| 摘要: |
| 阿里位于青藏高原西部，是太阳能资源极其丰富的地区。本次在西藏阿里噶尔县（海拔4280 m，32°30′02″N，80°06′01″E）夏至日前后，对波长在280—1200 nm的太阳光谱进行了短期观测。结果显示：阿里2020年6月21日12∶34，在482 nm波长处出现了太阳光谱辐射强度的最大值2.33 W·m−2·nm−1，对比观测点拉萨的最高太阳光谱强度出现在2020年6月27日13∶56，波长482 nm处光谱强度为2.80 W·m−2·nm−1，在太阳直接辐射、大气中云层及微粒的散射辐射、地表面反射辐射的叠加下，这两地的最高太阳光谱强度都超过了AM0最高光谱强度；将阿里2020年6月22日日中时刻的太阳光谱与AM0、AM1.5标准光谱进行对比，可以看出：阿里的紫外、可见光谱的强度明显高于AM1.5，且接近AM0；阿里2020年6月21日出现了“日食”现象，太阳光谱也随着日食的初亏—食甚—复圆变化。此次观测为青藏高原西部地区提供了稀有的太阳光谱数据支撑，有利于整个西藏太阳能利用的发展。 |
| 关键词: 阿里 太阳光谱 辐射强度 观测 |
| DOI：10.7515/JEE212009 |
| CSTR：32259.14.JEE212009 |
| 分类号: |
| 基金项目:西藏自治区教育科学研究2019年度课题青年专项（XZJKY19420）；西藏自治区自然科学基金项目（XZ2018ZRG-08）；西藏大学培育基金项目资助（ZDCZJH20-17） |
| 英文基金项目:Youth Project of Educational Science Research of Tibet Autonomous Region in 2019 (XZJKY19420); NaturalScience Foundation of Tibet Autonomous Region (XZ2018ZRG-08); Tibet University Cultivation Foundation Project (ZDCZJH20-17) |
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| Ground-based Measurements Of Solar Spectrum In Ngari |
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ZHOU Yi, Norsang Gelsor, WANG Qian, ZHOU Yanxia
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1. Geophysics Institute, Tibet University, Lhasa 850000, China
2. School of information science and technology, Tibet University, Lhasa 850000, China
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| Abstract: |
| Background, aim, and scope Located in the western Qinghai-Tibet Plateau, Ngari Prefecture of Tibet boasts extremely abundant solar energy resources with an average elevation of more than 4,500 m. Therefore, to observe the ground surface solar spectrum and analyze the solar radiation intensity at each wavelength is of great significance for the utilization of solar energy in Ngari. By now, scholars have observed and recorded the total solar radiation and solar ultraviolet radiation in high altitude areas such as Ngari for many times, but according to relevant information, the observations of solar spectrum in Ngari are still in the preliminary stage. This observation was made around June 21, 2020 (the day of summer solstice), when the solar radiation was the strongest, and the wavelength ranged from 280 nm and 1200 nm, in a bid to contribute to the utilization of solar energy resources in Ngari with solid data. Materials and methods The solar spectrum observation in this work adopts the SolarSIM-G solar spectral irradiance meter, which features a measurable wavelength of 280—1200 nm and very high spectral measurement accuracy— the solar radiation intensity is observable every 1 nm. The time interval of the observation ranges between 1.0 S and 3600.0 S. All data are automatically recorded between sunrise and sunset with an ultimate data unit of W·m−2·nm−1. This observation involves two points: Gar County, Ngari, Tibet (4280 m above the sea, 32°30′02″N, 80°06′01″E) and Chengguan District, Lhasa, Tibet (3683 m above the sea, 29°39′01″N, 91°10′05″E). The observation in Ngari started on Jun. 20, 2020 and ended on Jun. 22, 2020, totalling to 3 days, in which Jun. 21, 2020 is the summer solstice. The observation data of the solar spectrum in Lhasa from Jun. 24, 2020 to Jun. 30, 2020 (7 days) were used for comparison. Only the observation data on clear days were included in the analysis. Results At 12:34 on Jun. 21, 2020, in Ngari, the peak solar spectral radiant intensity (2.33 W·m−2·nm−1) was observed at a wavelength of 482 nm. In comparison, the maximum solar spectral intensity in Lhasa (2.80 W·m−2·nm−1) appeared at 13:56 on Jun. 27, 2020 at a wavelength of 482 nm wavelength. The “eclipse of the sun” was observed on Jun. 21 in Ngari, where the solar spectrum changed along with the process of first contact, magnitude of eclipse, and last contact. The solar spectrum in Ngari at noon on Jun. 22, 2020 under fine weather conditions is significantly stronger than the AM1.5 standard spectrum on the ground surface. However, the spectral intensity is smaller than the AM0 exo-atmosphere standard spectrum. Discussion Ngari is at a high altitude with low O2, H2O, CO2 and other molecular components in the atmosphere. Therefore, there is less absorption of the solar spectrum. In particular, when there is less absorption of the ultraviolet spectrum in the sunlight because of low O3 molecular content in the atmosphere, the ultraviolet spectral intensity is much higher than that in the standard spectrum. Surface solar radiation includes not only direct solar radiation but also large amounts of scattering radiation from clouds, dust and particles. Moreover, Ngari is mainly surrounded by deserts and dry bare land of high surface albedo and strong back radiation. Under the overlapping effect of direct radiation, scattering radiation and back radiation, the peak radiation intensity in this observation exceeds the direct solar radiation of the upper bound of the atmosphere (AM0). The “eclipse” in Ngari was observed on the very day of the summer solstice when the daytime is the longest throughout the year. This day should have been the day of the highest total solar radiation of the year but turned out to be the lowest of recent years due to the eclipse. Conclusions This solar spectrum observation in Ngari is the first solar spectrum observation in the wavelength range of 280—1200 nm in Ngari in recent years. The wavelength region covers ultraviolet, visible and near-infrared bands in solar energy utilization. The observation leads to sporadic characteristics of the surface solar spectrum in Ngari and provides rare data supporting the western Tibetan Plateau, being an area with rich solar energy resources. Recommendations and perspectives At present, most of the solar spectral observations in Ngari remain sporadic observations. It is necessary to conduct more systematic observations of the ground surface solar spectrum in the western Tibetan Plateau, with the consideration of the increase of data volume, the selection of time nodes, the diversity of data comparisons and other factors. As the data become more systematized, more researches on the combined use of solar spectrum and ecological environment, such as solar radiation on skin health, plant growth, material aging, should be conducted in the future. |
| Key words: Ngari solar spectrum irradiance measurement |
