影响东海气候的太阳活动信息分析

采用逐次滤波法逐次提取东海气温资料序列中蕴涵的太阳活动影响信息并加以分析,发现东海气候年代际变化特征十分清楚,主要表现为:(1)突变性,东海夏季7月海平面层及对流层大气温度场在过去半个多世纪中发生过一次急剧变化,突变点是1978年7月.从1978年7月由历时30多年的温度偏低时期跃变为持续高温时期,高温期持续至20世纪末,升温幅度超过0.4℃.资料分析表明,整个对流层东海夏季大气温度都具有这种年代际变化特征;(2)高空气候持续增温型,东海夏季7月平流层中部10 hPa大气温度表现为一种波动式的持续升温过程,50多年来温度升高4℃,年升温率超过0.075℃/a.东海平流层底部100 hPa温度也具有持续升温的特点,从1948年至今呈缓慢升高的趋势,53 a升高了1.9℃,升温率为0.036℃/a;(3)周期性,东海不同高度大气温度都具有显著程度不同的22 a周期性年代际变化特征,22 a周期分量的振幅由高空到低空迅速减小,表明22 a周期高空清楚,低空不太明显.东海对流层中部和平流层底部还具有显著的11 a周期性年代际变化.据分析认为22 a周期是太阳黑子磁场磁性变化周期所激发,11 a周期与太阳黑子相对数11 a周期相吻合,二者均为太阳活动在大气气候中的反映.

Relationship between East China Sea Kuroshio and Climatic Elements in East China

Using long term observation data in the main part of East China Sea Kuroshio, variations of Kuroshio upper layer temperature and salinity, their relationships with surface temperature and precipitation in east China are studied. Results reveal that the Kuroshio upper layer temperature experienced slight rise while salinity decreased in the past 50 years. In winter, Kuroshio upper layer temperature is closely related to the surface temperature in east China, and large area in east China shows positive correlation to the Kuroshio upper layer temperature, which might be related to the mass temperature reduction as a result of the cold air activities in winter. In summer, the increase of the precipitation causes the increase of diluted Yangtze River water into the shelf sea, thereby results in the salinity decrease of Kuroshio in the upper layer.

Study on the Seasonal Variation of the Suspended Sediment Distribution and Transportation in the East China Seas Based on SeaWiFS Data

The monthly mean suspended sediment concentration in the upper layer of the East China Seas was derived from the retrieval of the monthly binned SeaWiFS Level 3 data during 1998 to 2006. The seasonal variation and spatial distribution of the suspended sediment concentration in the study area were investigated. It was found that the suspended sediment distribution presents apparent spatial characteristics and seasonal variations, which are mainly affected by the resuspension and transportation of the suspended sediment in the study area. The concentration of suspended sediment is high inshore and low offshore, and river mouths are generally high concentration areas. The suspended sediment covers a much wider area in winter than in summer, and for the same site the concentration is generally higher in winter. In the Yellow and East China Seas the suspended sediment spreads farther to the open sea in winter than in summer, and May and October are the transitional periods of the extension. Winds, waves, currents, thermocline, halocline, pycnocline as well as bottom sediment feature and distribution in the study area are important influencing factors for the distribution pattern. If the 10rag L^-1 contour line is taken as an indicator, it appears that the transportation of suspended sediment can hardly reach 124^o00＇E in summer or 126^o00＇E in winter, which is due to the obstruction of the Taiwan Warm Current and the Kuroshio Current in the southern Yellow Sea and the East China Sea.

