CISK、蒸发-风反馈机制和热带大气30-60天振荡

建立一个包含ＣＩＳＫ机制和蒸发－风反馈机制（Ｅｖａｐｏｒａｔｉｏｎ－ＷｉｎｄＦｅｅｄｂａｃｋＭｅｃｈａｎｉｓｍ，简写为：ＥＷＦＭ）的热带大气运动的无耗散、线性斜压半地转模式，引入反映ＣＩＳＫ的无量纲凝结潜热参数η和反映ＥＷＦＭ的无量纲参数α，并求得模式系统的解析解。动力学分析和模式大气的计算结果进一步说明了ＣＩＳＫ和ＥＷＦＭ的共同作用是激发和驱动热带大气低频振荡的重要物理过程。     

大气环流模式的完全控制试验与模式大气的年际异常研究

对大气环流模式提出了完全控制试验（ＦＣ）的概念，对包括陆面下垫面在内的整个地球表面的热力强迫作了控制。在ＦＣ中，可以更好地分离出大气内动力过程对于模式大气短期气候异常的影响。利用ＩＡＰ２－ＬＡＧＣＭ（中国科学院大气物理所二层大气环流模式）实施了完全控制试验。结果表明，北半球夏半年ＦＣ的月平均海平面气压（ＳＬＰ）年际异常较Ｃ的小，而全球或南半球ＦＣ与Ｃ的ＳＬＰ无明显差别。东亚－西太平洋区域夏半年ＦＣ的月平均ＳＬＰ年际异常甚至高于Ｃ的，意味着该区域模式大气环流短期气候异常中大气内动力过程的作用不可忽视。     

ECMWF参考大气谱模式在Convex320机上的发展

将ＥＣＭＷＦ预报模式移植到Ｃｏｎｖｅｘ３２０机上，修改了Ｉ／Ｏ结构，使得该模式在该机上顺利运行，在模式中引入了参考大气。计算了６个实例，取得了较好的结果，另外，在该模式上还ＣＸＳ格式，节省了计算时间，也提高了计算精度。     

中尺度数值模式中湿过程参数化的敏感性试验

本文利用一个三维中尺度模式，分别采用两种不同的湿过程处理方案ＦＰＡ和ＮＣＡ模拟同一个洋面冷锋个例，以考察模拟结果对湿过程参数化方案的敏感性。两种方案的区别在于前一种使用了次网格湿对流参数化而后者没有。通过比较分别使用ＦＰＡ和ＮＣＡ方案所进行的模拟ＦＰＳ和ＮＣＳ，发现冷锋结构在两者间出现较大差异。从８５０ hPa等压面|Δθe|等值线图所显示的结构看，ＮＣＳ中冷锋呈现为一长一短两条锋带，而ＦＰＳ中冷锋仅呈现为一条锋带。在相应的冷锋横向垂直剖面中，ＮＣＳ中存在两个相邻的锋面垂直环流，而ＦＰＳ中只有一个。另外，ＮＣＳ中对流不稳定的冷锋区出现垂直运动过分发展的现象，而ＦＰＳ中不存在这个问题。通过与卫星云图比较，我们注意到，ＮＣＳ中尽管出现了垂直运动过分发展的现象，但相对于ＦＰＳ而言，其模拟的冷锋结构与实际较为接近，成功地模拟出云图上显示的双冷锋结构。ＮＣＳ中垂直运动过分发展的一个重要原因是模式中采用的静力平衡近似。ＦＰＳ中次网格对流参数化方案的使用，通过减少甚至消除对流不稳定度，一方面使垂直运动的过分发展倾向受到约束，另一方面也可能使在对流不稳定层结下的锋区环境中本应出现的中尺度结构失去了形成的机会。     

DRAFT PROPLSAL FOR THE SOUTH CHINA SEA MONSOON EXPERIMENT(SCSMEX)

ＤＲＡＦＴＰＲＯＰＯＳＡＬＦＯＲＴＨＥＳＯＵＴＨＣＨＩＮＡＳＥＡＭＯＮＳＯＯＮＥＸＰＥＲＩＭＥＮＴ（ＳＣＳＭＥＸ）ＣｈｅｎＬｏｎｇｘｕｎ（陈隆勋）ＤＲＡＦＴＰＲＯＰＯＳＡＬＦＯＲＴＨＥＳＯＵＴＨＣＨＩＮＡＳＥＡＭＯＮＳＯＯＮＥＸＰＥＲＩＭＥＮＴ（ＳＣ...     

