云辐射效应在华北持续性大雾维持和发展中的作用
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摘要
观测研究发现华北地区的持续性大雾天气通常伴随高层云的存在,具有云-雾共存结构特征,为揭示云在持续性大雾维持和发展中的作用,利用中尺度数值模式WRF,结合华北雾霾观测试验期间的卫星、探空、地面观测、系留气艇、微波辐射计等观测资料,研究了2011年12月3—6日和2013年1月28—31日两次华北持续性大雾天气形成和发展演变过程。在模拟与观测对比检验研究的基础上,重点开展了云辐射效应在大雾维持和发展中作用的探讨。研究结果表明:两次大雾过程持续时间超过48 h,近地面具有偏南暖湿平流,在持续性大雾发展过程中,均出现了由单层雾发展为云-雾共存结构,一般是雾形成24 h以后有中高云移到雾层之上,云底高度在3 km以上,云厚超过3.5 km,云中以冰晶和雪晶为主。白天云-雾共存结构出现后,云-雾的反照率效应使地表接收的短波辐射减少71%—84%,地面增温效应显著减小,从而阻碍了大雾的消散过程,使大雾天气得以维持,同时由于云-雾产生的温室效应,湍流过程加强,使地面雾向上扩展,雾在稳定层内维持;夜晚云-雾共存时,由于云-雾温室效应使地表净长波辐射增大超过70 W/m2,导致地面长波辐射冷却过程减弱,并不利于雾的加强,但云对雾的增温效应有利于混合层内的湍流扩散过程,促使雾在更高的空间内得以维持。可见,在云-雾共存结构中,云辐射效应有利于低层大雾的长时间维持,对持续性大雾的形成和发展产生了重要作用。
Observations have shown that persistent heavy fog events in northern China are usually accompanied by the presence of clouds above the fog and characterized by co-existing clouds and fog. Combined with satellite, radiosonde and ground observations, tethered balloon soundings, and microwave radiometer data, the mesoscale model WRF is applied to investigate the role of cloud radiative effect in the maintenance and development of two persistent fog events occurred on 3-6 December 2011 and 28-31 January 2013, respectively. Horizontal distributions of fog and clouds as well as vertical profiles of temperature and relative humidity from the WRF simulations are compared with and verified against observations. The results indicate that the persistent fog processes lasted for more than 48 hours and accompanied by southward warm moist advection at lower levels near the ground. During the development of heavy fog events, the single-layer fog gradually developed into a cloud-fog coexisting state. The middle and high clouds with ice and snow particles covered the foggy area 24 hours after the fog formed. The cloud base was above 3 km height, and the cloud thickness was larger than 3.5 km. During the daytime, due to the co-existence of clouds and fog and enhanced solar radiation reflection by the clouds and fog, the solar radiation at the surface was greatly reduced by 71%-84%. This weakened the surface warming and prevented the fog from dissipating. Meanwhile, the greenhouse effect caused by the clouds and fog enhanced the turbulent mixing, which promoted the fog to extend upward and maintain in the stable layer. At the nighttime, longwave radiative cooling at the surface was reduced due to the greenhouse effect of the clouds and fog, and the surface net radiation increased by more than 70 W/m~2. This was not conducive to further development of the fog event. However, the enhanced turbulent diffusion process due to the greenhouse effect of clouds and fog was favorable for the development of the fog event in the vertical direction. Thus, the presence of clouds above the fog plays an important role in the maintenance and development of the long-lasting fog event through cloud radiative effect.
