Changes in Mixed Layer Depth and Spring Bloom in the Kuroshio Extension under Global Warming

The mixed layer is deep in January-April in the Kuroshio Extension region. This paper investigates the response in this region of mixed layer depth （MLD） and the spring bloom initiation to global warming using the output of 15 models from CMIP5. The models indicate that in the late 21st century the mixed layer will shoal and the MLD reduction will be most pronounced in spring at about 33~N on the southern edge of the present deep-MLD region. The advection of temperature change in the upper 100 m by the mean eastward flow explains the spatial pattern of MLD shoaling in the models. Associated with the shoaling mixed layer, the onset of spring bloom inception is projected to advance due to the strengthened stratification in the warming climate.

Influence of Warm Oxide Layer on Wettability and Contact Angle for Heat Transport Devices

Recently, high heat density has become a problem in electronic devices. Therefore, high heat-transfer efficiency is required in copper heat exchangers. Improvement ofwettability is reported to improve the heat-transfer efficiency. In previous studies, copper oxide layer improves the wettability. In this study, we focus on a copper oxide layer produced under warm conditions （from 200 to 300 ℃）, which are suitable oxidation conditions for improving wettability. Experimental results showed that the surface of the specimens was covered by the oxidation layer and took on a black color. Furthermore, the wettability was improved by the warm copper oxide layer. While, the surface roughness was approximately constant to each warm oxidized specimen. Whereat, the warm oxide layer was observed by SEM （sanning electron microscope）. The results from SEM observations showed that the warm copper oxide layer consisted of stacks and combinations of nanoscopic warm oxidation particles. Thus, the warm oxidation layer has nanoscopic surface asperities. It is seemed that these nanoscopic asperities improved the wettability.

CHARACTERISTICS OF INTRASEASONAL VARIATIONS IN THE MIXED LAYER OF "WARM POOL" AREAS

Observational data obtained during the TOGA-COARE IOP in the "warm pool" area of the West-ern Tropical Pacific were used to analyze some characteristics of the intraseasonal variations in the mixedlayer. The influence of westerly burst and rainfall on SST, salinity. and mixed layer depth are discussed.There are two pairs of counteracting processes in the "warm pool" mixed layer: (1) The increase of mixedlayer depth caused by local westerly bursts and the decrease of mixed layer depth caused by larger scaleeasterly relaxation;(2) the vertical mixing by local wind and the strong stratification due to rainfall in themixed layer. Some possible mechanisms through the interactions between the intraseasonal time scale varia-tions of the oceanic mixed layer and atmospheric low frequency oscillations are revealed.

A numerical study of Stokes drift and thermal effects on the oceanic mixed layer

This study explores the influence of Stokes drift and the thermal effects on the upper ocean bias which occurs in the summer with overestimated sea surface temperature(SST)and shallower mixed layer depth(MLD)using Mellor-Yamada turbulence closure scheme.The upper ocean thermal structures through Princeton ocean model are examined by experiments in the cases of idealized forcing and real observational situation.The results suggest that Stokes drift can generally enhance turbulence kinetic energy and deepen MLD either in summer or in winter.This effect will improve the simulation results in summer,but it will lead to much deeper MLD in winter compared to observational data.It is found that MLD can be correctly simulated by combining Stokes drift and the thermal effects of the cool skin layer and diurnal warm layer on the upper mixing layer.In the case of high shortwave radiation and weak wind speed,which usually occurs in summer,the heat absorbed from sun is blocked in the warm layer and prevented from being transferred downwards.As a result,the thermal effects in summer nearly has no influence on dynamic effect of Stokes drift that leads to deepening MLD.However,when the stratification is weak in winter,the thermal effects will counteract the dynamic effect of Stokes drift through enhancing the strength of stratification and suppress mixing impact.Therefore,the dynamic and thermal effects should be considered simultaneously in order to correctly simulate upper ocean thermal structures in both summer and winter.