PROGRESSES OF THE STUDY ON IMPACTS OF CLIMATE CHANGE ON AGRICULTURAL PRODUCTION IN CHINA

ＰＲＯＧＲＥＳＳＥＳＯＦＴＨＥＳＴＵＤＹＯＮＩＭＰＡＣＴＳＯＦＣＬＩＭＡＴＥＣＨＡＮＧＥＯＮＡＧＲＩＣＵＬＴＵＲＡＬＰＲＯＤＵＣＴＩＯＮＩＮＣＨＩＮＡ￥ＷａｎｇＦｕｔａｎｇ（王馥棠）ＰＲＯＧＲＥＳＳＥＳＯＦＴＨＥＳＴＵＤＹＯＮＩＭＰＡＣＴＳＯＦＣＬＩ...     

PERSPECTIVES OF TROPICAL CYCLONE UNUSUAL MOTIONS──THE DIFFICULTIES IN CURRENT TROPICAL CYCLONE FORECASTIN

ＰＥＲＳＰＥＣＴＩＶＥＳＯＦＴＲＯＰＩＣＡＬＣＹＣＬＯＮＥＵＮＵＳＵＡＬＭＯＴＩＯＮＳ──ＴＨＥＤＩＦＦＩＣＵＬＴＩＥＳＩＮＣＵＲＲＥＮＴＴＲＯＰＩＣＡＬＣＹＣＬＯＮＥＦＯＲＥＣＡＳＴＩＮＧＣｈｅｎＬｉａｎｓｈｏｕ（陈联寿）ＣｈｉｎｅｓｅＡｃａｄｅｍ...     

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

ＴｈｅＥａｒｌｙＳｕｍｍｅｒＳｅａｓｏｎａｌＣｈａｎｇｅｏｆＬａｒｇｅ－ｓｃａｌｅＣｉｒｃｕｌａｔｉｏｎｏｖｅｒＥａｓｔＡｓｉａａｎｄＩｔｓＲｅｌａｔｉｏｎｔｏＣｈａｎｇｅｏｆＴｈｅＦｒｏｎｔａｌＦｅａｔｕｒｅｓａｎｄＦｒｏｎｔａｌＲａｉｎｆａｌｌＥ...     

AN OVERVIEW ON THE RESEARCH PROGRESS OF SOME ASPECTS OF ATMOSPHERIC SCIENCES IN CAMS DURING LAST FIVE YEARS

ＡＮＯＶＥＲＶＩＥＷＯＮＴＨＥＲＥＳＥＡＲＣＨＰＲＯＧＲＥＳＳＯＦＳＯＭＥＡＳＰＥＣＴＳＯＦＡＴＭＯＳＰＨＥＲＩＣＳＣＩＥＮＣＥＳＩＮＣＡＭＳＤＵＲＩＮＧＬＡＳＴＦＩＶＥＹＥＡＲＳＣｈｅｎＬｉａｎｓｈｏｕ（陈联寿）ＡＮＯＶＥＲＶＩＥＷＯＮＴＨＥＲＥＳ...     

A Finite-Mode Model of Ideal Fluid Dynamics on the 2-Sphere

ＡＦｉｎｉｔｅ－ＭｏｄｅＭｏｄｅｌｏｆＩｄｅａｌＦｌｕｉｄＤｙｎａｍｉｃｓｏｎｔｈｅ２－ＳｐｈｅｒｅＷｅｉＭｏｚｈｅｎｇＣＲＣｆｏｒＳｏｕｔｈｅｒｎＨｅｍｉｓｐｈｅｒｅＭｅｔｅｏｒｏｌｏｇｙＣＳＩＲＯＤｉｖｉｓｉｏｎｏｆＡｔｍｏｓｐｈｅｒｉｃＲｅｓｅ...     

