The shallow meridional overturning circulation (upper 1000 m) in the northern Indian Ocean and its interannual variability are studied, based on a global ocean circulation model (MOM2) with an integration of 10 years ...The shallow meridional overturning circulation (upper 1000 m) in the northern Indian Ocean and its interannual variability are studied, based on a global ocean circulation model (MOM2) with an integration of 10 years (1987-1996). It is shown that the shallow meridional overturning circulation has a prominent seasonal reversal characteristic. In winter, the flow is northward in the upper layer and returns southward at great depth. In summer, the deep northward inflow upwells north of the equator and returns southward in the Ekman layer. In the annual mean, the northward inflow returns through two branches: one is a southward flow in the Ekman layer, the other is a flow that sinks near 10°N and returns southward between 500 m and 1000 m. There is significant interannual variability in the shallow meridional overturning circulation, with a stronger (weaker) one in 1989 (1991) and with a period of about four years. The interannual variability of the shallow meridional overturning circulation is intimately r展开更多
Aerosols are one of the important atmospheric constituents and exert indirect impact on climate through the modification of microphysical and radiative properties of clouds that in turn perturb the precipitation patte...Aerosols are one of the important atmospheric constituents and exert indirect impact on climate through the modification of microphysical and radiative properties of clouds that in turn perturb the precipitation pattern.Thus,the long term quantification of changes in aerosol and cloud characteristics and their interactions on both temporal as well as spatial scale will provide a crucial information for the better assessment of future climate change.In present study,18 years(2003-2020)MODerate Resolution Imaging Spectro-radiometer(MODIS)derived aerosol-cloud dataset over the Northern Indian Ocean(NIO)were analysed to assess climatology and trend of aerosol,cloud characteristics and their correlation.We found a strong heterogeneity in spatio-temporal variation of aerosol and cloud parameters over the NIO that are more prominent for the coastal region.The climatological mean of aerosol loading is found high(AOD≥0.5)over the outflow region along the Indian sub-continent and low(AOD≤0.2)over the northern equatorial open ocean.The climatological mean of cloud properties shows dominance of optically thicker deep convective(CTP<600 hPa and CTT<260 K)clouds over the southern Bay of Bengal(BoB)and thinner shallow(CTP>700 hPa and CTT>273 K)over the northwestern Arabian Sea(AS).Similarly,bigger effective radii(>17µm)observed along the equatorial open ocean whereas smaller CER(<17µm)were found over Indian sub-continental coastline and western AS.Further,trend analysis reveals an increasing pattern in AOD(0.002 yr^(-1)),CER(0.051µm yr^(-1)),LWP(0.033 gm^(-2) yr^(-1))and CF(0.002 yr^(-1))while COD,CTT and CTP show negative trend in order of-0.005 yr^(-1),-0.094 K yr^(-1) and-1.160 hPa yr^(-1),respectively.We also perform similar analysis for seven sub-region of interest(R1 to R7)across the NIO and results show a decreasing pattern in AOD(-0.001 yr^(-1))at R4 against maximum mean AOD(0.44±0.03).However,coastal sub-regions R1 and R5 illustrate maximum increase in aerosol loading(>0.003 yr^(-1))suggesting a significant impact of sub-continental outflow over the regions.The spatial correlation of cloud properties with respect to AOD shows a positive slope for CER(0.14)and CF(0.48)and a negative for COD(-0.19),LWP(-0.18),CTT(-0.37),CTP(-0.41).The present study provides in-depth information about the aerosol-cloud characteristics for a long term scale over NIO and could be useful in regional aerosol-cloud interaction induced climate forcing estimation.展开更多
