热带次表层海温对中国东部夏季气候的影响

热带海洋热状况是影响中国气候变化的主要因子之一,为了研究热带次表层海温如何影响中国气候,通过相关计算和合成分析等方法讨论了热带太平洋至印度洋次表层海温异常对中国东部夏季降水和温度的影响。结果表明:当冬季赤道东印度洋至西太平洋次表层海温偏暖(偏冷),中印度洋和东太平洋次表层海温偏冷(偏暖),夏季,长江中下游地区降水偏少(偏多),华南、华北和东北大部地区降水偏多(偏少);中国东部大范围高温(低温)。其可能的影响途径为,东亚夏季风环流对热带次表层海温异常的响应导致了其年际变化,进而引起中国东部夏季气候的异常分布。     

Different Responses of Sea Surface Temperature in the North Pacific to Greenhouse Gas and Aerosol Forcing

The responses of Sea Surface Temperature(SST) to greenhouse gas(GHG) and anthropogenic aerosol in the North Pa- cific are compared based on the historical single and all-forcing simulations with Geophysical Fluid Dynamics Laboratory Climate Model version 3(GFDL CM3). During 1860–2005, the effect of GHG forcing on the North Pacific SST is opposite to that of the aerosol forcing. Specifically, the aerosol cooling effect exceeds the GHG warming effect in the Kuroshio Extension(KE) region dur- ing 1950–2004 in the CM3 single forcing. The mid-latitude response of ocean circulation to the GHG(aerosol) forcing is to enhance(weaken) the Subtropical Gyre. Then the SST warming(cooling) lies on the zonal band of 40?N because of the increased(reduced) KE warm advection effect in the GHG(aerosol) forcing simulations, and the cooling effect to SST will surpass the warming effect in the KE region in the historical all-forcing simulations. Besides, the positive feedback between cold SST and cloud can also strengthen the aerosol cooling effect in the KE region during boreal summer, when the mixed layer depth is shallow. In the GHG(aerosol) forcing simulations, corresponding to warming(cooling) SST in the KE region, the weakened(enhanced) Aleutian Low appears in the Northeast Pacific. Consequently, the SST responses to all-forcing in the historical simulations are similar to the re- sponses to aerosol forcing in sign and spatial pattern, hence the aerosol effect is quite important to the SST cooling in the mid-latitude North Pacific during the past 55 years.     

Blend with the Sea Surface Temperature from Different Satellites and Their Comparison in the Southeast Pacific Ocean

The daily sea surface temperature(SST) data from three kinds of different satellites of GMI, GOES and MODIS were applied to do the blend in the Southeast Pacific Ocean throughout the whole year of 2020. The coverage rates of the SST of the blend result were improved highly and more stable throughout the whole year, compared with the result of the single satellite of GMI,GOES, and MODIS. The yearly average coverage rates of GMI, GOES, MODIS, and blend were 43%, 48%, 30%, and 76%, and their corres...     

北极海冰范围时空变化及其与海温气温间的数值分析

本文利用美国国家冰雪中心提供的1989-2014年海冰范围资料,分析了北极海冰范围的年际变化和季节变化规律。分析发现,北极海冰范围呈减少趋势,每年减小\begin{array}{c}5.91\times {10}^4\mathit{k}{m}^2\end{array},夏季减少趋势显著,冬季减少趋势弱。北极海冰范围显现相对稳定的季节变化规律,海冰的结冰和融化主要发生在各个边缘海,夏季期间的海冰具有融化快、冻结快的特征。结合海温、气温数据,进行北极海冰范围与海温、气温间的数值分析,结果表明北极海冰范围变化通过影响北极海温变化进而影响北极气温变化。海冰范围的季节变化滞后于海温和气温的季节变化。基于北极考察走航海温气温数据,进行楚科奇海海冰范围线与海温气温间的数值分析,发现楚科奇海海冰范围线所在区域的海温、气温与纬度高低、离陆地远近有关。     

Seasonal Variations of Terrestrial OC Sources in Aerosols over the East China Sea: The Influence of Long-Range Air Mass Transport

