本文選題：鉆孔溫度方法 + 多年凍土��； 參考：《蘭州大學(xué)》2015年博士論文

【摘要】：對(duì)過(guò)去氣候變化的研究有助于我們理解現(xiàn)在氣候變化和預(yù)測(cè)未來(lái)氣候。作為地球“第三極”的青藏高原,具有獨(dú)特的地理位置和熱力系統(tǒng),并對(duì)氣候變化非常敏感。了解青藏高原過(guò)去氣候變化歷史、變化特征,對(duì)于準(zhǔn)確評(píng)估目前氣候變化與預(yù)測(cè)未來(lái)青藏高原氣候變化提供了重要依據(jù)。然而青藏高原的氣象觀測(cè)資料觀測(cè)時(shí)間短,觀測(cè)站點(diǎn)少且覆蓋不均,因此僅靠氣象觀測(cè)不足以讓我們了解青藏高原長(zhǎng)時(shí)間尺度的氣候變化。過(guò)去地表溫度變化的氣候信息可通過(guò)分析近期觀測(cè)的鉆孔溫度剖面進(jìn)行重建。青藏高原作為多年凍土大區(qū),多年凍土內(nèi)部土壤凍結(jié),地溫?zé)醾鬟f主要以熱傳導(dǎo)方式進(jìn)行,適宜利用鉆孔溫度方法的開(kāi)展。鉆孔溫度方法較其他代用指標(biāo)方法是基于地溫剖面和地表溫度變化的物理聯(lián)系之上的,具有更強(qiáng)的物理意義。本文利用青藏高原多個(gè)鉆孔溫度剖面和地?zé)崽荻?重建青藏高原不同地區(qū)過(guò)去地表溫度變化歷史。地溫垂直溫度剖面受地中熱流和地表溫度變化影響。地球內(nèi)部熱流通過(guò)地?zé)崽荻扔绊懙販匦纬煞�(wěn)態(tài)溫度,在此基礎(chǔ)上地表溫度變化以熱傳導(dǎo)方式向地下傳播使穩(wěn)態(tài)地溫發(fā)生擾動(dòng)而產(chǎn)生偏離,偏離穩(wěn)態(tài)溫度的這部分地溫作為瞬時(shí)溫度記錄了過(guò)去地表溫度變化的信息。鉆孔溫度方法利用近期觀測(cè)到的鉆孔溫度剖面,根據(jù)地溫梯度分離出穩(wěn)態(tài)溫度,進(jìn)而利用一維熱傳導(dǎo)模型分析瞬時(shí)溫度剖面,重建過(guò)去地表溫度變化。由于年際地表溫度變化隨深度明顯衰減,而十年或更長(zhǎng)時(shí)期的溫度變化(“古氣候信號(hào)”)向多年凍土更深處傳播,多年凍土溫度分布是氣候變化和地表能量平衡長(zhǎng)期變化的敏感指示。陸地作為天然的氣候低通濾波器,使得多年凍土區(qū)的地溫剖面可用來(lái)重建過(guò)去地表溫度低頻變化趨勢(shì)。在研究鉆孔溫度重建過(guò)去地表溫度變化的反問(wèn)題之前,首先需要理解正向問(wèn)題,地溫如何響應(yīng)地表溫度變化。對(duì)于簡(jiǎn)單一次氣候變化情形,根據(jù)一維熱傳導(dǎo)模型,對(duì)于不同類型地表溫度變化地下溫度場(chǎng)具有顯式的解析解。對(duì)于多年凍土區(qū)域熱傳導(dǎo)且考慮相變的復(fù)雜過(guò)程,僅能通過(guò)數(shù)值方法求解。本文利用控制體積方法數(shù)值模擬多年凍土地溫相變問(wèn)題�？刂企w積方法在離散程度上介于有限差分和有限元方法之間,具有更直接的物理解釋。計(jì)算時(shí)考慮未凍水含量及相變潛熱,并隨時(shí)間重新計(jì)算各深度熱物理參數(shù)進(jìn)而準(zhǔn)確計(jì)算地溫變化。通過(guò)地表周期變化情形闡明控制體積方法數(shù)值模擬多年凍土相變問(wèn)題的過(guò)程及未凍水含量對(duì)熱參數(shù)、地溫的影響�；趯�(duì)正問(wèn)題的理解,本文對(duì)鉆孔溫度重建過(guò)去地表溫度變化的反問(wèn)題提出改進(jìn)的tikhonov方法�；谶^(guò)去地表溫度變化和近期鉆孔地溫剖面間的物理聯(lián)系,在對(duì)問(wèn)題參數(shù)化后我們利用tikhonov正則化方法來(lái)重建過(guò)去地表氣候變化。此方法是基于奇異值分解(svd)方法之上的,具有相同的參數(shù)化,都將問(wèn)題轉(zhuǎn)化為求解不適定的矩陣方程。本文利用兩個(gè)數(shù)值例子模擬地表升溫和復(fù)雜氣候事件來(lái)驗(yàn)證方法有效性以及與奇異值分解方法相比的改進(jìn)效果。由于鉆孔溫度觀測(cè)具有無(wú)法避免的觀測(cè)誤差,我們對(duì)模擬的地溫剖面添加隨機(jī)擾動(dòng)誤差來(lái)模擬觀測(cè)誤差。利用擾動(dòng)的地溫剖面重建地表溫度變化并與假設(shè)的地溫剖面比較從而驗(yàn)證方法有效性。兩個(gè)實(shí)驗(yàn)例子中重建的地表溫度及相關(guān)不確定性分析表明tikhonov方法可較好地重建地表溫度,并且改進(jìn)方法可成功壓制噪音導(dǎo)致的不穩(wěn)定性得到更平滑的地表溫度變化。通過(guò)比較地表溫度誤差可選出更適合tikhonov正則化的正則化參數(shù)選取方法。此外,本文利用tikhonov方法分析了鉆孔溫度方法的求解能力,可更好地理解重建的地表溫度。鉆孔溫度重建地表溫度變化的結(jié)果是依賴于所選取的反演方法,我們基于熱傳導(dǎo)方程反邊界值問(wèn)題給出創(chuàng)新的基本解方法。基本解方法根據(jù)熱傳導(dǎo)方程的基本解將問(wèn)題參數(shù)化之后轉(zhuǎn)化為待定線性系統(tǒng),由于反問(wèn)題的不適定性,此方程組受鉆孔溫度觀測(cè)誤差影響無(wú)法直接求解。利用tikhonov正則化和廣義交叉核實(shí)方法選取正則化參數(shù)求解待定參數(shù),進(jìn)而同時(shí)重建地表溫度變化和地表溫度熱流變化。數(shù)值模擬例子表明基本解方法是可行且穩(wěn)定的,并且對(duì)模擬鉆孔溫度剖面添加不同水平隨機(jī)誤差擾動(dòng)后仍能有效降低誤差擾動(dòng)帶來(lái)的不適定性,得到精確的地表溫度變化。利用鉆孔溫度重建地表溫度變化與其他地球物理反問(wèn)題相同,最大的求解難點(diǎn)在于觀測(cè)誤差導(dǎo)致的結(jié)果不穩(wěn)定性。由于不同方法采用不同的參數(shù)化和優(yōu)化方法,因此鉆孔溫度問(wèn)題的結(jié)果依賴于所選取的方法。本文綜合比較應(yīng)用較廣泛的泛函空間反演(fsi)、奇異值分解方法(svd)、改進(jìn)的tikhonov方法以及創(chuàng)新的基本解方法(mfs)。通過(guò)五類不同類型地表溫度變化的模擬例子來(lái)比較各方法數(shù)值結(jié)果:(1)階梯變化;(2)線性升溫;(3)光滑線性升溫;(4)周期變化;(5)復(fù)雜周期變化,并在模擬例子中添加不同水平模擬觀測(cè)誤差。重建的地表溫度結(jié)果比較表明,在鉆孔溫度剖面具有較小誤差擾動(dòng)下,所有方法均能給出較精確的地表溫度變化重建結(jié)果。盡管四種方法具有不同的參數(shù)化方式和正則化方法選取,重建地表溫度變化具有相似結(jié)果,僅在氣候時(shí)間和溫度幅度上有細(xì)微差別。方法的有效性是依賴于地表溫度變化類型的�；窘夥椒ǜm用于重建周期變化和復(fù)雜周期變化信號(hào)。對(duì)于其他類型地表溫度變化,Tikhonov方法在較小鉆孔溫度誤差0.001℃和0.01℃情形下,結(jié)果最精確。泛函空間反演方法較在鉆孔溫度剖面誤差較大時(shí)仍能重建地表溫度變化趨勢(shì),但對(duì)初始地表溫度重建較其他方法相比有較大誤差。