An Analysis of the Causes of Decadal Variations of Rainfall in Shandong in Summer

The precipitation in Shandong in July, August as well as the whole summer (JJA) and the corresponding 500 hPa geopotential height fields are analyzed by means of the SVD (singular value decomposition) methodology. It is found that the general circulations in East Asia and the Western Pacific underwent decadal changes around 1979. The geopotential height, in particular over key areas like the South China Sea and the Philippines, increased after 1979. Corresponding to the changes in the geopotential height, the rainfall in Shandong started to decrease around 1979. The synthesized analysis shows that when the geopotential height at 500hPa level decreases in the key areas, the Western Pacific subtropical high shifts northward and an anticyclonic anomalous cell enforces the southerly flow over Shandong-Korea-Japan, Shandong could experience a wet period. A dry period is likely to occur when the geopotential height increases in these key areas, the subtropical high moves southward or expands westward to a great distance, and a cyclonic anomalous cell controls Shandong. Respective conceptual models for the causative mechanism are obtained for the cases of July, August and the whole summer (JJA) .

Warming trend in northern East China Sea in recent four decades

Global warming has become a notable trend especially since an abrupt climate change in 1976. Response of the East China Sea （ECS） to the global warming trend, however, is not well understood because of sparse long-term observation. In this paper, hydrographic observation data of 1957-1996 are collected and reviewed to study climatological variability in northern ECS. Significant warming trends are found in both summer and winter. In summer, the average SST is about 0.46℃ higher during the period of 1977-1996 than that of 1957-1976, and the Taiwan Warm Current Water （TWCW） was strengthened. In winter, despite of the cooling effect in the coastal areas adjacent to the Changjiang （Yangtze） River Estuary （CRE）, the average SST increase was about 0.53℃ during the same period. The causes of this SST warming up in summer are different from in winter. The warming trend and intensification of the TWCW in summer were primarily influenced by the strengthening of the Kuroshio transport, while the warming in winter was mainly induced by the variability of the climate system.

Impact of Sea Surface Temperature Front on Stratus-Sea Fog over the Yellow and East China Seas-A Case Study with Implications for Climatology

A stratus-sea fog event that occurred over the Yellow and East China Seas on 3 June 2011 is investigated using observations and a numerical model, with a focus on the effects of background circulation and Sea Surface Temperature Front （SSTF） on the transition of stratus into sea fog. Southerly winds of a synoptic high-pressure circulation transport water vapor to the Yellow Sea, creating conditions favorable for sea fog/stratus formation. The subsidence from the high-pressure contributes to the temperature inversion at the top of the stratus. The SSTF forces a secondary circulation within the ABL （Atmospheric Boundary Layer）, the sinking branch of which on the cold flank of SSTF helps lower the stratus layer fiLrther to reach the sea surface. The cooling effect over the cold sea surface counteracts the adiabatic warming induced by subsidence. The secondary circulation becomes weak and the fog patches are shrtmk heavily with the smoothed SSTE A conceptual model is proposed for the transition of stratus into sea fog over the Yellow and East China Seas. Finally, the analyses suggest that sea fog frequency will probably decrease due to the weakened SSTF and the reduced subsidence of secondary circulation under global wanning.

Monsoon-Ocean Coupled Modes in the South China Sea and Their Linkage with the Eastern Indian Ocean-Western Pacific Warm Pool

Monsoon-ocean coupled modes in the South China Sea （SCS） were investigated by a combined singular value decomposition （CSVD） analysis based on sea surface temperature （SST） and sea surface wind stress （SWS） fields from SODA （Simple Ocean Data Assimilation） data spanning the period of 1950-1999. The coupled fields achieved the maximum correlation when the SST lagged SWS by one month, indicating that the SCS coupled system mainly reflected the response of the SST to monsoon forcing. Three significant coupled modes were found in the SCS, accounting for more than 80% of the cumulative squared covariance fraction. The first three SST spatial patterns from CSVD were： （Ⅰ） the monopole pattern along the isobaths in the SCS central basin; （Ⅱ） the north-south dipole pattern; and （Ⅲ） the west-east seesaw pattern. The expansion coefficient of the SST leading mode showed interdecadal and interannual variability and correlation with the Indo-Pacific warm pool （IPWP）, suggesting that the SCS belongs to part of the IPWP at interannual and interdecadal time scales. The second mode had a lower correlation coefficient with the warm pool index because its main period was at intra-annual time scales instead of the interannual and interdecadal scales with the warm pools. The third mode had similar periods to those of the leading mode, but lagged the eastern Indian Ocean warm pool （EIWP） and western Pacific warm pool （WPWP） by five months and one year respectively, implying that the SCS response to the warm pool variation occurred from the western Pacific to the eastern Indian Ocean, which might have been related to the variation of Indonesian throughflow. All three modes in the SCS had more significant correlations with the EIWP, which means the SCS SST varied much more coherently with the EIWP than the WPWP, suggesting that the SCS belongs mostly to part of the EIWP. The expansion coefficients of the SCS SST modes all had negative correlations with the Nino3 index, which they lag by several months, indicating a remote response of SCS SST variability to the El Nifio events.