Aerosols represent an important source of terrestrial organic carbon (OC) from the East Asian continent to the China marginal seas,thus their provenance and transport play important roles in the global carbon cycle.Fifty samples of total suspended particle were collected seasonally from the nearshore Huaniao Island (HNI) in East China Sea (ECS) from April 2018 to January2019;and they were analyzed for total organic carbon (TOC) content and stable carbon isotope (δ~(13)C),as well as terrestrial biomarkers including n-alkanes (C_(20)-C_(33)),n-alkanols (C_(20)-C_(32)) and n-fatty acids (n-FAs,C_(20)-C_(30)),to distinguish the seasonal variabilities of terrestrial OC sources and reveal the influence of the long-range air mass transport on these sources.The TOC-δ~(13)C values(range from-27.3‰to-24.3‰) and molecular distributions of terrestrial biomarkers both suggested that terrestrial OC contributions to aerosols had significant seasonal variations.The source indices of terrestrial biomarkers (e.g.,Fossil%=82.8%for n-alkanes)revealed that the fossil fuel OC contributions,including coal burning and vehicular emission,were higher in winter,mainly because of the long-range air mass transport from the north of the East Asian continent.The terrestrial plant OC contributions were higher in summer (e.g.,Wax%=32.4%for n-alkanes),likely due to local vegetation sources from HNI and East Asian continental air masses.Cluster analysis of air mass backward-trajectories clearly showed that transport pathway plays an important role in determining the organic constituents of aerosols in China marginal seas.A comparison of these terrestrial OC contributions from different air mass origins suggested that fossil fuel OC showed less variations among various air mass origins from northern China in winter,while terrestrial plant OC sources from northern and southern China in summer contributed more than that from the air masses transported through the ECS.These results provided a basis for future quantification of terrestrial OC from different origins in marine aerosols,by combining biomarker index and carbon isotopes.     

Predictability of Chinese Summer Extreme Rainfall Based on Arctic Sea Ice and Tropical Sea Surface Temperature

Chinese summer extreme rainfall often brings huge economic losses, so the prediction of summer extreme rainfall is necessary. This study focuses on the predictability of the leading mode of Chinese summer extreme rainfall from empirical orthogonal function(EOF) analysis. The predictors used in this study are Arctic sea ice concentration(ASIC) and regional sea surface temperature(SST) in selected optimal time periods. The most important role that Arctic sea ice(ASI) plays in the appearance of EOF1 may be strengthening the high pressure over North China, thereby preventing water vapor from going north. The contribution of SST is mainly at low latitudes and characterized by a significant cyclone anomaly over South China. The forecast models using predictor ASIC(PA), SST(PS), and the two together(PAS) are established by using data from 1980 to 2004. An independent forecast is made for the last 11 years(2005-2015). The correlation coefficient(COR) skills between the observed and cross-validation reforecast principal components(PC) of the PA, PS, and PAS models are 0.47, 0.66, and 0.76, respectively. These values indicate that SST is a major cause of Chinese summer extreme rainfall during 1980-2004. The COR skill of the PA model during the independent forecast period of 2004-2015 is 0.7, which is significantly higher than those of the PS and PAS models. Thus, the main factor influencing Chinese summer extreme rainfall in recent years has changed from low latitudes to high latitudes. The impact of ASI on Chinese summer extreme rainfall is becoming increasingly significant.     

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 39 020.63 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.     

Characteristics of Vertical Distributions of Fatty Acids in Surface Sediments of the Yellow Sea and East China Sea

Fatty acids(FAs) in sediment collected from three different stations in the Yellow Sea and the East China Sea were analyzed for their distributions and to determine evidence of harmful algal blooms in the sediment core.Less diverse FAs were found in the Yellow Sea(YS) station,whereas in the two stations of the East China Sea(ECS) the FAs were more diverse.Concentrations of some FA species in the two ECS stations displayed an occasional surge in their vertical profile.The highest concentration of FAs was found in the surface layer of station QT3(43.28 μg g~(-1)).Monounsaturated FAs were more susceptible to degradation compared to their saturated counterparts,and changes of 16:0,18:2 and 20:5 accounted for the most variability in total concentrations of FAs as those species made up most of the quantified FAs.The origins of the major fraction of FAs were attributed to autotrophic sources,and bacterial FAs accounted for only a small fraction of the total FAs in the region.Nutrient availability was a possible regulating factor controlling bacteria abundances in marine sediments in the ECS and the YS.A principal component analysis(PCA) was applied to analyze the FA dataset and to reveal the principal environmental factors that control the composition of FAs in the sediments.PC2,which explains 15% of the variance,was estimated to reflect the diagenetic effects on the FA compositional changes in sediments influenced by bacterial degradation.     

不同时间尺度的西北太平洋海洋表面温度距平模态的比较

本文利用经验正交分解法(Empirical Orthogonal Function,EOF)对不同月平均和10天平均的西北太平洋海洋表面温度距平数据进行分解,得到月平均和10天平均的西北太平洋海洋表面温度距平分布模态,并对分布模态进行比较。发现尽管数据源相同,但是不同时间分辨率的EOF结果出现正好相反的情况,文章最后从数学的角度解释了月平均和10天平均的海洋表面温度距平模态及其时间系数发生反向的原因。     

The Contribution of Opal-Associated Phosphorus to Bioavailable Phosphorus in Surface and Core Sediments in the East China Sea

