Characterizing Potential Fishing Zone of Skipjack Tuna during the Southeast Monsoon in the Bone Bay-Flores Sea Using Remotely Sensed Oceanographic Data

Potential fishing zones for skipjack tuna in the Bone Bay-Flores Sea were investigated from satellite-based oceanography and catch data, using a linear model (generalized linear model) constructed from generalized additive models and geographic information systems. Monthly mean remotely sensed sea surface temperature and surface chlorophyll-a concentration during the southeast monsoon (April-August) were used for the year 2012. The best generalized additive model was selected to assess the effect of marine environment variables (sea surface temperature and chlorophyll-a concentration) on skipjack tuna abundance (catch per unit effort). Then, the appropriate linear model was constructed from the functional relationship of the generalized additive model for generating a robust predictive model. Model selection process for the generalized additive model was based on significance of model terms, decrease in residual deviance, and increase in cumulative variance explained, whereas the model selection for the linear model was based on decrease in residual deviance, reduction in Akaike’s Information Criterion, increasing cumulative variance explained and significance of model terms. The best model was selected to predict skipjack tuna abundance and their spatial distribution patterns over entire study area. A simple linear model was used to verify the predicted values. Results indicated that the distribution pattern of potential fishing zones for skipjack during the southeast monsoon were well characterized by sea surface temperatures ranging from 28.5℃ to 30.5 ℃ and chlorophyll-a ranging from 0.10 to 0.20 mg·m-3. Predicted highest catch per unit efforts were significantly consistent with the fishing data (P 2 = 0.8), suggesting that the oceanographic indicators may correspond well with the potential feeding ground for skipjack tuna. This good feeding opportunity for skipjack was driven the dynamics of upwelling operating within study area which are capable of creating a highly potential fishing zone during the southeast monsoon.

Climatology and Interannual Variability of the Southeast Asian Summer Monsoon

In this paper, results from a pilot study for the South China Sea Monsoon Experiment are reported. Based on analyses of 9 years of pentad and monthly mean data, the climatology of subseasonal features and interannual variability of the Southeast Asian monsoon (SEAM) are documented. The present analysis is focused on the sudden onset of the South China Sea monsoon and its relation to the atmospheric and oceanic processes on the entire Asian monsoon region. \ \ It is found that the onset of the SEAM occurs around mid-May, signaling the earliest stage of the entire Asian summer monsoon system. The establishment of monsoon rainfall over the South China Sea is abrupt, being accompanied by substantial changes in the large scale atmospheric circulation and sea surface temperature in the adjacent oceans. The onset and fluctuations of SEAM involve the interaction and metamorphosis of the large scale convection over the Indo-China, the South China Sea and the southern Bay of Bengal. Results show that the onset time of the SEAM differs greatly from one year to another. The delayed (advanced) onset of the monsoon may be related to basin-wide warm (cold) events of the Pacific and Indian Oceans. We also present evidence showing that the SEAM fluctuations in May may foreshadow the development of the full-scale Asian summer monsoon during the subsequent months.

Eurasian Snow Conditions and Summer Monsoon Rainfall over South and Southeast Asia: Assessment and Comparison

This study reveals the complex nature of the connection between Eurasian snow and the following summer season＇s monsoon rainfall by using four different indicators of snow conditions and correlating each of them to summer monsoon rainfall. Using 46 years of historical records of mean winter snow depth, maximum snow depth, and snow starting dates, and 27 years of snow area coverage from remote sensing observations over Eurasia, the authors found diverse correlation patterns between snow conditions and the following warm season＇s rainfall over South and Southeast Asia. Some of the results contradict the well-known inverse relationships between snow and the summer monsoon. This study provides an easy comparison of results in that it shows the connections between Eurasian snow and monsoon rainfall by using different Eurasian snow indicators based on the best available historical records without discrimination of regional variations in snow conditions.

