Variation in the rotation rate of Earth and its role as a climate change indicator between 1972 and 2022
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摘要: 作为反映地球自转速率累积变化的参数(世界时UT1-UTC)和时变特性的参数(日长变化ΔLOD),UT1-UTC在现实项目中有重要应用,而ΔLOD则主要用于科学研究,联合两者探讨地球自转速率变化的规律有重要的意义. 本工作针对近50年的世界时观测数据分析其特性,重点关注近期出现的异常现象:2020年5月以来,地球自转趋势由原来的长期减慢逆转为加快;同时对日长变化序列进行分解,分析地球自转速率变化的可能激发源,并评估其中的气候因素对近期地球自转加快的贡献. 结果表明,扣除其他影响因素后,日长年际项与气候变化指数表现出高度的一致性;近三年期间,检测到两次中等强度的拉尼娜事件以及第二次事件的延续,其对近期地球自转加快的贡献大约为9%.Abstract: The universal time (UT1-UTC) and length of day change (ΔLOD) are two parameters that describe the Earth's rotation rate variations. UT1-UTC is typically used in space projects, whereas ΔLOD is used for scientific investigations. Therefore, studying the variations between the two parameter sequences is very important. In this study, we reviewed the Earth's rotation rate over the last five decades and revealed an abnormal phenomenon in UT1-UTC. Since May 2020, the Earth's rotation has reversed from a deceleration trend to an acceleration trend. Besides, we used ΔLOD to find the possible geophysical contributors and focused on the climate-related contributions. Results revealed that the interannual LOD exhibited a notable degree of consistency with ENSO indices after using the Difference+FDSR method to remove the internally and externally induced signals. Notably, two La Nina with intermediate strength and the beginning of a closely followed third trough were detected in the last three years. The contributions of these events to the latest rotation acceleration are approximately 9%.
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Key words:
- Earth's rotation rate variations /
- climate change /
- El Nino /
- La Nina
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图 3 1972年1月至2022年9月仅与流体贡献相关的ΔLOD年际项(黑线)、AAM年际变化(浅蓝线)与ENSO指数序列对比.(a)ΔLOD和AAM年际项;(b)大气压变化指数;(c)海温变化指数
Figure 3. Climate-related ΔLOD (black curve), interannual AAM (light blue curve), and ENSO indices between January 1972 and September 2022. (a) Interannual variations of ΔLOD and AAM; (b) MSOI; (c) NINO 3.4
表 1 1972年1月至2022年9月期间发生的气候事件的类别、持续时间以及呈现的温度变化和造成的自转速率变化极值信息统计
Table 1. Climate event statistics of the type, duration, and extreme values of temperature changes and induced rotation rate variations from January 1972 to September 2022
事件
类别跨越
时间/年持续
月长/月SST变化
极值/℃日长年际
变化极值/ms事件
类别跨越
时间/年持续
月长/月SST变化
极值/℃日长年际
变化极值/msEl Nino 1972—1973 11 2.1 0.16 El Nino 2002—2003 9 1.3 0.12 La Nina 1973—1974 15 −2.0 −0.22 El Nino 2004—2005 8 0.7 0.13 La Nina 1974—1976 19 −1.7 −0.20 La Nina 2005—2006 5 −0.9 −0.13 El Nino 1976—1977 6 0.9 El Nino 2006—2007 5 0.9 0.20 El Nino 1977—1978 5 0.8 0.24 La Nina 2007—2008 13 −1.6 El Nino 1979—1980 5 0.6 0.18 La Nina 2008—2009 5 −0.8 −0.14 El Nino 1982—1983 15 2.2 0.43 El Nino 2009—2010 9 1.6 0.10 La Nina 1983—1984 19 −1.0 −0.30 La Nina 2010—2011 12 −1.6 −0.16 La Nina 1984—1985 19 −1.1 La Nina 2011—2012 10 −1.1 El Nino 1986—1988 18 1.7 0.14 El Nino 2014—2016 19 2.6 0.42 La Nina 1988—1989 13 −1.8 −0.27 La Nina 2016—2016 5 −0.7 −0.04 El Nino 1991—1992 14 1.7 0.09 La Nina 2017—2018 7 −1.0 −0.08 El Nino 1994—1995 7 1.1 0.16 El Nino 2018—2019 10 0.9 0.14 La Nina 1995—1996 8 −1.0 −0.13 La Nina 2020—2021 10 −1.3 −0.22 El Nino 1997—1998 13 2.4 0.36 La Nina 2021—2022 13 −1.1 −0.19 La Nina 1998—2001 32 −1.7 −0.30 -
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