Observations have shown that persistent heavy fog events in northern China are usually accompanied by the presence of clouds above the fog and characterized by co-existing clouds and fog. Combined with satellite, radiosonde and ground observations, tethered balloon soundings, and microwave radiometer data, the mesoscale model WRF is applied to investigate the role of cloud radiative effect in the maintenance and development of two persistent fog events occurred on 3-6 December 2011 and 28-31 January 2013, respectively. Horizontal distributions of fog and clouds as well as vertical profiles of temperature and relative humidity from the WRF simulations are compared with and verified against observations. The results indicate that the persistent fog processes lasted for more than 48 hours and accompanied by southward warm moist advection at lower levels near the ground. During the development of heavy fog events, the single-layer fog gradually developed into a cloud-fog coexisting state. The middle and high clouds with ice and snow particles covered the foggy area 24 hours after the fog formed. The cloud base was above 3 km height, and the cloud thickness was larger than 3.5 km. During the daytime, due to the co-existence of clouds and fog and enhanced solar radiation reflection by the clouds and fog, the solar radiation at the surface was greatly reduced by 71%-84%. This weakened the surface warming and prevented the fog from dissipating. Meanwhile, the greenhouse effect caused by the clouds and fog enhanced the turbulent mixing, which promoted the fog to extend upward and maintain in the stable layer. At the nighttime, longwave radiative cooling at the surface was reduced due to the greenhouse effect of the clouds and fog, and the surface net radiation increased by more than 70 W/m~2. This was not conducive to further development of the fog event. However, the enhanced turbulent diffusion process due to the greenhouse effect of clouds and fog was favorable for the development of the fog event in the vertical direction. Thus, the presence of clouds above the fog plays an important role in the maintenance and development of the long-lasting fog event through cloud radiative effect.
引文
曹伟华, 梁旭东, 李青春. 2013. 北京一次持续性雾霾过程的阶段性特征及影响因子分析. 气象学报, 71(5): 940-951. Cao W H, Liang X D, Li Q C. 2013. A study of the stageful characteristics and influencing factors of a long-lasting fog/haze event in Beijing. Acta Meteor Sinica, 71(5): 940-951 (in Chinese)
郭丽君, 郭学良. 2015. 利用地基多通道微波辐射计遥感反演华北持续性大雾天气温、湿度廓线的检验研究. 气象学报, 73(2): 368-381. Guo L J, GUO X L. 2015. Verification study of the atmospheric temperature and humidity profiles retrieved from the ground-based multi-channels microwave radiometer for persistent foggy weather events in northern China. Acta Meteor Sinica, 73(2): 368-381(in Chinese)
郭丽君, 郭学良. 2016. 北京2009～2013年期间持续性大雾的类型、垂直结构及物理成因. 大气科学, 40(2): 296-310. Guo L J, Guo X L. 2016. The type, vertical structure and physical formation mechanism of persistent heavy fog events during 2009-2013 in the Beijing region. Chinese J Atmos Sci, 40(2): 296-310 (in Chinese)
何晖, 郭学良, 刘建忠等. 2009. 北京一次大雾天气边界层结构特征及生消机理观测与数值模拟研究. 大气科学, 33(6): 1174-1186. He H, Guo X L, Liu J Z, et al. 2009. Observation and simulation study of the boundary layer structure and the formation, dispersal mechanism of a heavy fog event in Beijing area. Chinese J Atmos Sci, 33(6): 1174-1186 (in Chinese)