Teleconnection between Winter Arctic Oscillation and Southeast Asian Summer Monsoon in the Pre-Industry Simulation of a Coupled Climate Model

A 600-year pre-industrial simulation with Bergen Climate Model(BCM)Version 2 is used to investigate the linkage between winter Arctic Oscillation(AO)and the Southeast Asian summer monsoon(SEASM)on the inter-decadal timescale.The results indicate an in-phase relationship between the AO and SEASM with periods of approximately 16–32 and 60–80 years.During the positive phase of winter AO,an anomalous surface anti-cyclonic atmosphere circulation appears over North Pacific in winter.The corresponding anomalies in ocean circulation and surface heat flux,particularly the latent and sensible heat flux,resemble a negative Pacific Decadal Oscillation(PDO)-like sea surface temperature(SST)pattern.The AO-associated PDO-like winter SST can persist into summer and can therefore lead to inter-decadal variability of summer monsoon rainfall in East and Southeast Asia.

Effect of climate change on seasonal monsoon in Asia and its impact on the variability of monsoon rainfall in Southeast Asia

Global warming and climate change is one of the most extensively researched and discussed topical issues affecting the environment.Although there are enough historical evidence to support the theory that climate change is a natural phenomenon,many research scientists are widely in agreement that the increase in temperature in the 20 th century is anthropologically related.The associated effects are the variability of rainfall and cyclonic patterns that are being observed globally.In Southeast Asia the link between global warming and the seasonal atmospheric flow during the monsoon seasons shows varying degree of fuzziness.This study investigates the impact of climate change on the seasonality of monsoon Asia and its effect on the variability of monsoon rainfall in Southeast Asia.The comparison of decadal variation of precipitation and temperature anomalies before the 1970 s found general increases which were mostly varying.But beyond the 1970 s,global precipitation anomalous showed increases that almost corresponded with increases in global temperature anomalies for the same period.There are frequent changes and a shift westward of the Indian summer monsoon.Although precipitation is observed to be 70%below normal levels,in some areas the topography affects the intensity of rainfall.These shifting phenomenon of other monsoon season in the region are impacting on the variability of rainfall and the onset of monsoons in Southeast Asia and is predicted to delay for 15 days the onset of the monsoon in the future.The variability of monsoon rainfall in the SEA region is observed to be decadal and the frequency and intensity of intermittent flooding of some areas during the monsoon season have serious consequences on the human,financial,infrastructure and food security of the region.

Impact of El Nino on Large-scale Circulation of Southeast Asian Summer Monsoon

Multi-year SST and NCEP/NCAR reanalyzed wind data were employed to study the impacts of El Nio on the Southeast Asian summer monsoon (SEASM). It was found that the impacts of El Nio on the SEASM differed distinctly from those on the East Asian summer monsoon (EASM) and the Indian summer monsoon (ISM). Composite analysis indicated that the "gear point" of coupling between the Indo-monsoon circulation and the Pacific-Walker circulation was located in the western margins of Southeast Asia when the developing stage of El Nio events covered the boreal summer. The anomalous circulations in the lower and upper troposphere and divergent circulation are all favorable for the strengthening of the SEASM during this period. Following the evolution of El Nio, the "gear point" of the two cells shifted eastward to the central Pacific when the mature or decaying period of El Nio events covered the boreal summer. The anomalous circulations are favorable for the weakening of the SEASM. The anomalous indexes of intensity of SEASM accord well with the above results. Additionally, the difference of SSTA patterns in the tropical Indo-Pacific Ocean between the two stages of the El Nio may play an important role.

IMPACTS OF THE ONSET OF THE SOUTHEAST ASIAN SUMMER MONSOON ON THE BEGINNING OF THE RAINY SEASON IN YUNNAN

Summer monsoon in Southeast Asia can cause large-scale precipitation in the region in early summer, which is featured by prevailing low-level southwesterly from the Bay of Bengal to South China Sea （SCS）. It has characteristics of its own as well as those of Asian monsoons in general. As found in studies over recent years on East Asian monsoons, the earliest onset of the Southeast Asian summer monsoon occurs in early summer over the SCS, among all members of the monsoon system. It then advances westward to India and northward to eastern China, Japan and Korean Peninsula. As pointed out by Lau and Yang121, the end of April is the earliest time when the Asian monsoon sets up at the southern tip of Indo-china Peninsula. Being the earliest signal for the whole summer monsoon system in Asia, it may be of some predictive value for the establishment of Asian summer monsoon （ASM）.

