北极海冰区1981—2020年辐射通量的时空变化特征与分析

Spatial-temporal variation of surface radiation budget over the Arctic sea ice region from 1981 to 2020

  • 摘要: 北极海冰快速消退,表面净辐射及云辐射强迫变化显著,综合分析其时空变化特征对认识全球气候环境变化具有重要意义。基于ERA5再分析资料分析了1981—2020年北极海冰区域表面净辐射(短波净辐射、长波净辐射和总净辐射)及云辐射强迫(短波云辐射强迫、长波云辐射强迫和全波长云辐射强迫)的季节、年际和年代际变化特征。结果表明,1981—2020年北极夏季海冰区域总净辐射的均值为84.16 W·m-2,其对地表起加热作用;总的云辐射强迫均值为-16.78 W·m-2,云对地表起冷却效应。短波辐射对表面净辐射与云辐射强迫的贡献最大。1981—2020年短波净辐射呈显著增加趋势(2.22 W·m-2·decade-1),但2011—2020年却以-6.58 W·m-2·decade-1的速率显著下降;短波云辐射强迫在1981—2020年夏季的均值为-67.91 W·m-2,以-2.75 W·m-2·decade-1的速率显著下降,表明云对地表的冷却效应增强。北极边缘海域辐射通量变化剧烈,特别是巴伦支海-喀拉海,该海域夏季总的净辐射与云辐射强迫变化速度最快。

     

    Abstract: Objectives: The surface net radiation and cloud radiative forcing are of great importance to understand global climate and environmental changes, which change significantly with the rapidly decline of sea ice in the Arctic. Methods: A long-term dataset of 40 years (1981-2020) from the ERA5 reanalysis data is adopted to investigate the seasonal, annual and decadal variations in surface net shortwave radiation, surface net longwave radiation, surface net all-wave radiation, shortwave cloud radiative forcing, longwave cloud radiation forcing, and all-wave cloud radiative forcing. Results: The results showed that the surface net all-wave radiation exhibited a warming effect in summer over the Arctic sea ice region from 1981-2020 and the average was 84.16 W m-2. In contrast, the all-wave cloud radiative forcing caused -16.78 W m-2 of cooling in summer. Conclusions: Shortwave radiation contributes most to the surface net radiation and cloud radiative forcing. The shortwave net radiation showed a significant increasing trend from 1981 to 2020 with 2.22 W m-2 decade-1, while declined at a speed of -6.58 W m-2 decade-1 in 2011-2020. The summer average of shortwave cloud radiative forcing was -67.91 W m-2, and it decreased deeply by -2.75 W m-2 decade-1, indicating that the cooling effect of cloud on the surface was enhanced. The spatial distribution of summer trends showed that the highest changing rate of surface radiation fluxes existed in the Arctic marginal sea area, especially in the Barents-Kara Sea, where the surface net all-wave radiation and all-wave cloud radiation forcing changed fastest in summer.

     

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