并且泛函空間反演在重建近期地表溫度變化時(shí)具有更高分辨率,更精確�；阢@孔溫度方法研究,本文根據(jù)青藏高原不同地區(qū)鉆孔溫度剖面對(duì)各研究點(diǎn)進(jìn)行過(guò)去地表溫度變化的單點(diǎn)重建研究,利用鉆孔溫度方法反演得到不同時(shí)間區(qū)間古氣候信息:1)黑河上游100米鉆孔PT1鉆孔由于氣候變暖導(dǎo)致進(jìn)入多年凍土的長(zhǎng)期凈熱流約為0.014 Wm-2,深處穩(wěn)態(tài)熱流約0.0247 Wm-2。PT1鉆孔1952年至2012年地表溫度由-2.7℃線性升高約0.5至0.65℃;2)黑河上游150米鉆孔PT9鉆孔地?zé)崽荻葹?.25℃/100m,1895年至2015年地表溫度由-2.3℃升溫至-1.5℃;3)奇異值分解方法和Tikhonov方法根據(jù)五道梁120米鉆孔溫度剖面重建地表溫度結(jié)果表明在過(guò)去1930年至2013年間地表溫度升溫1.8(±0.2)℃,且劇烈升溫過(guò)程開(kāi)始于1980年代。五道梁氣象觀測(cè)站的氣溫觀測(cè)結(jié)果驗(yàn)證了Tikhonov方法重建2008年至2012年間的地表溫度波動(dòng),且在時(shí)間重合階段氣溫和重建的地表溫度具有相同趨勢(shì)。4)根據(jù)昆侖山鉆孔220米鉆孔溫度剖面,奇異值分解方法和Tikhonov方法重建地表溫度結(jié)果表明,1700年至2013年地表溫度由-6.5(±0.8)℃升高至-2.8(±0.2)℃。兩方法重建的地表溫度變化具有相同趨勢(shì),具體升溫時(shí)間和幅度略有差別。根據(jù)五道梁觀測(cè)站的氣溫觀測(cè)數(shù)據(jù)對(duì)比表明,Tikhonov方法重建的地表溫度更可靠。5)柴達(dá)木盆地7個(gè)鉆孔(最大深度220米至400米)溫度反演表明此區(qū)域過(guò)去514年地表溫度由6.1℃升高了1.2℃(-0.11~2.21℃),并表現(xiàn)出1500年至1900年間的小冰期寒冷信號(hào)。最冷時(shí)期發(fā)生在1780至1790年間,當(dāng)時(shí)的地表溫度為5.4℃。在19世紀(jì)和20世紀(jì)間,重建的地表溫度具有升溫趨勢(shì),且在20世紀(jì)末達(dá)到最高值,隨后開(kāi)始降溫。重建的地表溫度變化幅度已由EdGCM模式模擬的地表平均氣溫所驗(yàn)證,細(xì)節(jié)溫度特征得到代用指標(biāo)結(jié)果驗(yàn)證�；阢@孔溫度方法研究,本文給出鉆孔溫度方法的改進(jìn)方法和創(chuàng)新方法,并進(jìn)行方法比較。本論文根據(jù)青藏高原中部不同地區(qū)鉆孔溫度剖面進(jìn)行過(guò)去地表溫度變化的單點(diǎn)重建研究,并利用地溫梯度反演得到各鉆孔位置的過(guò)去地表溫度變化信息。
[Abstract]:The study of past climate change will help us understand the present climate change and predict the future climate. As the "third pole" of the earth, the Qinghai Tibet Plateau has unique geographical location and thermal system, and is very sensitive to climate change. It provides an important basis for climate change in the Qinghai Tibet Plateau in the future. However, the observation time of the meteorological observation data in the Qinghai Tibet Plateau is short, the observation site is few and the coverage is uneven. Therefore, the meteorological observation alone is not enough to let us understand the climate change of the long time scale of the Qinghai Tibet Plateau. The Qinghai Xizang Plateau, as a large area of permafrost, freezes the soil in permafrost, and the heat transfer is mainly carried out in the heat conduction mode, which is suitable for the development of the borehole temperature method. The borehole temperature method is the physical relation of the geothermal profile and the surface temperature change compared with the other substitution index methods. In this paper, the history of surface temperature changes in different regions of the Qinghai Tibet Plateau is rebuilt by using the temperature profiles and geothermal gradients in the Qinghai Tibet Plateau. The vertical temperature profiles of the Qinghai Tibet Plateau are influenced by the changes of the heat flow and surface temperature in the earth. On this basis, the change of surface temperature changes by heat conduction way to the ground to cause the deviation of the steady state temperature, and the part of the ground temperature deviating from the steady state temperature as the instantaneous temperature records the information of the change of the surface temperature in the past. The transient temperature profile is analyzed by one dimensional heat conduction model, and the change of surface temperature in the past is rebuilt. The temperature variation