Results are presented about the changes in chlorophyll a density, carbon fixation and nutrient levels in the surfacewaters of three transects of the southern South China Sea （SCS）, northern Java Sea （JS） and easte...Results are presented about the changes in chlorophyll a density, carbon fixation and nutrient levels in the surfacewaters of three transects of the southern South China Sea （SCS）, northern Java Sea （JS） and eastern Indian Ocean （IO） duringApril 5-16 of 2011. The in situ Chl a concentration and carbon fixation showed decreasing trends from high to low latitudealong the three transects, while the photosynthetic rate of phytoplankton estimated from 14C incorporation displayed no simplevariation with latitude. Chl a concentration and carbon fixation in the IO water was lower than that in the JS water. Highersalinity and lower contents of dissolved inorganic nitrogen （DIN） and silicate （SiO3^2-） characterized the IO water as comparedto the SCS or JS water, and the PO4^3- content was lower in the IO water than in the SCS or JS water in most cases. Our resultsalso indicate the importance of DIN and SiO3^2- concentrations for the geographical changes in phytoplankton biomass andprimary productivity among the three regions.展开更多
We objectively define the onset date of the South China Sea (SCS) summer monsoon, after having evaluated previous studies and considered various factors. Then, interannual and interdecadal characteristics of the SCS s...We objectively define the onset date of the South China Sea (SCS) summer monsoon, after having evaluated previous studies and considered various factors. Then, interannual and interdecadal characteristics of the SCS summer monsoon onset are analyzed. In addition, we calculate air-sea heat fluxes over the Indian Ocean using the advanced method of CORARE3.0, based on satellite remote sensing data. The onset variation cycle has remarkable interdecadal variability with cycles of 16 a and 28 a. Correlation analysis between air-sea heat fluxes in the Indian Ocean and the SCS summer monsoon indicates that there is a remarkable lag correlation between them. This result has important implications for prediction of the SCS summer monsoon, and provides a scientific basis for further study of the onset process of this monsoon and its prediction. Based on these results, a linear regression equation is obtained to predict the onset date of the monsoon in 2011 and 2012. The forecast is that the onset date of 2011 will be normal or 1 pentad earlier than the normal year, while the onset date in 2012 will be 1-2 pentads later.展开更多
对比两个同化资料GODAS(Global Ocean Data Assimilation System)和SODA(Simple Ocean Data Assimila-tion),考察中国科学院大气物理研究所大气科学和地球流体力学数值模拟国家重点实验室发展的气候系统海洋模式LICOM(LASG/IAP Climate ...对比两个同化资料GODAS(Global Ocean Data Assimilation System)和SODA(Simple Ocean Data Assimila-tion),考察中国科学院大气物理研究所大气科学和地球流体力学数值模拟国家重点实验室发展的气候系统海洋模式LICOM(LASG/IAP Climate system Ocean Model)模拟的北印度洋经向环流及热输送的气候态。LICOM能抓住北印度洋大尺度环流的季节变化特征,模拟的年平均越赤道热输送为-0.24 PW(1 PW=1015W),较之以往的数值模式结果更接近观测和同化资料。与同化资料的差异主要体现在季节变化强度,北半球夏季在赤道以南偏弱0.5 PW,这与模式夏季的纬向风应力偏弱,热输送中的大项Ekman热输送模拟偏弱,从而模拟的经圈翻转环流较浅有关。展开更多
