Impacts of Ice-Ocean Stress on the Subpolar Southern Ocean:Role of the Ocean Surface Current

The mechanical influences involved in the interaction between the Antarctic sea ice and ocean surface current(OSC)on the subpolar Southern Ocean have been systematically investigated for the first time by conducting two simulations that include and exclude the OSC in the calculation of the ice-ocean stress(IOS), using an eddy-permitting coupled ocean-sea ice global model. By comparing the results of these two experiments, significant increases of 5%, 27%, and 24%, were found in the subpolar Southern Ocean when excluding the OSC in the IOS calculation for the ocean surface stress,upwelling, and downwelling, respectively. Excluding the OSC in the IOS calculation also visibly strengthens the total mechanical energy input to the OSC by about 16%, and increases the eddy kinetic energy and mean kinetic energy by about38% and 12%, respectively. Moreover, the response of the meridional overturning circulation in the Southern Ocean yields respective increases of about 16% and 15% for the upper and lower branches;and the subpolar gyres are also found to considerably intensify, by about 12%, 11%, and 11% in the Weddell Gyre, the Ross Gyre, and the Australian-Antarctic Gyre, respectively. The strengthened ocean circulations and Ekman pumping result in a warmer sea surface temperature(SST), and hence an incremental surface heat loss. The increased sea ice drift and warm SST lead to an expansion of the sea ice area and a reduction of sea ice volume. These results emphasize the importance of OSCs in the air-sea-ice interactions on the global ocean circulations and the mass balance of Antarctic ice shelves, and this component may become more significant as the rapid change of Antarctic sea ice.

Diversity on the Interannual Variations of Spring Monthly Precipitation in Southern China and the Associated Tropical Sea Surface Temperature Anomalies

There is a continuous and relatively stable rainy period every spring in southern China(SC).This spring precipitation process is a unique weather and climate phenomenon in East Asia.Previously,the variation characteristics and associated mechanisms of this precipitation process have been mostly discussed from the perspective of seasonal mean.Based on the observed and reanalysis datasets from 1982 to 2021,this study investigates the diversity of the interannual variations of monthly precipitation in spring in SC,and focuses on the potential influence of the tropical sea surface temperature(SST)anomalies.The results show that the interannual variations of monthly precipitation in spring in SC have significant differences,and the correlations between each two months are very weak.All the interannual variations of precipitation in three months are related to a similar western North Pacific anomalous anticyclone(WNPAC),and the southwesterlies at the western flank of WNPAC bring abundant water vapor for the precipitation in SC.However,the WNPAC is influenced by tropical SST anomalies in different regions each month.The interannual variation of precipitation in March in SC is mainly influenced by the signal of El Nino-Southern Oscillation,and the associated SST anomalies in the equatorial central-eastern Pacific regulate the WNPAC through the Pacific-East Asia(PEA)teleconnection.In contrast,the WNPAC associated with the interannual variation of precipitation in April can be affected by the SST anomalies in the northwestern equatorial Pacific through a thermally induced Rossby wave response.The interannual variation of precipitation in May is regulated by the SST anomalies around the western Maritime Continent,which stimulates the development of low-level anomalous anticyclones over the South China Sea and east of the Philippine Sea by driving anomalous meridional vertical circulation.

Characteristics of nitrogen forms in the southern Huanghai Sea surface sediments

The distributions of different forms of nitrogen in the surface sediments of the southern Huanghai Sea are different and affected by various factors. The contents of IEF-N, SOEF-N and TN gradually decrease eastward, and those of SAEF-N northward, while those of WAEF-N westward. Around the seaport of the old Huanghe (Yellow) River, the contents of both SOEF-N and TN are the highest. Among all the factors, the content of fine sediment is the predominant factor to affect the distributions of different forms of nitrogen. The contents of IEF-N, SOEF-N, and TN have visibly positive correlation with the content of fine sediments, and the correlative coefficient is 0.68, 0.58 and 0.71 respectively, showing that the contents of the three forms of nitrogen increase with those of fine sediments. The content of WAEF-N is related to that of fine sediments to a certain extent, with a correlative coefficient of 0.35; while the content of SAEF-N is not related to that of fine sediments, showing that the content of SAEF-N is not controlled by fine grain-size fractions of sediments. In addition, the distributions of different forms of nitrogen are also interacted one another, and the contents of IEF-N and SOEF-N are obviously affected by TN, while those of inorganic nitrogen (WAEF-N, SAEF-N and IEF-N) are not affected by SOEF-N and TN obviously, although they are interacted each other.

