Occurrence of microorganic pollutants in the atmosphere of Singapore during haze and non-haze periods

Microorganic pollutants such as polycylic aromatic hydrocarbons （PAHs）, organochlorine pesticides （OCPs）, polychlorinated biphenyls （PCBs） and total petroleum hydrocarbons （TPHs） are known to be present in urban ambient air. These organic compounds are prone to atmospheric transport and deposition over long distances, thus enabling them to accumulate even in regions remote from their sources. Deposition from the atmosphere can be via direct deposition and exchange with crops that may be directly or indirectly ingested by humans. It can also take place via wet and dry deposition and air-water exchange. Following their deposition, these microorganic pollutants tend to accumulate in soils, sediments and in human and ecological food chains. There are many reports in the literature on the atmospheric concentrations of microorganic pollutants, but there are few reports and data in Asia. This study was performed in Singapore to determine the relative amounts of persistent organic pollutants and TPHs in ambient aerosols. One of the important sources of these organic compounds in Southeast Asia is thought to be biomass burning （vegetation fires）. Hence, air sampling was conducted during both smoke haze and non-haze periods. The data obtained from this study will be presented and discussed.     

Evaluation of oceanic transport parameters using transient tracers from observations and model output

A method is presented to find the age distribution of ocean waters, the transit-time distribution (TTD), by combining an eddying global ocean model’s estimate of the TTD with hydrographic observations of CFC-11, temperature, and salinity. The method uses a mixture model of an assumed form of the TTD, an inverse Gaussian (IG), and an established Bayesian statistical method. All known significant sources of uncertainty are propagated to arrive at estimates of two oceanic transport parameters associated with the IG TTD, the mean age (Γ) and either the half-variance (${\mathrm{\Delta }}^2$) or the Peclet number ($\mathit{Pe}={\mathrm{\Gamma }}^2/{\mathrm{\Delta }}^2$). It is found that the uncertainties on Γ do not overlap zero in most locations using only CFC-11, temperature, and salinity. However, the uncertainty on the other IG parameter does not overlap zero in only a few locations. With the inclusion of another transient tracer (³He/³H), the uncertainty on this other IG parameter does not overlap zero in just a few additional locations in the deep North Atlantic Ocean. Neither a single- nor mixture-IG representation is adequate for representing the full TTD in the ocean, particularly in the Southern Ocean.Differences between the IG parameters estimated using the model’s tracers as data (BayesPOP) and those estimated using tracer observations as data (BayesObs) provide information about the sources of model biases, and give a more nuanced picture than can be found by comparing the simulated CFCs with observed CFCs. Using the differences between each of the oceanic transport parameters from BayesObs and those from BayesPOP with and without a constant Pe assumption along each of the hydrographic cross-sections considered here, it is found that the model’s eddy mixing biases often lead to larger model errors than the model’s mean advection time biases. It is also found that mean advection time biases in the model can be statistically significant at the 95% level where mode water is found in the Southern Ocean.     

全球热带海表温度异常的POP预报模型

在对全球热带海表温度异常（ＳＳＴＡ）进行主振荡型（ＰＯＰ）分析的基础上上综合考虑大尺度海洋运动状况和长期预报的特征引入了相位划分预报方案,将典型ＰＯＰ模态进行相位划分并综合考虑它们的相关位承替规律预报ＳＳＴＡ未来发展趋势,独立样本事后预报结核下实相位划分预报方案能提供较好的预报信息。     

欧亚500 hPa环流、雪盖和中国降水量3—4年耦合振荡

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Simultaneous Determination of PIP and POP in Seawater

1INTRODUCTIONInrecentyearsglobalclimatechangehasbeenanissueofbothpublicandscientificconcern.Oceanscover71 %ofearthandplayamajorroleinglobalclimatechange.Phosphorus,asacriticalelement,regulatespri maryproductioninaquaticecosystems.Therefore,thefunctionofphosphorusinoceansystemhasreceivedin creasingscientificinterest(Songetal.,2 0 0 3 ) .PP (particulatephosphorus)isanimportantforminphosphorustransferinseawater(Song,2 0 0 1 ) .Pro portionofPPintotalphosphorus(TP)inseawatervar iesfrom 1 0 …     