CH4 emission from various rice fields in P.R. China

Summary The CH₄ emission rates from Chinese rice fields have been measured in five typical areas representing all of the five major rice culture regions in People's Republic of China (P.R. China). Four types of diurnal variations (afternoon peak, night peak, afternoon-night double peaks and random pattern) of CH₄ emission rates have been found. The first pattern was normally found in clear weather, the second and the third types were only found occasionally in particular place, while the fourth were found in cloudy or rainy weather. Due to the irregular pattern of the methane production observed in the morning-afternoon comparison experiment, the transport pathway influenced by certain factors, may be the major factor governing the diurnal variation of CH₄ emission. Seasonal variation patterns of CH₄ emission differ slightly with different field locations, where climate system, cropping system and other factors are different. Two and three emission peaks were generally found during single and early rice vegetation periods, with the peak magnitude and time of appearance differing to small degree in individual sites. A decreasing trend of seasonal variation was always observed in late rice season. A combination of seasonal change of transport efficiency and that of CH₄ production rate in the paddy soil explains well the CH₄ emission. The role of rice plant in transporting CH₄ varied over a large range in different rice growing stages. The reasons for internnual changes of CH₄ flux are not yet clear.Great spatial variation of the CH₄ emission has been found, which can be attributed to the differences in soil type and soil properties, local climate condition, rice species, fertilizer and water treatment. Experiments showed that while the application of some mineral fertilizers will reduce the CH₄ emission and CH₄ production in the soil, the application of organic manure will enhance CH₄ emission and CH₄ production in the soil. Any measures which can get off easily decomposed carbon from organic manure may reduce C supply for CH₄ production, and hence reduce CH₄ emission. Fermented sludges from biogas generators and farmyard-stored manure seem to be promising. In some parts of China, separate application of the organic and mineral manure instead of mixed application could be another option. Frequent Scientific drainage and ridge cultivation, which are often used water management techniques in Chinese rice agriculture, have been proved in the experiments to be a very efficient mitigation measures to reduce CH₄ emission from rice fields.By summarizing the present available data, China's rice fields contribute about 13.3 Tg yr^–1 (11.4–15.2) CH₄ to the atmosphere. The total methane emission from global rice fields can be estimated 33–60 Tg yr^–1, much less than the estimates made before.If we extrapolate the measured data in China with a consideration of measured data in other Asian country, the total global emission of CH₄ from rice fields are estimated to be about 35–60 Tg yr^–1 With 2 Figures     

我国甲烷排放情景分析:IPAC模型结果

近期发布的IPCC第六次评估报告再次强调了短寿命期温室气体减排对温升减缓的作用。甲烷是最重要的短寿命期非CO₂温室气体。在各国提出各自新的减排目标之后,针对甲烷减排的行动方案也越来越多。甲烷减排正在成为下一阶段各国和全球合作的重点领域之一。本文在我国碳减排目标下的能源转型基础上,结合其他非能源活动的减排排放源的减排技术选择基础上,利用IPAC模型对未来甲烷的排放情景进行了分析。在模型设定的两个情景分析基础之上,研究发现,到2050年的能源转型可明显减少能源活动的甲烷排放,和2015年相比能源活动的排放可减少67％。和其他行业相比,能源部门的甲烷减排具有更好的协同性。如果考虑进一步减排甲烷,则需要在考虑其他大气污染物减排的基础上,可通过实现天然气的进一步减排来实现。同时其他部门的甲烷减排也具有很大潜力,低甲烷排放情景可以实现到2050年将甲烷排放减少到1 494万吨,和2015年相比全范围排放可减排58％。     