Influence of Sea Surface Temperature on Outbreak of Ulva prolifera in the Southern Yellow Sea,China

In this study,using Moderate Resolution Imaging Spectroradiometer(MODIS)satellite images and environmental satellite CCD images,the spatio-temporal distribution of Ulva prolifera in the southern Yellow Sea during the period of 2011–2018 was extracted and combined with MODIS Level3 Photosynthetically Active Radiation(PAR)product data and Earth System Research Laboratory(ESRL)Sea Surface Temperature(SST)data to analyze their influences on the growth and outbreak of Ulva prolifera.The following conclusions were drawn:1)comprehensive analysis of Ulva prolifera distribution during the eight-year period revealed that the coverage area of Ulva prolifera typically exhibited a gradually increasing trend.The coverage area of Ulva prolifera reached a maximum of approximately 1714.21 km^2 during the eight-year period in late June 2015.The area affected by Ulva prolifera fluctuated.In mid-July 2014,the area affected by Ulva prolifera reached a maximum of approximately 39020.63 km^2.2)The average growth rate of Ulva prolifera was positive in May and June but negative in July.During the outbreak of Ulva prolifera,the SST in the southern Yellow Sea tended to increase each month.The SST anomaly and average growth rate of Ulva prolifera were positively correlated in May(R^2=0.62),but not significantly correlated in June or July.3)The variation trends of PAR and SST were approximately the same,and the PAR during this time period maintained a range of 40–50 mol/(m^2·d),providing sufficient illumination for the growth and outbreak of Ulva prolifera.In addition,the abundant nutrients and suitable temperature in the sea area near northern Jiangsu shoal resulted in a high growth rate of Ulva prolifera in May.In summary,the outbreak of Ulva prolifera was closely related to the environmental factors including SST,nutrients,and PAR.Sufficient nutrients and suitable temperatures resulted in a fast growth rate of Ulva prolifera.However,under poor nutrient conditions,even more suitable temperatures were not sufficient to trigger an outbreak of Ulva prolifera.

Forms of phosphorus and silicon in the natural grain size surface sediments of the southern Bohai Sea

The forms of phosphorus and silicon in the natural grain sizes surface sediments of the southern Bohai Sea were studied. In sediments, the organic matter bound form of phosphorus was the main form of transferable phosphorus and ranged from 0.37 μmol/g to 1.57 μmol/g, accounting for 10.7% of the total phosphorus, others were the carbonate bound form, iron manganese oxide bound form and ion exchange able form; the transferable form of phosphorus accounted for 19.2% of the total phosphorus. Silicon’s carbonate bound form was predominant over others among its transferable forms, and content ranged from 1.55 μmol/g to 8.94 μmol/g, accounting for 0.05% of the total silicon; the total amount of transferable silicon forms accounted for only 0.12% of the total silicon. Therefore, 19.2% of the total phosphorus and 0.12% of the total silicon contained in the surface sediments of the southern Bohai Sea could participate in the biogeochemical cycling.

Grain-size related nitrogen distribution in southern Yellow Sea surface sediments

Forty-eight surface sediments of the southern Yellow Sea are separated into three grain-size frac- tions. Four forms of extractable nitrogen (nitrogen in ion-exchangeable form (Nie), nitrogen in weak-acid ex- tractable form (Nwa), nitrogen in strong-alkali extractable form (Nsa) and nitrogen in strong-oxidant form (Nso)) are obtained by the sequential extraction. The results show that the contents and the distributions of the extract- able nitrogen in the southern Yellow Sea surface sediments are closely related to sediment grain size. The distri- butions of Nie, Nso and total nitrogen (TN) present positive correlations with fine particles content, while Nwa and Nsa does not have such correlation. The net contents of all the forms of nitrogen increase with sediment grain size finer.

