Model for Methane Emission from Rice Fields and Its Application in Southern China

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Distribution of methane content and methane fluxes in the Sea of Japan,Sea of Okhotsk,and near-Kuril Pacific

The spatial distribution of methane content and methane fluxes in the water in the north-western part of the Sea of Japan, in the Kuril basin of the Sea of Okhotsk, and in the near-Kuril part of the Pacific Ocean is studied using the data of marine research expeditions in 2005, 2010, and 2011. The studies revealed the significant variability of the methane flux depending on the source presence and on the sea surface conditions. The high emission of methane from water to the atmosphere is registered in the areas where its concentration exceeds the equilibrium values with the atmosphere. The use of the model of computation of the fields of currents and contaminant transport for the investigated water area enabled explaining the formation of the high concentration of methane in the center of vortices in the zones of sea water convergence in the water areas under study.     

Methane emission at the main stages of technological cycle of sewage waste water purification at Rostov-on-Don aeration station

The methane concentration in the waste water coming to the aeration station is 1130 μl/l on average and it decreases to 11 μl/l after all purification stages. Experimentally measured methane fluxes to the atmosphere from the waste water under purification and sewage sediments of silt fields varied within 0.2–50.1 and 98.3–188.8 mg/m² per hour, respectively, and correlated closely enough with the gas content in them. An approximate total methane emission by the purification plants is about 475 kg per day and the major contribution (83%) belongs to the silt field sediments characterized by its extremely high content (42.42–199.49 μg/g of the damp sediment). It is demonstrated that the regression equations obtained by the authors before and approximating the relation of the methane content in the water and bottom deposits of water bodies with its fluxes to the atmosphere can be used to estimate the methane amount emitted during the waste water purification.     

稻田甲烷排放的初级模式

本文建立了一个区域尺度稻田生态系统CH4排放的初步模式，该模式能从理论上反映稻田CH4产生、传输与排放的机理，并提供了一种估计不同区域气候和土壤条件下稻田生态系统CH4排放总量的有效方法。模式主要包括三个部分:水稻的生长、土壤有机物的分解和CH4的产生、传输及排放过程。模式分别模拟了早稻和晚稻CH4的排放，模拟结果与实测比较接近，CH4的季平均排放量，模拟值与实测值的偏差在10% 左右。模式的敏感性实验表明，温度是稻田CH4排放规律的主要控制因子。     

大气甲烷浓度的差分吸收测量

该文讨论了用双He-Ne激光监测环境大气中甲烷的差分吸收方法，在实验室测量了甲烷对He-Ne激光波长的吸收系数，并且用3.3922 μm和3.3912 μm线在室外进行了甲烷浓度的测量。测量获得当地近地面自然大气中的甲烷平均浓度值为1.78 ppm，标准偏差σx=0.238 ppm。     

Studying methane emission in the north of Western Siberia

Methane emitted into the atmosphere from sources located in the Urengoi natural gas field is estimated from direct methane concentration measurements in the atmospheric boundary layer and modeling. The results of direct profile measurements in the summer-fall season of 2003 are generalized versus the data from the previous field studies and background monitoring of greenhouse gases in the northern polar region. The use of models for calculating the intensity of emission from sources located in the field area together with a set of methane concentration measurements at three altitudes allowed the authors to develop a method of verification of emission from a specific source, a deposit. The method estimates the emission both from part of the field area and from the whole field with an irregular distribution of the intensity of sources across the deposit area.     

Computing the methane cycle elements in the aquatic ecosystems of the Sea of Azov and the World Ocean based on empirical formulae

Empirical relationships between methane concentration and the rates of its oxidation and emission in the sediment-water-atmosphere system are computed using the experimental data and the data presented in the literature. For the Sea of Azov and the World Ocean the possibility is demonstrated of using the empirically derived formulae to compute the methane cycle elements in aquatic ecosystems. The comparability of methane volumes in the water column and bottom sediments as well as of those oxidized and released from water and sediments computed using these formulae, demonstrates the adequacy of the obtained formulae. It is shown that depending on morphological parameters of reservoirs of aquatic ecosystems and on their volume and area, the ratio of the amounts of methane that is oxidized and released to the atmosphere, changes as well as the rate of its turnover.     