不同处理对轮台白杏种子发芽及幼苗生长的影响

【目的】掌握轮台白杏种子的最佳育苗方法,为高效科学育苗提供技术支撑,为揭示杏休眠机理提供理论依据。【方法】以轮台白杏种子为研究对象,设置激素法、温汤浸种法、低温层积法、激素+低温层积法打破种子休眠,统计发芽率,将萌发的种子播种到土壤中,30 d后测定幼苗特性。【结果】1)GA_(3)和温汤浸种处理不去皮种子,发芽率很低,表明轮台白杏具有种皮休眠特性。带壳轮台白杏种子经低温层积80 d才开始萌发,说明轮台白杏具有种壳休眠特性。2)在不同处理中,有两个处理方法发芽率及出苗率均较高,其中500 mg/L的GA_(3)处理半去皮轮台白杏种子,发芽率高达94.00%,出苗率高达88.00%,种苗根系发达,不易徒长,育苗成本最低,每千株为276元,育苗效率最高。温汤浸种轮台白杏种子在50℃浸种全去皮轮台白杏种子30 min,发芽率和出苗率均较高,分别为98.00%和84.00%,成本较低,效率较高。低温层积带壳种子120 d时发芽率最高为80.67%,所有低温层积处理出苗率低于70%,育苗成本较高,效率最低。3)先用激素浸泡种24 h,后层积综合处理发现,轮台白杏种子发芽率及出苗率均不高,且成本最高,育苗效率不高。【结论】杏具有种皮、种壳休眠特性。500 mg/L的GA_(3)浸泡半去皮种子24 h与50℃浸种全去皮轮台白杏种子30 min,育种成本较低,效率较高,均可用作生产中的育苗方法。

温拌LDHs改性沥青混合料抗紫外老化性能及应用研究

采用层状双金属氢氧化物(LDHs)作为抗紫外添加剂,温拌剂作为降黏添加剂,制备了一种新型抗紫外沥青混合料。通过透射电子显微镜研究了LDHs的晶体稳定性,同时通过黏度试验研究了温拌剂的降黏效果,再通过物理性能试验、车辙试验、水稳定性试验研究了LDHs的最佳掺量及温拌LDHs改性沥青混合料的抗紫外老化性能,最后铺筑温拌LDHs改性沥青混合料试验段,对试验路用性能进行评价。结果表明:在170℃下,LDHs具有良好的晶体稳定性,温拌剂能显著降低LDHs改性沥青的黏度,LDHs能够有效提高温拌沥青混合料的抗紫外性能和力学性能,推荐实体工程中掺加LDHs质量与沥青质量之比为0.03。

温阳散结治疗恶性肿瘤的研究进展

恶性肿瘤发病率和病死率仍在攀升,严重威胁人类健康及生活质量。中医强调,阳气充盛能促进机体扶正祛邪,是防治肿瘤的关键。近年来,无论是临床报道还是基础实验都证实,温阳类复方在治疗肿瘤中收效显著。现将上述研究进展进行归纳整理,望为中医药治疗肿瘤提供理论依据,给同仁带来参考和启发。

2023年4月18日厦门暖区特大暴雨中尺度特征及低空急流的作用

2023年4月18日厦门遭遇入汛以来最强暖区暴雨过程,过程具有降水强度大、局地性强等特点。利用常规观测资料、地面自动站观测资料以及双偏振雷达、风廓线雷达、雨滴谱仪等新型探测资料对此次暴雨的天气背景、中尺度对流系统发展演变及低空急流在其中的作用进行了分析,结果表明:(1)此次暖区暴雨主要影响系统为偏南风天气尺度低空急流和东南风边界层急流,其强烈发展增强了局地的水汽及不稳定条件;(2)低质心的线状中尺度对流系统(MCS)嵌有类超级单体风暴在低空急流左侧辐合区内形成发展,MCS在福建南部沿海长时间维持,形成“列车效应”导致厦门极端强降水的发生;(3)类超级单体风暴强回波区差分反射率因子(ZDR)、差分传播相移(KDP)与相关系数(CC)均较大,质心低于经典超级单体风暴。此外,强降水云具有高浓度的小雨滴与大雨滴并存的暖区暴雨云微物理特征。(4)低空急流迅速增强和向下扩展与强降水密切相关,双低空急流耦合产生的上升运动是此次暖区暴雨主要的天气尺度触发机制。