Surface pollen and modern vegetation in Southern Xinjiang,China

The study of modern pollen,and vegetation can improve the accuracy of paleoenvironmental reconstruction based on fossil pollen data.A total of 188 pollen surface samples were collected from Southern Xinjiang(34°00’–43°00’N,74°00’–94°00’E)in China,with an elevation range of 888–4530 m.Surface pollen and vegetation were studied in the northern region of the Kunlun Mountains and the southern region of the Tianshan Mountains.The results showed that the surface pollen assemblages on the southern slope of the Tianshan Mountains(3530–1124 m)were divided into three pollen zones,namely,montane steppe,montane desert steppe,and montane desert.These zones were dominated by Artemisia,Chenopodiaceae,and Ephedra pollen.The surface pollen assemblages in the eastern Pamir Plateau(4530–1287 m)could be divided into alpine meadow,montane desert steppe,and montane desert zones,which were predominantly characterized by Artemisia,Chenopodiaceae,and Asteraceae pollen.However,the Southern Tarim Basin(3548–888 m)comprised montane desert steppe and montane desert zones,which was dominated by Artemisia and Chenopodiaceae pollen.The geographic distribution of the surface pollen sites obtained using ArcGIS,the R-value,and Pearson correlation analyses indicated that the over-represented Picea and Pinus pollen were of external origin and were transported by wind,water(rivers),and ice(glacier movement).Over-representation of Ephedra and Nitraria pollen was mainly distributed in the montane desert and desert steppe zones,respectively.Pollen from Chenopodiaceae and Artemisia were over-represented and broadly distributed across Southern Xinjiang.Juglans pollen was concentrated in areas with walnut trees,strongly indicating the presence of local parent plants.According to the Hybrid Singleparticle Lagrangian Integrated Trajectory model,more Pinus pollen was transported to the Pamir region by external airflows during spring and summer,resulting in its higher surface pollen content.Research elucidating the relationship between modern pollen and vegetation in southern Xinjiang could provide data describing the surface palynological database of Xinjiang for use in large-scale paleoenvironmental reconstructions.

基于海表温度遥感资料重构的热带不稳定波特征分析

[目的]研究赤道东太平洋热带不稳定波(tropical instability waves,TIWs)的时空分布特征及其驱动机制.[方法]利用数据插值经验正交函数方法对MODIS卫星2003-2018年赤道东太平洋海表面温度(sea surface temperature,SST)数据进行重构,进而提取TIWs的波长和速度,并分析其时空分布特征以及与赤道风场和流场的关系.[结果]研究发现:TIWs在纬向上呈正负相位交替分布,在经向上则表现为双峰结构.季节性方面,TIWs在3-5月强度最弱,而在8-10月强度最强.纬向风场通过影响赤道纬向流场,特别是南赤道流(South Equatorial Current,SEC)的北分支(SEC-N)和北赤道逆流(North Equatorial Countercurrent,NECC)的剪切调控TIWs的生成;经向风场则通过调制“冷舌”边缘的SST梯度影响TIWs的生成.在年际尺度上,TIWs在厄尔尼诺(El Nino)年受到抑制,在拉尼娜(La Nina)年得到加强.纬向风场、纬向流场和TIWs三者的异常均超前于厄尔尼诺-南方涛动(El Nino-Southern Oscillation,ENSO)指数所刻画的赤道东太平洋SST异常,这表明纬向风场影响下的纬向流场剪切同样驱动TIWs的年际变化.NECC上空纬向风异常较弱,而SEC-N上空纬向风异常较强,这使得SEC-N年际变化主导流场剪切的强度,对TIWs的年际特征有重要作用.[结论]这一发现强调了大气风场和海洋动力过程共同驱动TIWs的季节性特征和年际变化.