Satellite observations of coastal upwelling in the northern Arafura Sea

Coastal upwelling is significant for marine ecosystems by lifting nutrient-rich deep waters into the euphotic zone,thereby increasing primary and secondary productivity.The satellite observations show that the northern Arafura Sea(NAS),especially in the coastal region,features high chlorophyll-a(chl-a)concentrations,implying a strong coastal upwelling.However,coastal upwelling in the NAS has not received much attention.Based on a semi-automatic image processing technology,the seasonal and interannual variability of coastal upwelling in the NAS are investigated in this study using satellite-observed sea surface temperature(SST)and wind data.The results suggest that there are seasonal coastal upwelling events in the NAS modulated by upwelling-favorable southeast monsoon(SEM).The annual mean days,mean area,and annual mean intensity of coastal upwelling events during the SEM season are 92 days,6514 km^(2),and-5.31×10^(5),respectively,while the corresponding values during the northwest monsoon(NWM)season are 32 days,5569 km^(2),and-1.41×10^(5).It is also found that the SEM coastal upwelling in the NAS displays prominent interannual variability.The strong upwelling events are found in 2010,2013,2016,and 2017 when the southeast monsoon winds were weaker.Further analysis suggests that at the interannual scale,the upwelling index(UI)averaged in the SEM season is negatively correlated with that of three upwelling indicators.This can be attributed to the limitation of onshore geostrophic flow which is evidenced by the negative correlation between the UI and the alongshore difference in sea surface height.This study highlights the important role of the southeast monsoon in the temporal variability of coastal upwelling in the NAS.

季风吹拂的土地:东南亚生态电影与全球南方主义

全球生态美学的表述与实践大多源于全球北方,但全球南方呈现出独特的美学特征与认识论模式,蕴含着比全球北方更具批判性的政治潜能。从以东南亚为代表的全球南方的角度来看待人类世的新兴生态电影美学,主要呈现为幽灵影像、季风影像和盖娅影像三个方面。当生态已经成为超越国族疆界而逐渐走向去政治化的生物区域主义的时候,东南亚电影将生态问题置入全球南方框架下,进而变得再政治化了。同时,它们启示我们必须成为生态电影类型学中的行动者,即从批判实践走向社会行动,以此书写自己的地球奥德赛。

近30余年来盛夏东亚东南季风和西南季风频率的年代际变化及其与青藏高原积雪的关系

利用地面观测资料和NCEP/NCAR再分析资料集,使用相关分析、合成分析等方法,在将地面风分为东南季风和西南季风的基础上,分析了近30余年来盛夏东亚季风频率的年代际变化特征。结果表明:盛夏东南季风、西南季风频率和前期春季青藏高原积雪均在21世纪初期发生了显著的年代际变化;东南季风、西南季风频率由较少改变为较多,春季青藏高原积雪则由深变浅。由于青藏高原积雪厚度发生了年代际变浅,说明青藏高原发生了年代际变暖和南亚高压变强,南亚高压的年代际变强,使得其下游对流层低层(18°~28°N,108°~118°E)的反气旋性环流异常增强,有利于东亚西南季风频率的增加;同时,由于高原发生湿反馈作用,使得淮河地区降水发生年代际变多,由Sverdrup涡度平衡关系,降水的异常增多通过潜热释放,使得东亚副热带高压异常加强,而副热带高压异常变强则有利于盛夏东亚东南季风频率发生年代际增加。

江西九江地区晚更新世生态变迁的土壤有机质碳同位素证据

根据我国江西九江地区４个土壤剖面的土壤有机质及其δ１３Ｃ值的分析结果，认为末次冰期旋回内生态转型是由于季风效应和ＣＯ２共同作用的表现；北大西洋末次冰期内的Ｈｅｉｎｒｉｃｈ事件对中国东部的气候也产生剧烈的影响，其分布直接控制着Ｃ３和（或）Ｃ４植物的转型及其沉积物的类型．ＣＯ２及其温室气体可能是Ｈｅｉｎｒｉｃｈ事件的重要驱动因素之一．

