KMS of Xinjiang Astronomical Observatory, CAS
| 慕士塔格选址点光学天文观测条件监测与研究 | |
| Alternative Title | Monitoring and Research on Optical Astronomical Observing Conditions at Muztagh-ata Site |
许竞
| |
| Subtype | 博士 |
| Thesis Advisor | 艾力·伊沙木丁 |
| 2020 | |
| Degree Grantor | 中国科学院大学 |
| Place of Conferral | 北京 |
| Degree Name | 理学博士 |
| Degree Discipline | 天文技术与方法 |
| Keyword | 天文选址,天文观测条件,大气视宁度,逆温层,可沉降水汽含量 |
| Abstract | 随着地基光学望远镜口径的不断增大，光学天文台址的观测条件已经成为决定这些大口径光学望远镜能否发挥极限设计性能的关键因素。近十几年来，在Mauna Kea和智利阿卡塔玛沙漠等地开展的选址工作为TMT、E-ELT等项目选出了最佳的观测台址，我国也亟需优良的址点来运行新一代10米级光学/红外望远镜。着眼于国内大口径光学望远镜的建设，本论文主要工作是在慕士塔格选址点开展台址天文观测条件参数测量与研究，并深入分析该台址天文气象条件，为望远镜设计建设与运行提供参考依据。 本论文第一章叙述了地球大气对地基天文望远镜观测的影响，介绍了评估光学天文台址观测条件的主要参数，以及前期帕米尔高原天文台址资源勘查结果。此外，还介绍了国内外光学/红外望远镜选址工作的进展，以及国内光学天文台址与国际大口径光学望远镜候选址点的天文观测条件。 第二章对慕士塔格选址点的地理地质条件、综合保障条件、选址设备做了详细的介绍。慕士塔格选址点于2017年开始定点监测，主要对址点天文气象条件（温度、相对湿度、大气压强、风速、风向、云量）、大气视宁度、夜天光、大气水汽含量等参数进行了为期三年的连续测量，本章中给出了慕士塔格选址点进行定点监测的设备参数以及布局情况。 第三章统计分析了慕士塔格选址点天文气象参数与夜天光监测统计结果。该址点三年的监测结果显示：夜间温度年中值为-6.2℃，夜间相对湿度年中值为49%，夜间大气压强年中值为587hPa，夜间风速年中值为5.5ms-1，主风向为西南风；全天云量图像的监测结果给出年可观测时长大于三小时的夜晚比例占到63.1%；慕士塔格选址点无月夜的夜天光年中值为21.7mag•arcsec-2。通过对无月夜全天云量图像合成分析表明，苏巴什达板314国道上的车灯是址点主要光污染源。 第四章对慕士塔格选址点视宁度条件、近地层湍流分布以及近地层逆温进行了分析研究。在整个测量周期内，慕士塔格选址点11米高度视宁度中值为0.82 arcsec，月中值统计显示每年冬季为最佳观测季节，最佳的月视宁度统计中值可以达到0.6 arcsec。采取多台DIMM在不同高度同时运行的方法，对慕士塔格选址点近地层湍流分布进行了初步研究，11米高度与地面的视宁度中值差为0.18 arcsec，而11米高度与6米高度视宁度中值差很小，说明该址点近地层湍流能量主要集中在6米以下区域。对近地层逆温现象的长时间监测显示，逆温与视宁度存在很强的相关性；通过对逆温与气象参数的相关性分析认为，辐射逆温是慕士塔格选址点产生近地层逆温现象的主要原因。 第五章对慕士塔格选址点PWV（Precipitable water vapor，可沉降水汽含量）地面测量结果与遥感数据再分析结果进行了统计研究。2018年有七个月（1月、2月、8月、9月、10月、11月、12月）共49天进行了地面PWV测量，其中2月份月中值最低，为0.93mm； 9月份月中值最高，为2.76mm。ECMWF遥感数据再分析结果得到2018年与2019年晴天时的PWV年中值分别为2.28mm与2.37mm；2018年与2019年晴天PWV值小于1mm的数据占比11.5%，小于2mm的数据占比40.8%；结合全天云量观测数据，慕士塔格选址点PWV在晴天时的地面测量结果与遥感数据再分析结果一致性很好，低空云量较多时会影响地基PWV测量结果的准确性。 论文最后总结了慕士塔格选址点的台址综合条件，并将慕士塔格选址点的光学天文观测条件与国内外天文台址以及选址点进行了比较，结果表明慕士塔格选选址点的台址综合条件好于目前国内的光学天文观测台站和选址点，可以满足大口径光学望远镜的运行需要 |
| Other Abstract | work of this thesis is to measure and research on the astronomical observing condition parameters at Muztagh-ata site, which will provide reference for the design and operation strategy of telescopes.The first chapter began with the introduction of influence of earth’s atmosphere to the observation of ground-based optical telescopes, the parameters used for evaluating optical astronomical observing conditions and the previous exploration of astronomical observation resources in the Pamir Plateau. Further, the introduction of research progress in large optical/infrared telescopes’ site-testing and optical observing conditions of domestic observatories and international candidate sites for large optical telescopes was given.The second chapter introduced the Muztagh-ata site from the aspects of geographical and geological conditions, comprehensive support capacity, site-testing facilities. The Muztagh-ata site began its continuous monitoring of the parameters, including astro-meteorological conditions (air temperature, relative humidity, air pressure, wind speed and direction), seeing, night sky brightness and PWV, in early 2017. The layout and detailed information of the monitoring equipment also were presented in this chapter.Statistics and analysis results of astro-meteorological parameters and night-sky brightness were shown in the third chapter. The yearly median values of meteorological parameters during night were: the temperature was -6.2 ℃, the relative humidity was 49%, the air pressure was 587hPa, the wind