Record-breaking summer-autumn drought in southern China in 2022:Roles of tropical sea surface temperature and Eurasian warming

From summer to autumn in 2022,a severe drought lasted in southern China,posing serious effects on economic growth and ecological systems.This study explored the atmospheric circulations accounting for this persistent drought event.It shows that the drought in southern China during the summer of 2022 was strongly linked to the divergence of water vapor flux and descending motions,which were respectively caused by the anomalous anticyclone over the western North Pacific and the northward movement of the East Asian subtropical jet(EASJ).Differently,the atmospheric background responsible for the sustained drought in autumn is manly featured by a cyclonic circulation anomaly over the region from the Bay of Bengal to the South China Sea,which led to decreased moisture and descending motions in southern China.Further investigation suggests that the rarely strong surface warming over northern Eurasia and the extreme La Nina-like pattern over the tropical Pacific jointly resulted in the anomalous anticyclone over the western North Pacific and the northward shift of the EASJ in the summer of 2022,while the cyclonic circulation anomaly prevailing over the region from the Bay of Bengal to the South China Sea in autumn was largely attributed to the extremely negative anomalies of the tropical Indian Ocean sea surface temperature.

南海海表盐度变化特征及机制研究

海表面盐度(Sea surface salinity,SSS)的变化机制复杂,主要受海气交换及海洋环流过程影响。南海SSS存在显著的年际及年代际变化,受厄尔尼诺与南方涛动(El Nino-Southern oscillation,ENSO)和太平洋十年涛动(Pacific decadal oscillation,PDO)的复合作用机制尚不明确。本文融合海洋再分析数据和卫星遥感数据,处理生成151 a(1871—2021年)的长期南海SSS数据集,采用EOF和相关分析等方法,分析了南海SSS的长期时空变化特征及机制。研究结果表明:近150年来,南海SSS整体变化不明显,但1940—1958年SSS显著上升(每10年上升0.31);珠江口和吕宋海峡受径流和黑潮作用,SSS变化幅度最大(每10年为-0.04和每10年为0.03);南海SSS整体变化主要由降水和黑潮控制,相关系数分别为-0.41和-0.49,南海陆架和近海海域SSS受河流径流影响显著,相关系数为-0.45;ENSO在年际尺度上控制南海的降水,PDO在年代际尺度上影响黑潮入侵南海的变化,当PDO正位相时,厄尔尼诺事件会导致降水减少,同时黑潮入侵南海强度增加,两者共同作用使南海SSS显著上升。本研究对理解南海海气交换和海洋环流变化有重要意义。

2023年华南开汛偏早与大气环流和海温的关系

采用合成、相关分析及相关物理量诊断等方法,分析了华南地区三重La Ni1a背景下2023年华南开汛偏早的大气环流和海温特征并与2022年作对比,结果表明:(1)2022和2023年3月广东降水偏多与前冬北太平洋暖海温相关,2022、2023年华南开汛偏早分别与前冬中印度洋海岭海域海温、前冬东太平洋海丘的以东海域海温增暖有关。(2)2022和2023年3月850 hPa风场华南沿海均呈现反气旋式分布,华南处于西南到偏南气流中有利水汽输送。两年开汛偏早与冷空气南下有关。(3)2022和2023年3月华南地区局地哈德莱环流在赤道附近北支上升气流加强,北支下沉支减弱且南退,在0°N—20°N范围内为负距平,有利于2022和2023年3月广东降水偏多。

赣南马尾松林地表细小死可燃物含水率动态及模型

[目的]建立森林地表细小死可燃物(枯落叶、细枯枝、枯草等)含水率预测模型,预警区域森林火灾引燃的可能性及其潜在火行为。[方法]基于野外长期定位观测的赣南地区典型植被类型马尾松林地表细小死可燃物含水率数据,在不同地形条件和时间段进行气象因子随机森林相对重要性排序和皮尔逊相关性分析,建立地表细小死可燃物含水率随机森林模型和气象要素回归模型,比较不同模型精度指标,筛选适合赣南地区的森林火灾预测模型。[结果]赣南地区马尾松林地表细小死可燃物含水率具有明显变异性,阴坡含水率显著高于阳坡,在防火期初期最明显。地表细小死可燃物含水率与各气象要素(温度、相对湿度、风速、光照强度)具有极显著相关性(P<0.001);随机森林模型预测精度高于气象要素回归模型,阴坡2种模型精度均高于阳坡;具有滞后效应的光照强度因子对地表细小死可燃物含水率影响最大,影响地表细小死可燃物含水率的关键因素在阳坡是相对湿度、阴坡是风速。[结论]具有滞后效应的气象因子对赣南地区马尾松林地表细小死可燃物含水率有显著影响,考虑增加这些因素能更好预测地表细小死可燃物含水率变化,为火险预警提供可靠依据。