To improve the burial flux calculations of bioavailable phosphorus(P) and study opal-associated P(Opal-P) in the East China Sea(ECS), surface and core sediments were collected in the Changjiang Estuary(CE) and the south of the Cheju Island. In this study, sedimentary P was operationally divided into seven different forms using modified sedimentary extraction(SEDEX) technique: LSor-P(exchangeable or loosely sorbed P), Fe-P(easily reducible or reactive ferric Fe-bound P), CFA-P(authigenic carbonate fluorapatite and biogenic apatite and CaCO_3-bound P), Detr-P(detrital apatite), Org-P(organic P), Opal-P and Ref-P(refractory P). The data revealed that the concentrations of the seven different P forms rank as Detr-P CFA-P Org-P Ref-P Opal-P Fe-P LSor-P in surface sediments and CFA-P Detr-P Org-P Ref-P Fe-P Opal-P LSor-P in core sediments. The distributions of the total phosphorus(TP), TIP, CFA-P, Detr-P are similar and decrease from the CE to the south of the Cheju Island. Meanwhile, Org-P and Opal-P exhibit different distribution trends; this may be affected by the grain size and TOM. The concentrations of potentially bioavailable P are 9.6-13.0 μmol g~(-1) and 10.0-13.6 μmol g~(-1), representing 61%-70% and 41%-64% of the TP in surface and core sediments, respectively. The concentrations of Opal-P are 0.6-2.3 μmol g~(-1) and 0.6-1.4 μmol g~(-1) in surface and core sediments, accounting for 5.3%-19.8% and 4.2%-10.6% of bioavailable P, respectively. The total burial fluxes of Opal-P and bioavailable P are 1.4×10~9 mol yr~(-1) and 1.1×10~10 mol yr~(-1) in the ECS, respectively. Opal-P represents about 12.7% of potentially bioavailable P, which should be recognized when studying P cycling in marine ecosystems.     

Variations in Dissolved Methane in the Yellow Sea During the Spring Algal Blooms of 2009

Methane(CH_4) is an important greenhouse gas and oceans are net sources of atmospheric CH_4. The effects of environmental factors on the CH_4 variation during different phases of the spring algal blooms were examined during two cruises conducted in the Yellow Sea(YS) from February to April of 2009. During the pre-bloom period from February to March, low CH_4 saturation( 134%) was observed in the surface water, except at two nearshore stations where the CH_4 levels were above 140% in March due to mixing with the coastal water. During the bloom period, CH_4 increased obviously at two bloom-tracking stations, especially at the surface with mean saturations of 140% and 170%. The increase in CH_4 concentration/saturation is thought to be the result of in situ CH_4 production. The particulate organic carbon(POC) and chlorophyll a contents were believed to be important factors that influenced the CH_4 production. In addition, the presence of different dominant phytoplankton species and the grazing pressure may have stimulated the CH_4 production by supplying potential methanogenic substrates(such as dimethylsulphoniopropionate(DMSP)). Both the incubation data and the in situ estimations further evidenced the significant influence of the spring blooms on the CH_4 production. The calculated sea-to-air CH_4 fluxes during the bloom period were not significantly higher than those during the pre-bloom period despite the bloom-increased CH_4 saturation. This is due to the variation in physical forcing(such as wind speed), which is the main driver for determining the CH_4 flux. Finally, we estimated the annual CH_4 flux in the YS as 9.0 μmol m~(-2) d~(-1); the findings suggest that the YS is a natural source of atmospheric CH_4.     

Two Different Dust Storms in Northeast China:the Sources and Influences in East Asia

Dust storms in Northeast China become more se-rious in recent years due to the global warming and local land use and cover change (LUCC) around the sand lands in western and northwestern Jilin Province. Field investigations and urban testing re-vealed that the amount of dusts brought by dust storm reaches a higher level in the past two years. According to an experiment on the “mud-snow”in April, 2000 and an observation in March, 2002, the dusts coming from the western Jilin and fall…     

Two Different Dust Storms in Northeast China:the Sources and Influences in East Asia

There are two different dust storms in Northeast China, normal dust and alkali dust, from Kerqin sand land and Songnen saline land. As well as visible damages of the dust storms, there are some invisible influences. The authors provide evidences that the bacteria carried by dusts from remote area should not be ignored, but the damages of the alkali dusts are still not clear.     

