Monitoring absolute vertical land motions and absolute sea-level changes from GPS and tide gauges data over French Polynesia

In this study,we estimate the absolute vertical land motions at three tidal stations with collocated Global Navigation Satellite System(GNSS)receivers over French Polynesia during the period 2007-2020,and obtain,as ancillary results,estimates of the absolute changes in sea level at the same locations.To verify our processing approach to determining vertical motion,we first modeled vertical motion at the International GNSS Service(IGS)THTI station located in the capital island of Tahiti and compared our estimate with previous independent determinations,with a good agreement.We obtained the following estimates for the vertical land motions at the tide gauges:Tubuai island,Austral Archipelago-0.92±0.17 mm/yr,Vairao village,Tahiti Iti:-0.49±0.39 mm/yr,Rikitea,Gambier Archipelago-0.43±0.17 mm/yr.The absolute variations of the sea level are:Tubuai island,Austral Archipelago 5.25±0.60 mm/yr,Vairao village,Tahiti Iti:3.62±0.52 mm/yr,Rikitea,Gambier Archipelago 1.52±0.23 mm/yr.We discuss these absolute values in light of the values obtained from altimetric measurements and other means in French Polynesia.

Influence of Irregular Coastlines on a Tornadic Mesovortex in the Pearl River Delta during the Monsoon Season. Part Ⅰ:Pre-storm Environment and Storm Evolution

The Pearl River Delta(PRD),a tornado hotspot,forms a distinct trumpet-shaped coastline that concaves toward the South China Sea.During the summer monsoon season,low-level southwesterlies over the PRD’s sea surface tend to be turned toward the west coast,constituting a convergent wind field along with the landward-side southwesterlies,which influences regional convective weather.This two-part study explores the roles of this unique land–sea contrast of the trumpet-shaped coastline in the formation of a tornadic mesovortex within monsoonal flows in this region.Part I primarily presents observational analyses of pre-storm environments and storm evolutions.The rotating storm developed in a lowshear environment(not ideal for a supercell)under the interactions of three air masses under the influence of the land–sea contrast,monsoon,and storm cold outflows.This intersection zone(or“triple point”)is typically characterized by local enhancements of ambient vertical vorticity and convergence.Based on a rapid-scan X-band phased-array radar,finger-like echoes were recognized shortly after the gust front intruded on the triple point.Developed over the triple point,they rapidly wrapped up with a well-defined low-level mesovortex.It is thus presumed that the triple point may have played roles in the mesovortex genesis,which will be demonstrated in Part II with multiple sensitivity numerical simulations.The findings also suggest that when storms pass over the boundary intersection zone in the PRD,the expected possibility of a rotating storm occurring is relatively high,even in a low-shear environment.Improved knowledge of such environments provides additional guidance to assess the regional tornado risk.

Prediction of the joint impacts of sea level rise and land development on distribution patterns of mangrove communities

Mangrove distribution along shorelines shows distinct zonation patterns;thus,different communities may face various influences from sea level rise(SLR)and land use.However,long-term change predictions are usually based only on the total extent of mangroves.Few studies have revealed how SLR and land development such as agriculture,aquaculture,and urbanization jointly affect different intertidal mangrove communities.This study proposed a novel framework combining SLAMM(Sea Level Affecting Marshes Model)and the CLUE-S(Conversion of Land Use and its Effect at Small regional extent)model to assess the potential impacts on upper and lower intertidal mangrove communities.Maoweihai in Guangxi,China,was selected as the study area and the potential impacts from the squeeze effect and mangrove expansion potential were evaluated.We established three scenarios combining SLR and land use patterns to predict mangrove coverage projections by 2070.The results showed that,under a single SLR driver,the upper intertidal mangroves would be more adaptive to rapid SLR than the lower intertidal mangroves.However,under the combined influence of the two drivers,the upper intertidal mangroves would experience larger squeeze effects than the lower intertidal mangroves,with up to 80.5%of suitable habitat lost.Moreover,the expansion potential of upper intertidal mangroves would be considerably more limited than that of lower intertidal mangroves.The length of the expandable habitat patch boundary of upper intertidal mangroves only reached 1.4–1.8 km,while that of the lower intertidal mangroves reached up to99.2–111.2 km.Further,we found that aquaculture ponds and cropland are the top two land development types that could occupy suitable habitat and restrict the mangrove expansion potential.Our results highlight that timely improvement of land use policies to create available landward accommodation space for mangrove migration is essential to maintain the coverage and diversity of mangrove communities under SLR.The proposed method can be a helpful tool for adaptive mangrove conservation and management under climate change.