东南亚地区夏季风异常对云南2005年初夏干旱的影响

2005年春末夏初云南大部地区出现了50年一遇的高温干旱天气,通过对东南亚地区的水汽及对流进行诊断分析,发现中南半岛地区夏季风爆发的早迟与云南雨季开始的早迟有显著的正相关关系;前期4月孟加拉湾水汽向北输送强(弱)以及苏门答腊岛附近的对流活动强(弱),则云南雨季开始早(迟)。分析表明造成云南2005年初夏干旱的主要原因是中南半岛地区的夏季风爆发较常年偏晚,前期孟加拉湾地区的经向水汽输送以及苏门答腊岛附近的对流活动较常年偏弱。

东南亚地区夏季风爆发对云南雨季开始的影响

东南亚地区的夏季风在亚洲季风系统中首先爆发后,通过风场与对流场的变化对周边地区造成影响。通过对亚洲近地面层经向水汽通道的研究,发现在前期影响云南雨季开始的早迟最重要的一支南风水汽通道位于孟加拉湾(80～90°E)附近。该南风水汽通道一般在春季开始建立,它的建立有助于夏季风在东南亚地区爆发。在季风建立前,当这一水汽通道中南风水汽输送异常偏强时,相应地中南半岛附近的对流也增强,对应着云南的雨季开始偏早,初夏降水偏多,反之则初夏降水偏少。研究表明,该水汽输送的强弱可以作为预报云南雨季开始期及初夏雨量的一个重要信号。研究还发现,前期赤道中东太平洋的冷海温有利于孟加拉湾经向水汽输送的加强,从而影响到云南的雨季开始和初夏的雨量。

1979年5月东南亚夏季风的建立和青藏高原的作用

东南亚夏季风开始于５月，它是大气环流向夏季环流过渡的一个重要阶段。本文用ＦＧＧＥ－ＩＩｂ全球网格点资料，分析１９７９年４月２６日到５月２５日，大范围（４０°Ｓ～５０°Ｎ，３０～１６０°Ｅ）温度、湿度和风场变化特征，计算了垂直速度、辐散风场、热源和水汽汇收支，研究了东南亚夏季风的性质和来源，其中着重分析了青藏高原的热力和动力作用与东南亚夏季风建立的关系。东南亚夏季风建立的主要因素是中纬度的环流形势，来自热带海洋的西南气流和青藏高原的作用。东南亚夏季风开始时，高空大气环流发生调整，青藏高原上空为波脊，两侧为波槽。低空东南亚夏季风区的辐合气流有四个来源：１）同经度范围的偏南辐散风，２）高原南侧的偏西辐散风，３）高原东侧的偏北辐散风，４）西太平洋上的偏东辐散风。分析表明，东南亚夏季风降水受高原西南侧的中纬度西风带波动影响。低空西南气流来源于８０～１２０°Ｅ的南半球热带地区，西南气流输送水汽并且加强低空辐合。主要的热源位于东南亚，主要是潜热释放形成的，它是驱动东南亚夏季风环流的主要机制。整个分析期，青藏高原是一热源，抬升的感热加热和动力作用形成和维持了高原上空的高压脊和两侧的波槽，从而有助于东南亚夏季风的建立。

厦门和福州季风气候特点差异的初步分析

厦门、福州季风气候的特点,与华北温带季风气候不同,也与华南热带季风气候不同.而且两地本身季风特点也有差异,表现在各时期季风的强弱、规模、进退、消长的程度不同,反映在气温、降水等天气变化上,同时也指出不同季风季的季风,有其冷暖不同的气团源地,进而分析了两地季风气候特点差异的原因.