Methane Production, Emission and Possible Control Measures in the Rice Agriculture

In the rice field methane is produced in the soil layer with depths of 2-25 cm. The vertical profile of methane production rate in the paddy soil during the water covering period differs from that in the paddy soil in dry phase. Only a small part, about 30%. of the produced methane is emitted to the atmosphere through rice plant, air bubbles, and molecular diffusion. Therefore, the methane emission rate from the rice field depends not only on the methane production rate in the soil, but also on the transport efficiency of the rice plant, air bubble formation that in turn depends on the production rate, and molecular diffusion.Field measurements show that methane emission rates from a particular rice field have very large diurnal, seasonal and interannual variations, which are related to soil characteristics, water regime, farming procedure, local climate, and rice growing activities. The relationship between the methane emission rate and the above mentioned factors is very complicated. The emission rate     

中国稻田甲烷产生和排放研究 Ⅱ.模式研究和减排措施

主要介绍了近 2 0年来稻田甲烷排放的模式研究和排放量的估算以及减少稻田甲烷排放的措施。数值模式是估算稻田甲烷排放量的一条有效途径 ,模式的研究现在正处于发展阶段。介绍了几个主要的模型 ,既有物理过程模型也有经验模型。年排放量的估算范围为 6 79～ 4 1 4Tg ,随着技术的发展和大量实验的进行估算值的精度正得到不断的提高。减排措施是减少稻田甲烷排放的必要手段 ,但是目前的减排技术均处于研究阶段 ,应用还不成熟     

PRELIMINARY STUDY OF BAROTROPIC STOCHASTIC DIFFERENCE MODEL APPLIED TO WEATHER PREDICTION

In order to consider both the deterministic and the stochastic property of atmospheric motion simul-taneously,in this paper,the weather prediction is proposed as the problem of the evolution of meteorologicalfield.The historical viewpoint of atmospheric motion is emphasized here.Based on time series analysis te-chnique,a stochastic-dynamical model with multiple initial fields is derived.Thus,weather forecasting is sum-meal up as a problem of solving a set of stochastic difference equations.For the barotropic atmosphere,thenumerical solutions of the equations are obtained by using the method of empirical orthogonal functions(EOF),and examples of medium-range weather prediction are given here.Meanwhile,selecting the order oftime series,i.e.,determining the number of initial fields properly,is also discussed.     

北半球冬半年平流层大气低频振荡特征的研究

利用NCEP/NCAR(1970～1999年)位势高度场和风场再分析资料,通过小波分析的方法,研究并揭示了北半球冬半年平流层大气低频振荡的周期,然后通过滤波等方法,揭示了冬半年平流层大气低频振荡的空间结构、传播规律、地域分布特征及北半球低频遥相关的一些分布特征,并且与对流层大气低频振荡作比较.作者对北半球平流层大气低频振荡进行的系统分析研究结果表明:在北半球冬半年平流层,大气低频振荡十分显著,其振荡周期以60天最为显著,在垂直方向上表现出正压结构特征,在水平方向上表现为一致西传,并且以北极涛动(the arctic oscillation)占据主导地位.北半球冬半年平流层大气低频振荡主要活动区域为北极地区,并且在45°N附近还存在3个活动中心,即欧亚大陆、北太平洋和北大西洋中心.     

Methane concentration in the atmospheric boundary layer from the measurements at north pole-36 and north pole-39 drifting ice stations

Episodic emissions ofmethane with the concentration of4 ppm to the lower atmosphere near the continental slope of the Arctic Ocean are considered. It is revealed that such methane emissions can be associated with the erosion of sediments containing gas hydrates, for example, as a result of the effects of mudflows caused by the instability of slope currents as well as by the geologic activity in the zone of significant depth drops. The high background concentration of methane is registered in the central part of the Arctic Ocean that is probably provoked by biologic activity within sea ice and on its bottom.     