基于2004—2018年Argo(Array for Real-Time Geostrophic Oceanography)浮标观测的温度、盐度数据,利用经验正交函数(EOF)分析和小波分析等方法对北印度洋(40°—105°E,5°S—25°N)障碍层时空分布特征进行分析。结果...基于2004—2018年Argo(Array for Real-Time Geostrophic Oceanography)浮标观测的温度、盐度数据,利用经验正交函数(EOF)分析和小波分析等方法对北印度洋(40°—105°E,5°S—25°N)障碍层时空分布特征进行分析。结果显示:北印度洋的东部常年存在障碍层,而西部障碍层出现的概率相对较低;较厚的障碍层出现在阿拉伯海东南部(67°—75°E,3°—12°N)、孟加拉湾(82°—93°E,11°—20°N)和赤道东印度洋(81°—102°E,4°S—3°N)。阿拉伯海东南部和孟加拉湾障碍层厚度以年变化为主,且呈同位相变化,均为冬季最大,夏季最小。赤道东印度洋区域则主要呈现半年周期变化,在夏季和冬季各出现一次峰值。进一步分析表明,孟加拉湾和赤道东印度洋障碍层厚度主要受等温层深度变化影响,混合层深度变化对障碍层厚度变化的影响相对较小;阿拉伯海障碍层厚度同时受等温层深度变化和混合层深度变化影响,其中等温层深度变化对其影响更大。展开更多
根据中国远洋渔业协会鱿钓技术组和公海围拖网技术组提供的2017—2019年印度洋北部鸢乌贼(Sthenoteuthis oualaniensis)生产统计资料,对灯光敷网、灯光罩网和鱿钓3种捕捞方式的鸢乌贼作业次数、产量和捕捞努力量渔获量(catch per unit e...根据中国远洋渔业协会鱿钓技术组和公海围拖网技术组提供的2017—2019年印度洋北部鸢乌贼(Sthenoteuthis oualaniensis)生产统计资料,对灯光敷网、灯光罩网和鱿钓3种捕捞方式的鸢乌贼作业次数、产量和捕捞努力量渔获量(catch per unit effort,CPUE)进行统计分析。通过产量重心分析、聚类分析和方差分析,对3种捕捞方式的渔场时空分布及其年间差异进行比较。结果表明,2017、2018和2019年印度洋北部鸢乌贼产量分别为28347、68535和180094t,产量逐年上升。从年间变化来看,CPUE波动较大;从月间变化来看,各月产量与CPUE的变化趋势均保持一致。3种捕捞方式各月产量重心呈现逆时针变化规律,从南到北,自东向西移动。通过聚类分析可将灯光敷网分为5类,灯光罩网分为4类,鱿钓分为6类;渔获量主要分布于12.5°N~14.5°N,58°E~60°E和16°N~18°N,61.5°E~63°E海域内。以时间和空间为影响因素,对不同经度间海域分析发现,CPUE在不同时间、空间上有明显差异;而不同捕捞方式也均存在显著差异。研究认为,今后应该加强时间序列的样本采集工作,综合考虑环境因子分析鸢乌贼渔场的变化规律及其根本原因,为后续合理开发该渔业和建立相关渔情预报模型提供依据。展开更多
基金This study was supported by National Natural Science Foundation of China(NSFC)under Grant No.40233033.
文摘The shallow meridional overturning circulation (upper 1000 m) in the northern Indian Ocean and its interannual variability are studied, based on a global ocean circulation model (MOM2) with an integration of 10 years (1987-1996). It is shown that the shallow meridional overturning circulation has a prominent seasonal reversal characteristic. In winter, the flow is northward in the upper layer and returns southward at great depth. In summer, the deep northward inflow upwells north of the equator and returns southward in the Ekman layer. In the annual mean, the northward inflow returns through two branches: one is a southward flow in the Ekman layer, the other is a flow that sinks near 10°N and returns southward between 500 m and 1000 m. There is significant interannual variability in the shallow meridional overturning circulation, with a stronger (weaker) one in 1989 (1991) and with a period of about four years. The interannual variability of the shallow meridional overturning circulation is intimately r
文摘Aerosols are one of the important atmospheric constituents and exert indirect impact on climate through the modification of microphysical and radiative properties of clouds that in turn perturb the precipitation pattern.Thus,the long term quantification of changes in aerosol and cloud characteristics and their interactions on both temporal as well as spatial scale will provide a crucial information for the better assessment of future climate change.In present study,18 years(2003-2020)MODerate Resolution Imaging Spectro-radiometer(MODIS)derived aerosol-cloud dataset over the Northern Indian Ocean(NIO)were analysed to assess climatology and trend of aerosol,cloud characteristics and their correlation.We found a strong heterogeneity in spatio-temporal variation of aerosol and cloud parameters over the NIO that are more prominent for the coastal region.The climatological mean of aerosol loading is found high(AOD≥0.5)over the outflow region along the Indian sub-continent and low(AOD≤0.2)over the northern equatorial open ocean.The climatological mean of cloud properties shows dominance of optically thicker deep convective(CTP<600 hPa and CTT<260 K)clouds over the southern Bay of Bengal(BoB)and thinner shallow(CTP>700 hPa and CTT>273 K)over the northwestern Arabian Sea(AS).Similarly,bigger effective radii(>17µm)observed along the equatorial open ocean whereas smaller CER(<17µm)were found over Indian sub-continental coastline and western