西藏两个小湖高分辨率的花粉记录

西藏东南部封闭湖泊高分辨率的花粉记录反映，在１６ ｋａ ＢＰ以前花粉组合以藜科（Ｃｈｅｎｏｐｏｄｉａｃｅａｅ） 和蒿属（Ａｒｔｅｍｉｓｉａ） 为主，花粉浓度很低，应为荒漠草原植被。当时气候寒冷干燥，１ 、７ 月份和年均温分别低于现在当地７ ～１０ ℃，０．５～１．５ ℃和４～６ ℃。年降水量仅２５０ ｍｍ 是现今当地年降水量的４０ ％ ；１２ ｋａ ＢＰ以后气温和降水逐渐增加，出现木本植物花粉，桦属（ Ｂｅｔｕｌａ） 和松属（ Ｐｉｎｕｓ）等，在９ ．２～５ ｋａ ＢＰ发育森林或森林草甸；８～６ ｋａ ＢＰ是研究区气候最适宜期，１、７ 月份气温均高于现在２～３ ℃，年降水量比现在当地高１００ ｍｍ 左右；５．５ ｋａ ＢＰ以后气温和降水呈非线性下降，主要发育草原植被。

热带海温异常对东南亚夏季风爆发的影响

通过季风指数Im定义了能表征东南亚地区降水实况的东南亚夏季风指数,根据东南亚夏季风指数测算出东南亚夏季风爆发的平均时间为5月7日。利用东南亚夏季风指数分析热带海温场及垂直速度场的变化后发现,在东南亚夏季风爆发的前期秋、冬季节,中东太平洋地区以及中西印度洋地区的冷海温有利于东南亚地区夏季风的提前爆发。当中东太平洋地区是冷(暖)海温时,对应着纬向的Walker环流及季风环流圈强(弱),东南亚地区的对流也强(弱),则东南亚地区夏季风爆发早(迟)。

1994年6月中国东南部夏季风的两次北跳

利用美国国家环境预报中心(NCEP)1994年6月格点资料,对我国东南部夏季风的发展和演变进行了分析,并且与夏季风发展正常的1979年的相应结果作了比较.研究结果表明:1994年6月我国东南部夏季风的推进十分异常,出现了2次突变性的北跳,在第一次北跳后季风发生了南退现象.在季风正常的1979年6月,季风只出现了1次北跳.与季风的2次北跳相对应,我国东南部与夏季风相联系的暖湿气团、雨带以及最大正涡度区也出现了2次突变性的北跳,而且时间上相当一致.1994年6月西太平洋副热带高压和对流层上层的南亚高压也出现了2次突变性的北跳,但其北跳时间要比我国东南部夏季风的北跳略早一些;南亚高压第一次北跳尚未跳上高原,南支西风急流仍然维持,亚洲环流形势仍然为冬季形势,南下强冷空气与华南、江南的夏季风交汇导致了华南、江南的暴雨.1979年6月西太平洋副热带高压和南亚高压只出现了一次北跳.

南海夏季风建立的数值模拟试验

利用中国科学院大气物理研究所全球谱模式(T42L9)对南海夏季风建立的过程进行了数值模拟试验.试验结果表明:通过青藏高原的动力作用和东南亚地区强大的潜热加热产生印度洋上跨赤道的偏南辐散风、高原南侧的偏西辐散风、高原东侧的偏北辐散风和西太平洋上的偏东辐散风,这4支散度流加强南海海域大尺度低空辐合,南海的雨季和西南季风爆发.

东南亚夏季风中断、过渡与活跃期的区域能量学研究

对两次季风演变过程的能量学研究表明，季风演变具有鲜明的阶段性能量学特征。中断期，积云加热小，两个转换函数值很小；过渡期，积云加热增强明显，两个转换函数值迅速加大，边界输送作用也明显朝有利方向变化，同时，纬向平均气流变为向季风供应扰动动能；活跃期，大尺度加热变得重要，积云加热维持，两个转换函数也保持大的正值。分析表明，印度季风东传对东南亚季风活跃的触发作用是重要的，但季风活跃的维持则主要依靠区域内部能量学过程。