大气和积雪中气溶胶的数值模拟研究

发布时间：2018-02-11 22:07

  本文关键词： 气溶胶 积雪 光学厚度 直接辐射强迫 WRF-Chem模式 雪水当量 温度　出处：《兰州大学》2016年博士论文　论文类型：学位论文

【摘要】：作为气候系统中一个关键的强迫因子,大气气溶胶通过改变地球-大气系统的能量收支平衡和云滴粒径、停留周期,对全球气候、水循环以及生态系统平衡产生极为重要的影响。因此,准确地模拟气溶胶在大气和积雪中的时空分布以及其复杂的物理化学反应过程对于研究气溶胶的气候效应具有十分重要的意义。近年来,随着数值模式不断的发展和改进,已经可以对大气中气溶胶的来源、分布、传输以及沉降过程进行准确与精细的模拟研究。本文主要是在前人的基础上,对区域气候模式WRF-Chem(Weather Research and Forcasting couple with Chemistry,以下简称WRF-Chem)进行改进,研究全球尺度范围内季节性积雪中气溶胶的辐射强迫和空间分布以及气溶胶在太平洋上的传输和演变。本文的主要结论如下:(1)利用类全球WRF-Chem模式模拟2010年至2014年气溶胶的全球分布,并利用观测数据对气溶胶在太平洋传输区域的气象场及气溶胶特性进行评估分析。结果表明,模式可以很好的模拟这一地区的降水和风场。总体而言,模式模拟太平洋地区的气溶胶光学厚度(以下简称:AOD)和吸收性气溶胶光学厚度(以下简称:AAOD)与卫星反演的结果一致,主要受污染性气溶胶、沙尘和海盐的影响。Angstrom波长指数模拟结果表明,模式中气溶胶粒子大小分布比较合理。此外,模式可以较好的模拟太平洋地区近地面由海盐气溶胶引起的消光系数垂直廓线和季节变化以及4 km高度以上由污染型气溶胶和沙尘引起的消光系数垂直廓线和季节变化。模式中海盐气溶胶排放源的偏差以及卫星反演误差是引起模式和卫星结果差异的主要原因。与美国西海岸地面观测相比,本文的模式能较好模拟地面上沙尘、硫酸盐和硝酸盐的密度,但是明显低估了含碳气溶胶的密度,主要原因是模式在处理生物燃料和二次有机气溶胶的时空变化时存在一定的偏差。敏感性试验结果表明,沙尘、硫酸盐和硝酸盐通过太平洋传输明显的影响美国西海岸的地面空气质量,但是含碳气溶胶主要受北美排放源影响。观测和模拟结果均显示,2010年至2014年的气溶胶特性变化很小。本文主要证实了类全球WRF-Chem模式能够很好地模拟气溶胶在太平洋上的传输过程,并且为利用高精度区域模式研究太平洋传输污染物对美国西海岸的空气质量和气候的影响提供可靠的化学侧边界条件。(2)将SNICAR模式(Snow,Ice,and Aerosol Radiation,以下简称SNICAR)耦合到WRF-Chem模式中,并利用2010年1月至2月中国东北地区季节性积雪采集试验结果对模式模拟积雪中黑碳和沙尘气溶胶含量以及辐射强迫进行评估。结果表明,模式对表层积雪中黑碳和沙尘的模拟结果与观测相一致。模式轻微地低估了干洁地区的黑碳含量,而明显高估了污染地区的黑碳含量。但是模式结果与观测的变化趋势一致,且合理的分布在不确定范围之内。在源区,积雪中黑碳和沙尘气溶胶浓度最高可以分别达到5000 ng g-1和5 mg g-1;当远离源区时,迅速减小为50 ng g-1和1μg g-1。积雪中黑碳和沙尘颗粒能够产生等量的辐射加热量级(~+10 W m-2),并且与大气中黑碳和沙尘引起的辐射冷却量级相近。本文主要讨论了区域模式框架下季节性积雪中黑碳和沙尘浓度的模拟及其直接辐射强迫。尽管本文利用观测资料与模式模拟结果进行对比,但是模式结果还存在一定的不确定性,需要利用更多的大气和积雪中气溶胶的观测资料以及气溶胶的沉降通量资料对模式进行评估和改进。(3)利用已耦合的类全球WRF-Chem模式模拟研究气溶胶对积雪覆盖和地表温度的影响。研究区域主要集中在东亚和欧洲。结果表明,东亚和欧洲大气中沙尘和黑碳在地表的辐射强迫有明显的季节变化,最大值出现在春季;而积雪中沙尘和黑碳的辐射强迫最大值出现在冬季。东亚地区,积雪中气溶胶通过改变地表反照率,增加地面净辐射通量,导致雪水当量减少;而欧洲地区,积雪中气溶胶增加地面的雪水当量,主要是通过增加零摄氏度以下降水。气溶胶通过吸收和散射太阳辐射以及改变地表的感热和潜热,影响地表温度。大气中气溶胶增加了地表的感热和潜热,减少地表的净辐射。东亚地区,积雪中气溶胶主要是通过增加地表净辐射,导致地表温度增加;而欧洲地区,主要是通过感热、潜热和地表净辐射共同作用影响地表温度。
[Abstract]:As a key force factor in the climate system, atmospheric aerosol by changing the earth atmosphere system energy balance and droplet size, retention period, on the global climate, water cycle and ecosystem balance has the extremely important influence. Therefore, the simulated climate effect distribution in atmosphere and snow and aerosol physics the reaction of complex process for the study of aerosol accurately is very important. In recent years, with the continuous development and the improvement of numerical model, already can be distributed on sources of atmospheric aerosol, accurate and fine simulation of transmission and the settlement process. This paper is mainly on the basis of previous studies, to WRF-Chem regional climate model (Weather Research and Forcasting couple with Chemistry, hereinafter referred to as WRF-Chem) was improved, the study of global scale season The snow of aerosol radiative forcing and the spatial distribution of aerosols in the Pacific and the transmission and evolution. The main conclusions of this paper are as follows: (1) from 2010 to 2014 the global distribution of aerosol by global WRF-Chem model, and using the observation data of aerosol in the meteorological field and the Pacific aerosol transmission area evaluation. The results show that the model can be in the area of precipitation and wind field simulation very well. Overall, the simulation model of aerosol optical thickness in the Pacific region (hereinafter referred to as: AOD) and absorbing aerosol optical thickness (hereinafter referred to as: AAOD) consistent with the satellite retrieval results, mainly affected by the pollution of dust and sea salt aerosol. The effect of.Angstrom wavelength index simulation results show that the model of aerosol particle size distribution is reasonable. In addition, the Pacific Ocean area near the ground simulation model can be better The change of vertical profiles of the extinction coefficient of variation of vertical profiles of the extinction coefficient caused by sea salt aerosol and the seasonal and height of 4 km above the pollution caused by aerosol and dust and seasonal sea salt aerosol emissions