Climate change in IAP RAS global model taking account of interaction with methane cycle under anthropogenic scenarios of RCP family

Carried out are numerical experiments with the IAP RAS global climate model (IAP RAS CM) under new RCP scenarios of anthropogenic impact for the 18th–21st centuries taking account of the response of the methane emission from the soil to the atmosphere and effects of chemical processes in the atmosphere on the climate changes. The model generally simulates the preindustrial and present-day characteristics of the methane cycle. Methane emissions from the soil to the atmosphere (within the range of 150–160 Mt CH₄/year for the present-day period) reach 170–230 Mt CH₄/year by the late 21st century depending on the scenario of anthropogenic impact. The methane concentration under the most aggressive RCP 8.5 anthropogenic scenario increases up to 3900 ppb by the late 21st century. Under more moderate RCP 4.5 and 6.0 anthropogenic scenarios, it reaches 1850–1980 ppb in the second half of the 21st century and decreases afterwards. Under RCP 2.6 scenario, the methane concentration maximum of 1730 ppb in the atmosphere is reached in the second decade of the 21st century. The taking account of the interaction between the processes in the soils and the climate leads to the additional increase in the methane content in the atmosphere by 10–25% in the 21st century depending on the scenario of anthropogenic impact. The taking account of the methane oxidation in the atmosphere in the case of warming reduces the increase in its concentration by 5–40%. The associated changes in the surface air temperature turn out to be small (less than 0.1 K globally or 4% of the warming expected by the late 21st century).     

淮河流域南部丘陵森林地区土壤-植被-大气相互作用:长期野外试验观测的初步分析

本文简要介绍了包括三部分观测的安徽淮南长期野外试验观测站,特别是土壤-植被-大气的集中观测,对小塔运行前三个月(2018年6月至8月)的数据,并结合同一时段大塔获得的数据,进行了初步分析.结果表明这些资料有合理的变化特征,日变化和夏季值特征显著,各月份间气象变化有明显差异.土壤水分和温度受降雨影响,在不同的下垫面条件下...     

闪电定位和雷达观测资料在云分析中的应用及数值试验

本文针对2016年6月山西、山东地区一次强对流活动,通过GRAPES（Global/Regional Assimilation andPrediction Enhanced System）云分析系统融合了多普勒雷达反射率三维组网拼图资料和ADTD（Active DirectoryTopology Diagrammer）闪电定位资料,对模式初始场的云水、云冰等云微物理变量进行了调整和分析,并对这次强对流过程设计了3组数值试验。结果表明:（1）云分析系统在加入雷达反射率资料以后,能在模式初始场中较准确的计算模式的初始水物质;（2）闪电定位资料转换成的替代雷达反射率对原有的雷达反射率有一定的补充作用,使模式的初始场与真实状况更接近;（3）从模式降水的角度看,在加入雷达资料以后,GRAPES云分析可以显著提高6小时以内降水的模拟效果,而闪电定位资料的加入,对中雨以上量级的降水模拟有进一步的改进作用。     

区域复杂地形大气污染扩散的模拟研究

围绕复杂地形区域尺度大气污染物的扩散问题,以贵州西部山区"西电东送"大型火电厂六枝电厂所在区域为例,采用局部嵌套的高分辨率复杂地形大气扩散模式系统,模拟了该区域大气边界层气象场和污染物散布的浓度场,给出二级空气质量标准下各级保证率的小时平均和日均浓度分布,进而得出其年均浓度分布,分析其时空分布及变化特征,研究了山区复杂地形上大气污染物的扩散特性和散布规律。     

An exact solution for two-dimensional frictionless motion in the atmosphere

A solution of the nonlinear problem for determining the wind velocity in frictionless atmosphere (the gradient wind) under given geopotential (pressure) field is proposed. The approach is analytical and is based on quadratic polynomial approximation of the geopotential field and linear approximation of the wind velocity field with respect to x and y, the coefficients of the expansions being functions of the time t. The derived system of ordinary nonlinear differential equations is analyzed as a dynamical system. Exact analytical solutions are found for some par-ticular cases, Some of their properties bear a resemblance to those or really existing atmospheric vortices (cyclones and anticyclones).     

