Seasonal changes in Hermit Thrush (Catharus guttatus) song syntax

In many songbird species,birdsong features phonological syntax,meaning that the units within their vocal se-quences are ordered in a non-random way that adheres to a rule.While such syntactical patterns have been richly described in many species,comparatively little is known about how those patterns contribute to song achieving its important functions.For each of song’s main functions,territorial defense and mate attraction,evidence of a role for syntax is limited.One species for which syntax has been thoroughly described is the Hermit Thrush(Catharus guttatus),which presents song types from their repertoires in a semi-predictable order and,in doing so,rapidly cycle up and down the frequency spectrum.The objective of the present study was to explore the importance of song syntax in the Hermit Thrush through a within-subject examination of how measures of syntax,such as the predictability of song type order within song sequences,shift over the breeding season.We hypothesized that,if such syntactical characteristics are important to breeding behaviour,they would be most prominent at the start of the breeding season when activity associated with territory establishment and mate attraction is most intense.Analysis revealed that,as predicted,the rigidness of song type ordering within se-quences was highest at the start of the season and declined thereafter.That song type sequences were most predictable at the vitally important early part of the breeding season fit our hypothesis that this aspect of song syntax is important to song’s functions related to territory establishment and/or mate attraction.Future work will clarify whether that role relates to one of song’s two main functions or serves song transmission in some broader way.

Seasonal Dynamics of Terrestrial Net Primary Production in Response to Climate Changes in China

Study on seasonal responses of terrestrial net primary production (NPP) to climate changes is to help understand feedback between climate systems and terrestrial ecosystems and mechanisms of increased NPP in the northern middle and high latitudes. In this study, time series dataset of normalized difference vegetation index (NDVI) and corresponding ground-based information on vegetation, climate, soil, and solar radiation, together with an ecological process model, were used to explore the seasonal trends of terrestrial NPP and their geographical differences in China from 1982 to 1999. As the results,. seasonal total NPP in China showed a significant increase for all four seasons (spring, summer, autumn and winter) during the past 18 years. The spring NPP indicated the largest increase rate, while the summer NPP was with the largest increase in magnitude. The response of NPP to climate changes varied with different vegetation types. The increased NPP was primarily led by an advanced growing season for broadleaf evergreen forest, needle-leaf evergreen forest, and needle-leaf deciduous forest, whilst that was mainly due to enhanced vegetation activity (amplitude of growth cycle) during growing season for broadleaf deciduous forest, broadleaf and needle-leaf mixed forest, broadleaf trees with groundcover, perennial grasslands, broadleaf shrubs with grasslands, tundra, desert, and cultivation. The regions with the largest increase in spring NPP appeared mainly in eastern China, while the areas with the largest increase in summer NPP occurred in most parts of Northwestern China, Qinghai-Xizang Plateau, Mts. Xiaoxinganling-Changbaishan, Sanjiang Plain, Songliao Plain, Sichuan Basin, Leizhou Peninsula, part of the middle and lower Yangtze River, and southeastern mountainous areas of China. In autumn, the largest NPP increase appeared in Yunnan Plateau-Eastern Xizang and the areas around Hulun Lake. Such different ways of the NPP responses depended on regional climate attributes and their changes.

Seasonal Changes in the Ultrastructure of the Vascular Cambium in Shoots of Populus tomentosa

Wood is the product of cambial activity in trees, and the seasonal activity style of cambium directly influences wood biomass production, structures and properties. The seasonal changes in the ultrastructure of the vascular cambium activity of Populus tonientosa Carr. planted in Beijing area were examined in shoot tissues collected during 15 months by means of transmission electron microscopy. Before xylem mother cells reactivated completely, the dividing fusiform cells in cambium and new phloem cells had appeared at the same time. The initiation of cambial activity may be related to the bud sprouting and the young leaf growth in shoots. More details about the ultrastructural changes of cambial cells at the onset of cambial activity have been gained. When the large vacuole in active cambial cells divided into smaller ones during the dormant phase, proteinaceous material that disappeared in active cambial cells refilled many of these small vactioles. In addition, lipid droplets and starch granules had the same cycles as proteinaceous material. The plasmalemma invaginations of fusiform cells were observed not only in active phase but also in dormancy. The endomembrane system consisting of nuclear membrane, endoplasmic reticulum (ER), dictyosomes and their secretory vesicles, changed in form and distribution at different phases during a cycle and performed important roles at the onset of active cambium and during the wall formation process of secondary xylem cells. The tangential walls remained relatively thin throughout the year but the radial walls thickened markedly when the cambium was dormant. During the transition from dormancy to activity, a partial autolysis occurred in the radial walls of the cambial cells, especially at the cell wall junctions. A notable feature of the cells at the onset of cambial activity was the thinning of the radial walls.