Relations between Low-Frequency Modes of Climate Variability and Air-Sea Heat Flux at the Mediterranean Interface

The main objective of this work is to examine statistical causality relationships between low-frequency modes of climate variability and winter （December to February） anomaly of net heat flux at the Mediterranean air-sea interface. The introduction of the concept of Granger causality allowed us to examine the influence of these climates indices on the net heat flux anomaly and to select Mediterranean surface regions that really influenced by each index. Results show that the winter anomaly of the net heat flux in the Algerian basin south and the gulf of Lion is mainly caused by the Arctic Oscillation. El Nifio-Southern Oscillation influences much more the Algerian basin north and the northern lonian Sea. The Quasi-Biennial Oscillation affects only the Alboran and the Tyrrhenian Seas. But the Adriatic and Levantine basin are impacted by any climate index. They also show that these climate indices can increase explained variance in winter variations of air-sea net heat flux by 10% to 15%, with a lag of three seasons. These relationships are less persistent and spatially limited.

Holocene Temperature Records from the East China Sea Mud Area Southwest of the Cheju Island Reconstructed by theU_(37)~K~' and TEX_(86) Paleothermometers

As an important marginal sea under the influences of both the Changjiang River and the Kuroshio, the East China Sea （ECS） environment is sensitive to both continental and oceanic forcing. Paleoenvironmental records are essential for understanding the long-term environmental evolution of the ECS and adjacent areas. However, paleo-temperature records from the ECS shelf are currently very limited. In this study, the U^K_37 and TEX86 paleothermometers were used to reconstruct surface and subsurface temperature changes of the mud area southwest of the Cheju Island （Site F10B） in the ECS during the Holocene. The results indicate that temperature changes of F 10B during the early Holocene （11.6-6.2 kyr） are associated with global climate change. During the period of 6.2-2.5 kyr, the similar variability trends of smoothing average of AT （the difference between surface and subsurface temperature） of Site F10B and the strength of the Kuroshio suggest that the Kuroshio influence on the site started around 6.2kyr when the Kuroshio entered the Yellow Sea and continued to 2.5 kyr. During the late Holocene （2.5-1.45 kyr）, apparent decreases of U^K_37 sea surface temperature （SST） and AT imply that the direct influence of the Kuroshio was reduced while cold eddy induced by the Kuroshio gradually controlled hydrological conditions of this region around 2.5 kyr.

An East Asian Monsoon in the Mid-Pliocene

In this study, the authors simulate the East Asian climate changes in the mid-Pliocene (～3.3 to 3.0 Ma BP) with the Community Atmosphere Model version 3.1 (CAM3.1) and compare the simulated East Asian monsoon with paleoclimate data. The simulations show an obvious warming pattern in East Asia in the mid-Pliocene compared with the pre-industrial climate, with surface air temperature increasing by 0.5 4.0°C. In the warm mid-Pliocene simulation, the East Asian Summer Monsoon (EASM) becomes stronger, while the East Asian Winter Monsoon (EAWM) is similar relative to the pre-industrial climate. Compared with the paleoclimate data, our simulations depict the intensified EASM well but cannot reproduce the weakened EAWM. This model-data discrepancy may be attributed to the uncertainty in the reconstructed mid-Pliocene sea surface temperature.