Late Cenozoic Geomorphology, Geochronology and Physiography of Yuntaishan in Southern Taihang Mountain, North China

The late Cenozoic geomorphic features and geochronologic data of the Zhingfang River catchment in the Yuntaishan World Geopark are studied. Several quarternary geochronologic methods, including electron spin resonance （ESR）, optically stimulated luminescence （OSL）, thermo-luminescence （TL） and U-series are presented in this paper. The results suggest that there are two planation surfaces, named as the Taihang surface which is a peneplain of Taihang stage formed during Oligocene or Oligocene to early-middle Miocene period, and Tang-hien surface which is a mature wide valley of Tang-hien stage formed during late Miocene-Pliocene or Piiocene-early Pleistocene period and probably ended prior to 2.2-2.6 Ma based on ESR dating. After the Tang-hien stage, the incision and aggradation of the river formed six stream terraces with heights of 3-5 m, 8-12 m, 22-24 m, 28-38 m, 50-62 m and 80-85 m above the river bottom, respectively. The dating results of the alluvium sediments suggest that these terraces were formed during Holocene, 20-23 ka B.P., 110-120 ka B.P., 200-240 ka B.P., 840-1200 ka B.P. or ~450 ka B.P. and 1600-1800 ka B.P. or -1100 ka B.P., respectively. These results indicate that episodic incision of the river, which controls the formation of the scenery in the Yuntaishan World Geopark, was mainly influenced by the periodic dry-wet climate change during late Cenozoic mountain uplift.

Evaluation of reanalysis and satellite-based sea surface winds using in situ measurements from Chinese Antarctic Expeditions

Sea surface winds from reanalysis （NCEP-2 and ERA-40 datasets） and satellite-based products （QuikSCAT and NCDC blended sea winds） are evaluated using in situ ship measurements from the Chinese National Antarctic Research Expeditions （CH1NAREs） from 1989 through 2006, with emphasis on the Southern Ocean （south of 45°S）. Compared with ship observations, the reanalysis winds have a positive mean bias （0.32 m·s-1 for NCEP-2 and 0.13 m·s-1 for ERA-40）, and this bias is more pronounced in the Southern Ocean （0.57 m·s-1 and 0.45 m·s-1, respectively）. However, mean biases are negative in the tropics and subtropics. The satellite-based winds also show positive mean biases, larger than those of the reanalysis data. All four wind products overestimate ship wind speed for weak winds （〈4 m·s-1） but underestimate for strong winds （〉10 m·s-1）. Differences between the reanalysis and satellite winds are examined to identify regions with large discrepancies.

Surface Temperature Changes Projected by FGOALS Models under Low Warming Scenarios in CMIP5 and CMIP6

To meet the low warming targets proposed in the 2015 Paris Agreement,substantial reduction in carbon emissions is needed in the future.It is important to know how surface climates respond under low warming targets.The present study investigates the surface temperature changes under the low-forcing scenario of Representative Concentration Pathways(RCP2.6)and its updated version(Shared Socioeconomic Pathways,SSP1-2.6)by the Flexible Global Ocean-Atmosphere-Land System(FGOALS)models participating in phases 5 and 6 of the Coupled Model Intercomparison Project(CMIP5 and CMIP6,respectively).In both scenarios,radiative forcing(RF)first increases to a peak of 3 W m^−2 around 2045 and then decreases to 2.6 W m^−2 by 2100.Global mean surface air temperature rises in all FGOALS models when RF increases(RF increasing stage)and declines or holds nearly constant when RF decreases(RF decreasing stage).The surface temperature change is distinct in its sign and magnitude between the RF increasing and decreasing stages over the land,Arctic,North Atlantic subpolar region,and Southern Ocean.Besides,the regional surface temperature change pattern displays pronounced model-to-model spread during both the RF increasing and decreasing stages,mainly due to large intermodel differences in climatological surface temperature,ice-albedo feedback,natural variability,and Atlantic Meridional Overturning Circulation change.The pattern of tropical precipitation change is generally anchored by the spatial variations of relative surface temperature change(deviations from the tropical mean value)in the FGOALS models.Moreover,the projected changes in the updated FGOALS models are closer to the multi-model ensemble mean results than their predecessors,suggesting that there are noticeable improvements in the future projections of FGOALS models from CMIP5 to CMIP6.

