An extremely heavy rainfall event lasting from 17 to 22 July 2021 occurred in Henan Province of China, with accumulated precipitation of more than 1000 mm over a 6-day period that exceeded its mean annual precipitatio...An extremely heavy rainfall event lasting from 17 to 22 July 2021 occurred in Henan Province of China, with accumulated precipitation of more than 1000 mm over a 6-day period that exceeded its mean annual precipitation. The present study examines the roles of persistent low-level jets(LLJs) in maintaining the precipitation using surface station observations and reanalysis datasets. The LLJs triggered strong ascending motions and carried moisture mainly from the outflow of Typhoon In-fa(2021). The varying directions of the LLJs well corresponded to the meridional shifts of the rainfall. The precipitation rate reached a maximum during 20-21 July as the LLJs strengthened and expanded vertically into double LLJs, including synoptic-weather-system-related LLJs(SLLJs) at 850–700 hPa and boundary-layer jets(BLJs)at ~950 hPa. The coupling of the SLLJ and BLJ provided strong mid-and low-level convergence on 20 July, whereas the SLLJ produced mid-level divergence at its entrance that coupled with low-level convergence at the terminus of the BLJ on21 July. The formation mechanisms of the two types of LLJs are further examined. The SLLJs and the low-pressure vortex(or inverted trough) varied synchronously as a whole and were affected by the southwestward movement of the WPSH in the rainiest period. The persistent large total pressure gradient force at low levels also maintained the strength of low-level geostrophic winds, thus sustaining the BLJs on the synoptic scale. The results based on a Du-Rotunno 1D model show that the Blackadar and Holton mechanisms jointly governed the BLJ dynamics on the diurnal scale.展开更多
针对中国石油化工集团有限公司开发的以餐饮废油为原料生产生物质喷气燃料(简称生物喷气燃料)两段加氢(SRJET)技术,基于生命周期的评价分析,确定核算边界,分析了生物喷气燃料生命周期碳足迹(单位产品生命周期过程中所导致的直接和间接的...针对中国石油化工集团有限公司开发的以餐饮废油为原料生产生物质喷气燃料(简称生物喷气燃料)两段加氢(SRJET)技术,基于生命周期的评价分析,确定核算边界,分析了生物喷气燃料生命周期碳足迹(单位产品生命周期过程中所导致的直接和间接的CO_(2)排放总量)。通过对比生物喷气燃料与石油基喷气燃料的生命周期碳足迹评价了生物喷气燃料替代石油基喷气燃料的碳减排效果,通过不确定性分析及各环节参数因子敏感性分析,明确了生命周期模型参数对碳足迹评价的影响水平。结果表明,生物喷气燃料的生命周期碳足迹总量为0.55 kg kg,在模型预测结果90%置信区间内,相比于石油基喷气燃料,生物喷气燃料生命周期碳排放总量(以CO_(2)计)降低80.9%~93.2%。生物质喷气燃料技术推广和产业链构建对助力我国“碳达峰、碳中和”战略目标实现具有重要意义。展开更多
基金supported by Guangdong Major Project of Basic and Applied Basic Research(2020B0301030004)the National Natural Science Foundation of China(Grant Nos.42122033,41875055,and 42075006)Guangzhou Science and Technology Plan Projects(202002030346 and 202002030196).
文摘An extremely heavy rainfall event lasting from 17 to 22 July 2021 occurred in Henan Province of China, with accumulated precipitation of more than 1000 mm over a 6-day period that exceeded its mean annual precipitation. The present study examines the roles of persistent low-level jets(LLJs) in maintaining the precipitation using surface station observations and reanalysis datasets. The LLJs triggered strong ascending motions and carried moisture mainly from the outflow of Typhoon In-fa(2021). The varying directions of the LLJs well corresponded to the meridional shifts of the rainfall. The precipitation rate reached a maximum during 20-21 July as the LLJs strengthened and expanded vertically into double LLJs, including synoptic-weather-system-related LLJs(SLLJs) at 850–700 hPa and boundary-layer jets(BLJs)at ~950 hPa. The coupling of the SLLJ and BLJ provided strong mid-and low-level convergence on 20 July, whereas the SLLJ produced mid-level divergence at its entrance that coupled with low-level convergence at the terminus of the BLJ on21 July. The formation mechanisms of the two types of LLJs are further examined. The SLLJs and the low-pressure vortex(or inverted trough) varied synchronously as a whole and were affected by the southwestward movement of the WPSH in the rainiest period. The persistent large total pressure gradient force at low levels also maintained the strength of low-level geostrophic winds, thus sustaining the BLJs on the synoptic scale. The results based on a Du-Rotunno 1D model show that the Blackadar and Holton mechanisms jointly governed the BLJ dynamics on the diurnal scale.
文摘针对中国石油化工集团有限公司开发的以餐饮废油为原料生产生物质喷气燃料(简称生物喷气燃料)两段加氢(SRJET)技术,基于生命周期的评价分析,确定核算边界,分析了生物喷气燃料生命周期碳足迹(单位产品生命周期过程中所导致的直接和间接的CO_(2)排放总量)。通过对比生物喷气燃料与石油基喷气燃料的生命周期碳足迹评价了生物喷气燃料替代石油基喷气燃料的碳减排效果,通过不确定性分析及各环节参数因子敏感性分析,明确了生命周期模型参数对碳足迹评价的影响水平。结果表明,生物喷气燃料的生命周期碳足迹总量为0.55 kg kg,在模型预测结果90%置信区间内,相比于石油基喷气燃料,生物喷气燃料生命周期碳排放总量(以CO_(2)计)降低80.9%~93.2%。生物质喷气燃料技术推广和产业链构建对助力我国“碳达峰、碳中和”战略目标实现具有重要意义。