A Case Modeling of Sea-Land Breeze in Macao and Its Neighborhood

PSU / NCAR MM5 was utilized to simulate the sea-land breeze circulation in Macao and the three-dimensional flow around the Pearl River estuary. Four two-way nested grids having resolution of 1, 3, 9, and 27 km were included in the simulation. It was initialized with conventional observational data, and a 30 h simulation and analysis of one sea-land breeze case were performed. It was shown, that the model with a finer resolution (1 km) captures the sea breeze and land breeze in Macao with reasonable skill. The sea breeze front and the thermal internal boundary layer (TIBL) were also obviously revealed. However, the coarser horizontal resolution (3 km) could capture the sea breeze but not the land breeze.

The Mesozoic Basin-Mountain Coupling Process of the Southern East China Sea Shelf Basin and its Adjacent Land Area

Basin-mountain coupling is a key issue for basin formation and evolution. The analysis of basin-mountain coupling process, as well as quantitative or semiquantitative restoration of prototype basin and the evolution of continental margin, can be used to interpret the geological process of basin-range conversion and reconstruct early prototype basins, which is a difficult and leadin~ scientific oroblem of basin research.

The sea/land breeze in the northern coastal area of Shandong Peninsula

In this paper the seasonal variation and structural characteristics of the sea/ land breeze in the northern coastal area of' Shandong Peninsula are studied in two ways: one is the analysis of the observed wind data, and the other is numerical simulation and experiments. Firstly, the hour to hour wind data through the year 1984 at Longkou Meteorological Station and Yantai Oceanographic Station are analysed through energy spectra and hodograph. It is revealed from the analysed results that the effects of the sea/ land breeze in the area are notable in spring, summer and fall, especially in May. However, in winter the effects of sea / land breeze are not obvious. because the cold noitherly is prevailing. Secondly, a two-dimensional non- linear model of primitive equations is used to study the sea / land breeze circulation in May in the area. The results of numerical simulation consist basically with the analysed results of the observed sea / land breeze. A reasonable theoretical structure of the sea / land breeze circulation is displayed, and a new undeerslanding of the developmental mechanism of land breeze circulation in that area is obtained. Lastly, numerical experiments about the effects of large scale wind and temperature fields upon the sea / land breeze circulation are performed.

Analytic Study of Sea-Land Breezes

An analytic study of the structure of sea-land breezes is presented, with special attention paid to the dependence on the model parameters. In this linearized model, the wind speed of the sea-land breezes is directly proportional to the difference of sea and land heating rates. For the same differential heating, the sea-land breeze is more prominent if the stratification is weakly stable, or if the frictional force is small. The horizontal penetration from the coast is also investigated, and found to be asymmetric between the land and the sea. The above results are in agreement with observation.

THERMAL INFLUENCES OF LAND-SEA CONTRAST AND TOPOGRAPHY ON SUMMER MONSOON IN 1998

In this work, the SCSMEX data are used to diagnose and compare the local land-sea thermal conditions, with the focus of discussion on possible influences of thermal forcing of the western Pacific and the Tibetan Plateau on the onset and development of summer monsoon in 1998. Results show a close relationship between the distribution of the heat sources and the land-sea contrast. Due to the blocking effect of terrain, main maximum zones of the heat sources in areas with more evident north-south land-sea contrast are more obviously southward located than those exclusively with oceans. The surface heating is characterized with apparent seasonal variation and difference between land and sea. The relationship between the western Pacific and the onset of summer monsoon is reflected in the variations of the sea surface temperature (SST) and the latent heat. The influence mechanism of the Tibetan Plateau during the summer monsoon is different: it is dominated by sensible heating during the South China Sea monsoon and by condensed latent heating during the Indian monsoon.

THE FLUX OF LAND-BASED SOURCE POLLUTANTS FROM TUMEN RIVER SYSTEM ENTERING THE SEA OF JAPAN

The influence of land based source pollutants to marine ecological environment is principally in coastal or enclosed sea waters. Flux of land based source pollutants into the sea will be effected due to social and economic development in the Tumen River basin. Pollutant type and primary pollution factor of the Tumen River in Northeast China is described by weighted coefficient method in this paper. The results indicate that the river is organic pollution type and primary pollution factor is COD. Fresh water fraction proves that the estuary is not affected by tide cycle. COD annual flux entering the Sea of Japan calculated by zero dimension model in 1993 was 90.50 ×10 3 tons. It is estimated with emission coefficient method that the COD will be 176.4 ×10 3 and 458.6 ×10 3 tons for the years of 2000 and 2010 respectively.