AS.Further,trend analysis reveals an increasing pattern in AOD(0.002 yr^(-1)),CER(0.051µm yr^(-1)),LWP(0.033 gm^(-2) yr^(-1))and CF(0.002 yr^(-1))while COD,CTT and CTP show negative trend in order of-0.005 yr^(-1),-0.094 K yr^(-1) and-1.160 hPa yr^(-1),respectively.We also perform similar analysis for seven sub-region of interest(R1 to R7)across the NIO and results show a decreasing pattern in AOD(-0.001 yr^(-1))at R4 against maximum mean AOD(0.44±0.03).However,coastal sub-regions R1 and R5 illustrate maximum increase in aerosol loading(>0.003 yr^(-1))suggesting a significant impact of sub-continental outflow over the regions.The spatial correlation of cloud properties with respect to AOD shows a positive slope for CER(0.14)and CF(0.48)and a negative for COD(-0.19),LWP(-0.18),CTT(-0.37),CTP(-0.41).The present study provides in-depth information about the aerosol-cloud characteristics for a long term scale over NIO and could be useful in regional aerosol-cloud interaction induced climate forcing estimation.
基金National Natural Science Foundation of China(41206132,41276162,41130855)Chinese Academy of Sciences Strategic Pilot Science and Technology(XDA11020202,XDA05030403)+2 种基金National Project of Basic Sciences and Technology(2012FY112400,2013FY111200)Chinese Academy of Sciences Knowledge Innovation Program(SQ201115)Natural Science Foundation of Guangdong Province(S2011040000151)
文摘Results are presented about the changes in chlorophyll a density, carbon fixation and nutrient levels in the surfacewaters of three transects of the southern South China Sea （SCS）, northern Java Sea （JS） and eastern Indian Ocean （IO） duringApril 5-16 of 2011. The in situ Chl a concentration and carbon fixation showed decreasing trends from high to low latitudealong the three transects, while the photosynthetic rate of phytoplankton estimated from 14C incorporation displayed no simplevariation with latitude. Chl a concentration and carbon fixation in the IO water was lower than that in the JS water. Highersalinity and lower contents of dissolved inorganic nitrogen （DIN） and silicate （SiO3^2-） characterized the IO water as comparedto the SCS or JS water, and the PO4^3- content was lower in the IO water than in the SCS or JS water in most cases. Our resultsalso indicate the importance of DIN and SiO3^2- concentrations for the geographical changes in phytoplankton biomass andprimary productivity among the three regions.
基金Supported by the Knowledge Innovation Program of Chinese Academy of Sciences (No. KZCX2-YW-Q11-02)
文摘We objectively define the onset date of the South China Sea (SCS) summer monsoon, after having evaluated previous studies and considered various factors. Then, interannual and interdecadal characteristics of the SCS summer monsoon onset are analyzed. In addition, we calculate air-sea heat fluxes over the Indian Ocean using the advanced method of CORARE3.0, based on satellite remote sensing data. The onset variation cycle has remarkable interdecadal variability with cycles of 16 a and 28 a. Correlation analysis between air-sea heat fluxes in the Indian Ocean and the SCS summer monsoon indicates that there is a remarkable lag correlation between them. This result has important implications for prediction of the SCS summer monsoon, and provides a scientific basis for further study of the onset process of this monsoon and its prediction. Based on these results, a linear regression equation is obtained to predict the onset date of the monsoon in 2011 and 2012. The forecast is that the onset date of 2011 will be normal or 1 pentad earlier than the normal year, while the onset date in 2012 will be 1-2 pentads later.
