南亚高压与西太平洋副热带高压对我国西南地区夏季降水异常的影响

利用1961～2010年全国台站观测资料中逐日平均降水资料，及同期NCEP／NCAR再分析资料，通过统计方法，研究分析了南亚高压东脊点和西太平洋副热带高压西脊点对我国西南地区夏季区域降水的影响。分析得到：对于1961～2010年我国西南地区夏季降水异常，南亚高压与西太平洋副热带高压其东西脊点之间的经距，在31候、36～37候以及45～46候，体现出明显异常特征。特别是涝年和旱年对比中，在这3个时段上存在明显差异。并且发现，31候时南亚高压东脊点与西太平洋副热带高压西脊点之间经距，与前一年的差距越大，我国西南地区该年夏季降水偏多，特别是中部与东部，效果更为显著。

热带西太平洋海温变化及其与赤道东太平洋海温变化的关系

利用１９５１－１９８８年１０°Ｓ－５０°Ｎ太平洋的ＳＳＴ资料对热带西太平洋海表温度的变化及其与赤道东太平洋海表温度变化的关系进行了分析，发现热带西太平洋ＳＳＴ存在准两年周期的变化。这种变化与ＥＮＳＯ活动相联系：Ｅ１Ｎｉｎｏ年的ＳＳＴ距平值位于谷值；反Ｅ１Ｎｉｎｏ年的ＳＳＴ距平值位于峰值。热带西太平洋与赤道东太平洋的ＳＳＴ变化存在弱的反相关关系。两者间存在位相差，前者的变化比后者超前几个月甚至１年。文中还分析了西太平洋暖池次表层海温的变化，发现它存在准两年周期的振荡。Ｅ１Ｎｉｎｏ发生的前一年均有次表层海温升高，然而并不是每一次的次表层海温出现正距平都对应会发生一次Ｅ１Ｎｉｎｏ事件。暖池次表层海温在５０－２００ｍ之间变化最大，振幅最大达±５℃。

川西北的洪涝与西太平洋副热带高压的环流特征

从历史资料中统计出川西北地区洪涝出现的特点、规律、区域分布与副高关系的特征．在副高季节性西伸北跳南撤时，将副高分为经向型和纬向型两种来研究，其经向型副高是产生川西北大范围严重洪涝乃至罕见洪涝的主要环流特征。

陕西太平国家森林公园绿色旅游产品策划初探

陕西太平国家森林公园位于陕西西安市西南部，秦岭北坡上部，太平峪内。森林风景资源保护面积6085公顷，森林景观优美，物种资源丰富，从1998年开业运营以来，市场影响日趋广泛，发展态势十分看好。但是，

Application of Argo Data in the Analysis of Water Masses in the Northwest Pacific Ocean

The temperature and salinity distributions, and the water mass structures in Northwest Pacific Ocean are studied using the temperature and salinity data obtained by Argo profiling floats. The T-S relation in this region indicates there exist 8 water masses, they are the North Pacific Tropical Surface Water （NPTSW）, North P, acific Subsurface Water （NPSSW）, North Pacific Intermediate Water （NPIW）, North Pacific Subtropical Water （NPSTW）, North Pacific Deep Water （NPDW） and Equatorial Surface Water （ESW）, and the South Pacific Subsurface Water （SPSSW） and South Pacific Intermediate Water （SPIW）.

Characteristics of Semi-diurnal Internal Tides in the Western Equatorial Pacific Ocean Around 1°45′S,156°E

The analyses of a data series obtained during TOGA- COARE show the existence of remarkable semi-diurnal intemal tides in the western equatorial Pacific Ocean around 1°45＇S, 156°E. Some characteristic parameters of the internal tides are vertical wavenumber -1.6×10^-3 m^-1, horizontal wavenumber （wavelength） 3.3×10^-2 km^-1 （210 km）, vertical propagation speed -3.8 cm/s and horizontal propagation speed 2.0 m/s. The waveforms propagate downwards slantingly, that is, the wave energy transfers upwards slantingly. Depth-distribution of the＇rotary spectral levels is a saddle-shape. The depths of the trough and the deeper peaks are almost coincident with those of the south boundaries of the South Equatorial Current and the Equatorial Undercurrent, respectively. The mean orientation of the rotary spectral ellipse changes with depth： 30° from north to east at 40 m, and changes into 14° from east to south at 324 m, and generally, it points to northeastward, which indicates ＂that waves come from the southwest.