Seasonal changes in the number of Relict Gull (Larus relictus) at Ebinur Lake, Western China

The Relict Gull(Larus relictus) is recognized as a vulnerable species,with a worldwide population of about 6,000 individuals.Always inhabiting the extreme arid regions of Central Asia,their migratory routes and winter grounds are unclear.This research focused on distribution sites,habitat,behavior,population size and seasonal changes of Relict Gull.Line transects and point counts in every month were used to investigate the gulls around the Ebinur Lake.The result showed Relict Gull was summer visitor to Xinjiang,Western China.Population curve with a single peak was obtained.This gull appeared in early April and was 63 individuals(1% of the global population).The number remained stable from May to July in 2009.The discovery of fledglings indi-cates that Relict Gull may breed here.They left Ebinur Lake in August.Relict Gull in Ebinur Lake should belong to the Central Asian subpopulation,which was the most westerly record in China.

Seasonal changes in sperm parameters, testicular histology and circulating levels of reproductive hormones in the male African straw-colored fruit bat (Eidolon helvum)

Objective: To investigate seasonal changes in some reproductive characteristics of the male African straw-colored fruit bat [Eidolon (E.) helvum] in a tropical rain forest area of South-East Nigeria.Methods: Spermatozoal characteristics in the testes and cauda epididymides, testicular histology, and the circulating levels of the reproductive hormones, testosterone, follicle stimulating hormone and luteinizing hormone were evaluated in male bats captured in late January (peak dry season), late May (early rainy season) and late September (late rainy season) of 2019. The bats were captured in Obiagu community in Enugu State, South-East Nigeria. Data were analyzed with analysis of variance. Results: There were high serum concentrations of testosterone in early and late rainy season and of luteinizing hormone in early rainy season, but the concentrations of both hormones were low during peak dry season. These hormonal changes corresponded with the testicular seminiferous and spermatogenic activities and testicular and epididymal sperm concentrations, which were also maximal during early and late rainy season but minimal during peak dry season. Epididymal sperm motility and vitality were also high in early and late rainy season but low in peak dry season, while sperm morphological abnormalities were low in early and late rainy season but elevated in peak dry season. There was histological evidence that spermatogenesis did not cease completely during testis regression, but continued at a reduced rate during the dry season. Conclusions: The findings do not support concurrent epididymal sperm storage with testis regression in E. helvum. Altogether, these indicate that seasonal changes significantly alter sperm characteristics, testicular histology and circulating levels of reproductive hormones in E. helvum within the study area.

Structure and seasonal changes in atmospheric boundary layer on coast of the east Antarctic continent

The temperature, humidity, and vertical distribution of ozone in the Antarctic atmospheric boundary layer（ABL） and their seasonal changes are analyzed, by using the high-resolution profile data obtained during the International Polar Year 2008 to 2009 at Zhongshan Station, to further the understanding of the structure and processes of the ABL. The results show that the fre- quency of the convective boundary layer in the warm season accounts for 84% of its annual occurrence frequency. The frequency of the stable boundary layer in the cold season accounts for 71% of its annual occurrence frequency. A neutral boundary layer ap- pears rarely. The average altitude of the convective boundary layer determined by the parcel method is 600 m; this is 200 to 300 m higher than that over inland Antarctica. The average altitude of the top of the boundary layer determined by the potential tempera- ture gradient and humidity gradient is 1 200 m in the warm season and 1 500 m in the cold season. The vertical structures of ozone and specific humidity in the ABL exhibit obvious seasonal changes. The specific humidity is very high with greater vertical gradi- ent in the warm season and very low with a lesser gradient in the cold season under 2 000 m. The atmospheric ozone in the ABL is consumed by photochemical processes in the warm season, which results in a slight difference in altitude. The sub-highest ozone center is located in the boundary layer, indicating that the ozone transferred from the stratosphere to the troposphere reaches the low boundary layer during October and November in Antarctica.

