastern Pacific, resulting in a weaker Walker cell, and at the same time inducing an anomalous Walker cell in the western Pacific and an enhanced EAHC, leading to a weaker EASM. Furthermore, the interdecadal variation of summer precipitation over North China is found to be the south of Lake Baikal through enhancing and reducing strongly regulated by the velocity potential over the regional vertical motions.     

南极涛动异常及其对冬春季北半球大气环流影响的数值模拟试验

利用IAP9L-AGCM模式考察了模式中与南极涛动异常相关的海温敏感区,发现南半球高纬海温异常能够强迫出南极涛动异常,而赤道东太平洋海温异常与太平洋南美型密切相关.研究了南极涛动异常对冬春季北半球大气环流及亚洲北部气温的影响,结果表明,南极涛动加强,能够引起北半球高纬环流异常和欧亚西风加强,以及亚洲北部地表气温和850 hPa气温显著增温.数值模拟支持了已有的诊断结果,也证实了冬春季节南极涛动异常下两半球高纬间的经向遥相关存在.