of the interannual surface temperature changes with the depth obviously, and the temperature change ("paleoclimate signal") of ten years or longer ("paleoclimate signal") propagates deeper into the permafrost, and the temperature distribution of permafrost is the climate change and the surface energy. The land temperature profile of the permafrost region can be used to reconstruct the low frequency trend of the surface temperature in the permafrost region as a natural climate low pass filter. Before the inverse problem of the surface temperature changes in the reconstruction of the borehole temperature, the first need to solve the forward problem and how the geotemperature respond to the surface temperature change. For a simple one time climate change, according to the one-dimensional heat conduction model, the underground temperature field of different types of surface temperature changes has an explicit analytical solution. For the complex process of heat conduction in permafrost regions and considering the phase transformation, the numerical method can only be solved by numerical method. This paper uses the method of controlling volume to simulate the perennial frozen land. The control volume method is between the finite difference and the finite element method in the discrete degree, and has a more direct physical explanation. The calculation of the unfrozen water content and the latent heat of the phase change is taken into account, and the thermal physical parameters of each depth are recalculated and then the ground temperature change is accurately calculated with time. The control volume is clarified through the change of the surface period. The process of the phase transformation of permafrost and the influence of the content of unfrozen water on the thermal parameters and the ground temperature are numerically simulated. Based on the understanding of the positive problem, an improved Tikhonov method is proposed for the inverse problem of the reconstruction of the surface temperature in the past. Based on the physical relations between the surface temperature changes and the recent borehole geothermal profiles, After the problem is parameterized, we use the Tikhonov regularization method to reconstruct the surface climate change in the past. This method is based on the singular value decomposition (SVD) method and has the same parameterization. All the problems are transformed into an ill posed matrix equation. Two numerical examples are used to simulate the surface temperature rise and complex climate events. The effectiveness of the method and the improved effect compared with the singular value decomposition method. As the observation error of the borehole temperature is unavoidable, we add random perturbation error to the Simulated Geothermal profile to simulate the observation error. Method effectiveness. The reconstruction of surface temperature and correlation uncertainty in two experimental examples shows that the Tikhonov method can better reconstruct the surface temperature, and the improved method can successfully suppress the noise induced instability to get a more smooth surface temperature change. By comparing the surface temperature error, it is more suitable for Tikhonov