Effect of Foliar Application of Iron on Seasonal Changes of Minerals Composition in Petioles and Berries of Halwani Lebanon and Kamali Grape Cultivars （Vitis vinifera L,）

A field experiment was conducted in 2009 and 2010 growing seasons, to study the effect of foliar application of iron-chelated ＂Fe-EDTA＂ at concentration 0, 100 and 200 mg/L on the seasonal dynamic of mineral composition of N, P, K, Fe and Zn in petioles and berries of Halwani Lebanon and Kamali grape cultivars, grown on a calcareous soil in Mosul region, Iraq. The results revealed that the foliar application of 200 mg Fe/L caused a significant increase of N, P, K, Fe and Zn concentrations in petioles and berries compared with the control for both seasons. Additionally, the N, P, K, Fe and Zn concentration in petioles were high at the beginning of the growth season, whereas, decrease towards in the end of the growth season in both cultivars and seasons. While the N, P, K, Fe and Zn in berry content was increased towards from berry set to veraison and ripening stage in both cultivars and seasons. So there are various element contents in the cultivars.

Seasonal metal fluxes derived by the interaction of surface water and groundwater in an aquaculture estuary

Submarine groundwater discharge(SGD)plays a major role as a conveyor of metals to coastal waters.However,the seasonal change of metal fluxes derived through SGD is unclear.Here,we evaluated the behaviours and fluxes of trace metals(Mn,Fe,Ba,Pb,U,Cr,Zn,Cu)in an estuary under different seasonal conditions.The behaviours of trace metals revealed that SGD was the source of Mn(3.51 mmol/(m^(2)·d)),Fe(0.174 mmol/(m^(2)·d))and Ba(0.024 mmol/(m^(2)·d)),but the Cu sink(−0.55μmol/(m^(2)·d))and other metals exhibited a seasonal source‒sink conversion.The seasonal variation of dissolved organic matter and the fresh groundwater proportion in subterranean estuaries may have an important effect on metals fluxes especially for the Fe,Mn and Ba.Our result shows that the single seasonal metal fluxes estimation applied to the annual scale will cause a large deviation,up to 3.6 times for Fe,5.5 times for Mn,and 15 times for Ba.Therefore,the influence of seasonal fluctuations on SGDderived metal fluxes cannot be ignored,and our findings will be important for comprehending the metal budget and cycle in nearshore environment.

Seasonal characteristics of Carex lasiocarpa biomass and nutrient accumulation in the typical wetland of Sanjiang Plain, China

Seasonal dynamics of above- and belowground biomass and nutrient characteristics （nitrogen, carbon, and phosphorus） of Carex lasiocarpa were investigated in the typical wetland of Sanjiang Plain, China from May 2007 to September 2008. The results show that the changes of aboveground biomass during the growing season are best described by the twice function curve model, whereas the changes of belowground biomass follow the exponential increase curve model. Both the organic carbon contents in the above- and belowground plant parts show significant positive linear correlations with the growing time, and the coefficients R2 are 0.983 and 0.746, respectively. The carbon accu-mulations of the above- and belowground plant parts during the growing season show the same dynamics as those of the biomass. However, the nitrogen contents and accumulation in C. lasiocarpa aboveground and belowground parts show exponential increase during the growing season. The dynamics of C. lasiocarpa phosphorus contents follows the twice function curve model, whereas the accumulation of phosphorus shows the linear increase. The ratios of C/N in different parts of C. lasiocarpa fit the negative linear relations with total nitrogen content in the growing season. Moreover, the ratios of C/P in C. lasiocarpa plant also fit the negative linear relations with total phosphorus content. The results show that nitrogen is the primary limiting nutrient for C. lasiocarpa growth as compared with carbon and phosphorus.

