A POSSIBLE IMPACT OF EL NIO MODOKI ON SEA SURFACE TEMPERATURE OF CHINA'S OFFSHORE AND ITS ADJACENT REGIONS

El Nio Modoki,similar to but different from canonical El Nio,has been observed since the late1970s.In this paper,using HadISST and NCEP/NCAR wind data,we analyze the relationship between El Nio Modoki and Sea Surface Temperature(SST)in the offshore area of China and its adjacent waters for different seasons.Our results show a significant negative correlation between El Nio Modoki in summer and SST in autumn in the offshore area of China and its adjacent waters,particularly for regions located in the east of the Kuroshio.It is also found that during El Nio Modoki period,anomalous northerlies prevail over the regions from the northern part of the Philippines to the offshore area of China,indicating that the northerlies are unfavorable for the transport of warm water from the western tropical Pacific to the mid-latitude area.Consequently,El Nio Modoki in summer may play a substantial role in cold SST anomalies in the offshore area of China and its adjacent waters in autumn through the influence of the Kuroshio,with a lagged response of the ocean to the atmospheric wind field.     

Remote quantification of phycocyanin in potable water sources through an adaptive model

Cyanobacterial blooms in water supply sources in both central Indiana USA (CIN) and South Australia (SA) are a cause of great concerns for toxin production and water quality deterioration. Remote sensing provides an effective approach for quick assessment of cyanobacteria through quantification of phycocyanin (PC) concentration. In total, 363 samples spanning a large variation of optically active constituents (OACs) in CIN and SA waters were collected during 24 field surveys. Concurrently, remote sensing reflectance spectra (R_rs) were measured. A partial least squares–artificial neural network (PLS–ANN) model, artificial neural network (ANN) and three-band model (TBM) were developed or tuned by relating the R_rs with PC concentration. Our results indicate that the PLS–ANN model outperformed the ANN and TBM with both the original spectra and simulated ESA/Sentinel-3/Ocean and Land Color Instrument (OLCI) and EO-1/Hyperion spectra. The PLS–ANN model resulted in a high coefficient of determination (R²) for CIN dataset (R² = 0.92, R: 0.3–220.7 μg/L) and SA (R² = 0.98, R: 0.2–13.2 μg/L). In comparison, the TBM model yielded an R² = 0.77 and 0.94 for the CIN and SA datasets, respectively; while the ANN obtained an intermediate modeling accuracy (CIN: R² = 0.86; SA: R² = 0.95). Applying the simulated OLCI and Hyperion aggregated datasets, the PLS–ANN model still achieved good performance (OLCI: R² = 0.84; Hyperion: R² = 0.90); the TBM also presented acceptable performance for PC estimations (OLCI: R² = 0.65, Hyperion: R² = 0.70). Based on the results, the PLS–ANN is an effective modeling approach for the quantification of PC in productive water supplies based on its effectiveness in solving the non-linearity of PC with other OACs. Furthermore, our investigation indicates that the ratio of inorganic suspended matter (ISM) to PC concentration has close relationship to modeling relative errors (CIN: R² = 0.81; SA: R² = 0.92), indicating that ISM concentration exert significant impact on PC estimation accuracy.     

A three-band semi-analytical model for deriving total suspended sediment concentration from HJ-1A/CCD data in turbid coastal waters

The accurate assessment of total suspended sediment (TSM) concentration in coastal waters by means of remote sensing is quite challenging, due to the optical complexity and significant variability of these waters. In this study, three-band semi-analytical TSM retrieval (TSTM) model with HJ-1A/CCD spectral bands was developed for the retrieval of TSM concentration from turbid coastal waters. This model was calibrated and validated by means of one calibration dataset and three independent validation datasets obtained from three different turbid waters. It was found that the TSTM model may be used to retrieve accurate TSM concentration data from highly turbid waters without the spectral slope of the model requiring further optimization. Finally, the TSM concentration data were quantified from the HJ-1A/CCD images after atmospheric correction using the dark-object subtraction technique. Upon comparing the model-derived and field-measured TSM concentration data, it was observed that the TSTM model produced <29% uncertainty in deriving TSM concentration from the HJ-1A/CCD data. These findings imply that the TSTM model may be used for the quantitative monitoring of TSM concentration in coastal waters, provided that the atmospheric correction scheme for the HJ-1A/CCD imagery is available.     

中国近海温带气旋的时空变化特征

基于1979-2012年共34年的ECMWF逐日4次平均海平面气压的再分析资料,采用英国雷丁大学气旋客观追踪算法,对出现在我国近海的温带气旋(气旋生命史1d以上,移动距离大于500km)的时空分布特征进行统计分析。结论包括以下几点:(1)1979-2012年进入中国近海的温带气旋平均每年45个,气旋数量呈现春夏多而秋冬少的特点。20世纪90年代初至今,气旋数量呈增加趋势,其中北部海区气旋数量增加达到显著水平,东部海区气旋数量表现为不显著减少,故认为影响中国近海的气旋路径有北移的趋势。(2)进入我国近海的温带气旋主要有4个生成源地,按比例由高到低分别是江淮气旋(38.9%),东海气旋(25.2%),黄河气旋(24.3%)以及蒙古气旋(11.6%)。气旋入海后,当大气海洋条件适合时,可以爆发性增长,气旋爆发性增长的主要区域在朝鲜半岛及以东洋面以及日本以东洋面,在我国近海气旋爆发的比例较小。(3)气旋生命史主要为1~7d,但生命史为1~4d的气旋比例最大,平均占气旋总数的52%,其中夏季长生命史气旋(大于10d)的比例最大,为8%,冬季最少,接近3%。冬季气旋最强,气压分布区间大;夏季弱气旋多,中心气压分布集中。     

