The Pioneering Works of Professor Duzheng YE on Atmospheric Dispersion,Tibetan Plateau Meteorology,and Air–Sea Interaction

This paper provides an overview of the impacts of the original works of Professor Duzheng YE on a selected set of observational and model studies with which the present author has been associated over the past several decades. The main themes of these works include atmospheric energy dispersion, air–land interactions over the Tibetan Plateau, and El Ni n?orelated air–sea coupling over East Asia.The dispersive behavior of observed atmospheric fluctuations accompanying cold surge events in East Asia is demonstrated. Cold air outbreaks over Korea and southern China are coincident with the successive downstream development of troughs and ridges, with the group velocity of such wave packets being notably faster than the phase propagation speed of individual troughs and ridges. In a more general context, dispersive features are also discernible from lagged teleconnection charts and cross-spectra of observed and model-simulated geopotential height variations on 10–30-day time scales.Using the output from a high-resolution general circulation model, the relative contributions of condensational, sensible, and radiative heating to the atmospheric energy budget over the Tibetan Plateau are documented. The rapid changes of the upper tropospheric Tibetan anticyclone and East Asian mei-yu("plum rain") precipitation band associated with the development of the Asian monsoon system are described.The principal anomalies in sea level pressure, surface wind, precipitation and sea surface temperature over southeastern China and the Philippine Sea region during El Nio events are presented. The contributions of remote El Nio-related forcing and local air–sea interaction to the occurrence of these anomalies are assessed.     

Contrasting the Skills and Biases of Deterministic Predictions for the Two Types of El Nio

The tropical Pacific has begun to experience a new type of El Nio, which has occurred particularly frequently during the last decade, referred to as the central Pacific(CP) El Nio. Various coupled models with different degrees of complexity have been used to make real-time El Nio predictions, but high uncertainty still exists in their forecasts. It remains unknown as to how much of this uncertainty is specifically related to the new CP-type El Nio and how much is common to both this type and the conventional Eastern Pacific(EP)-type El Nio. In this study, the deterministic performance of an El Nio–Southern Oscillation(ENSO) ensemble prediction system is examined for the two types of El Nio. Ensemble hindcasts are run for the nine EP El Nio events and twelve CP El Nio events that have occurred since 1950. The results show that(1) the skill scores for the EP events are significantly better than those for the CP events, at all lead times;(2) the systematic forecast biases come mostly from the prediction of the CP events; and(3) the systematic error is characterized by an overly warm eastern Pacific during the spring season, indicating a stronger spring prediction barrier for the CP El Nio. Further improvements to coupled atmosphere–ocean models in terms of CP El Nio prediction should be recognized as a key and high-priority task for the climate prediction community.     

The oil spill behaviour model of the canadian atmospheric environment service. Part II: Evaluation of model guidance for emergency response

Abstract

In a companion paper the theoretical basis for the Canadian Atmospheric Environment Service oil spill behaviour model was discussed along with its evaluation, in non‐real time, using data collected from field experiments and a real spill. This paper deals with the use of the model in real time to provide guidance in support of the emergency created by an oil spill in the Canadian Beaufort Sea. The spill of about 2440 barrels of diesel oil occurred in September 1985, the result of storm damage to an artificial island used for hydrocarbon exploration.

Model simulations were carried out for two time periods while the spill was being tracked. These simulations identified the marked shifts in the direction of movement of the spill. While the predictive skills for the two time periods varied, with re‐initialization the final observed slick location was predicted to within 2 km. This model prediction was used by the regulatory authorities as guidance information in locating the slick when it could not be easily spotted from the air. The prediction of the size of the slick 27 h after initial time was in very good agreement with observations. A qualitative evaluation of the model‐simulated weathering of the oil was also carried out.     

Impacts of two types of El Niño on atmospheric circulation in the Southern Hemisphere

Based on NCEP/NCAR （National Centers for Environmental Prediction/National Center for Atmo- spheric Research） reanalysis data from 1979 to 2010, the impacts of two types of E1 Nino on atmospheric circulation in the Southern Hemisphere （SH） are analyzed. It is shown thaL when a warming event occurs in the equatorial eastern Pacific （EP E1 Nino）, there is a negative sea level pressure （SLP） anomaly in the east- ern Pacific and a positive one in the western Pacific. Besides, there exists a negative anomaly between 40°S and 60°S and a positive anomaly to the south of 60°S. When a warming event in the central Pacific （CP E1 Nino） occurs, there appears a negative SLP anomaly in the central Pacific and a positive SLP anomaly in the eastern and western Pacific, but the SLP anomalies are not so evident in the SH extratropics. In particular, the Pacific-South America （PSA） pattern induced by the CP E1 Nino is located more northwestward, with a weaker anomaly compared with the EP E1 Nino. This difference is directly related with the different position of heating centers associated with the two types of E1 Nino events. Because the SST anomaly associated with CP E1 Nino is located more westward than that associated with EP El Nino, the related heating center tends to move westward and the response of SH atmospheric circulation to the tropical heating changes accordingly, thus exciting a different position of the PSA pattern. It is also noted that the local meridional cell plays a role in the SH high latitudes during EP E1 Nino. The anomalous ascending motion due to the enhancement of convection over the eastern Pacific leads to an enhancement of the local Hadley cell and the meridional cell in the middle and high latitudes, which in turn induces an anomalous descending motion and the related positive anomaly of geopotential height over the Amundsen-Bellingshausen Sea.     