regularization. In addition, the Tikhonov method is used to analyze the solving ability of the borehole temperature method, which can better understand the surface temperature of the reconstructed surface. The result of the change of the surface temperature in the reconstruction of the borehole temperature depends on the selected inversion method. Based on the inverse boundary value problem of the thermal conduction equation, we give the basic solution. According to the basic solution of the heat conduction equation, the basic solution transforms the problem into a undetermined linear system. Due to the discomfort of the inverse problem, the equation can not be solved directly by the influence of the borehole temperature observation error. Tikhonov regularization and the generalized cross verifying method are used to select the regularized parameters to solve the undetermined parameters. At the same time, the surface temperature change and surface temperature heat flux are rebuilt. The numerical simulation example shows that the basic solution method is feasible and stable. And after adding different horizontal random error disturbance to the simulated borehole temperature profile, it can effectively reduce the discomfort caused by the error disturbance, and get the exact surface temperature change. The variation of ground surface temperature is the same as other geophysical inverse problems. The most difficult problem is the instability of the results caused by the observation error. Because different methods are used for different methods of parameterization and optimization, the result of the temperature problem depends on the selected method. FSI), singular value decomposition method (SVD), improved Tikhonov method and innovative basic solution (MFS). Numerical results of five different types of surface temperature variations are compared: (1) ladder change; (2) linear temperature rise; (3) smooth linear heating; (4) periodic variation; (5) complex periodic changes, and added in simulation examples Compared with the simulated observation errors at different levels, the results of the rebuilt surface temperature show that, under the small error disturbance of the borehole temperature profile, all the methods can give more accurate results of the surface temperature change reconstruction. Although the four methods have different parameterization methods and the regularized square method, the reconstruction of the surface temperature change has a similar knot. The effectiveness of the method is dependent on the type of surface temperature change. The basic solution is more suitable for the reconstructive cycle and the complex periodic change signals. For the other types of surface temperature changes, the Tikhonov method results in the case of a smaller drill hole temperature error of 0.001 and 0.01 degrees centigrade. Most accurate. The functional space inversion method can still reconstruct the trend of surface temperature change when the error of the borehole temperature profile is large, but the initial surface temperature reconstruction has a larger error compared with other methods. And the functional space inversion has higher resolution and more accurate in the reconstruction of the surface temperature in