Swells of the East China Sea

Over the past few decades,an increasing number of marine activities have been conducted in the East China Sea,including the construction of various marine structures and the passage of large ships.Marine safety issues are paramount and are becoming more important with respect to the likely increase in size of ocean waves in relation to global climate change and associated typhoons.In addition,swells also can be very dangerous because they induce the resonance of floating structures,including ships.This study focuses on an investigation of swells in the East China Sea and uses hindcast data for waves over the past 5 years in a numerical model,WAVEWATCH III(WW3),together with historical climate data.The numerical calculation domain covers the entire North West Pacific.Next,swells are separated and analyzed using simulated wave fields,and both the characteristics and generation mechanisms of swells are investigated.

NUMERICAL SIMULATION OF THE INFLUENCE OF INDIAN OCEAN DIPOLE ON CLIMATIC VARIATIONS OVER EAST ASIAN MONSOON REGION DURING EQUATORIAL EAST PACIFIC OCEAN SSTA

This paper investigates the influence of Indian Ocean Dipole (IOD) on climatic variations over East Asian monsoon region, based on CAS IAP AGCM-Ⅱduring Equatorial East Pacific Ocean SSTA or not. The results show that the southwest monsoon over East Asian will break out later than normal, the intensity of the summer monsoon over the South China Sea (SCS) is stronger than normal, and more rainfall on Chinese main land is simulated when only IOD forcing exists. With both IOD and Equatorial East Pacific Ocean SSTA forcing, the southwest monsoon will break out much later than normal, the intensity of the SCS summer monsoon also is weaker than normal, and less rainfall in North China is simulated. Therefore, Equatorial East Pacific Ocean SSTA and IOD have a synergic effect.

Unprecedented East Asian warming in spring 2018 linked to the North Atlantic tripole SST mode

An unusually warm East Asia in spring 2018,when exceptionally high surface air temperatures were recorded in large areas of Asia,such as northern China,southern China,and Japan,was investigated based on the ERA-Interim reanalysis.The East Asian warming anomalies were primarily attributed to a tripole mode of North Atlantic SST anomalies,which could have triggered anomalous Rossby wave trains over the North Atlantic and Eurasia through modulating the North Atlantic baroclinic instability.Atlantic-forced Rossby waves tend to propagate eastward and induce anomalously high pressure and anticyclonic activity over East Asia,leading to a northward displacement of the Pacific subtropical high.As a result,descending motion,reduced precipitation,and increased surface solar radiation due to less cloud cover appear over East Asia,accompanied by remarkably warm advection from the ocean to southern China,northern China,and Japan.The transportation of anomalously warm advection and the feedbacks between soil moisture and surface temperature were both favorable for the recordbreaking warmth in East Asia during spring 2018.The seasonal‘memory’of the North Atlantic tripole SST mode from the previous winter to the following spring may provide useful implications for the seasonal prediction of East Asian weather and climate.

The Different Effects of Sea Surface Temperature and Aerosols on Climate in East Asia During Spring

In this study, we used the NCAR CAM3.0 model to study the climate effects of both decadal global Sea Surface Temperature(SST) changing and the increasing aerosol concentration in East Asia in boreal spring. In the decadal SST changing experiment, a prominent sea surface cyclone anomaly occurred west of the Northwest Pacific warming SST. The cyclone anomaly is conductive to anomalous rising motion and more rainfall over the Northwest Pacific and southeast coast areas of China, but less rainfall in central China. Caused by the only aerosol concentration increasing, the change of climate in East Asia is totally different from that induced by the regime shift of SST around 1976/77 with the same model. The sulfate and black carbon aerosol concentrations were doubled respectively and synchronously in East Asia(20?–50?N, 100?–150?E) to investigate the climate effects of these two major aerosol types in three experiments. The results show that, in all three aerosol concentration changing experiments, the rainfall during boreal spring increases in North China and decreases in central China. It's worth noting that in the DTWO experiment, the rainfall diminishes in central China while it increases in the north and southeast coast areas of China, which is similar to observations. From the vertical profile between 110?E and 120?E, it is found that sulfate and black carbon aerosols first change the temperature of lower troposphere owing to their direct radiative effect, and then induce secondary meridional circulation anomaly through the different dynamic mechanisms involved, and at last generate precipitation and surface temperature anomalous patterns mentioned above.