Dominant SST Mode in the Southern Hemisphere Extratropics and Its Influence on Atmospheric Circulation

The variability in the Southern Ocean（SO） sea surface temperature（SST） has drawn increased attention due to its unique physical features; therefore, the temporal characteristics of the SO SST anomalies（SSTA） and their influence on extratropical atmospheric circulation are addressed in this study. Results from empirical orthogonal function analysis show that the principal mode of the SO SSTA exhibits a dipole-like structure, suggesting a negative correlation between the SSTA in the middle and high latitudes, which is referred to as the SO Dipole（SOD） in this study. The SOD features strong zonal symmetry, and could reflect more than 50% of total zonal-mean SSTA variability. We find that stronger（weaker） Subantarctic and Antarctic polar fronts are related to the positive（negative） phases of the SOD index, as well as the primary variability of the large-scale SO SSTA meridional gradient. During December–January–February, the Ferrel cell and the polar jet shift toward the Antarctic due to changes in the SSTA that could be associated with a positive phase of the SOD, and are also accompanied by a poleward shift of the subtropical jet. During June–July–August, in association with a positive SOD, the Ferrel cell and the polar jet are strengthened, accompanied by a strengthened subtropical jet. These seasonal differences are linked to the differences in the configuration of the polar jet and the subtropical jet in the Southern Hemisphere.

Impact of Past Mining Activities on Water Resources Around Active and Abandoned Mines and Quarries in Ebonyi State,South-Eastern Nigeria-A Mini Review

This paper presents a review on previous activities of mining on water resources around active and abandoned mines/quarries across Ebonyi State,South-Eastern,Nigeria.As high demand for water increases due to population growth and rapid development across the state,it is of upmost importance to periodically review water quality and also monitor water resources.However,less information is available on evaluation of impact on mining activities on water resources.For the purpose of this research,related articles were downloaded from Google,published article on effect of mining on water resources was download and thoroughly studied to evaluate effect of mining on water resources of the study area.Findings revealed that past mining activities has lead to chains of complex chemical reactions that has altered the quality of water resources.

Impacts of El Nino-Southern Oscillation events on China＇s rice production

This paper aims to demonstrate the relationships between ENSO and rice production of Jiangxi province in order to identify the reason that ENSO might have little effect on Chinese rice production. Using a data set with measures of Jiangxi＇s climate and rice production, we find the reason that during 1985 and 2004 ENSO＇s well correlated with rainfall did not promote Chinese rice production. First, the largest effects of ENSO mostly occur in the months when there is no rice in the field. Second, there is almost no temperature effect. Finally, the monthly distribution of rainfall is almost the same in ENSO and neutral years because the largest effects are during months when there is the least rain. In addition, due to the high irrigation share and reliable and effective irrigation facilities of cultivated land, China＇s rice production is less climate-sensitive.

Sea surface temperature anomalies in the South China Sea during mature phase of ENSO

Based on the 18-year(1993–2010) National Centers for Environmental Prediction optimum interpolation sea surface temperature(SST) and simple ocean data assimilation datasets,this study investigated the patterns of the SST anomalies(SSTAs) that occurred in the South China Sea(SCS) during the mature phase of the El Ni?o/Southern Oscillation.The most dominant characteristic was that of the outof-phase variation between southwestern and northeastern parts of the SCS,which was influenced primarily by the net surface heat flux and by horizontal thermal advection.The negative SSTA in the northeastern SCS was caused mainly by the loss of heat to the atmosphere and because of the cold-water advection from the western Pacific through the Luzon Strait during El Ni?o episodes.Conversely,it was found that the anomalous large-scale atmospheric circulation and weakened western boundary current during El Ni?o episodes led to the development of the positive SSTA in the southwestern SCS.