Preliminary analysis on the interdecadal variation characteristics of typhoon over the Northwestern Pacific in the past sixty years

Using typhoon data over the Northwestern Pacific （NWP） in 60 years （1950-2009）, the interdecadal variations of typhoon frequency, track and intensity are statistically analyzed. The results showed that the frequency of typhoon over the NWP was high in 1960s and low in 1970s. From the late 1990s, the frequency is low again. The track of typhoon was mainly shifting, and the average track was at the southern NWP in 1960s and 1970s, but in recent 10 years, the track was at the northern NWP. The intensity of typhoon was strong in 1950s and 1960s, but becomes weak in recent 25 years. In high frequency periods of typhoon, the subtropical high of NWP was weak and its position appears easternly. The distribution of Sea Surface Temperature （SST） shows characteristics of ＂La Nina＂ event. In low frequency periods of typhoon, the subtropical high of NWP is strong and its position appears westernly. The distribution of SST shows characteristics of ＂El Nino＂ event.

Two Northward Jumps of the Summertime Western Pacific Subtropical High and Their Associations with the Tropical SST Anomalies

Based on the pentad mean ridgeline index of the western Pacific subtropical high (WPSH), the authors identified the two northward jumps of the WPSH from 1979 to 2008 and revealed their associations with the tropical SST anomalies. The authors show that the northward jumps, especially the second jump, exhibited remarkable interannual variability. In addition, the authors find that the two northward jumps were mutually independent and were influenced by the SST anomalies in the different regions of the tropical Pacific. The first jump was positively correlated with the SST anomalies in the tropical central Pacific from the preceding winter to June. In contrast, the second jump was positively related to ENSO in the preceding winter, but this correlation tended to weaken with the decay of ENSO and disappeared in July. Instead, a positive correlation was found in the Indian Ocean. We therefore suggest that ENSO plays an indirect role in the second jump through the capacitor effect of the Indian Ocean.

An Investigation of the Formation of the Heat Wave in Southern China in Summer 2013 and the Relevant Abnormal Subtropical High Activities

In the summer of 2013, an unprecedented heat wave was experienced over a vast area of southern China. The great areal extent, duration, and strength of this high temperature are very rare. For the 2013 hot spell, the major and direct influence mostly came from the anomaly of the western Pacific subtropical high(WPSH). The abnormally strong and stable WPSH was associated with specific surrounding circulations. The eastward extension of a stronger Qinghai-Xizang high favored the westward extension of the WPSH. The weaker cold air activity from the polar region led to the northward shift of the WPSH and helped it to remain stable. In the tropics, the western segment of the ITCZ was abnormally strong in the period, and supported the maintenance of the WPSH from the south. In addition, the interdecadal variation of the WPSH provided a decadal background for the anomaly variation of the WPSH that summer.

Influence of Tropical Western Pacific Warm Pool Thermal State on the Interdecadal Change of the Onset of the South China Sea Summer Monsoon in the Late-1990s

An interdecadal shift in the onset date of the South China Sea summer monsoon(SCSSM) is identified during the late 1990 s by using the European Centre for Medium-Range Weather Forecasts Interim Reanalysis dataset. The mean onset date was brought forward by two pentads during 1999–2013 compared to that during 1979–1998. The large-scale atmospheric and oceanic change associated with this shift exhibits a significant interdecadal variation signal around 1998/1999, indicating that the shift during the late 1990 s is robust. Different from the well-known mid-1990 s shift, this shift carried more important systematical significance. Diagnostic analysis suggests that the earlier outbreak of the SCSSM was due to the interdecadal warming of the warm pool, which brought stronger convection anomalies and led to a weak western Pacific subtropical high(WPSH) during boreal spring(March–May). The earlier retreat of the WPSH was a direct cause of this shift.

Standardizing CPUE of Ommastrephes bartramii for Chinese squid-jigging fishery in Northwest Pacific Ocean

Generalized linear models （GLM） and generalized additive models （GAM） were used to standardize catch per unit fishing effort （CPUE） of Ommastrephes bartramii for Chinese squid-jigging fishery in Northwest Pacific Ocean. Three groups of variables were considered in the standardization： spatial variables （longitude and latitude）, temporal variables （year and month） and environmental variables, including sea surface temperature （SST）, sea surface salinity （SSS） and sea level height （SLH）. CPUE was treated as the dependent variable and its error distribution was assumed to be log-normal in each model. The model selections of GLM and GAM were based on the finite sample-corrected Akaike information criterion （AICC） and pseudo-coefficient （Pcf） combined P-value, respectively. Both GAM and GLM analysis showed that the month was the most important variable affecting CPUE and could explain 21.3% of variability in CPUE while other variables only explained 8.66%. The interaction of spatial and temporal variables weakly influenced the CPUE. Moreover, spatio-temporal factors may be more important in influencing the CPUE of this squid than environmental variables. The standardized and nominal CPUEs were similar and had the same trends in spatio-temporal distribution, but the standardized CPUE values tended to be smaller than the nominal CPUE. The CPUE tended to have much higher monthly variation than annual variations and their values increased with month. The CPUE became higher with increasing latitude-high CPUE usually occurred in 145°E-148°E and 149°E-162°E. The CPUE was higher when SST was 14-21℃ and the SLH from -22 cm to -18 cm. In this study, GAM tended to be more suitable than GLM in analysis of CPUE.

