0 引言
图1 基于观测与重建记录的中全新世以来相对于1850年的温度及东亚夏季风变化[a:全球平均温度的全新世暖期多指标重建集成结果(数据来源于文献[10])和当前增暖的再分析结果(数据来源于文献[18]);b:根据山西省吕梁山公海湖(数据来源于文献[11])、黄土高原六盘山天池(数据来源于文献[12])化石孢粉记录重建的全年降水量及EASM下游区域年降水观测记录(数据来源于GPCC[19]);c:甘肃省陇南市乌鸦洞氧同位素变化(数据来源于文献[20])和基于20CR数据集的夏季850 hPa经向风变化(数据来源于文献[18])。] Fig.1 Variations in temperature and East Asian Summer Monsoon since the Mid-Holocene relative to 1850 based on observational and reconstructed records [a: Multi-proxy integrated reconstruction results of Holocene Thermal Maximum global mean temperature (data from reference [10]) and reanalysis results for the current warming (data from reference [18]); b: Reconstructed annual precipitation from fossil spore-pollen records of Gonghai Lake, Lüliang Mountains, Shanxi Province (data from reference [11]) and Tianchi, Liupan Mountain, Loess Plateau (data from reference [12]), and observational data of annual precipitation in the downstream area of the EASM (data from GPCC[19]); c: The variations of oxygen isotopes in Wuya Cave, Longnan City, Gansu Province (data from reference [20]), and the variations of summer 850 hPa meridional wind from the 20CR dataset (data from reference [18]).] |
1 数据和方法
2 结果
2.1 两种增暖背景下东亚夏季风响应的模拟结果
2.2 当前增暖下东亚夏季风演变影响因素模拟
图3 全新世暖期(a)以及当前增暖下全强迫(b)、温室气体强迫(c)、气溶胶强迫(d)模拟试验中的年累积降水变幅和夏季850 hPa经向风场变幅Fig.3 Annual cumulative precipitation anomalies and summer 850 hPa meridional wind field variability in simulated experiments under the Holocene Thermal Maximum(a), current warming conditions with full forcing (b), greenhouse gases forcing (c),and aerosol forcing (d) |
2.3 两种增暖背景下东亚夏季风演变的机理分析
图5 全新世暖期(a)与当前增暖下(b) 夏季 850 hPa经向风场、地表气温和海平面压力变化以及夏季850 hPa经向风场变幅(c)、年累积降水变幅(d)对海陆热力对比变幅的响应Fig.5 Variations of summer 850 hPa meridional wind, surface air temperature and sea level pressure under the Holocene Thermal Maximum (a) and current warming (b), as well as responses of 850 hPa summer meridional wind field anomaly (c) and annual cumulative precipitation anomaly (d) to land-sea thermal contrast anomaly |