the near future. In this paper, a single point reconstruction of the surface temperature changes in the past is carried out on the basis of the borehole temperature profiles in different areas of the Qinghai Tibet Plateau. The paleoclimate information of different time intervals is retrieved by the method of borehole temperature: 1) the long-term net heat flow of the PT1 boreholes in the 100 meter borehole in the upper reaches of Heihe is about 0.014 due to the warming of the climate. Wm-2, deep steady heat flow about 0.0247 Wm-2.PT1 boreholes from 1952 to 2012, the surface temperature rises from -2.7 C to 0.5 to 0.65 degrees C; 2) the geothermal gradient of 150 m boreholes in the upper reaches of Heihe is 2.25 centigrade /100m, the surface temperature from 1895 to 2015 is heated from -2.3 to -1.5, 3) and 3) the singular value decomposition method and the Tikhonov method are based on the five beam 120 meters. The results of surface temperature reconstruction from the pore temperature profile show that the surface temperature increased by 1.8 (+ 0.2) C in the past 1930 to 2013, and the intense heating process began in 1980s. The temperature observation results of the five road meteorological observation station verified that the Tikhonov method rebuilt the ground surface temperature fluctuations from 2008 to 2012, and the temperature and weight in the time reclosing stage The ground surface temperature has the same trend.4) according to the 220 meter borehole temperature profile of the borehole in Kunlun Mountains. The results of the surface temperature reconstruction by the singular value decomposition method and the Tikhonov method show that the surface temperature rises from -6.5 (+ 0.8) C to -2.8 (+ 0.2) C from 1700 to 2013. The surface temperature change of the two method has the same trend and the specific heating time. According to the temperature observation data of the five beam observation station, the surface temperature rebuilt by the Tikhonov method is more reliable.5). The temperature inversion of the 7 boreholes in the Qaidam Basin (the maximum depth of 220 to 400 m) shows that the surface temperature in this area has increased by 1.2 (-0.11~2.21 C) at 6.1 C in the past 514 years, and shows from 1500 to 1900. The cold signal of the small ice period of the year. The coldest period occurred between 1780 and 1790, at that time the surface temperature was 5.4. In 19th Century and 20th Century, the rebuilt surface temperature had a warming trend, and reached the peak at the end of twentieth Century, and then began to cool. The surface temperature change of the reconstructed surface has been measured by the average surface temperature simulated by the EdGCM model. It is verified that the characteristics of the detail temperature are verified by the substituting index. Based on the study of the borehole temperature method, this paper gives the improved method and innovation method of the borehole temperature method, and compares the methods. Temperature gradient inversion is used to get the information of past surface temperature changes in each borehole.
【學(xué)位授予單位】：蘭州大學(xué)
【學(xué)位級(jí)別】：博士
【學(xué)位授予年份】：2015
【分類號(hào)】：P467
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本文編號(hào)：2101730