發(fā)布時間：2018-02-11 22:07

  本文關(guān)鍵詞： 氣溶膠 積雪 光學厚度 直接輻射強迫 WRF-Chem模式 雪水當量 溫度　出處：《蘭州大學》2016年博士論文　論文類型：學位論文

【摘要】：作為氣候系統(tǒng)中一個關(guān)鍵的強迫因子,大氣氣溶膠通過改變地球-大氣系統(tǒng)的能量收支平衡和云滴粒徑、停留周期,對全球氣候、水循環(huán)以及生態(tài)系統(tǒng)平衡產(chǎn)生極為重要的影響。因此,準確地模擬氣溶膠在大氣和積雪中的時空分布以及其復(fù)雜的物理化學反應(yīng)過程對于研究氣溶膠的氣候效應(yīng)具有十分重要的意義。近年來,隨著數(shù)值模式不斷的發(fā)展和改進,已經(jīng)可以對大氣中氣溶膠的來源、分布、傳輸以及沉降過程進行準確與精細的模擬研究。本文主要是在前人的基礎(chǔ)上,對區(qū)域氣候模式WRF-Chem(Weather Research and Forcasting couple with Chemistry,以下簡稱WRF-Chem)進行改進,研究全球尺度范圍內(nèi)季節(jié)性積雪中氣溶膠的輻射強迫和空間分布以及氣溶膠在太平洋上的傳輸和演變。本文的主要結(jié)論如下:(1)利用類全球WRF-Chem模式模擬2010年至2014年氣溶膠的全球分布,并利用觀測數(shù)據(jù)對氣溶膠在太平洋傳輸區(qū)域的氣象場及氣溶膠特性進行評估分析。結(jié)果表明,模式可以很好的模擬這一地區(qū)的降水和風場�？傮w而言,模式模擬太平洋地區(qū)的氣溶膠光學厚度(以下簡稱:AOD)和吸收性氣溶膠光學厚度(以下簡稱:AAOD)與衛(wèi)星反演的結(jié)果一致,主要受污染性氣溶膠、沙塵和海鹽的影響。Angstrom波長指數(shù)模擬結(jié)果表明,模式中氣溶膠粒子大小分布比較合理。此外,模式可以較好的模擬太平洋地區(qū)近地面由海鹽氣溶膠引起的消光系數(shù)垂直廓線和季節(jié)變化以及4 km高度以上由污染型氣溶膠和沙塵引起的消光系數(shù)垂直廓線和季節(jié)變化。模式中海鹽氣溶膠排放源的偏差以及衛(wèi)星反演誤差是引起模式和衛(wèi)星結(jié)果差異的主要原因。與美國西海岸地面觀測相比,本文的模式能較好模擬地面上沙塵、硫酸鹽和硝酸鹽的密度,但是明顯低估了含碳氣溶膠的密度,主要原因是模式在處理生物燃料和二次有機氣溶膠的時空變化時存在一定的偏差。敏感性試驗結(jié)果表明,沙塵、硫酸鹽和硝酸鹽通過太平洋傳輸明顯的影響美國西海岸的地面空氣質(zhì)量,但是含碳氣溶膠主要受北美排放源影響。觀測和模擬結(jié)果均顯示,2010年至2014年的氣溶膠特性變化很小。本文主要證實了類全球WRF-Chem模式能夠很好地模擬氣溶膠在太平洋上的傳輸過程,并且為利用高精度區(qū)域模式研究太平洋傳輸污染物對美國西海岸的空氣質(zhì)量和氣候的影響提供可靠的化學側(cè)邊界條件。(2)將SNICAR模式(Snow,Ice,and Aerosol Radiation,以下簡稱SNICAR)耦合到WRF-Chem模式中,并利用2010年1月至2月中國東北地區(qū)季節(jié)性積雪采集試驗結(jié)果對模式模擬積雪中黑碳和沙塵氣溶膠含量以及輻射強迫進行評估。結(jié)果表明,模式對表層積雪中黑碳和沙塵的模擬結(jié)果與觀測相一致。模式輕微地低估了干潔地區(qū)的黑碳含量,而明顯高估了污染地區(qū)的黑碳含量。但是模式結(jié)果與觀測的變化趨勢一致,且合理的分布在不確定范圍之內(nèi)。在源區(qū),積雪中黑碳和沙塵氣溶膠濃度最高可以分別達到5000 ng g-1和5 mg g-1;當遠離源區(qū)時,迅速減小為50 ng g-1和1μg g-1。積雪中黑碳和沙塵顆粒能夠產(chǎn)生等量的輻射加熱量級(~+10 W m-2),并且與大氣中黑碳和沙塵引起的輻射冷卻量級相近。本文主要討論了區(qū)域模式框架下季節(jié)性積雪中黑碳和沙塵濃度的模擬及其直接輻射強迫。盡管本文利用觀測資料與模式模擬結(jié)果進行對比,但是模式結(jié)果還存在一定的不確定性,需要利用更多的大氣和積雪中氣溶膠的觀測資料以及氣溶膠的沉降通量資料對模式進行評估和改進。(3)利用已耦合的類全球WRF-Chem模式模擬研究氣溶膠對積雪覆蓋和地表溫度的影響。研究區(qū)域主要集中在東亞和歐洲。結(jié)果表明,東亞和歐洲大氣中沙塵和黑碳在地表的輻射強迫有明顯的季節(jié)變化,最大值出現(xiàn)在春季;而積雪中沙塵和黑碳的輻射強迫最大值出現(xiàn)在冬季。東亞地區(qū),積雪中氣溶膠通過改變地表反照率,增加地面凈輻射通量,導致雪水當量減少;而歐洲地區(qū),積雪中氣溶膠增加地面的雪水當量,主要是通過增加零攝氏度以下降水。氣溶膠通過吸收和散射太陽輻射以及改變地表的感熱和潛熱,影響地表溫度。大氣中氣溶膠增加了地表的感熱和潛熱,減少地表的凈輻射。東亞地區(qū),積雪中氣溶膠主要是通過增加地表凈輻射,導致地表溫度增加;而歐洲地區(qū),主要是通過感熱、潛熱和地表凈輻射共同作用影響地表溫度。
[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.

【學位授予單位】：蘭州大學
【學位級別】：博士
【學位授予年份】：2016
【分類號】：X513;X16
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本文編號：1504111