speed was 5.5 ms-1 and the prevailing wind direction was southwest. The proportion of observable night (observable time more than 3 hours) , which concluded from all-sky images, was 63.1%. The night sky background brightness without moon was 21.74mag•arcsec-2, and it can be confirmed that the vehicle lights from G314 national road on the Subashi Daban was the main light pollution through the method synthesizing all-sky images.The fourth chapter analyzed and researched on seeing condition, distribution of turbulence and temperature inversion in surface-layer at the Muztagh-ata site. During the whole measurement periods we obtained the seeing median values of 0.82 arcsec at 11 meter. The monthly statistics results showed that the best season for optical observation is winter and the lowest month seeing median value can reach 0.6 arcsec in this season. The DIMMs were operated Simultaneously at different heights for preliminary study on the distribution of turbulence in the surface layer at the Muztagh-ata site. The difference of the seeing median value between at 11 meter and ground level was 0.18 arcsec and the difference between at 11 meter and 6 meter is very small, which indicates that the turbulence in the surface layer concentrates in the area below 6 meter. It was also found that the seeing and temperature inversion are highly correlated. By analyzing the dependence of inversion on meteorological parameters, one conclusion can be made that radiation inversion is the main reason for the existence of inversion in the surface-layer at Muztagh-ata site.PWV (Precipitable Water Vapor) statistics results got from ground-based measurement and remote sensing data reanalysis were presented in the fifth chapter. Ground-based measurement of PWV was made for 49 days in total during seven months (January, February, August, September, October, November, December) in 2018, and the lowest month median value was February of 0.93mm while highest was September of 2.76mm. The yearly median values of PWV in clear days during 2018 and 2019 by ECMWF data reanalysis were 2.28mm and 2.37mm respectively. The proportion of the PWV data less than 1mm and 2mm in clear days during the two years were 11.5% and 40.8% respectively. It was found that the consistency between PWV values from ground-based measurement and remote sensing data reanalysis was good in clear days by checking all-sky iamges results. When there are much low cloud covered, the accuracy of PWV from ground-based measurement will be affected.This thesis finally summarized the comprehensive conditions of the Muztagh-ata site and compared its observing conditions with various astronomical observatories and candidate sites domestic and foreign. The results proved that the comprehensive conditions of Muztagh-ata site are better than domestic optical astronomical observatories and candidate sites, it satisfies the operation requirement of large optical/infrared telescopes. |
| Pages | 108 |
| Language | 中文 |
| Document Type | 学位论文 |
| Identifier | http://ir.xao.ac.cn/handle/45760611-7/4142 |
| Collection | 研究生学位论文 |
| Affiliation | 中国科学院新疆天文台 |
| First Author Affilication | Xinjiang Astronomical Observatory, Chinese Academy of Sciences |
| Recommended Citation GB/T 7714 | 许竞. 慕士塔格选址点光学天文观测条件监测与研究[D]. 北京. 中国科学院大学,2020. |
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| 许竞.pdf（3380KB） | 学位论文 | 暂不开放 | CC BY-NC-SA | Application Full Text | ||
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