Estimates of indirect global warming potentials for CH4, CO and NOX

Emissions may affect climate indirectly through chemical interactions in the atmosphere, but quantifications of such effects are difficult and uncertain due to incomplete knowledge and inadequate methods. A preliminary assessment of the climatic impact of changes in tropospheric O₃ and CH₄ in response to various emissions is given. For a 10% increase in the CH₄ emissions the relative increase in concentration has been estimated to be 37% larger. The radiative forcing from enhanced levels of tropospheric O₃ is estimated to 37% of the forcing from changes in CH₄. Inclusion of indirect effects approximately doubles the climatic impact of CH₄ emissions. Emissions of NO_x increase tropospheric O₃, while the levels of CH₄ are reduced. For emissions of NO_x from aircraft, the positive effects via O₃ changes are significantly larger than the negative through changes in CH₄. For NO_x emitted from surface sources, the effects through changes in O₃ and CH₄ are estimated to be of similar magnitude and large uncertainty is connected to the sign of the net effect. Emissions of CO have positive indirect effects on climate through enhanced levels of tropospheric o₃ and increased lifetime of CH₄. These results form the basis for estimates of global warming potentials for sustained step increases in emissions.     

Surface measurements of carbon dioxide and methane at Alert during an Arctic haze event in April, 1986

Carbon dioxide (CO₂) has been measured at Alert by grab flask sampling since 1975 as part of the World Meteorological Organization's Background Air Pollution Monitoring Program. Deviations of CO₂ concentration from the mean annual cycle have previously been attributed to air masses arriving at Alert from the source regions of the industrialized parts of Europe and the Soviet Union. In situ measurements of ambient CO₂ and methane (CH₄) were made at Alert using an automated gas chromatograph, as part of the Arctic Haze Study during April 1986. The temporal behaviour of CO₂ and CH₄ during this period was found to be highly correlated with measurements of particulate sulphate and other atmospheric trace species of anthropogenic origin. Examination of calculated air mass back-trajectories provided further evidence that the observed short-term increases in CO₂ and CH₄ mixing ratios were due to long-range transport from anthropogenic source regions.     

Field studies of methane emission from termite nests into the atmosphere and measurements of methane uptake by tropical soils

The flux of CH₄ and CO₂ from termite nests into the atmosphere has been measured in a broad-leafed-type savannah in South Africa. Measurements were carried out on nests of species of six genera, i.e., Hodotermes, Macrotermes, Odontotermes, Trinervitermes, Cubitermes, and Amitermes. The flux rates of CH₄ relative to the flux rate of CO₂ in terms of carbon obtained for the individual species showed ratios of 2.9×10^-3, 7.0×10^-4, 6.7×10^-5, 8.7×10^-3, 2.0×10^-3 and 4.2×10^-3, respectively. Using data published on the assimulation efficiencies of termites, the flux of carbon as CH₄ accounts for 6.0×10^-5 to 2.6×10^-3 of the carbon ingested which results in a global CH₄ emission by termites of 2 to 5×10¹² g/yr. Methane is decomposed in the soil with average decomposition rates of 52 g/m²/h. The annual CH₄ consumption in the tropics and subtropics is estimated to be 21×10¹² g which exceeds the CH₄ emission rate by termites.     

Methane emission from rice paddies

Methane release rates from rice paddies have been measured in Andalusia, Spain, during almost a complete vegetation period in 1982 using the static box system. The release rates ranged between 2 and 14 mg/m²/h and exhibited a strong seasonal variation with low values during the tillering stage and shortly before harvest, while maximum values were observed at the end of the flowering stage. The CH₄ release rate, averaged over the complete vegetation period, accounted for 4 mg/m²/h which results in a worldwide CH₄ emission from rice paddies of 35–59×10¹² g/yr if we assume that the observed CH₄ release rates are representative of global conditions. The CH₄ release rates showed diurnal variations with higher values late in the afternoon which were most likely caused by temperature variations within the upper layers of the paddy soils. Approximately 95% of the CH₄ emitted into the atmosphere by rice paddies was due to transport through the rice plants. Transport by bubbles or diffusion through the paddy water was of minor importance. Incubation experiments showed that CH₄ was neither produced nor consumed in the paddy water. The relase of CH₄ from rice paddies caused a diurnal variation of CH₄ in ambient air within the rice-growing area with maximum values of up to 2.3 ppmv during the early morning, compared to average daytime values of 1.75 ppmv.     