边界层参数化方案对华南一次暖区强对流过程的模拟影响研究

基于天气研究和预报模式(WRF)中尺度数值模式,比较分析四种边界层参数化方案(YSU、MYJ、MYNN、 ACM2)对华南暖区强对流过程模拟的影响。结果表明:(1)四个方案均模拟出广东区域午后有强对流天气发展,但模拟的平均降水量比实况偏小,最大降水强度出现时间滞后1~2 h。(2)四个方案模拟的气温垂直分布与实况非常接近,模拟的850 h Pa以下的低层湿度整体偏大,而模拟的800~950 h Pa风速整体偏小。(3)相比之下,YSU非局地闭合方案模拟的对流回波形态整体与实况最接近,MYJ方案对低层区域800~950 h Pa的风速模拟效果更好,且模拟的较强降水出现时段更接近实况。(4)MYJ和MYNN虽同为局地闭合方案,但模拟结果有较大差异,MYNN方案模拟的低层风速、地面感热通量和潜热通量要明显小于MYJ方案,而YSU和ACM2方案模拟结果差异相对较小。

温拌超薄磨耗层技术在高速公路施工中的应用

为研究温拌超薄磨耗层施工技术在高速公路养护中的应用,提高沥青路面使用性能,论文依托实际工程,详细阐述了温拌橡胶沥青超薄磨耗层混合料各原材料的指标要求,重点研究了温拌橡胶沥青超薄磨耗层施工中旧路面处理、施工准备、混合料拌和、混合料摊铺机碾压、施工质量检查等环节的技术要点。

北部湾一次持续性混合型海雾过程分析

利用北部湾沿岸海岛站观测资料和ERA5数据,对混合型(高压后部型转西南倒槽型)海雾出现概率和一次典型过程进行了分析。结果表明:(1)2015—2020年混合型海雾过程出现概率最高,累计出现15次(58天),占比34.9%(39.5%)。(2)2016年3月15—23日海雾过程具有持续时间长、范围广的特点。前期北部湾受入海高压后部偏东气流影响,后期高原槽发展东移,北部湾逐渐转为受西南倒槽边缘偏南气流控制。(3)热力条件上,低空急流的强暖湿输送,一方面使北部湾上空比湿增大,饱和层从近地面延伸至800 hPa,另一方面使逆温层建立,逆温层与其下方高湿区配合形成稳定状态。动力条件方面,垂直方向维持一定强度的风切变,有利于边界层的湍流混合,并与斜压大气形成有利于低层稳定层结维持的配置。此外800 hPa以下为弱上升运动,利于水汽在低层抬升凝结,促进海雾发展及维持。(4)海雾发生期间,前期(后期)气海温差大多在0~1.5℃(1.5~2.5℃)之间。

2023年4月闽南沿海一次暖区暴雨过程中尺度分析

本文利用常规和非常规资料对2023年4月18日闽南沿海地区一次特大暴雨过程进行了中尺度特征分析和研究。结果表明:此次特大暴雨过程是副高北抬和南风暖湿气流强迫背景下形成的强对流天气,东南季风绕过台湾省形成地形高压,南海水汽通道建立与弱冷空气触发是此次过程的降水机制。“列车效应”在雷达图中表现突出,针对区域性冷空气的入侵,风廓线雷达资料较常规资料更精细,地形正面阻挡对边界层偏南急流造成的暖区暴雨大值落区判断有指示意义。

Highway Roadway Stability Influenced by Warm Permafrost and Seasonal Frost Action:A Case Study from Glennallen,Alaska,USA