The upper ocean response to tropical cyclones in the northwestern Pacific analyzed with Argo data

A large number of autonomous profiling floats deployed in global oceans have provided abundant temperature and salinity profiles of the upper ocean. Many floats occasionally profile observations during the passage of tropical cyclones. These in-situ observations are valuable and useful in studying the ocean’s response to tropical cyclones, which are rarely observed due to harsh weather conditions. In this paper, the upper ocean response to the tropical cyclones in the northwestern Pacific during 2000–2005 is analyzed and discussed based on the data from Argo profiling floats. Results suggest that the passage of tropical cyclones caused the deepening of mixed layer depth (MLD), cooling of mixed layer temperature (MLT), and freshening of mixed layer salinity (MLS). The change in MLT is negatively correlated to wind speed. The cooling of the MLT extended for 50–150 km on the right side of the cyclone track. The change of MLS is almost symmetrical in distribution on both sides of the track, and the change of MLD is negatively correlated to pre-cyclone initial MLD.

Large-Scale Circulation Features Typical of Wintertime Extensive and Persistent Low Temperature Events in China

A pair of northeast-southwest-tilted mid-tropospheric ridges and troughs on the continental scale was observed to be the key circulation feature common among wintertime extensive and persistent low tempera-ture events (EPLTE) in China.During the persistence of such anomalous circulations,the split flow over the inner Asian continent and the influent flow over the southeast-ern coast of China correspond well to the expanded and amplified Siberian high with tightened sea level pressure gradients and hence,a strong,cold advection over south-eastern China.The western Pacific subtropical high tends to expand northward during the early stages of most EPLTEs.

Intraseasonal variation of the East Asian summer monsoon in La Ni?a years

Based on the composite result of six major the intraseasonal variation of the East Asian La Nina events during 1979-2012, the authors reveal summer monsoon （EASM） and summer rainfall in East Asia in La Nino years. Due to a higher SST over the western Pacific warm pool in the proceeding winter and spring, warm pool convection in summer is enhanced, leading to a cyclonic anomaly in the subtropical western Pacific. As a result, the western Pacific subtropical high is located more northeastward, and the seasonal march in East Asia is thus accelerated.This anomalous pattern tends to change with the seasonal march, with a maximum anomaly in July. Besides, there is less Mei-yu rainfall in the Yangtze River basin, with an earlier start and termination. The rainfall distribution in East Asia during La Nino years is characterized bya zonal pattern of less rainfall in eastern China and more rainfall over the oceanic region of the western Pacific. By comparison, a meridional pattern is found during El Nino years, with less rainfall in the tropics and more rainfall in the subtropics and midlatitudes. Therefore, the influence of La Nino on the EASM cannot be simply attributed to an antisymmetric influence of El Nino.

The study on fishing ground of neon flying squid, Ommastrephes bartrami,and ocean environment based on remote sensing data in the Northwest Pacific Ocean

The relationships between the neon flying squid, Ommastrephes bartrami, and the relative ocean environmental factors are analyzed. The environmental factors collected are sea surface temperature （SST）, chlorophyll concentration （Chl-α） and sea surface height （SSH） from NASA, as well as the yields of neon flying squid in the North Pacific Ocean. The results show that the favorable temperature for neon flying squid living is 10℃-22℃ and the favorite temperature is between 15℃-17℃. The Chl-α concentration is 0.1-0.6 mg/m^3. When Chl-α concentration changes to 0.12-0.14 mg/m^3, the probability of forming fishing ground becomes very high. In most fishing grounds, the SSH is higher than the mean SSH. The generalized additive model （GAM） was applied to analyze the correlations between neon flying squid and ocean environmental factors. Every year, squids migrate northward from June to August and return southward during October-November, and the characteristics of the both migrations are very different. When squids migrate to the north, most relationships between the yields and SST are positive. The relationships are negative when squids move to southward. The relationships between the yields and Chl-a concentrations are negative from June to October, and insignificant in November. There is no obvious correlation between the catches of squid and longitude, but good with latitude.

