Interdecadal variability of summer precipitation in the Three River Source Region: Influences of SST and zonal shifts of the East Asian subtropical westerly jet

Summer precipitation in the Three Rivers Source Region(TRSR)of China is vital for the headwaters of the Yellow,Yangtze,and Lancang rivers and exhibits significant interdecadal variability.This study investigates the influence of the East Asian westerly jet(EAWJ)on TRSR rainfall.A strong correlation is found between TRSR summer precipitation and the Jet Zonal Position Index(JZPI)of the EAWJ from 1961 to 2019(R=0.619,p<0.01).During periods when a positive JZPI indicates a westward shift in the EAWJ,enhanced water vapor anomalies,warmer air,and low-level convergence anomalies contribute to increased TRSR summer precipitation.Using empirical orthogonal function and regression analyses,this research identifies the influence of large-scale circulation anomalies associated with the Atlantic–Eurasian teleconnection(AEA)from the North Atlantic(NA).The interdecadal variability between the NA and central tropical Pacific(CTP)significantly affects TRSR precipitation.This influence is mediated through the AEA via a Rossby wave train extending eastward along the EAWJ,and another south of 45°N.Moreover,the NA–CTP Opposite Phase Index(OPI),which quantifies the difference between the summer mean sea surface temperatures of the NA and the CTP,is identified as a critical factor in modulating the strength of this teleconnection and influencing the zonal position of the EAWJ.

Factors of Adherence to Concurrent Tuberculosis Treatment and Antiretroviral Therapy among HIV-TB Co-Infected Individuals in the East Region, Cameroon in the COVID-19 Era: A Retrospective Cohort Study

Context/Objectives: Tuberculosis (TB) and HIV co-infection is a serious health problem in Cameroon. The problems associated with poor adherence to treatment are on the increase worldwide. This problem can be observed in all situations where patients are required to administer their own medication, whatever the type of illness. The general objective of this study was to assess the factors affecting adherence to treatment among HIV-TB co-infected patients in health facilities in the East Region in the COVID context. Method: A retrospective cohort study before and during COVID-19 was conducted in HIV care units in 13 health districts in the East Region of Cameroon. Data were collected using a questionnaire recorded in the Kobo Collect android application, analyzed using SPSS version 25 software and plotted using Excel. Results: The pre-COVID-19 cohort compared to the during-COVID-19 cohort had a 1.90 risk of not adhering to treatment (OR: 1.90, CI {1.90 - 3.37}) and the difference was statistically significant at the 5% level (p-value = 0.029). Frequency of adherence was 65.4% (140/214). Adherence before COVID-19 was 56.9% whereas during COVID-19, it was 74.3%. Conclusion: The implementation of targeted interventions in the COVID-19 context, using evidence-based data and integrating the individual needs of HIV-TB co-infected patients, improved adherence to concurrent anti-tuberculosis treatment and antiretroviral therapy during the COVID-19 Era.

Regional Variability of Climate Change Hot-Spots in East Asia

The regional climate change index （RCCI） is employed to investigate hot-spots under 21st century global warming over East Asia. The RCCI is calculated on a 1-degree resolution grid from the ensemble of CMIP3 simulations for the B1, AIB, and A2 IPCC emission scenarios. The RCCI over East Asia exhibits marked sub-regional variability. Five sub-regional hot-spots are identified over the area of investigation： three in the northern regions （Northeast China, Mongolia, and Northwest China）, one in eastern China, and one over the Tibetan Plateau. Contributions from different factors to the RCCI are discussed for the sub-regions. Analysis of the temporal evolution of the hot-spots throughout the 21st century shows different speeds of response time to global warming for the different sub-regions. Hot-spots firstly emerge in Northwest China and Mongolia. The Northeast China hot-spot becomes evident by the mid of the 21st century and it is the most prominent by the end of the century. While hot-spots are generally evident in all the 5 sub-regions for the A1B and A2 scenarios, only the Tibetan Plateau and Northwest China hot-spots emerge in the B1 scenario, which has the lowest greenhouse gas （GHG） concentrations. Our analysis indicates that subregional hot-spots show a rather complex spatial and temporal dependency on the GHG concentration and on the different factors contributing to the RCCI.