Ground temperatures from four of the seven extensively studied highway cross-sections near Gulkana/Glennallen,Alaska during 1954;962,were chosen to better understand the impacts of highway construction on warm permafrost.Both the thawing of permafrost and seasonal frost action impacted on road surface stability for about 6 years until the maximum summer thaw reached about 3 m in depth.Seasonal frost action caused most of the ensuing stability problems.Unusually warm summers and the lengths of time required to re-freeze the active layer were far more important than the average annual air temperatures in determining the temperatures of the underlying shallow permafrost,or the development of taliks.The hypothesized climate warming would slightly and gradually deepen the active layer and the developed under-lying talik,but its effect would be obscured by unusually warm summers,by warmer than usual winters,and by the vari-able lengths of time of the zero curtains.At least one period of climate mini-cooling in the deeper permafrost during the early 20th century was noted.

Salinity effects on the 2014 warm “Blob” in the Northeast Pacific

A significant strong, warm “Blob”(a large circular water body with a positive ocean temperature anomaly) appeared in the Northeast Pacific (NEP) in the boreal winter of 2013 2014, which induced many extreme climate events in the US and Canada. In this study, analyses of the temperature and salinity anomaly variations from the Array for Real-time Geostrophic Oceanography (Argo) data provided insights into the formation of the warm “Blob” over the NEP. The early negative salinity anomaly dominantly contributed to the shallower mixed layer depth (MLD) in the NEP during the period of 2012 2013. Then, the shallower mixed layer trapped more heat in the upper water column and resulted in a warmer sea surface temperature (SST), which enhanced the warm “Blob”. The salinity variability contributed to approximately 60% of the shallowing MLD related to the warm “Blob”. The salinity anomaly in the warm “Blob” region resulted from a combination of both local and nonlocal effects. The freshened water at the surface played a local role in the MLD anomaly. Interestingly, the MLD anomaly was more dependent on the local subsurface salinity anomaly in the 100-150 m depth range in the NEP. The salinity anomaly in the 50-100 m depth range may be linked to the anomaly in the 100-150 m depth range by vertical advection or mixing. The salinity anomaly in the 100-150 m depth range resulted from the eastward transportation of a subducted water mass that was freshened west of the dateline, which played a nonlocal role. The results suggest that the early salinity anomaly in the NEP related to the warm “Blob” may be a precursor signal of interannual and interdecadal variabilities.

On the Response of the Global Subduction Rate to Global Warming in Coupled Climate Models

The response of the global subduction rate to global warming was assessed based on a set of Intergovernmental Panel on Climate Change （IPCC） Fourth Assessment Report （AR4） models. It was found that the subduction rate of the global ocean could be significantly reduced under a warming climate, as compared to a simulation of the present-day climate. The reduction in the subduction volume was quantitatively estimated at about 40 Sv and was found to be= primarily induced by the decreasing of the lateral induction term due to a shallower winter mixed layer depth. The shrinking of the winter mixed layer would result from intensified stratification caused by increased heat input into the ocean under a warming climate. A reduction in subduction associated with the vertical pumping term was estimated at about 5 Sv. F^rther, in the Southern Ocean, a significant reduction in subduction was estimated at around 24 Sv, indicating a substantial contribution to the weakening of global subduction.

Seasonal variability in the thermohaline structure of the Western Pacific Warm Pool