Preliminary study on seasonal succession and development pathway of phytoplankton community in the Bohai Sea

Phytoplankton species composition and species succession were determined in 1998-1999 based on 2 nestle investigation cruises in the Bohai Sea and two monthly monitoring stations at Penglai and Changdao for 15 months. The seasonal succession and pathway of phytoplankton community in the Bohai Sea were discussed complementarily with history data. The main process of Phytoplankton community development in the Bohai Sea was controlled by temperature and nutrient replenishes. There were two cell abundance peaks in an annual variation, the main peak in April and the secondary peak in September. In winter, the cell abundance was low due to the low temperature, the phytoplankton community was mainly made up of small-celled diataoms. In spring, the phytoplankton community was developed very quickly by small-celled diatom in suitable conditions of temperature and nutrients. In summer, the cell abundance decreased and big-celled diatoms became predominated. In autumn, because of the replenish of nutrient, big-celled diatoms and dinoflagellates formed another cell abundance peak. during the annual variation of phytoplankton community in the Bohai Sea, species succession was the main process of community development, the species sequence just occur at special areas and special periods. The evolution of phytoplankton community in the Bohai Sea accords with the hypothesis of Margalef's phytoplankton community of four stages. But the size feature is contrary to the hypothesis, which may be caused by nutrient replenish in autumn in Bohai Sea and the top to down control.

Community Structure and Seasonal Variation of Soil Arthropods in the Forest-Steppe Ecotone of the Mountainous Region in Northern Hebei,China

Soil fauna have been receiving more and more attention because they play an important role in nutrient cycling.However,there is a lack of information on soil arthropods in the forest-steppe ecotone in the mountainous region of northern Hebei,which makes it difficult to meet the need of protecting biodiversity in this area.Soil arthropod communities were investigated in the forest-steppe ecotone in northern Hebei province to provide basic information on changes in mountain soil fertility,which could promote the development of soil arthropod communities in mountain ecotones.From the preliminary identification,a total of 7994 individual soil arthropods were collected,which belonged to 25 groups,6 classes and 24 orders.Acarina,Hymenoptera and Collembola were the dominant groups in the ecotone.The number of Acarina was higher than Collembola,and this phenomenon was obviously different from other areas in the same climate zone.The increased abundance of rare groups in the Forest zone with the richer vegetation,higher arthropod abundance and more substantial litter depth,could be interpreted as a reaction to the suitable soil environment and food supply.And these rare groups were sensitive to environmental changes,which could be regarded as biotic indicators for evaluating soil quality.The analysis of community diversity showed that the abundance index (d),the Shannon-Wiener index (H'),the evenness index (J) and the density-group index (DG) were significantly higher in the forest zone,lower in the forest-steppe zone,and lowest in the meadow-steppe zone.Seasonal variations in community composition correlated with changes in average air temperature and precipitation in this ecotone.Groups and individuals of soil arthropod communities in the three zones were present in greater numbers in the middle of the rainy season than in the early or late periods of the rainy season as a whole.At the same time,seasonal changes in soil arthropod communities from different plots were also influenced by habitat condition.

Seasonal dynamics of soil water content in the typical vegetation and its response to precipitation in a semi-arid area of Chinese Loess Plateau

Soil water content is a key limiting factor for vegetation growth in the semi-arid area of Chinese Loess Plateau and precipitation is the main source of soil water content in this area.To further understand the impact of vegetation types and environmental factors such as precipitation on soil water content,we continuously monitored the seasonal dynamics in soil water content in four plots(natural grassland,Caragana korshinskii,Armeniaca sibirica and Pinus tabulaeformis)in Chinese Loess Plateau.The results show that the amplitude of soil water content fluctuation decreases with an increase in soil depth,showing obvious seasonal variations.Soil water content of artificial vegetation was found to be significantly lower than that of natural grassland,and most precipitation events have difficulty replenishing soil water content below a depth of 40 cm.Spring and autumn are the key seasons for replenishment of soil water by precipitation.Changes in soil water content are affected by precipitation,vegetation types,soil evaporation and other factors.The interception effect of vegetation on precipitation and the demand for water consumption by transpiration are the key factors affecting the efficiency of soil water replenishment by precipitation in this area.Due to artificial vegetation plantation in this area,soil will face a water deficit crisis in the future.

Community Structure and Diversity of Ladybugs in Baihualing of Gaoligong Mountain Ⅱ——Seasonal Change Trends of Species Diversity

[ Objective] The paper was to explore the effect of seasonal changes on community diversity of ladybugs in Baihualing of Gaoligong Mountain. [ Meth- od] The seasonai change rule of community diversity of ladybugs in Baihualing of Gaoligeng Mountain was studied during April 2008 to January 2009. [ Result ] The species diversity of ladybugs from April to June in 2008 gradually increased, which reached the peak in June and September, and then declined gradually after October. The community similarities of ladybugs in the months with less difference in temperature and rainfall were relatively high. [ Conclusion] The study pro- vided theoretical basis for the further study on ladybugs in Baihualing of Gaoligong Mountain.