中南地区一次飞机颠簸的物理量场分析

利用ERA-interim再分析资料和中南地区航空器空中报告,分析2017年2月4日20:00前后的颠簸报告位置与物理量场分布特征,结果表明:与颠簸位置对应最好的是散度场的强梯度区和温度平流的等零度线两侧,靠近涡度大值中心的强梯度区和垂直速度的大值区或大梯度区附近也容易发生颠簸,若满足以上条件的物理量场达3个或以上的区...     

World-wide increase in tropospheric methane, 1978–1983

Tropospheric concentrations of methane in remote locations have averaged a yearly world-wide increase of 0.018±0.002 parts per million by volume (ppmv) during the period from January 1978 to December 1983. The concentrations in the north temperate zone are always greater than those in the south temperate zone by 7±1% because the major methane sources are all predominantly located in the northern hemisphere. The average world-wide tropospheric concentration of methane in dry air was 1.625 ppmv at the end of 1983, measured against an NBS standard certified as 0.97 ppmv (but with an accuracy of only ±1%). The world-wide concentration increases are described by a linear equation with a standard deviation of 0.003 ppmv for ten different collection periods during 1978–1983. The precision of measurement of the methane concentration in the atmospheric samples and in the standard was measured to be ±0.4% for each. Repetitive measurements of an air sample collected in November 1977 have shown the same concentration for six years with a standard deviation for these data of ±0.003 ppmv.The causes for the steady increase in methane concentration in the troposphere cannot be fixed with certainty from present data. Contributing causes can include increases in the source strengths from cattle and rice fields. The atmospheric concentrations of CO, CH₄ and HO are all closely coupled with one another, and increased concentrations of CO and/or CH₄ should cause reduced concentrations of HO, which in turn should lengthen the atmospheric lifetimes of CO and CH₄.Among other physical and chemical effects, a increase of 0.18 ppmv per decade should contribute a greenhouse warming of about 0.04°C per decade. Other secondary contributions to the greenhouse effect from increases in CH₄ may arise from methane-induced increases in stratospheric H₂O, in tropospheric O₃, and in numerous other trace species whose concentration is controlled by reaction with HO radicals.An increased CH₄ source strength may result from the effect of increasing atmospheric temperatures on the known aqueous biological CH₄ sources, such as swamps, and may be an added consequence of the greenhouse effect.     

基于多元数据分析的我国PM2.5浓度及其主控因子的时空分布特征研究

基于2013~2016年空气质量监测台站资料,利用经验正交分解、功率谱分析、BP典型相关分析等多元数据分析方法解析了中国地区细颗粒物（PM2.5）主要模态的时空特征,并与排放源和气象场建立了相关关系,得到以下结论:中国地区PM2.5场存在两个主要模态,其中第一主模态为一致增加模态,强度中心位于西北地区东部—华北南部地区;其时间序列呈显著下降趋势。第二主模态主要表现为南北反向变化的偶极子型分布,其大值区分别位于华北中南部和长江中下游地区。其中,PM2.5第一模态可以看作平均态,主要受平均排放场和环流场及大地形的影响,在北方的表现更为显著。PM2.5第二模态可看作偏离平均场的一种变化态,在冬季更可能和冷空气活动有关。冷空气的强弱决定了污染累积的位置以及输送的方式,其作用是使得南方的污染明显偏离平均态,故第二主模态在南方的表现更为显著。本研究有效地利用了多元数据分析方法研究了我国大气污染的演变机理,可为进一步认清大气污染的形成规律提供科技支撑。