MEASUREMENTS AND MODEL SIMULATIONS OF SURFACE OZONE VARIATIONS AT DIFFERENT BACKGROUND CONCENTRATIONS OF THE PRECURSORS*

Ozone photochemical production and loss in very different environments at Waliguan baseline station and Lin'an background station were simulated by using the measurement data and photochemical box model.The results show that net ozone photochemical production rate is negative,about 0.5 ppb/d,at Waliguan baseline sation,because of very low precursor concentrations.But at Lin'an background station,the net photochemical ozone production is positive,about 2-3 ppb/h.which is very closed with the measurement at Lin'an.That means ozone production was controlled by photochemical reactions at Lin'an background station,because of the higher precursor concentrations.The net destruction rate,at Waliguan Mt.,is not large,so that future increase in anthropogenic emission of reactive nitrogen will lead to larger production rates of steady-state O₃ concentration.     

Harmonious Inter-decadal Changes of July–August Upper Tropospheric Temperature Across the North Atlantic, Eurasian Continent,and North Pacific

The authors have developed an integral view of the inter-decadal variability of July–August(JA)tro- pospheric temperature across the entire subtropical Northern Hemisphere.Using reanalysis data and com- plementary balloon-borne measurements,the authors identify one major mode of variability for the period 1958–2001 which exhibits a significant cooling center over East Asia and warming centers over the North Atlantic and North Pacific.The cooling(warming)signals barotropically penetrate through the troposphe...     

Spatial patterns of Tropospheric Biennial Oscillation and its numerical simulation

In order to investigate the spatial patterns of the Tropospheric Biennial Oscillation （TBO） on the global scale, the Climate Prediction Center （CPC） Merged Analysis of Precipitation （CMAP） monthly averaged precipitation and the Climate Diagnostics Center （CDC） monthly outgoing long-wave radiation （OLR） and SST are used in conjunction with TBO bandpass-filtering. The results indicate active biennial variability in the tropical eastern-central Pacific regions. It is evident that observations reflect the biennial component of the ENSO rather than the TBO itself. Since some studies have pointed out that the TBO is a broad-scale phenomenon differing from the ENSO, to investigate the pure TBO the ENSO signal must be excluded. The Scale Interaction Experiment-FRCGC （SINTEX-F） coupled general circulation model （CGCM） developed at Japan Frontier Research Center for Global Change （FRCGC） can capture both the ENSO and the biennial signals. Air-sea interactions in the tropical eastern-central Pacific are decoupled to eliminate the effects of ENSO in a experiment by SINTEX-F and the results show that biennial variability still exists even without ENSO. It seems to mean that the TBO and ENSO are independent from each other. Furthermore, the model results indicate that the two key regions are southwest Sumatra and the tropical western Pacific for the TBO cycle.     

Simulation of Tropospheric Ozone with MOZART-2： An Evaluation Study over East Asia

Climate changes induced by human activities have attracted a great amount of attention. With this, a coupling system of an atmospheric chemistry model and a climate model is greatly needed in China for better understanding the interaction between atmospheric chemical components and the climate. As the first step to realize this coupling goal, the three-dimensional global atmospheric chemistry transport model MOZART-2 (the global Model of Ozone and Related Chemical Tracers, version 2) coupled with CAM2 (the Community Atmosphere Model, version 2) is set up and the model results are compared against observations obtained in East Asia in order to evaluate the model performance. Comparison of simulated ozone mixing ratios with ground level observations at Minamitorishima and Ryori and with ozonesonde data at Naha and Tateno in Japan shows that the observed ozone concentrations can be reproduced reasonably well at Minamitorishima but they tend to be slightly overestimated in winter and autumn while underestimated a little in summer at Ryori. The model also captures the general features of surface CO seasonal variations quite well, while it underestimates CO levels at both Minamitorishima and Ryori. The underestimation is primarily associated with the emission inventory adopted in this study. Compared with the ozonesonde data, the simulated vertical gradient and magnitude of ozone can be reasonably well simulated with a little overestimation in winter, especially in the upper troposphere. The model also generally captures the seasonal, latitudinal and altitudinal variations in ozone concentration. Analysis indicates that the underestimation of tropopause height in February contributes to the overestimation of winter ozone in the upper and middle troposphere at Tateno.     

对流层大气的负熵流和熵产生

将原始熵平衡方程应用于大气系统，详细计算了对流层大气平均状态下的负熵流和熵产生及其各项分量，得出了它们之间的一些数量关系，并应用熵理论初步解释了大气运动的某些规律，对于天气预报和气候变化的研究具有一定参考意义。     

OH-bearing planar defects in olivine produced by the breakdown of Ti-rich humite minerals from Dabie Shan (China)