文摘对比两个同化资料GODAS(Global Ocean Data Assimilation System)和SODA(Simple Ocean Data Assimila-tion),考察中国科学院大气物理研究所大气科学和地球流体力学数值模拟国家重点实验室发展的气候系统海洋模式LICOM(LASG/IAP Climate system Ocean Model)模拟的北印度洋经向环流及热输送的气候态。LICOM能抓住北印度洋大尺度环流的季节变化特征,模拟的年平均越赤道热输送为-0.24 PW(1 PW=1015W),较之以往的数值模式结果更接近观测和同化资料。与同化资料的差异主要体现在季节变化强度,北半球夏季在赤道以南偏弱0.5 PW,这与模式夏季的纬向风应力偏弱,热输送中的大项Ekman热输送模拟偏弱,从而模拟的经圈翻转环流较浅有关。
文摘基于2004—2018年Argo(Array for Real-Time Geostrophic Oceanography)浮标观测的温度、盐度数据,利用经验正交函数(EOF)分析和小波分析等方法对北印度洋(40°—105°E,5°S—25°N)障碍层时空分布特征进行分析。结果显示:北印度洋的东部常年存在障碍层,而西部障碍层出现的概率相对较低;较厚的障碍层出现在阿拉伯海东南部(67°—75°E,3°—12°N)、孟加拉湾(82°—93°E,11°—20°N)和赤道东印度洋(81°—102°E,4°S—3°N)。阿拉伯海东南部和孟加拉湾障碍层厚度以年变化为主,且呈同位相变化,均为冬季最大,夏季最小。赤道东印度洋区域则主要呈现半年周期变化,在夏季和冬季各出现一次峰值。进一步分析表明,孟加拉湾和赤道东印度洋障碍层厚度主要受等温层深度变化影响,混合层深度变化对障碍层厚度变化的影响相对较小;阿拉伯海障碍层厚度同时受等温层深度变化和混合层深度变化影响,其中等温层深度变化对其影响更大。
文摘根据中国远洋渔业协会鱿钓技术组和公海围拖网技术组提供的2017—2019年印度洋北部鸢乌贼(Sthenoteuthis oualaniensis)生产统计资料,对灯光敷网、灯光罩网和鱿钓3种捕捞方式的鸢乌贼作业次数、产量和捕捞努力量渔获量(catch per unit effort,CPUE)进行统计分析。通过产量重心分析、聚类分析和方差分析,对3种捕捞方式的渔场时空分布及其年间差异进行比较。结果表明,2017、2018和2019年印度洋北部鸢乌贼产量分别为28347、68535和180094t,产量逐年上升。从年间变化来看,CPUE波动较大;从月间变化来看,各月产量与CPUE的变化趋势均保持一致。3种捕捞方式各月产量重心呈现逆时针变化规律,从南到北,自东向西移动。通过聚类分析可将灯光敷网分为5类,灯光罩网分为4类,鱿钓分为6类;渔获量主要分布于12.5°N~14.5°N,58°E~60°E和16°N~18°N,61.5°E~63°E海域内。以时间和空间为影响因素,对不同经度间海域分析发现,CPUE在不同时间、空间上有明显差异;而不同捕捞方式也均存在显著差异。研究认为,今后应该加强时间序列的样本采集工作,综合考虑环境因子分析鸢乌贼渔场的变化规律及其根本原因,为后续合理开发该渔业和建立相关渔情预报模型提供依据。