Methane,carbon monoxide and methylchloroform in the southern hemisphere

New observational data on CH₄, CO and CH₃CCl₃ in the southern hemisphere are reported. The data are analysed for long term trends and seasonal cycles. CH₃CCl₃ data are used to scale the OH fields incorporated in a two dimensional model, which in turn, is used to constrain the magnitude of a global CH₄ source function. The possible causes of observed seasonality of CH₃CCl₃, CH₄ and CO are identified, and several other aspects of observed CH₄ variability are discussed.Possible future research directions are also given.     

青藏高原上空甲烷的时空分布特征及其夏季高值形成机制分析

利用搭载在美国Aqua卫星上的大气红外探测仪(AIRS)观测资料反演的全球甲烷(CH_4)产品和NCEP再分析资料,分析了2003~2014年青藏高原上空CH_4的时空变化特征,探讨了夏季CH_4高值变化与季风的关系。研究结果表明:就青藏高原整体而言,CH_4浓度随高度增加递减;对流层中高层CH_4含量季节变化较为明显,其平均浓度在7~9月处于高值,6月、10月次之,其余月份处于低值。2003~2014年CH_4含量呈逐年上升趋势,年增长率约为4.66ppb(10-9)。高原上空CH_4空间分布分析显示,高原北部CH_4浓度高于南部地区。夏季风期间,随着高原上的强对流输送和上空南亚高压的阻塞,对流层中高层CH_4浓度明显增加并不断积累,在8月底至9月初出现最大值。在分析季风指数的基础上发现,夏季季风影响下的强对流输送是高原对流层中高层CH_4高值形成的主要原因之一,对流层中高层CH_4浓度最大值出现时间较季风指数的峰值滞后约半至一个月,随着夏季风的撤退,CH_4浓度高值迅速降低。     

NUMERICAL SIMULATION OF ATMOSPHERIC METHANE TRENDS OVER THE LAST 150 YEARS*

A global two-dimensional chemistry model is developed to study long-term trends of CH₄ since industrial revolution.The sources of CH₄,CO and NO_x are parameterized as functions of latitude and time.With two long-term emission scenarios,long-term trends of CH₄ are simulated.The results have a good agreement with observation from ice cores.The modeled CH₄ increased from 760 ppbv in 1840 to 1611.9 ppbv in 1991, while the modeled number concentration of tropospheric OH decreased from 7.17×10⁵ cm^-3 in 1840 to 5.79×10⁵ cm^-3 in 1991.The increase of atmospheric CH₄ can be explained by the increase of emission of CH₄ and build-up because of decrease of OH radicals that remove CH₄ from the atmosphere.The model is also used to simulate the distribution of CH₄.Comparisons between the model results and observations show that the model can simulate both latitudinal distribution and seasonal variation of CH₄ well.     

Effects of Plant Community Type on Soil Methane Flux in Semiarid Loess Hilly Region,Central Gansu Province,China

Methane (CH₄) is an important greenhouse gas second only to CO₂ in terms of its greenhouse effect. Vegetation plays an important role in controlling soil CH₄ fluxes, but the spatial variability of soil CH₄ fluxes during vegetation restoration in Loess Hilly Region (LHR) is not fully understood. The effects of different plant community types [Medicago sativa grassland (MS); Xanthoceras sorbifolium forestland (XS); Caragana korshinskii bushland (CK); Hippophae rhamnoides shrubland (HR); and Stipa bungeana grassland (SB)] on soil CH₄ flux in LHR were studied via the static chamber technique. The results showed that the five plant community types were sinks of soil CH₄ in LHR, the plant community type significantly affected the soil CH₄ flux, and the average CH₄ uptake from high to low was in SB, HR, CK, MS, and XS. During the whole study period, the soil CH₄ flux showed similar interannual variation. The maximum absorption of soil CH₄ appeared in the growing season, while the minimum appeared in winter. Soil CH₄ uptake was positively correlated with soil temperature and soil moisture. Soil temperature and moisture are important controlling factors for the temporal variability of soil CH₄ flux. In LHR, the Stipa bungeana grassland is the more suitable plant community type for reducing soil CH₄ emissions. In the process of vegetation restoration in LHR, the soil CH₄ absorption potential of different plant community types should be considered, ecological benefits should be taken into account, and vegetation more suitable for mitigating the greenhouse effect should be selected.