李娟, 毛节泰. 2005. 大气冰核浓度对冷云辐射特性的影响以及多年来冷云反照率的变化. 科学通报, 50(21): 2413-2421. Li J, Mao J T. 2006. Influence of atmospheric ice nucleus concentrations on cold cloud radiant properties and cold cloud reflectivity changes in past years. Chinese Sci Bull, 51(4): 480-489
李子华, 杨军, 石春娥等. 2008. 地区性浓雾物理. 北京: 气象出版社. Li Z H, Yang J, Shi C E, et al. 2008. The Physics of Regional Dense Fog. Beijing: China Meteorological Press (in Chinese)
杨军, 王蕾, 刘端阳等. 2010. 一次深厚浓雾过程的边界层特征和生消物理机制. 气象学报, 68(6): 998-1006. Yang J, Wang L, Liu D Y, et al. 2010. The boundary layer structure and the evolution mechanisms of a deep dense fog event. Acta Meteor Sinica, 68(6): 998-1006 (in Chinese)
杨悦, 高山红. 2016. 黄海海雾WRF数值模拟中垂直分辨率的敏感性研究. 气象学报, 74(6): 974-988. Yang Y, Gao S H. 2016. Sensitivity study of vertical resolution in WRF numerical simulation for sea fog over the Yellow Sea. Acta Meteor Sinica, 74(6): 974-988 (in Chinese)
Liou K N. 2004. 大气辐射导论. 郭彩丽, 周诗健, 译. 2版. 北京: 气象出版社, 493-497. Liou K N. 2004. An Introduction to Atmospheric Radiation. Guo C L, Zhou S J, trans. 2nd ed. Beijing: China Meteorological Press, 493-497 (in Chinese)
尹球, 许绍祖. 1994. 辐射雾生消的数值研究(Ⅱ):生消机制. 气象学报, 52(1): 60-67. Yin Q, Xu S Z. 1994. A numerical study on the formation and dissipation of radiation fog (Ⅱ) : The physical mechanism of radiation fog. Acta Meteor Sinica, 52(1): 60-67 (in Chinese)
赵丽娟, 牛生杰. 2012. 近地层辐射过程与雾微结构的相互作用特征. 大气科学学报, 35(6): 673-679. Zhao L J, Niu S J. 2012. Characteristics of interactions between radiation processes and fog microphysical structure. Trans Atmos Sci, 35(6): 673-679 (in Chinese)
Bergot T, Guedalia D. 1994. Numerical forecasting of radiation fog. Part I: Numerical model and sensitivity Tests. Mon Wea Rev, 122(6): 1218-1230
Brown R, Roach W T. 1976. The physics of radiation fog. Ⅱ: A numerical study. Quart J Roy Meteor Soc, 102(432): 335-354
Chen J Y, Carlson B E, Del Genio A D. 2002. Evidence for strengthening of the tropical general circulation in the 1990s. Science, 295(5556): 838-841
Choularton T W, Fullarton G, Latham J, et al. 1981. A field study of radiation fog in Meppen, West Germany. Quart J Roy Meteor Soc, 107(452): 381-394
Dupont J C, Haeffelin M, Protat A, et al. 2012. Stratus-fog formation and dissipation: A 6-day case study. Bound-Layer Meteor, 143(1): 207-225
Duynkerke P G. 1999. Turbulence, radiation and fog in Dutch stable boundary layers. Bound-Layer Meteor, 90(3): 447-477
Guo L J, Guo X L, Fang C G, et al. 2015. Observation analysis on characteristics of formation, evolution and transition of a long-lasting severe fog and haze episode in North China. Sci China Earth Sci, 58(3): 329-344
Haeffelin M, Bergot T, Elias T, et al. 2010. Parisfog: Shedding new light on fog physical processes. Bull Amer Meteor Soc, 91(6): 767-783
Oliver D A, Lewellen W S, Williamson G G. 1978. The interaction between turbulent and radiative transport in the development of fog and low-level stratus. J Atmos Sci, 35(2): 301-316
Pagowski M, Gultepe I, King P. 2004. Analysis and modeling of an extremely dense fog event in Southern Ontario. J Appl Meteor, 43(1): 3-16
Pilié R J, Mack E J, Rogers C W, et al. 1979. The formation of marine fog and the development of fog-stratus systems along the California coast. J Appl Meteor, 18(10): 1275-1286
Price J, Porson A, Lock A. 2015. An observational case study of persistent fog and comparison with an ensemble forecast model. Bound-Layer Meteor, 155(2): 301-327
Ramanathan V, Pitcher E J, Malone R C, et al. 1983. Response of a spectral general circulation model to refinements in radiative processes. J Atmos Sci, 40(3): 605-630
Ramanathan V. 1987. The role of earth radiation budget studies in climate and general circulation research. J Geophys Res, 92(D4): 4075-4095