A Regional Air-Sea Coupled Model and Its Application over East Asia in the Summer of 2000

A regional air-sea coupled model, comprising the Regional Integrated Environment Model System （RIEMS） and the Princeton Ocean Model （POM） was developed to simulate summer climate features over East Asia in 2000. The sensitivity of the model＇s behavior to the coupling time interval （CTI）, the causes of the sea surface temperature （SST） biases, and the role of air-sea interaction in the simulation of precipitation over China are investigated. Results show that the coupled model can basically produce the spatial pattern of SST, precipitation, and surface air temperature （SAT） with five different CTIs respectively. Also, using a CTI of 3, 6 or 12 hours tended to produce more successful simulations than if using 1 and 24 hours. Further analysis indicates that both a higher and lower coupling frequency result in larger model biases in air-sea heat flux exchanges, which might be responsible for the sensitivity of the coupled model＇s behavior to the CTI. Sensitivity experiments indicate that SST biases between the coupled and uncoupled POM occurring over the China coastal waters were due to the mismatch of the surface heat fluxes produced by the RIEMS with those required by the POM. In the coupled run, the air-sea feedbacks reduced the biases in surface heat fluxes, compared with the uncoupled RIEMS, consequently resulted in changes in thermal contrast over land and sea and led to a precipitation increase over South China and a decrease over North China. These results agree well observations in the summer of 2000.

SIMULATION OF PRESENT CLIMATE OVER EAST ASIA BY A REGIONAL CLIMATE MODEL

A 15-year simulation of climate over East Asia is conducted with the latest version of a regional climate model RegCM3 nested in one-way mode to the ERA40 Re-analysis data. The performance of the model in simulating present climate over East Asia and China is investigated. Results show that RegCM3 can reproduce well the atmospheric circulation over East Asia. The simulation of the main distribution patterns of surface air temperature and precipitation over China and their seasonal cycle/evolution, are basically agree with that of the observation. Meanwhile a general cold bias is found in the simulation. As for the precipitation, the model tends to overestimate the precipitation in northern China while underestimate it in southern China, particularly in winter. In general, the model has better performance in simulating temperature than precipitation.

Seasonal and Intraseasonal Variations of East Asian Summer Monsoon Precipitation Simulated by a Regional Air-Sea Coupled Model

The performance of a regional air-sea coupled model, comprising the Regional Integrated Environment Model System （RIEMS） and the Princeton Ocean Model （POM）, in simulating the seasonal and intraseasonal variations of East Asian summer monsoon （EASM） rainfall was investigated. Through comparisons of the model results among the coupled model, the uncoupled RIEMS, and observations, the impact of air-sea coupling on simulating the EASM was also evaluated. Results showed that the regional air sea coupled climate model performed better in simulating the spatial pattern of the precipitation climatology and produced more realistic variations of the EASM rainfall in terms of its amplitude and principal EOF modes. The coupled model also showed greater skill than the uncoupled RIEMS in reproducing the principal features of climatological intraseasonal oscillation （CISO） of EASM rainfall, including its dominant period, intensity, and northward propagation. Further analysis indicated that the improvements in the simulation of the EASM rainfall climatology and its seasonal variation in the coupled model were due to better simulation of the western North Pacific Subtropical High, while the improvements of CISO simulation were owing to the realistic phase relationship between the intraseasonal convection and the underlying SST resulting from the air-sea coupling.