The Role of Land–sea Distribution and Orography in the Asian Monsoon. Part I: Land–sea Distribution

A number of AGCM simulations were performed by including various land–sea distributions （LSDs）, such as meridional LSDs, zonal LSDs, tropical large-scale LSDs, and subcontinental-scale LSDs, to identify their effects on the Asian monsoon. In seven meridional LSD experiments with the continent/ocean located to the north/south of a certain latitude, the LSDs remain identical except the southern coastline is varied from 40 ° to 4 ° N in intervals of 5.6° . In the experiments with the coastline located to the north of 21° N, no monsoon can be found in the subtropical zone. In contrast, a summer monsoon is simulated when the continent extends to the south of 21 ° N. Meanwhile, the earlier onset and stronger intensity of the tropical summer monsoon are simulated with the southward extension of the tropical continent. The effects of zonal LSDs were investigated by including the Pacific and Atlantic Ocean into the model based on the meridional LSD run with the coastline located at 21 °N. The results indicate that the presence of a mid-latitude zonal LSD induces a strong zonal pressure gradient between the continent and ocean, which in turn results in the formation of an East Asian subtropical monsoon. The comparison of simulations with and without the Indian Peninsula and Indo-China Peninsula reveals that the presence of two peninsulas remarkably strengthens the southwesterly winds over South Asia due to the tropical asymmetric heating between the tropical land and sea. The tropical zonal LSD plays a crucial role in the formation of cumulus convection.

The Relationship of Land-Ocean Thermal Anomaly Difference with Mei-yu and South China Sea Summer Monsoon

Based on the NCEP/NCAR reanalysis data for the period of 1948-2004 and the monthly rainfall data at 160 stations in China from 1951 to 2004, the relationships among the land-ocean temperature anomaly difference in the mid-lower troposphere in spring （April-May）, the mei-yu rainfall in the Yangtze River- Huaihe River basin, and the activities of the South China Sea summer monsoon （SCSSM） are analyzed by using correlation and composite analyses. Results show that a significant positive correlation exists between mei-yu rainfall and air temperature in the middle latitudes above the western Pacific, while a significant negative correlation is located to the southwest of the Baikal Lake. When the land-ocean thermal anomaly difference is stronger in spring, the western Pacific subtropical high （WPSH） will be weaker and retreat eastward in summer （June-July）, and the SCSSM will be stronger and advance further north, resulting in deficient moisture along the mei-yu front and below-normal precipitation in the mid and lower reaches of the Yangtze River, and vice versa for the weaker difference case. The effects and relative importance of the land and ocean anomalous heating on monsoon variability is also compared. It is found that the land and ocean thermal anomalies are both closely related to the summer circulation and mei-yu rainfall and SCSSM intensity, whereas the land heating anomaly is more important than ocean heating in changing the land-ocean thermal contrast and hence the summer monsoon intensity.

Global Warming Induced Sea Level Rise on Soil, Land and Crop Production Loss in Bangladesh

Available data have been analyzed to assess impacts of global warming induced sea level rise on loss of soil and land resources and their implications on food security of Bangladesh. Scientists believe that because of sea level rise coastal zone of Bangladesh has already experienced noticeable impacts especially in terms of area of inundation and erosion, saline intrusion, loss of soil and land, loss of crop production in addition to migration of people from vulnerable areas. The loss of land mass and degradation of soil and land resources will adversely affect national food production and thereby food security. Sea level rise impacts are really high for Bangladesh, though the country plays insignificant role in green house gas emission. Development and implementation of adaptation policies and taking initiatives to realize those policies are the right ways to respond to sea level rise impacts in Bangladesh.

Study on the Strategy of Sea and Land Complex National Sea Rights-the Case of France

A land-sea composite state is a state based on land,close to the continental margin,with a long coastline and a certain degree of influence.In the development of sea-land complex countries,there are respective situations and strategic dilemmas in sea rights.Sea rights are closely linked to national destiny,and after years of development,experience and lessons are both present.France is a representative land and sea composite state.Its thought on sea rights has profound historical value and has made unique contributions to the development of global sea rights theory.Therefore,this paper takes the development of France’s sea power as a blueprint and studies the development of France’s sea power on land and sea composite countries,discusses the rise and fall of France’s sea power,and provides reference for China’s sea power strategy research.

Numerical Modelings of the Climatic Effects of the Land-Sea Distribution and Topography

The effects of the land-sea contrast and the topography on the climatic properties are simulated rn this paper by use of a p- a incorporated coordinate system mode! in a zonal domain.In this paper we firstly discuss the statistical features of the model and find that the capability of the model is stable,with the same land-sea distribution and topography seven monthly mean climate states are close to one another,their variance is even less than the initial one.Secondly,we focally discuss the effects of the land-sea contrast and the topography on the modeled climate fields.It is pointed out that the land-sea contrast and the topography influence the atmosphere mainly through the heating ef-fect and the former has larger influences on the simulated large scale climate fields than the latter.

Impact of Sea-Land Interaction on Evolution of Taihu Lake

Analyzed in this paper are the influencing factors, characteristics, and mechanism of land-sea interaction for the Taihu Lake Basin. The course of mass movement and energy transformation between land and sea in the Taihu Lake Basin has experienced three different stages, namely, ocean predominance, balance between land and sea, and land predominance. In the paper the process of the formation and the evolution of the Taihu Lake is studied considering the land-sea interaction.