The partial breakdown of Ti-chondrodite and Ti-clinohumite during exhumation from ultra-high pressure to amphibolite facies conditions in garnet-pyroxenites from Dabie Shan (China) produces coronas of olivine coexisting with ilmenite blebs. Fourier transform infrared (FTIR) spectra of this newly formed olivine exhibit absorption bands in the hydroxyl-stretching region. Two intense peaks were observed at 3,564 and 3,394 cm⁻¹, identical in energy to peaks in Ti-clinohumite. Transmission electron microscopy (TEM) of the same olivine domains revealed the presence of a complex (001) planar intergrowth. These interlayers have a 1.35 nm repeat distance, which is characteristic of clinohumite. Such interlayers are also enriched in Ti with respect to the adjacent olivine as shown by energy dispersive spectrometry. The combined evidence from FTIR spectroscopy and TEM indicates that OH is incorporated along Ti-clinohumite planar defects. This study provides evidence that the nominally anhydrous phase olivine may contain OH as a humite-type defect beyond the breakdown of the hydrous humite minerals and confirms earlier suggestions that Ti plays a key role in OH incorporation in mantle olivine. We suggest that olivine containing Ti-clinohumite defects is an important phase for water transport in subduction zones and for the storage of water in cold subcontinental mantle. However, these defects are unlikely to be stable in hotter parts of the oceanic mantle such as where basaltic magmas are generated.     

Photooxidation of Methacrolein in Fe(Ⅲ)-Oxalate Aqueous System and Its Atmospheric Implication

Iron and oxalic acids are widely distributed in the atmosphere and easily form ferric oxalate complex (Fe(Ⅲ)-Ox). The tropospheric aqueous-phase could provide a medium to enable the photo-Fenton reaction with Fe(Ⅲ)-Ox under solar irradiation. Although the photolysis mechanisms of Fe(Ⅲ)-Ox have been investigated extensively, information about the oxidation of volatile organic compounds (VOC), specifically the potential for Secondary Organic Aerosol (SOA) formation in the Fe(Ⅲ)-Ox system, is lacking. In this study, a ubiquitous VOC methacrolein (MACR) is chosen as a model VOC, and the oxidation of MACR with Fe(Ⅲ)-Ox is investigated under typical atmospheric water conditions. The effects of oxalate concentration, Fe(Ⅲ) concentration, MACR concentration, and pH on the oxidation of MACR are studied in detail. Results show that the oxidation rate of MACR greatly accelerates in the presence of oxalate when compared with only Fe(Ⅲ). The oxidation rate of MACR also accelerates with increasing concentration of oxalate. The effect of Fe(Ⅲ) is found to be more complicated. The oxidation rate of MACR first increases and then decreases with increasing Fe(Ⅲ) concentration. The oxidation rate of MACR increases monotonically with decreasing pH in the common atmospheric water pH range or with decreasing MACR concentration. The production of ferrous and hydrogen peroxide, pH, and aqueous absorbance are monitored throughout the reaction process. The quenching experiments verify that ·OH and (O-·2) are both responsible for the oxidation of MACR. MACR is found to rapidly oxidize into small organic acids with higher boiling points and oligomers with higher molecular weight, which contributes to the yield of SOA. These results suggest that Fe(Ⅲ)-Ox plays an important role in atmospheric oxidation.     

准实时地基GPS可降水量的解算方案与可靠性研究

对准实时地基GPS可降水量的解算方案与可靠性的探讨,围绕三个方面展开:准实时GPS对流层延迟解算的最佳方案的确定;GPS可降水量与无线电探空资料的比较;GPS可降水量与水汽辐射计数据的比较。为了实时应用于气象领域,准实时对流层延迟的最佳方案为快速预报星历松弛解。在快速预报星历松弛解GPS可降水量与无线电探空数据的比较中,两者的相关性为0.88,绝对值均值为5.4 mm。GPS可降水量与水汽辐射计资料比较得到两者差值的均方根为1.68 mm。最后得到了最佳的准实时地基GPS可降水量的解算方案和在气象领域可降水量的反演的可行性的结论。     

基于OMI的亚洲地区对流层NO2高分辨率反演产品POMINO v2.1及其与其他产品的定量对比

对流层二氧化氮(NO₂)是一种重要的痕量污染气体。现有基于OMI卫星探测器、覆盖亚洲地区的NO₂公开产品QA4ECV、OMNO2和POMINO受到广泛使用,然而对于这3个产品的差异的定量认识仍然不足。我们将前期开发的POMINO产品进行了改进和优化,更新至v2.1并将反演区域扩大至覆盖东亚、东南亚和南亚大部分地区,随后定量分析了QA4ECV、OMNO2 v4和POMINO v2.1对流层NO₂垂直柱浓度在2015年—2020年在不同采样条件下的异同。结果显示,POMINO版本的更新对自身NO₂柱浓度反演结果的整体影响较小(<10%)。当3个产品均基于POMINO v2.1进行一致采样时,产品之间在整个亚洲区域的平均差异约为10%,在京津冀等污染地区的差异最高可达40%。3个产品均显示,京津冀地区NO₂柱浓度在五年间下降了约30%,而长三角地区的变化趋势较小。当3个产品进行分别采样时,POMINO v2.1的有效数据量比其他两个产品增加了11%—44%,特别是更好地保留了重...