Using the 28℃ isotherm to define the Western Pacific Warm Pool （WPWP）, this study analyzes the seasonal variability of the WPWP thermohaline structure on the basis of the monthly-averaged sea temperature and salinity data from 1950 to 2011, and the dynamic and thermodynamic mechanisms based on the monthly-averaged wind, precipitation, net heat fluxes and current velocity data. A△T=-0.4℃ is more suitable than other temperature criterion for determining the mixed layer （ML） and barrier layer （BL） over the WPWP using monthly-averaged temperature and salinity data. The WPWP has a particular thermohaline structure and can be vertically divided into three layers, i.e., the ML, BL, and deep layer （DL）. The BL thickness （BLT） is the thickest, while the ML thickness （MLT） is the thinnest. The MLT has a similar seasonal variation to the DL thickness （DLT） and BLT. They are all thicker in spring and fall but thinner in summer. The temperatures of the ML and BL are both higher in spring and autumn but lower in winter and summer with an annual amplitude of 0.15℃, while the temperature of the DL is higher in May and lower in August. The averaged salinities at these three layers are all higher in March but lower in September, with annual ranges of 0.41-0.45. Zonal currents, i.e., the South Equatorial Current （SEC） and North Equatorial Counter Current （NECC）, and winds may be the main dynamic factors driving the seasonal variability in the WPWP thermohaline structure, while precipitation and net heat fluxes are both important thermodynamic factors. Higher （lower） winds cause both the MLT and BLT to thicken （thin）, a stronger （weaker） NECC induces MLT, BLT, and DLT to thin （thicken）, and a stronger （weaker） SEC causes both the MLT and BLT to thicken （thin） and the DLT to thin （thicken）. An increase （decrease） in the net heat fluxes causes the MLT and BLT to thicken （thin） but the DLT to thin （thicken）, while a stronger （weaker） precipitation favors thinner （thicker） MLT but thicker （thinner） BLT and DLT. In addition, a stronger （weaker） NECC and SEC cause the temperature of the three layers to decrease （increase）, while the seasonal variability in salinity at the ML, BL, and DL might be controlled by the subtropical cell （STC）.

温轧TWIP钢/高碳钢组织及力学性能研究

采用热轧-温轧工艺制备了孪生诱导塑性(TWIP)钢和高碳钢双层复合材料,通过金相显微镜、扫描电镜、电子探针等观察双层钢的显微组织与界面元素分布,发现两种材料界面结合良好、无缝隙和孔洞,Mn元素由TWIP钢侧向高碳钢侧扩散。复合材料热轧后进行铅浴处理,高碳钢区域形成细片状的索氏体组织,索氏体片层间距随铅浴温度升高而增大。520℃铅浴时平均片层间距为202 nm,抗拉强度为1592 MPa,延伸率9.9%,材料的综合力学性能较好。铅浴处理后的双层钢在300℃进行多道次温轧,进一步细化晶粒,产生位错增殖,抗拉强度随温轧压下量增大而增大,延伸率有所降低。轧制压下量达到70%时,高碳钢侧的索氏体片层间距进一步减小,TWIP钢侧发生剧烈塑性变形,晶粒沿轧制方向拉长。

增温对窄叶鲜卑花高寒灌丛生物量碳和氮分配的影响

文章以青藏高原东部窄叶鲜卑花灌丛为研究对象,采用开顶式生长室(OTCs)模拟增温实验(+1.2℃),分析增温对灌木层和草本层各器官碳、氮分配的影响及其影响因素,以揭示青藏高原东部高寒灌丛灌木层和草本层碳、氮分配对增温的响应策略。结果显示:(1)增温使窄叶鲜卑花灌木层叶、粗根、细根碳库显著增加18.8%、7.7%和139.4%,使灌木层细根氮库显著增加153.9%;增温使草本层地上和地下部分碳库显著增加60.4%和130.5%,使草本层地上和地下部分氮库显著增加46.1%和124.0%。(2)增温使灌木层茎和粗根碳分配比例显著降低18.9%和16.2%,使灌木层叶、茎和粗根氮分配比例显著降低25.2%、23.3%和14.4%,使灌木层细根碳、氮分配比例显著增加86.5%和96.2%;增温使草本层地上部分碳、氮分配比例显著降低19.5%和18.9%,使草本层地下部分碳、氮分配比例显著增加15.6%和24.8%。(3)Pearson相关分析和多元线性回归分析结果表明,空气温度和土壤微生物生物量是影响灌木层地上碳、氮分配的主要因子,能解释其变异的72.0%以上;土壤温度、土壤有机碳含量和土壤脲酶活性是影响灌木层地下碳、氮分配的主要因子,能解释其变异的92.0%以上;土壤有机碳含量、土壤转化酶和脲酶活性是影响草本层地上和地下碳、氮分配的主要因子,能解释其变异的92.8%以上。(4)土壤氮素有效性对灌木层和草本层生物量碳、氮分配的影响不显著。研究表明,气候变暖情景下,青藏高原东部窄叶鲜卑花高寒灌丛的灌木层和草本层植物通过提高地下部分碳、氮分配,进而更好地适应外界环境温度的提高。