The Early Summer Seasonal Change of Large－scale Circulation over East Asia and Its Relation to Change of The Frontal Features and Frontal Rainfall Environment During 1991 Summer

By using the rawinsonde data, upper cloud amount data and objective analysis data for global domain which all were produced by Numerical Prediction Division,JMA and by using daily and mean weather map issUed by JMA and daily rainfall data over the Huaihe River Basin from China,an observational study to the early summer seasonal change of large-scale circulation over East Asia and its relation to change of the frontal features and environment for the frontal rainfall has been carried out.Following reaults have been obtained:(1) The early summer seasonal change of large-scale circulation was occurred during 20-23 May 1991,which was about 10 days earlier than the normal.During the period the subtropical westerly jet and tropical easterlies abruptly moved northward;(2) The northward movement of the tropical easterlies was not uniform,it was earlier at 100 hpa level and about 24 hrs late at 200 hpa level.The phenomenon was associated with earlier disappearence of the subtropical westerly jet at 100 hpa level;(3)During the seasonal change there were two westerly jets in the upper level and changed their intensity with the time.before 18 May 1991,the southern one was more intense and then changed to more intense for the northern one and disappearence of the southern one,the phenomenon seemed to be appeared as northward movement of the southernjet;(4) A faster temperature(n rising in the upper level over the Tibetan Plateau was associated with the seasonalchange.From the T rising the T maximum moved onto the plateau,changing the T gradient from positive to negahve to the south flank of the plateau,the effect to leduce and disappear the southern westerlies.Also the T rising was associated with change of the frontal features over East Asia;(5) The seasonal change type during 1991 was same as that during 1992 and 1993,but different from that during 1990;(6) The environment for the frontal rainfall was change in the season,the differences were in the baroclinity in upper level and vertical wind speed and direction shear.

Simulation of Sea Ice in FGOALS-g2: Climatology and Late 20th Century Changes

Sea ice is an important component in the Earth＇s climate system. Coupled climate system models are indispensable tools for the study of sea ice, its internal processes, interaction with other components, and projection of future changes. This paper evaluates the simulation of sea ice by the Flexible Global Ocean- Atmosphere-Land System model Grid-point Version 2 （FGOALS-g2）, in the fifth phase of the Coupled Model Inter-comparison Project （CMIP5）, with a focus on historical experiments and late 20th century simu：ation. Through analysis, we find that FGOALS-g2 produces reasonable Arctic and Antarctic sea ice climatology and variability. Sea ice spatial distribution and seasonal change characteristics are well captured. The decrease of Arctic sea ice extent in the late 20th century is reproduced in simulations, although the decrease trend is lower compared with observations. Simulated Antarctic sea ice shows a reasonable distribution and seasonal cycle with high accordance to the amplitude of winter-summer changes. Large improvement is achieved as compared with FGOALS-gl.0 in CMIP3. Diagnosis of atmospheric and oceanic forcing on sea ice reveals several shortcomings and major aspects to improve upon in the future： （I） ocean model improvements to remove the artificial island at the North Pole; （2） higher resolution of the atmosphere model for better simulation of important features such as, among others, the Icelandic Low and westerly wind over the Southern Ocean; and （3） ocean model improvements to accurately receive freshwater input from land, and higher resolution for resolving major water channels in the Canadian Arctic Archipelago.

Seasonal and Spatial Variability of Microparticles in Snowpits on the Tibetan Plateau, China

The work presents microparticle concentrations in snowpits from the East Rongbuk Glacier on Mt. Qomolangma (Everest) (ER) (28.02°N, 86.96°E, 6536 m a.s.l.), the Zhadang Glacier on Mt. Nyainqentanglha (NQ) (30.47°N, 90.65°E, 5800m a.s.l.), and the Guoqu Glacier on Mt. Geladaindong (GL) (33.95°N, 91.28°E, 5823m a.s.l.) over the Tibetan Plateau (TP). Variations of microparticle and major ions (e.g. Mg2+, Ca2+) concentrations in snowpits show that the values of the microparticles and ions in the non-monsoon seasons are much higher than those in the monsoon seasons. Annual flux of microparticle deposition at ER is lower than those at NQ and GL, which could be attributed to the long distance away from the possible dust source regions as well as the elevation for ER higher than the others. Compared with other remote areas, microparticle concentrations in the southern TP are much lower than those in the northern TP, but still much higher than those in Greenland and Antarctica. The seasonal and spatial microparticle variations are clearly related to the variations of atmospheric circulation according to the air mass 5-day backward trajectory analyses of HYSPLIT Model. Resultingly, the high microparticle values in snow are mainly attributed to the westerlies and the strong dust storm outbreaks on the TP, while the monsoon circulation brings great amount of precipitation from the Indian Ocean, thus reducing in the aerosol concentrations.