西太平洋热带地区环流低频变化的主振荡型预测试验

用1994年逐日西太平洋热带地区200 hPa纬向风场资料建立主振荡预测模型,对低频纬向风场（30～50天）的传播进行独立预报试验。试验结果表明,在夏半年109次预测中提前15天预报的相关性预报技巧在0.50以上。它是揭示低频时空演变的有效工具。同时也讨论了有关模型参数的选取方法。     

海洋模式中Boussinesq近似误差讨论

根据全球增暖的特点,设计了一个理想的数值试验方案,用Boussinesq POP海洋模式和改进的非Boussinesq POP海洋模式定量讨论了Bousiinesq近似在海洋模式计算中的误差。结果发现,在只有热力驱动的热力环流背景下,由热膨胀引起的海平面上升在水平方向上是基本均匀的,在所给的初始边界条件下,这种由Boussinesq近似引起的最大海平面误差可以达到59％,在Boussinesq POP模式中,热源中心处的海面高度要远小于由非Boussinesq模式计算的海面高度,而其周围有虚假的海面高度下降;在只有加热引起的热盐环流过程中,当模式作了Boussinesq假设以后,计算的经向和纬向垂直环流都会产生虚假的加强,虽然这种误差只是在1％左右;在Bousiinesq近似假定下,热量经向通量在赤道上垂直剖面的积分误差比质量经向通量在赤道上垂直剖面的积分误差大一个量级;非Boussinesq模式计算的气压梯度所做功的垂向分布在3000m以下是有波动的,而Boussinesq模式计算的气压梯度所做功的垂向分布在3000m以下基本上是均匀的,它的误差在10％以上。     

A Hybrid Neural Network Model for ENSO Prediction in Combination with Principal Oscillation Pattern Analyses

El Ni?o-Southern Oscillation(ENSO)can be currently predicted reasonably well six months and longer,but large biases and uncertainties remain in its real-time prediction.Various approaches have been taken to improve understanding of ENSO processes,and different models for ENSO predictions have been developed,including linear statistical models based on principal oscillation pattern(POP)analyses,convolutional neural networks(CNNs),and so on.Here,we develop a novel hybrid model,named as POP-Net,by combining the POP analysis procedure with CNN-long short-term memory(LSTM)algorithm to predict the Ni?o-3.4 sea surface temperature(SST)index.ENSO predictions are compared with each other from the corresponding three models:POP model,CNN-LSTM model,and POP-Net,respectively.The POP-based pre-processing acts to enhance ENSO-related signals of interest while filtering unrelated noise.Consequently,an improved prediction is achieved in the POP-Net relative to others.The POP-Net shows a high-correlation skill for 17-month lead time prediction(correlation coefficients exceeding 0.5)during the 1994-2020 validation period.The POP-Net also alleviates the spring predictability barrier(SPB).It is concluded that value-added artificial neural networks for improved ENSO predictions are possible by including the process-oriented analyses to enhance signal representations.     

温度对POP Rb原子钟性能影响的研究

从温度对缓冲气体碰撞频移和弛豫率的影响出发,对充有Ar和N2这2种缓冲气体的POP(pulsed optically pumped,脉冲激光抽运)汽泡式铷原子钟的温度特性进行了理论和实验研究。研究表明,Ar与N2的气压比为1.6时,60℃的线性温度系数为0;不同温度时,布居数差弛豫率1和相干弛豫率2各不相同,若1 2,则POP铷原子钟Ramsey条纹包络在微波场与原子跃迁失谐为0附近为凹陷,信噪比较差,反之,为凸起,信噪比较高。研究结果对设计POP原子钟的缓冲气体气压比和工作温度,以及提高POP原子钟的中长期稳定度有一定借鉴作用。