The Extreme Summer Precipitation over East China during 1982-2007 Simulated by the LASG/IAP Regional Climate Model

The extreme summer precipitation over East China during 1982-2007 was simulated using the LASG/IAP regional climate model CREM(the Climate version of a Regional Eta-coordinate Model).The results show that the probability density functions(PDFs) of precipitation intensities are reasonably simulated,except that the PDFs of light and moderate rain are underestimated and that the PDFs of heavy rain are overestimated.The extreme precipitation amount(R95p) and the percent contribution of extreme precipitation to the total precipitation(R95pt) are also reasonably reproduced by the CREM.However,the R95p and R95pt over most of East China are generally overestimated,while the R95p along the coastal area of South China(SC) is underestimated.The bias of R95pt is consistent with the bias of precipitation intensity on wet days(SDII).The interannual variation for R95p anomalies(PC1) is well simulated,but that of R95pt anomalies(PC2) is poorly simulated.The skill of the model in simulating PC1(PC2) increases(decreases) from north to south.The bias of water vapor transport associated with the 95th percentile of summer daily precipitation(WVTr95) explains well the bias of the simulated extreme precipitation.

Characteristics of Anthropogenic Sulfate and Carbonaceous Aerosols over East Asia: Regional Modeling and Observation

The authors present spatial and temporal characteristics of anthropogenic sulfate and carbonaceous aerosols over East Asia using a 3-D coupled regional climate-chemistry-aerosol model, and compare the simulation with the limited aerosol observations over the region. The aerosol module consists of SO2, SO4^2-, hydrophobic and hydrophilic black carbon （BC） and organic carbon compounds （OC）, including emission, advections, dry and wet deposition, and chemical production and conversion. The simulated patterns of SO2 are closely tied to its emission rate, with sharp gradients between the highly polluted regions and more rural areas. Chemical conversion （especially in the aqueous phase） and dry deposition remove 60% and 30% of the total SO2 emission, respectively. The SO4^2- shows less horizontal gradient and seasonality than SO2, with wet deposition （60%） and export （27%） being two major sinks. Carbonaceous aerosols are spatially smoother than sulfur species. The aging process transforms more than 80% of hydrophobic BC and OC to hydrophilic components, which are removed by wet deposition （60%） and export （30%）. The simulated spatial and seasonal SO4^2-, BC and OC aerosol concentrations and total aerosol optical depth are generally consistent with the observations in rural areas over East Asia, with lower bias in simulated OC aerosols, likely due to the underestimation of anthropogenic OC emissions and missing treatment of secondary organic carbon. The results suggest that our model is a useful tool for characterizing the anthropogenic aerosol cycle and for assessing its potential climatic and environmental effects in future studies.

East China Summer Rainfall during ENSO Decaying Years Simulated by a Regional Climate Model

The performance of the Climate version of the Regional Eta-coordinate Model （CREM）, a regional climate model developed by State Key Laboratory of Numerical modeling for Atmospheric Science and Geophysical Fluid Dynamics/Institute of Atmospheric Physics （LASG/IAP）, in simulating rainfall anomalies during the ENSO decaying summers from 1982 to 2002 was evalu- ated. The added value of rainfall simulation relative to reanalysis data and the sources of model bias were studied. Results showed that the model simulated rainfall anomalies moderately well. The model did well at capturing the above-normal rainfall along the Yangtze River valley （YRV） during E1 Nifio decaying summers and the below and above-normal rainfall centers along the YRV and the Huaihe River valley （HRV）, respectively, during La Nifia decaying summers. These features were not evident in rainfall products derived from the reanalysis, indicating that rainfall simulation did add value. The main limitations of the model were that the simulated rainfall anomalies along the YRV were far stronger and weaker in magnitude than the observations during E1 Nifio decaying summers and La Nifia decaying summers, respectively. The stronger magnitude above-normal rainfall during E1 Nifio decaying summers was due to a stronger northward transport of water vapor in the lower troposphere, mostly from moisture advection. An artificial, above-normal rainfall center was seen in the region north to 35°N, which was associated with stronger northward water vapor transport. Both lower tropospheric circulation bias and a wetter model atmosphere contributed to the bias caused by water vapor transport. There was a stronger southward water vapor transport from the southern boundary of the model during La Nifia decaying summers; less remaining water vapor caused anomalously weaker rainfall in the model as compared to observations.