Surface diurnal warming in the East China Sea derived from satellite remote sensing

Process of sea surface diurnal warming has drawn a lot of attention in recent years, but that occurs in shelf seas was rarely addressed. In the present work, surface diurnal warming strength in the East China Sea was calculated by the sea surface temperature(SST) data derived from the MODIS sensors carried by the satellites Aqua and Terra. Due to transit time difference, both the number of valid data and the surface diurnal warming strength computed by the MODIS-Aqua data are relatively larger than Terra. Therefore, the 10-year MODIS-Aqua data from 2005 to 2014 were used to analyze the monthly variability of the surface diurnal warming. Generally, the surface diurnal warming in the East China sea is stronger in summer and autumn but weaker in winter and spring, while it shows different peaks in different regions. Large events with ΔT≥5 K have also been discussed. They were found mainly in coastal area, especially near the Changjiang(Yangtze) River estuary. And there exists a high-incidence period from April to July. Furthermore, the relationship between surface diurnal warming and wind speed was discussed. Larger diurnal warming mainly lies in areas with low wind speed. And its possibility decreases with the increase of wind speed. Events with ΔT ≥2.5 K rarely occur when wind speed is over 12 m/s. Study on surface diurnal warming in the East China Sea may help to understand the daily scale air-sea interaction in the shelf seas. A potential application might be in the marine weather forecasts by numerical models. Its impact on the coastal eco-system and the activities of marine organisms can also be pursued.     

Effects of spectral nudging on the 2010 East Asia summer monsoon using WRF model

The performance of spectral nudging in an investigation of the 2010 East Asia summer monsoon was assessed using the Weather Research and Forecasting (WRF) model, forced by 1-degree NCEP Global Final Analysis (FNL). Two pairs of experiments were made, spectral nudging (SP) and non-spectral nudging (NOSP), with five members in each group. The members were distinguished by different initial times, and the analysis was based on the ensemble mean of the two simulation pairs. The SP was able to constrain error growth in large-scale circulation in upper-level, during simulation, and generate realistic regional scale patterns. The main focus was the model ability to simulate precipitation. The Tropical Rainfall Measuring Mission (TRMM) 3B42 product was used for precipitation verification. Mean precipitation magnitude was generally overestimated by WRF. Nevertheless, SP simulations suppressed overestimation relative to the NOSP experiments. Compared to TRMM, SP also improved model simulation of precipitation in spatial and temporal distributions, with the ability to reproduce movement of rainbands. However, extreme precipitation events were suppressed in the SP simulations.     

The suspended sediment concentration distribution in the Bohai Sea, Yellow Sea and East China Sea

The distribution of the suspended sediment concentration (SSC) in the Bohai Sea, Yellow Sea and East China Sea (BYECS) is studied based on the observed turbidity data and model simulation results. The observed turbidity results show that (i) the highest SSC is found in the coastal areas while in the outer shelf sea areas turbid water is much more difficult to observe, (ii) the surface layer SSC is much lower than the bottom layer SSC and (iii) the winter SSC is higher than the summer SSC. The Regional Ocean Modeling System (ROMS) is used to simulate the SSC distribution in the BYECS. A comparison between the modeled SSC and the observed SSC in the BYECS shows that the modeled SSC can reproduce the principal features of the SSC distribution in the BYECS. The dynamic mechanisms of the sediment erosion and transport processes are studied based on the modeled results. The horizontal distribution of the SSC in the BYECS is mainly determined by the current-wave induced bottom stress and the fine-grain sediment distribution. The current-induced bottom stress is much higher than the wave-induced bottom stress, which means the tidal currents play a more significant role in the sediment resuspension than the wind waves. The vertical mixing strength is studied based on the mixed layer depth and the turbulent kinetic energy distribution in the BYECS. The strong winter time vertical mixing, which is mainly caused by the strong wind stress and surface cooling, leads to high surface layer SSC in winter. High surface layer SSC in summer is restricted in the coastal areas.     

Distributions of sulfur pollutants in East Asia

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基于卫星测高和卫星遥感海面温度探测的南海中尺度涡旋对比分析

基于海表面温度数据和海面高度异常数据,采用矢量几何法提取南海的中尺度涡旋并进行统计分析。结果显示,从海表面温度和海面高度异常数据都可以提取涡旋,两者的提取能力差异很小。由海表面温度数据可以提取较小尺度的涡旋,但跟踪涡旋时存在不稳定性;由海面高度异常数据虽然不能检测到较小尺度的涡旋,但跟踪涡旋相对稳定。两种数据所提取涡旋的时间和空间分布规律具有一致性。     

基于Landsat TM影像不同地表温度反演算法的比较

地表温度是反映地表环境的一个重要参数,精确获取地表温度的方法对研究城市热岛效应、进行生态环境监测评价是必不可少的。利用遥感手段进行地表温度的反演是一种较新颖的方法,相对成熟的反演算法主要有单通道算法、辐射传输方程法及单窗算法。本文以山东省威海市Landsat TM数据为例,分别利用辐射传输方程法和单窗算法进行地表温度反演,通过遥感目视解译的方法提取研究区各类典型地物对应的地表温度,进行统计分析,结果表明,两者反演得到的地表温度具有一致的变化趋势,其中单窗算法中不同典型地物的地表温度整体标准差较小,如建设用地为0.530,起伏波动小,算法精度略优于辐射传输方程法。