EAWM-Related Air-Sea-Land Interaction and the Asian Summer Monsoon Circulation

Based on the data analysis, this study further explores the characteristics of East Asian winter monsoon (hereafter, EAWM, for brevity) as well as the related air-sea-land system, and illustrates how and to what degree anomalous signals of the subsequent Asian summer monsoon are rooted in the preceding EAWM activity. We identified an important air-sea coupled mode, i.e., the EAWM mode illustrated in Section 3. In cold seasons, strong EAWM-related air-sea two-way interaction is responsible for the development and persistence of the SSTA pattern of EAWM mode. As a consequence, the key regions, i.e., the western Pacific and South China Sea (hereafter, SCS, for brevity), are dominated by such an SSTA pattern from the winter to the following summer. In the strong EAWM years, the deficient snow cover dominates eastern Tibetan Plateau in winter, and in spring, this anomaly pattern is further strengthened and extended to the northwestern side of Tibetan Plateau. Thus, the combined effect of strong EAWM-related SSTA and Tibetan snow cover constitutes an important factor in modulating the Asian monsoon circulation. The active role of the EAWM activity as well as the related air-sea-land interaction would, in the subsequent seasons, lead to: 1) the enhancement of SCS monsoon and related stronger rainfall; 2) the northward displacement of subtropical high during Meiyu period and the related deficient rainfall over Meiyu rainband; 3) above-normal precipitation over the regions from northern Japan to northeastern China in summer; 4) more rainfall over the Arabian Sea and Northeast India, while less rainfall over southwest India and the Bay of Bengal. The strong EAWM-related air-sea interaction shows, to some degree, precursory signals to the following Asian summer monsoon. However, the mechanism for the variability of Indian summer monsoon subsequent to the strong EAWM years remains uncertain.

Effects of Land-Sea Distribution, Topography and Diurnal Change on Summer Monsoon Modeling

The effects of the land-sea distribution, the topography and the diurnal change of the solar radiation on the summer monsoon modelings are studied by use of a coupled modeling system with a 5-layer primitive equation model of the atmosphere and a 2-layer soil or ocean thermodynamic model which are all solved in a zonal model domain between 60°S and 60°N. The results of numerical simulations show that the quasi-stationary patterns of the mean monsoon circulations are mainly affected by the land-sea distribution and the topography, the effect of the diurnal change is the secondary. However, the inclusion of the diurnal change into the model system may improve the intensity of the simulated monsoon circulation, it can influence the distributive pattern of precipitation to a larger extent,without the diurnal change precipitation in the interior of land would decrease and in the coastal regions it would increase.

The research of sea-land breeze (SLB) on the west coast of Bohai Bay based on field observation

Four automatic meteorological stations were set up in a line from beach to inland perpendicular to the west coast of Bohai Bay. Wind direction and velocity at altitudes of 2 m, 4 m and 12 m were surveyed with 10 minute intervals. On ＂Sea-Land Breeze＂ （SLB） days, the transition from sea breeze to land breeze was very evident in the study area. Direction of sea breeze was basically perpendicular to the coast and mainly from the ENE and E. Duration of sea breeze varied by the stations＇ distance to the coastline, and the near-coast wind velocity was larger than that of the inland and decreases as it reaches inland. There was increased development of SLB on sunny days than on overcast days. The term ＂Climatic Coastal Zone＂ can be defined for the area influenced by SLB, which reaches more than 74 km inland on a typical SLB day but less than 10 km on a non-typical SLB day.

中国极端天气气候研究——“地球系统与全球变化”重点专项项目简介及最新进展

全球变暖背景下,极端天气气候事件频发,并表现出群发性、持续性、复合性等特点,不可预测性增加;持续性强降水、极端低温、复合型极端高温干旱、群发性热浪和台风等极端天气气候事件对我国经济社会和可持续发展影响巨大。然而,上述极端天气气候事件的新特征、关键过程和机理尚不完全清楚,重大极端事件的预报预测水平亟待提升。文章首先简要介绍“地球系统与全球变化”重点专项项目“中国极端天气气候事件的形成机理及其预测和归因”的基本情况。项目拟在分析全球变化背景下对我国造成重大影响的极端天气气候事件新特征的基础上,深入研究多尺度海-陆-气耦合过程影响极端天气气候事件的机理,挖掘极端天气气候事件次季节-季节预测的前兆信号;发展动力与物理统计相结合的极端事件预测新方法,研制针对中国极端事件的新一代高分辨率数值预报与检测归因系统。文章重点总结了自2022年12月项目立项至今取得的最新研究成果和进展。