Drought fluctuations based on dendrochronology since 1786 for the Lenglongling Mountains at the northwestern fringe of the East Asian summer monsoon region

The Lenglongling Mountains （LLM） located in northeastern part of the Tibet Plateau, belong to a marginal area of the East Asian summer monsoon （EASM） and are sensitive to monsoon dynamics. Two tree-ring width chronologies developed from six sites of Picea crassifolia in the LLM were employed to study the regional drought variability. Correlation and temporal correlation analyses showed that relationships between the two chronologies and self-calibrated Palmer Drought Severity Index （sc_PDSI） were significant and stable across time, demonstrating the strength of sc_PDSI in modeling drought conditions in this region. Based on the relationships, the mean sc_PDSI was reconstructed for the period from 1786 to 2013. Dry conditions prevailed during 1817-1819, 1829-1831, 1928-1931 and 1999-2001. Relatively wet periods were identified for 1792-1795 and 1954-1956. Spatial correlations with other fourteen precipitation/drought reconstructed series in previous studies revealed that in arid regions of Northwest China, long-term variability of moisture conditions was synchronous before the 1950s at a decadal scale （1791-1954）. In northwestern margin of the EASM, most of all selected reconstructions had better consistency in low-frequency variation, especially during dry periods, indicating similar regional moisture variations and analogous modes of climate forcing on tree growth in the region.

Landscape Design of East Dukang Road in Baishui County of Shaanxi Province Based on Regional Cultures

Components of urban road landscapes and regional cultures in the urban road landscape designs were analyzed. In view of the crisis that cities are confronting with, that is, lack of regional cultural features, landscape design for East Dukang Road in Baishui County, Shaanxi Province was taken for example, cultural background of the county, general situation and design orientation of the project, guiding concepts, overall designs and nodal layouts were elaborated, so as to explore the reasonable utilization of regional cultures in urban road landscape designs. Moreover, regional cultures were taken as an important foundation for landscape design, and its useful "genes" are available for creating road landscapes with features of regional cultures so as to demonstrate the individuality and characteristics of the city in a better way.

Variation Characteristics of the Large-scale Frost in East Region of the Yellow River of Gansu in Recent 40 Years

[Objective]The research aimed to study variation characteristics of large-scale frost in the east region of the Yellow River of Gansu in recent 40 years.[Method]Based on daily minimum temperature data at 15 meteorological stations over the east region of the Yellow River of Gansu from 1969 to 2008,according to common climatic statistical index of the frost,variation characteristics of the large-scale frost and continuous frost in the east region of the Yellow River of Gansu in recent 40 years were studied.[Result]Since the 1990s,average last frost date in the east region of the Yellow River of Gansu obviously advanced,and first frost date started to obviously postpone.Advancing time of the last frost date was longer than postponing time of the first frost date.Average frost-free period also obviously prolonged.Extremely early first frost date and extremely late last frost date mainly happened in the 1970s and the 1980s.Extremely late first frost date and extremely early last frost date mainly happened after the middle period of the 1990s.Extremely long frost-free period gradually started to appear frequently.In recent 40 years,the continuous frost gradually decreased,and the intensity also declined.[Conclusion]The research was favorable for understanding change characteristics of the frost and climate in the east region of the Yellow River of Gansu,and had important guidance significance for improving prediction capability of the abnormal frost disaster,effectively preventing frost disaster and improving crop yield in the area.

A Modified Double-Moment Bulk Microphysics Scheme Geared toward the East Asian Monsoon Region

Representation of cloud microphysical processes is one of the key aspects of numerical models.An improved double-moment bulk cloud microphysics scheme(named IMY)was created based on the standard Milbrandt-Yau(MY)scheme in the Weather Research and Forecasting(WRF)model for the East Asian monsoon region(EAMR).In the IMY scheme,the shape parameters of raindrops,snow particles,and cloud droplet size distributions are variables instead of fixed constants.Specifically,the shape parameters of raindrop and snow size distributions are diagnosed from their respective shape-slope relationships.The shape parameter for the cloud droplet size distribution depends on the total cloud droplet number concentration.In addition,a series of minor improvements involving detailed cloud processes have also been incorporated.The improved scheme was coupled into the WRF model and tested on two heavy rainfall cases over the EAMR.The IMY scheme is shown to reproduce the overall spatial distribution of rainfall and its temporal evolution,evidenced by comparing the modeled results with surface gauge observations.The simulations also successfully capture the cloud features by using satellite and ground-based radar observations as a reference.The IMY has yielded simulation results on the case studies that were comparable,and in ways superior to MY,indicating that the improved scheme shows promise.Although the simulations demonstrated a positive performance evaluation for the IMY scheme,continued experiments are required to further validate the scheme with different weather events.

