From Internal Variability to Aerosol Effects: Physical Mechanisms Behind Observed Decadal Trends in Surface Solar Radiation in the Western Pacific Ocean
IF 3.8 2区 地球科学Q2 METEOROLOGY & ATMOSPHERIC SCIENCES
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引用次数: 0
Abstract
The Pacific Ocean, spanning over 30% of the Earth's surface, provides an ideal setting for studying the surface radiative balance due to its relatively pristine atmospheric conditions, far from anthropogenic emission sources. In this study we investigated the causes for the decadal trends of surface solar radiation (SSR) observed at eight stations scattered across seven islands in the Western Pacific Ocean, and extrapolated the results to the whole Western Pacific region based on the understanding of physical processes. Our results show a contrast between the causes for SSR trends in the northwestern and in the southwestern Pacific. In the Southwestern Pacific region, changes in cloud cover play a major role in the SSR decadal trends and interannual variability. The cloud cover in these areas is strongly associated with sea surface temperature (SST) anomalies, especially those induced by El Nino Southern Oscillation (ENSO) and the Interdecadal Pacific Oscillation (IPO). Modes of variability such as ENSO and IPO affect evaporation and convection, impacting the large-scale dynamics of the atmosphere, therefore influencing the distribution of the regions of deep convection. This consecutively impacts the cloud cover on a regional level and therefore SSR. In the Northern Hemisphere, conversely, a strong influence of these modes on cloudiness and SSR was not found. Instead, indirect evidence suggests that anthropogenic aerosol transported from Eastern Asia plays a major role in the decadal SSR trends. These results contribute to an improved understanding of the physical processes relevant for the long-term SSR trends in remote regions.
太平洋横跨地球表面的 30% 以上,由于其相对原始的大气条件,远离人为排放源,为研究地表辐射平衡提供了理想的环境。在这项研究中,我们调查了在西太平洋七个岛屿上的八个观测站观测到的地表太阳辐射十年趋势的原因,并根据对物理过程的理解将结果推断到整个西太平洋地区。我们的研究结果表明,造成西北太平洋和西南太平洋 SSR 变化趋势的原因截然不同。在西南太平洋地区,云量变化在 SSR 十年趋势和年际变化中起着主要作用。这些地区的云量与海面温度(SST)异常密切相关,尤其是厄尔尼诺南方涛动(ENSO)和太平洋年代际涛动(IPO)引起的异常。厄尔尼诺/南方涛动和太平洋涛动等变率模式会影响蒸发和对流,影响大气的大尺度动态,从而影响深对流区域的分布。这将连续影响区域层面的云量,从而影响 SSR。相反,在北半球,没有发现这些模式对云量和 SSR 有很大影响。相反,间接证据表明,来自东亚的人为气溶胶在十年 SSR 趋势中发挥了重要作用。这些结果有助于加深对偏远地区 SSR 长期趋势相关物理过程的理解。
期刊介绍:
JGR: Atmospheres publishes articles that advance and improve understanding of atmospheric properties and processes, including the interaction of the atmosphere with other components of the Earth system.