地气耦合研究进展简介

简要介绍了近十多年来地气相互作用研究领域所取得的成果,并从整体地球系统的角度探索自然灾害(气象灾害和地震灾害)的成因.在总结和评述过去工作的基础上,提出了地幔对流节律性假说,并利用这一假说解释了板缘地震、地球自转和厄尼诺之间的关系;利用地幔中存在中小尺度对流这一设想并结合绝对涡度守恒原理讨论了板内地震、地热流和旱涝分布之间的联系.最后提出了对今后地气耦合研究工作的一些看法.     

Indian summer monsoon and El Nino

The associations between strong to moderate El Nino events and the all-India and subdivisional summer monsoon rainfall is examined for the period 1871 to 1978. The significance of the association is assessed by applying the Chi-square test to the contingency table. The analysis indicates that during 22 El Nino years the Indian monsoon rainfall was mostly below normal over most parts of the country. However, the association between El Nino and deficient rainfall or drought is statistically significant over the subdivisions west of longitude 80°E and north of 12°N. During the five strong El Nino years—1877, 1899, 1911, 1918, and 1972—many areas of India suffered large rainfall deficiencies and severe droughts. There are four moderate El Nino years—1887, 1914, 1953, and 1976—when the suffering was marginal. The relationship between El Nino and the Indian monsoon rainfall is expected to be useful in forecasting large-scale anomalies in the monsoon over India.     

1998年大气环流异常及其对中国气候异常的影响

１９９８年受ＥＮＳＯ事件和青藏高原冬春季积雪多等因素的影响,北半球大气环流的主要特征是：５００ｈＰａ西太平洋副高强大,夏季副高脊线位置偏南;冬、夏季风均较弱;赤道辐合带偏弱,在西太平洋生成和登陆影响我 斩台风和热带风暴异常偏少;夏季亚洲中高纬度经向环流发展,其它季节则以纬向环流为主;环流异常是影响１９９８年中国气候极其异常的主要原因。     

The interdecadal variation characteristics of arctic sea ice cover-Enso-East asian monsoon and their interrelationship at quasi-Four years time scale

l.Introducti0nTheclimateformationandvariabilityisnotonlythereflectionofatmosphericinternalbe-havi0rbutalsotheinnuencefromtheinteractionexistSintheclimatesystem.Becausetherela-tivecooIingandheatingsourcesofatmospherearelocatedinthePOlarandtropicalregionrespectively,itiseasytounderstandthattheArcticseaicecoverandSSTanomalieswhichim-pocttheatmosphericheatingtosomeextentcanexerttheirinfluenceontheremotCatmosphericcirculation-Inthisregard,thefocusrelatedtheinflueneeofArcticseaicecoverandtropica…     

Factors driving the seasonal distribution of planktonic and epiphytic ciliates in a eutrophicated Mediterranean Lagoon

We studied the distribution of planktonic and epiphytic ciliates coupled with environmental factors and microalgae abundance at five stations in Ghar El Melh Lagoon (Tunisia). Planktonic ciliates were monitored for a year and epiphytic ciliates were sampled during summer 2011 in concordance with the proliferation of the seagrass Ruppia cirrhosa. Ciliate assemblage was largely dominated by Spirotrichea followed respectively by Tintinnida of and Strombidiida. No significant difference was found in the distribution of ciliate species among the stations. Redundancy analysis indicates that abiotic factors (temperature and nutriments) have a significant effect on the dynamics of certain ciliates. For epiphytic ciliates, 4 species were identified: Tintinnopsis campanula, Aspidisca sp., Strombidium acutum and Amphorides amphora. Based on PERMANOVA analyses, ciliates exhibit significant correlations among months and stations. According to ACP, epiphyte distribution follows roughly those of R. cirrhosa and pH. Significant correlations were found between harmful dinoflagellates and both planktonic and epiphytic ciliates.     

Transition from mildly-tholeiitic to calc-alkaline suite: the case of Chichontepec volcanic centre, El Salvador, Central America

The Chichontepec volcano is a Plio-Pleistocene composite volcano that erupted lavas ranging from high-alumina basalts to dacites. It experienced a caldera-forming paroxysmal eruption during the early Pleistocene. Pre-caldera lavas are mildly tholeiitic and they evolved mainly by low pressure crystal fractionation, notwithstanding the fact that most mafic lavas (low-MgO high-alumina basalts) retain traces of polybaric evolution. Conversely, post-caldera lavas, which are mainly pyroxene andesites, are clearly calc-alkaline, having evolved by open-system crystal fractionation. Sr–Nd isotopic data and trace elements characteristics indicate that the same mantle source was involved in the petrogenesis of these series. Modelling the AFC process showed that it did not play any role in the petrogenesis of these rocks; a crystal fractionation model is considered to be more relevant. A slight variation in the fractionating assemblage could have caused the transition from an early mildly tholeiitic trend to a late calc-alkaline one. Mineralogical evidence, mass-balance calculations and elemental chemistry support this hypothesis, assuming that the greater amount of pyroxene on the liquidus is at the expense of plagioclase; this would have prevented the trend in iron enrichment.