Climate and extrema of ocean waves in the East China Sea

Wave climate plays an important role in the air-sea interaction over marginal seas. Extreme wave height provides fundamental information for various ocean engineering practices, such as hazard mitigation, coastal structure design, and risk assessment. In this paper, we implement a third generation wave model and conduct a high-resolution wave hindcast over the East China Sea to reconstruct a 15-year wave field from 1988 to 2002 for derivation of monthly mean wave parameters and analysis of extreme wave conditions. The numerical results of the wave field are validated through comparison with satellite altimetry measurements, low-resolution reanalysis, and the ocean wave buoy record. The monthly averaged wave height and wave period show seasonal variation and refined spatial patterns of surface waves in the East China Sea. The climatological significant wave height and mean wave period decrease from the open ocean in the southeast toward the continental area in the northwest, with the pattern generally following the bathymetry. Extreme analysis on the significant wave height at the buoy station indicates the hindcast data underestimate the extreme values relative to the observations. The spatial pattern of extreme wave height shows single peak emerges at the southwest of Ryukyu Island although a wind forcing with multi-core structure at the extreme is applied.

Interpreting the sea surface temperature warming trend in the Yellow Sea and East China Sea

Previous studies have demonstrated that the low-frequency sea surface temperature(SST) variability in the Yellow Sea and East China Sea(YECS) is linked to large-scale climate variability, but explanations on the mechanisms vary. This study examines the low-frequency variability and trends of some atmospheric and oceanic variables to discuss their different effects on the YECS warming. The increasing temperature trend is also observed at a hydrographic section transecting the Kuroshio.The increasing rate of ocean temperature decreases with depth, which might result in an increase in vertical stratification and a decrease in vertical mixing, and thus plays a positive role on the YECS warming. The surface net heat flux(downward positive)displays a decreasing trend, which is possibly a result of the YECS warming, and, in turn, inhibits it. Wind speeds show different trends in different datasets, such that its role in the YECS warming is uncertain. The trends in wind stress divergence and curl have large uncertainties, so their effects on SST warming are still unclear. The Kuroshio heat transport calculated in this study,displays no significantly increasing trend, so is an unlikely explanation for the SST warming. Limited by sparse ocean observations,sophisticated assimilative climate models are still needed to unravel the mechanisms behind the YECS warming.

The features of cloud overlapping in Eastern Asia and their effect on cloud radiative forcing

Characteristics of cloud overlap over Eastern Asia are analyzed using a threeyear dataset （20072009） from the cloud observing satellite CloudSat. Decorrelation depth Lis retrieved, which represents cloud overlap characteristics in the simulation of cloudradiation processes in global climate models. Results show that values of L in six study regions are generally within the range 03 km. By categorizing L according to cloud amount in subregions, peak L appears near subregions with cloud amount between 0.6 and 0.8. Average L is 2.5 km. L at higher altitudes is generally larger than at lower lati tudes. Seasonal variations of L are also clearly demonstrated. The sensitivity of cloud radiative forcing （CRF） to L;y in Community Atmosphere Model 3.0 of the National Center for Atmospheric Research （CAM3/NCAR） is analyzed. The result shows that L can have a big impact on simulation of CRF, especially in major monsoon regions and the MidEastern Pacif ic, where the difference in CRF can reach 4050 W m2. Therefore, accurate parameterization of cloud vertical overlap struc ture is important to CRF simulation and its feedback to climate.