Comparisons on seasonal and annual variations of δ^(18)O in precipitation

The spatial and temporal variations of stable oxygen isotope in precipitation on different time scales are analyzed according to the data from the IAEA/WMO stations with long survey series in the Northern Hemisphere. Temperature effect is mainly distributed in mid-high latitudes on seasonal scale except for Bamako and Addisababa stations. The δ 18 O/temperature slope displays the positive correlation against altitude for most of the statistical stations. Amount effect appears primarily in the region south of 30 o N and coastal areas. The δ 18 O/precipitation slope is indirectly proportional to precipitation amount. For some of the sampling stations at mid-high latitudes where their seasonal distribution of precipitation is contrary to that of temperature, coupled with temperature effect, the amount effect appears synchronistically. Either the temperature effect or the amount effect on seasonal scale, there are positive correlations to a certain extent between the annual weighted mean δ 18 O and the annual mean temperature for almost all the stations. The correlation between composite δ 18 O and temperature on spatial scale is much more marked, compared with that of individual station. There is a good agreement between 10-year moving average temperature curves I and II, with the values of the former all markedly smaller than corresponding ones of the latter, calculated by the monthly mean series group I and the annual mean series group II, respectively. However, two calculated d δ 18 O/d T curves display the distinct difference: the variation amplitude of slope series II is larger than that of slope series I. Both curves had similar ascending trend from the 1960s to the 1970s, and then, their variations display the anti-phase. Moreover, the analyses show that there is negative correlation between slope series II and temperature series II. However, the status is different for slope series I and temperature series I. Both series have contrary trend from the 1960s to the 1970s, whereas the same trend since the 1980s.

Research for length change of four seasons over China in recent 47 years

Using daily temperature data from 599 Chinese weather stations during 1961-2007, the length change trends of four seasons dur- ing the past 47 years were analyzed. Results show that throughout the region, four seasons＇ lengths are： spring becomes shorter （-0.8 d/10yrs）, summer becomes longer （3.2 d/10yrs）, autumn （-0.5 d/10yrs） and winter （-1.6 d/10yrs） becomes shorter. This trend is different in spatial distribution, namely it is very obvious in northern than southern China, and also remarkable in eastern than western China. Summer change is most obvious, but autumn has little change comparatively. This trend is highly obvious in North, East, Central and South China. In the Southwest starting in the 21st century, summer becomes longer and winter shortens. The trend in the Plateau region since the 1980s is that spring becomes longer and winter shortens. The average annual temperature increased during the past 47 years, and the change of the average annual temperature precedes seasons＇ length. Thus, the average annual temperature has a certain influence on the length change of seasons.

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.

Seasonal Change of Steric Sea Level in the GIN Seas

The Greenland Sea,Iceland Sea,and Norwegian Sea (GIN seas) form the main channel connecting the Arctic Ocean with other Oceans,where significant water and energy exchange take place,and play an important role in global climate change.In this study steric sea level,associated with temperature and salinity,in the GIN seas is examined based on analysis of the monthly temperature and salinity fields from Polar science center Hydrographic Climatology (PHC3.0).A method proposed by Tabata et al.is used to calculate steric sea level,in which,steric sea level change due to thermal expansion and haline contraction is termed as the thermosteric component (TC) and the halosteric component (SC),recpectively.Total steric sea level (TSSL) change is the sum of TC and SC.The study shows that SC is making more contributions than TC to the seasonal change of TSSL in the Greenland Sea,whereas TC contributes more in the Norwegian and the Iceland Seas.Annual variation of TSSL is larger than 50 mm over most regions of the GIN Seas,and can be larger than 200 mm at some locations such as 308 mm at 76.5 N,12.5 E and 246 mm at 77.5 N,17.5 W.