1972-2013年北欧海深层水增暖

The warming of deep waters in the Nordic seas is identified based on observations during Chinese 5th Arctic Expedition in 2012 and historical hydrographic data. The most obvious and earliest warming occurrs in the Greenland Basin(GB) and shows a coincident accelerated trend between depths 2 000 and 3 500 m. The observations at a depth of 3 000 m in the GB reveal that the potential temperature had increased from-1.30°C in the early 1970 s to-0.93°C in 2013, with an increase of about 0.37°C(the maximum spatial deviation is 0.06°C) in the past more than 40 years. This remarkable change results in that deep waters in the center of the Lofton Basin(LB) has been colder than that in the GB since the year 2007. As for the Norwegian Basin(NB), only a slight trend of warming have been shown at a depth around 2 000 m since the early 1980 s, and the warming amplitude at deeper waters is just slightly above the maximum spatial deviation, implying no obvious trend of warming near the bottom. The water exchange rate of the Greenland Basin is estimated to be 86% for the period from 1982 to 2013, meaning that the residence time of the Greenland Sea deep water(GSDW) is about 35 years. As the weakening of deep-reaching convection is going on, the abyssal Nordic seas are playing a role of heat reservoir in the subarctic region and this may cause a positive feedback on the deep-sea warming in both the Arctic Ocean and the Nordic seas.     

天津近岸海域海水富营养化评价及其主成分分析

于2013年7月对天津近岸海域海水营养盐和叶绿素a等水质因子进行采样调查,运用营养状态质量指数法和富营养化指数法对该海域海水富营养化水平进行评价,采用主成分分析法得出海水富营养化的驱动因子。结果表明,调查海域80.95%站位的无机氮以及61.90%站位的活性磷酸盐为劣四类海水水质;营养状态质量指数法评价与富营养化指数法评价结果基本一致:在北塘入海口周围近岸海域指数最高,其次为子牙新河入海口周围近岸海域,远岸海域的指数较低;影响调查海域海水富营养化的驱动因子为总氮和总磷。     

Winter distribution of diatom assemblages along the coastline of R. O. Korea in 2010

Diatoms are a globally successful and eukaryotic photosynthetic organism with an ornamented silica external wall. The relationship between their valve morphology and habitat means that diatoms can be used as bioindicators to characterize the aquatic environment. To estimate the differential distribution and diversity of diatom assemblages along the coastal line, we collected phytoplankton samples from 114 coastal sites of waters of R. O. Korea. We applied the unweighted pair-group technique usin...     

舟山西堠门水道潮流能资源评估及发电站选址

声音在儒艮的生命活动中起着重要的作用。为了研究儒艮发声的类型和特征,2019年3月20日至28日,在泰国立邦岛附近海域(99°25''E,7°13''N)对儒艮进行了被动声学监测。本文对泰国海域儒艮发声信号进行了细致分类,并统计了每种类型声信号的特征。将在立邦岛海域获取的野生儒艮发声信号划分为4种类型:chirp、trill、bark和 whistle。统计每种类型中高信噪比、轮廓清晰且无重叠的信号特征,结果表明:chirp为简单的窄带调频信号,持续时间大约为0.09s,基频介于0.99~12.84kHz,谐波数量为1~5;trill为调频信号,持续时间较长,一般大于0.90s,基频介于0.97~9.89kHz,有1~5次谐波;bark持续时间约0.20s,带宽范围为0.20~4.00kHz,whistle被定义为chirp和trill之间的一种过渡信号,其持续时间为0.05~0.89s,基频为1.11~7.69kHz,有1~5次谐波。这4种类型声信号所占比例各不相同,其中chirp信号占最高(比超过86%),trill和 whistle信号占比较低(分别约为7%和6%),bark信号占比最小(不到1%)。研究儒艮声信号类型和特征有利于分析儒艮的声行为,对野生儒艮的声学监测具有重要指导意义。     

内陆水体藻蓝蛋白遥感反演研究进展

藻蓝蛋白(PC),作为蓝藻的标志性色素,通常被用作进行蓝藻水华遥感监测的标志物.近年来,内陆水体水质恶化,富营养化加剧,藻华频发,PC遥感反演研究越来越受到关注.本文从PC光学特性、反演算法开发、卫星传感器应用等方面难点及干扰因素,综合梳理了过去30 a PC遥感反演研究的发展历程和趋势,以期理解国内外相关研究的新思路...     

浙北沿岸海域海面风场反演方法的研究

高质量的海面实况风场是海洋气象监测和预报的基础,卫星反演的大陆沿岸海域海面风场的准确率不高。文章基于反映近地面风速廓线变化的指数律公式,利用浙江北部沿岸海岛或滩涂上布设的中尺度自动站来反演附近海面风场,并使用客观分析方法将反演的离散风场值转换到中尺度网格上,从而获得完整的高分辨率海面风场。指数律中参数α值对于反演风场的准确率至关重要,它主要受到下垫面状况以及大气层结状态的影响,而后者的影响较前者更大。文章使用多个风塔站的风廓线率值进行了反演风场的误差试验,结果表明:目前单一风速廓线还无法取得最优的反演效果,有必要分季节使用多站风速廓线。使用混合风速廓线得到的总体样本的平均偏差为0.04 m·s~(-1),平均绝对误差为1.51 m·s~(-1),均方根误差为2.01 m·s~(-1)。对海面反演风场的优化可以将总体样本的平均绝对误差和均方根误差分别降低到1.28和1.68 m·s~(-1)。