model. The deviation and the satellite retrieval error is mainly caused by the satellite mode and the difference compared with the west coast of the United States. The ground observation, this model can simulate the ground dust, sulfate and nitrate density, but significantly underestimated the carbon density of the aerosol, the main reason is the mode of existence certain deviation in the temporal and spatial variation of processing bio fuel and two time machine aerosol. Sensitivity test results show that dust, sulfate and nitrate the ground air quality of the west coast of the United States Pacific influence transmission significantly, but the carbon aerosol is mainly affected by the North American sources. Observation and simulation The results showed that from 2010 to 2014, the aerosol properties change very little. This paper confirms the global WRF-Chem model can well simulate the transmission process of aerosol in the Pacific, and provide reliable boundary conditions for the chemical side effects using a regional model study of high precision transmission Pacific pollutants on air quality and climate of the West coast of the United States. (2) the SNICAR model (Snow Ice, and, Aerosol Radiation, hereinafter referred to as SNICAR) coupled to the WRF-Chem model, and from January 2010 to February in Northeast China Chinese seasonal snow collecting test results of simulated snow black carbon and dust aerosol concentration and radiative forcing were evaluated. The results show that the simulation results of black carbon and dust layer of snow patterns in the table are consistent with the observations. The model slightly underestimates the dry content of black carbon cleaning area, and significantly overestimated the pollution The black carbon content area. But the model results and the observations of the same trend, and the reasonable distribution in the uncertainty range. In the source region of snow, black carbon and dust aerosol concentration can reach 5000 ng g-1 and 5 mg g-1 respectively; when far from the source area decreases rapidly as the radiation heating and the magnitude of black carbon dust particles 50 ng g-1 and 1 g g-1. can produce an equal amount of snow (~+10 W m-2), and the magnitude of radiative cooling caused by black carbon and dust in the atmosphere is similar. This paper mainly discusses the regional model under the framework of simulation of black carbon and dust concentration in seasonal snow and direct radiative forcing. Although the observational data and the model simulation results were compared to model results but also has certain uncertainty, requires the use of atmospheric aerosol and snow more observations and aerosol deposition flux data of mode Evaluate and improve. (3) effect simulation of aerosol on the snow cover and surface temperature using the global WRF-Chem model has been coupled. The study area mainly concentrated in East Asia and Europe. The results showed that the dust and black carbon in East Asia and Europe in the atmosphere on the surface radiative forcing have obvious seasonal changes, the maximum value appears in spring; and radiation of dust and black carbon in snow forced the maximum value appears in winter. In East Asia, snow aerosol by changing the surface albedo, increase the surface net radiation flux, resulting in reduced and snow water equivalent; Europe, snow aerosol increased snow water equivalent ground, mainly through the increase of zero degrees Celsius precipitation. The aerosol scattering and absorption of solar radiation and changing the surface sensible heat and latent heat, influence of surface temperature. Atmospheric aerosols increase the surface sensible heat and latent heat, reducing surface Net radiation. In East Asia, aerosols in snow cover increase surface temperature by increasing surface net radiation. However, in Europe, surface temperature is mainly affected by sensible heat, latent heat and surface net radiation.

【学位授予单位】：兰州大学
【学位级别】：博士
【学位授予年份】：2016
【分类号】：X513;X16
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本文编号：1504111