Trends in major and minor meteorological variables and their influence on reference evapotranspiration for mid Himalayan region at east Sikkim, India

Abstract： Estimation of evapotranspiration （ET） for mountain ecosystem is of absolute importance since it serves as an important component in balancing the hydrologic cycle. The present study evaluates the performance of original and location specific calibrated Hargreaves equation （HARG） with the estimates of Food and Agricultural Organization （FAO） Penman Monteith （PM） method for higher altitudes in East Sikkim, India. The results show that the uncalibrated HARG model underestimates ET0 by 0.35 mm day^-1 whereas the results are significantly improved by regional calibration of the model. In addition, this paper also presents the variability in the trajectory associated with the climatic variables with the changing climate in the study site. Non- parametric Mann-Kendall （MK） test was used to investigate and understand the mean monthly trend of eight climatic parameters including reference evapotranspiration （ET0） for the period of 1985 - 2009. Trend of ET0 was estimated for the calculations done by FAO PM equation. The outcomes of the trend analysis show significant increasing （p ≤ 0.05） trend represented by higher Z-values, through MK test, for net radiation （Rn）, maximum temperature （Tmax） and minimum temperature （Train）, especially in the first months of the year. Whereas, significant （0.01 ≥ p ≤0.05） decreasing trend in vapor pressure deficit （VPD） and precipitation （P） is observed throughout the year. Declining trend in sunshine duration, VPD and ET0 is found in spring （March - May） and monsoon （June - November） season. The result displays significant （0.01≤ p ≤0.05） decreasing ET0 trend between （June - December） except in July, exhibiting the positive relation with VPD followed by sunshine duration at the station. Overall, the study emphasizes the importance of trend analysis of ET0 and other climatic variables for efficient planning and managing the agricultural practices, in identifying the changes in the meteorological parameters and to accurately assess the hydrologic water balance of the hilly regions.

Regional-scale Surface Air Temperature and East Asian Summer Monsoon Changes during the Last Millennium Simulated by the FGOALS-gl Climate System Model

The spatial patterns and regional-scale surface air temperature （SAT） changes during the last millennium,as well as the variability of the East Asian summer monsoon （EASM） were simulated with a low-resolution version of Flexible Global Ocean-Atmosphere-Land-Sea-ice （FGOALS-gl） model.The model was driven by both natural and anthropogenic forcing agents.Major features of the simulated past millennial Northern Hemisphere （NH） mean SAT variations,including the Medieval Climate Anomaly （MCA）,the Little Ice Age （LIA） and the 20th Century Warming （20CW）,were generally consistent with the reconstructions.The simulated MCA showed a global cooling pattern with reference to the 1961-90 mean conditions,indicating the 20CW to be unprecedented over the last millennium in the simulation.The LIA was characterized by pronounced coldness over the continental extratropical NH in both the reconstruction and the simulation.The simulated global mean SAT difference between the MCA and LIA was 0.14°C,with enhanced warming over high-latitude NH continental regions.Consistencies between the simulation and the reconstruction on regional scales were lower than those on hemispheric scales.The major features agreed well between the simulated and reconstructed SAT variations over the Chinese domain,despite some inconsistency in details among different reconstructions.The EASM circulation during the MCA was stronger than that during the LIA The corresponding rainfall anomalies exhibited excessive rainfall in the north but deficient rainfall in the south.Both the zonal and meridional thermal contrast were enhanced during the MCA.This temperature anomaly pattern favored a stronger monsoon circulation.