A CLIMATOLOGY OF EXTRATROPICAL TRANSITION OF TROPICAL CYCLONES IN THE WESTERN NORTH PACIFIC

Based on best-track data and JRA-25 reanalysis,a climatology of western North Pacific extratropical transition (ET) of tropical cyclone (TC) is presented in this paper. It was found that 35% (318 out of 912) of all TCs underwent ET during 1979-2008. The warm-season (June through September) ETs account for 64% of all ET events with the most occurrence in September. The area 120°E-150°E and 20°N-40°N is the most favorable region for ET onsets in western North Pacific. The TCs experiencing ET at latitudes 30°N-40°N have the greatest intensity in contrast to those at other latitude bands. The distribution of ET onset locations shows obviously meridional migration in different seasons. A cyclone phase space (CPS) method was used to analyze the TC evolution during ET. Except for some cases of abnormal ET at relatively high latitudes,typical phase evolution paths-along which TC firstly showed thermal asymmetry and an upper-level cold core and then lost its low-level warm core-can be used to describe the main features of ET processes in western North Pacific. Some seasonal variations of ET evolution paths in CPS were also found at low latitudes south of 15°N,which suggests different ET onset mechanisms there. Further composite analysis concluded that warm-season ETs have generally two types of evolutions,but only one type in cold season (October through next May). The first type of warm-season ETs has less baroclinicity due to long distance between the TC and upper-level mid-latitude system. However,significant interactions between a mid-latitude upper-level trough and TC,which either approaches or is absorbed into the trough,and TC's relations with downstream and upstream upper-level jets,are the fingerprints for both a second type of warm-season ETs and almost all the cold-season ETs. For each type of ETs,detailed structural characteristics as well as precipitation distribution are illustrated by latitude.

Surface sediment diatoms from the western Pacific marginal seas and their correlation to environmental variables

Diatom data of 192 surface sediment samples from the marginal seas in the western Pacific together with modern summer and winter sea surface temperature and salinity data were analyzed.The results of canonical correspondence analysis show that summer sea-surface salinity(SSS) is highly positively correlated with winter SSS and so is summer sea-surface temperature(SST) with winter SST.The correlations between SSSs and SSTs are less positively correlated,which may be due to interactions of regional current pattern and monsoon climate.The correlations between diatom species,sample sites and environmental variables concur with known diatom ecology and regional oceanographic characters.The results of forward selection of the environmental variables and associated Monte Carlo permutation tests of the statistical significance of each variable suggest that summer SSS and winter SST are the main environmental factors affecting the diatom distribution in the area and therefore preserved diatom data from down core could be used for reconstructions of summer SSS and winter SST in the region.

THE POSITION VARIATION OF THE WEST PACIFIC SUBTROPICAL HIGH AND ITS POSSIBLE MECHANISM

Using NCEP/NCAR daily reanalysis data and SCSMEX data, an investigation is carried out of the relationship between the position variation of the west Pacific subtropical high （WPSH） and the apparcnt heating in June 1998 based on the complete vertical vorticlty equation. It is tbund that the non-adiabatic heating plays an important role in the position variation of WPSH. In comparison with climatic mean status, the vertical change of non-adiabatic heating is stronger in the north side of WPSH in June 1998, but weaker in the south side of WPSH. The anomalous non-uniform heating induces anomalous cyclonic vorticity in South China, areas to lhe south of the Yangtze and its mid-lower valleys, but anomalous anticyclonic vorticity in the Indo-China Peninsula and South China Sea areas lead to the more southward position of WPSH than the mean.

Dynamic mechanism of interannual zonal displacements of the eastern edge of the western Pacific warm pool

The eastern edge of the western Pacific warm pool （WPWP） in the upper layer （shallower than 50m） exhibits significant zonal displacements on interannual scale. Employing an intermediate ocean model, the dynamic mechanism for the interannual zonal displacement of the WPWP eastern edge in the upper layer is investigated by diagnosing the dynamic impacts of zonal current anomalies induced by wind, waves （Kelvin and Rossby waves）, and their boundary reflections. The interannual zonal displacements of the WPWP eastern edge in the upper layer and the zonal current anomaly in the equatorial Pacific west of ll0~W for more than 30 years can be well simulated. The modeling results show that zonal current anomalies in the central and eastern equatorial Pacific are the dominant dynamic mechanism for the zonal displacements of the eastern edge of the upper WPWP warm water. Composite analyses suggest that the zonal current anomalies induced by waves dominate the zonal displacement of the WPWP eastern edge, whereas the role played by zonal wind-driven current anomalies is very small. A sensitivity test proves that the zonal current anomalies associated with reflected waves on the western and eastern Pacific boundaries can act as a restoring force that results in the interannual reciprocating zonal motion of the WPWP eastern edge.