气候变化背景下天目山落叶阔叶林乔木层1996—2017年动态研究

【目的】明确1996—2017年气候变化对天目山落叶阔叶林乔木层[胸径(DBH)≥10 cm的植株]的群落组成与结构、生物多样性和植物区系的影响。【方法】采用样地调查法对浙江天目山国家级自然保护区落叶阔叶林25个400 m2样地进行调查,使用2期(1996和2017年)调查数据和天目山1996—2017年气象数据,对落叶阔叶林乔木层动态进行分析。【结果】①乔木层树种生活型组成发生变化,常绿树种的株数占比从17.5%提高至35.5%,提高了102.9%,落叶树种的株数占比从82.5%下降至64.5%,下降了21.8%。群落外貌已悄然发生变化。②乔木层树种更替剧烈,整体退出4科6属8种,进入1科3属4种,退出和进入树种变幅达27.3%。稀有种和偶见种的退出和进入是引起乔木层物种数量变化的原因。③乔木层中不同树种的作用发生变化,重要值排前17位优势树种变幅为47.1%,其中,常绿树种交让木Daphniphyllum macropodum的重要值从第19位的1.88%增加到第3位的10.36%;常绿树种重要值占比从22.6%提高至36.3%。常绿树种在乔木层的作用正在不断增加。④乔木层α多样性稍有减少,各类指数降幅为−9.1%~−3.1%。常绿树种α多样性指数有所增加,变幅为−3.0%~51.8%。⑤植物区系趋于热带成分。科的热带成分占比从55.6%提高至58.3%;属的热带成分占比从25.0%提高至30.3%。⑥径级结构均呈倒“J”型,群落稳定;小径级常绿树种的株数提高了165.3%,中径级常绿树种的株数提高了45.5%,大径级无明显变化。1996年乔木层增长型树种有11种,稳定型树种有1种,衰退型树种有4种。2017年乔木层增长型树种有7种,稳定型树种有5种,衰退型树种没发生变化。短毛椴Tilia chingiana、青钱柳Cyclocarya paliurus、香槐Cladrastis wilsonii和色木槭Acer pictum退出增长型,进入稳定型。台湾松Pinus taiwanensis、细叶青冈Cyclobalanopsis shennongii、四照花Cornus kousa subsp.chinensis、交让木和天目槭Acer sinopurpurascens生长潜力增强。【结论】气候暖湿化背景下天目山落叶阔叶林乔木层动态变化非常显著,落叶阔叶林乔木层外貌已从落叶树种占据优势向常绿与落叶树种均衡状态演替,生物多样性稍有减少,植物区系趋向于热带成分。

纯镍挤压制造过程中的磨损行为和显微组织演变

挤压棒材表面形貌和显微组织是决定其力学性能的主要因素。本文作者采用现场挤压和有限元模拟相结合的方法,研究挤压工件的表面磨损行为及显微组织演化机制。结果表明,挤压温度对合金的表面形貌和显微组织有很大的影响。随着挤压温度的升高,磨损机制由磨粒磨损(脆性损伤)转变为粘着磨损(塑性损伤),并且表面粗糙度逐渐增大。挤压过程中坯料的温度和应力呈梯度分布,变形晶粒中的位错墙在激活的滑移系上运动,这导致层状结构产生变形。随着坯料梯度分布幅度和界面摩擦力的增大,层状结构变窄。此外,变形晶粒内几何必要位错的取向梯度也主导5种强理想织构。这些结果为纯镍及镍合金的精确挤压提供了理论依据。