Trace Metal Levels in Lichen Samples From Roadsides in East Black Sea Region,Turkey

Objective To determine the metal contents of lichen species from East Black Sea region of Turkey for investigation of trace metal pollution sourced traffic. Methods The levels of copper, cadmium, lead, zinc, manganese, iron, chromium, nickel, cobalt, palladium in lichen samples collected from East Black Sea region of Turkey were determined by flame and graphite furnace atomic absorption spectrometry after microwave digestion method. The accuracy of the method was corrected by standard reference material （NIST SRM IAEA-336 Lichen）. Results The contents of invest!gated trace metals in lichen samples were 7.19-22.4 μg/g for copper, 0.10-0.64 μg/g for cadmium, 4.03-44.6 μg/g for lead, 14.5-41.8 μg/g for zinc, 25.8-208 μg/g for manganese, 331-436 μg/g for iron, 1.20-3.01 μg/g for chromium, 1.48-3.90 μg/g for nickel, 0.20-3.55 μg/g for cobalt, 0.11-0.64 μg/g for palladium. The results were compared with the literature values. Conclusion Some lichen species such as Xanthoparmelia conspersa, Xanthoria calcicola, Peltigera membranacea, and Physcia adscendens are accumulated trace metals at a high ratio.

Geotectonic Subdivision and Paleozoic Subduction and Collision Orogeny of East Qinling and Its Adjacent Regions:Evidence from Geochemical Research

The regional lithospheric chemical heterogeneity in-ers that the East Qinling and its adjacent cratonic re-ions , as suggested by some authors , belong to two eotectonic units,the North China subdomain including he North China Craton and its southern continental largin (the North Qinling Belt), and the Yangtzean ubdomain comprising the Yangtze Craton and its torthern continental margin (the South Qinh'ng Belt). In the North Qinling Belt the metamorphosed olcanic rocks and graywackes of the Early Paleozoic Oanfeng Group south of the Early Proterozoic Qinling Froup show geochemical characteristics resembling hose of the arc volcanics and arc graywackes -espectively. The Early Paleozoic granites intruding in he Qinling Group also show similar geochemical features and similar compositional polarities to the arc-type granites . The Erlangping Group north of the Qinling Group is a volcanic-sedimentary sequence produced in an Early Paleozoic back - arc basin based on geochemical evidence . It is therefore believed that the North Qinling Belt comprised the active continental margin of the North China Craton , beneath which the ancient Qinling oceanic plate underthrusted and was consumed from 480 to 380Ma ago . The South Qinling Belt is generally considered to be a passive continental margin of the Yangtze Craton on which developed the thick Sinian and Paleozoic sediments of continental shelf and continental slope fades . The source of fine -grained clastic sedimentary rocks of various geological periods has been geochemically studied.The result demonstrates that the terrigenous elastics of the South Qinling Belt came only from the Yangtze Craton prior to the Silurian , and since then began to be fed by both the Yangtze Craton and the North Qinling . The Devonian sediments display a clear two - component mixing model in their source material . The change in the source materi-al strongly suggests that the Yangtze passive continental margin approached the active continental margin of the North China Craton and finally came into contact with it during the Silurian and the Early Devonian . On both sides of the Shangdan Fault Zone , the lithospheric megasuture of the Qinh'ng orogen , are distributed the Late Paleozoic (323-262 Ma ) granites which intruded in the Danfeng Group and the Qinling Group to the north , and in the Devonian strata to the south of the suture . The older granites of that time interval are comparable in geological and geochemical characteristics to the syn - collision granites from other continent-continent collision zones . The younger calc - alkaline granites which were em placed at about 260 Ma ago have been classified as the late - collision granites by various geochemical discrimination methods . On these grounds it may be deduced that the continent - continent collision orogeny did not begin to act until the late Early Carboniferous epoch and that its main episode was the Late Paleozoic , although it might have continued to the Early Mesozoic .The collision orogeny was separated from the subduction orogeny by an interval of about 60 Ma and the subduction of the oceanic crust was accompanied by the northward shifting of the Yangtze Craton and its passive continental margin . However , the ocean basin still remained in the South Qinling Belt for a long time after the disappearance of the ocean .

Key regions where land surface processes shape the East Asian climate

Land-atmosphere interaction,as one of the key processes affecting the atmosphere and climate over East Asia,has drawn increasing attention during the past few decades.However,the current level of understanding regarding the mechanisms through which land surface processes impact the East Asian climate needs to be improved.Based on existing studies,six key regions where land surface processes affect the East Asian climate are proposed in this study,which can provide a valuable reference for future research into land-atmosphere interaction in East Asia.

High-frequency climatic fluctuations over the past 30 ka in northwestern margin of the East Asian monsoon region, China

Whether millennial-to centennial-scale climate variations throughout the Holocene convey universal climate change is still widely debated.In this study,we aimed to obtain a set of high-resolution multi-proxy data(1343 particle size samples,893 total organic carbon samples,and 711 pollen samples)from an alluvial-lacustrine-aeolian sequence based on an improved age-depth model in the northwestern margin of the East Asian monsoon region to explore the dynamics of climate changes over the past 30 ka.Results revealed that the sequence not only documented the major climate events that corresponded well with those reported from the North Atlantic regions but also revealed many marked and high-frequency oscillations at the millennial-and centennial-scale.Specifically,the late stage of the last glacial lasting from 30.1 to 18.1 cal.ka BP was a dry and cold period.The deglacial(18.1-11.5 cal.ka BP)was a wetting(probably also warming)period,and three cold and dry excursions were found in the wetting trend,i.e.,the Oldest Dryas(18.1-15.8 cal.ka BP),the Older Dryas(14.6-13.7 cal.ka BP),and the Younger Dryas(12.5-11.5 cal.ka BP).The Holocene can be divided into three portions:the warmest and wettest early portion from 11.5 to 6.7 cal.ka BP,the dramatically cold and dry middle portion from 6.7 to 3.0 cal.ka BP,and the coldest and driest late portion since 3.0 cal.ka BP.Wavelet analysis results on the total pollen concentration revealed five substantially periodicities:c.5500,2200,900,380,and 210 a.With the exception of the c.5500 a quasi-cycle that was causally associated with the Atlantic meridional overturning circulation,the other four quasi-cycles(i.e.,c.2200,900,380,and 210 a)were found to be indirectly causally associated with solar activities.This study provides considerable insight into the dynamic mechanism of the Asian climate on a long-time scale and future climatic change.

Regional Endeavours Rrequired to Deal With Water Vulnerability in East and Southeast Asia

Booming economic development during the past decades has made the East and Southeast Asian region one of the most dynamic economies in the world and brought about rapid urbanization. It is expected that Asia will account for 12 of the world’s 25 cities with population exceeding 10 million by 2000. Tokyo will have more than 27 million people and Shanghai and Jakarta will each have more than 20 million people. Demand for water supply, as a result, will drastically increase. Data show that most of the East and Southeast Asian countries are faced with serious water shortage and contamination, in particular in the urbanized areas. The vulnerability of water supply constituents one of the greatest threats to the sustainable socio economic development of the region. Great efforts have been made to conserve both surface and subsurface water resources, to protect water from contamination and to use water in an efficient way. In addition to the establishment of administrative agencies under the governments in individual countries, a number of regional and country wide projects have been launched for a solution to ease the water vulnerability. The Coordinating Committee for Coastal and Offshore Geoscience Programmes in East and Southeast Asia (CCOP), an intergovernmental organization of the region, has devoted itself to coordinating regional endeavours to solve applied geoscientific problems through technology transfer, human resources development and regional data compilation. The regional map series and related databases produced by CCOP have provided useful information on regional geological background, which is also essential for the solution of water problems. However, it is obvious that regional efforts are not enough to meet the challenges we are faced with. In addition to raising public awareness and governmental concerns, advanced technologies, in particular those used in the petroleum industry to deal with oil and gas, a sort of fluid resources similar to water, must be adopted to the water supply industry. Since 1996, CCOP has, in cooperation with the developed countries, been working on a project called Petrowater. The Project aims at using the technology and infrastructures related to the oil industry to the water supply industry.