Roach W T, Brown R, Caughey S J, et al. 1976. The physics of radiation fog. Ⅰ: A field study. Quart J Roy Meteor Soc, 102(432): 313-333
Roach W T. 1995. Back to basics: Fog. Part 2: The formation and dissipation of land fog. Weather, 50(1): 7-11
Stephens G L. 2005. Cloud feedbacks in the climate system: A critical review. J Climate, 18(2): 237-273
Tardif R, Rasmussen R M. 2007. Event-based climatology and typology of fog in the New York City region. J Appl Meteor Climatol, 46(8): 1141-1168
Van der Velde I R, Steeneveld G J, Wichers Schreur B G J, et al. 2010. Modeling and forecasting the onset and duration of severe radiation fog under frost conditions. Mon Wea Rev, 138(11): 4237-4253
Vehil R, Monerris J, Guedalia D, et al. 1989. Study of the radiative effects (long-wave and short-wave) within a fog layer. Atmos Res, 23(2): 179-194
Westcott N E, Kristovich D A R. 2009. A climatology and case study of continental cold season dense fog associated with low clouds. J Appl Meteor Climatol, 48(11): 2201-2214
Ye X X, Wu B G, Zhang H S. 2015. The turbulent structure and transport in fog layers observed over the Tianjin area. Atmos Res, 153: 217-234
郭丽君, 郭学良. 2015. 利用地基多通道微波辐射计遥感反演华北持续性大雾天气温、湿度廓线的检验研究. 气象学报, 73(2): 368-381. Guo L J, GUO X L. 2015. Verification study of the atmospheric temperature and humidity profiles retrieved from the ground-based multi-channels microwave radiometer for persistent foggy weather events in northern China. Acta Meteor Sinica, 73(2): 368-381(in Chinese)
郭丽君, 郭学良. 2016. 北京2009～2013年期间持续性大雾的类型、垂直结构及物理成因. 大气科学, 40(2): 296-310. Guo L J, Guo X L. 2016. The type, vertical structure and physical formation mechanism of persistent heavy fog events during 2009-2013 in the Beijing region. Chinese J Atmos Sci, 40(2): 296-310 (in Chinese)
何晖, 郭学良, 刘建忠等. 2009. 北京一次大雾天气边界层结构特征及生消机理观测与数值模拟研究. 大气科学, 33(6): 1174-1186. He H, Guo X L, Liu J Z, et al. 2009. Observation and simulation study of the boundary layer structure and the formation, dispersal mechanism of a heavy fog event in Beijing area. Chinese J Atmos Sci, 33(6): 1174-1186 (in Chinese)
李娟, 毛节泰. 2005. 大气冰核浓度对冷云辐射特性的影响以及多年来冷云反照率的变化. 科学通报, 50(21): 2413-2421. Li J, Mao J T. 2006. Influence of atmospheric ice nucleus concentrations on cold cloud radiant properties and cold cloud reflectivity changes in past years. Chinese Sci Bull, 51(4): 480-489
李子华, 杨军, 石春娥等. 2008. 地区性浓雾物理. 北京: 气象出版社. Li Z H, Yang J, Shi C E, et al. 2008. The Physics of Regional Dense Fog. Beijing: China Meteorological Press (in Chinese)
杨军, 王蕾, 刘端阳等. 2010. 一次深厚浓雾过程的边界层特征和生消物理机制. 气象学报, 68(6): 998-1006. Yang J, Wang L, Liu D Y, et al. 2010. The boundary layer structure and the evolution mechanisms of a deep dense fog event. Acta Meteor Sinica, 68(6): 998-1006 (in Chinese)
杨悦, 高山红. 2016. 黄海海雾WRF数值模拟中垂直分辨率的敏感性研究. 气象学报, 74(6): 974-988. Yang Y, Gao S H. 2016. Sensitivity study of vertical resolution in WRF numerical simulation for sea fog over the Yellow Sea. Acta Meteor Sinica, 74(6): 974-988 (in Chinese)
Liou K N. 2004. 大气辐射导论. 郭彩丽, 周诗健, 译. 2版. 北京: 气象出版社, 493-497. Liou K N. 2004. An Introduction to Atmospheric Radiation. Guo C L, Zhou S J, trans. 2nd ed. Beijing: China Meteorological Press, 493-497 (in Chinese)
尹球, 许绍祖. 1994. 辐射雾生消的数值研究(Ⅱ):生消机制. 气象学报, 52(1): 60-67. Yin Q, Xu S Z. 1994. A numerical study on the formation and dissipation of radiation fog (Ⅱ) : The physical mechanism of radiation fog. Acta Meteor Sinica, 52(1): 60-67 (in Chinese)
赵丽娟, 牛生杰. 2012. 近地层辐射过程与雾微结构的相互作用特征. 大气科学学报, 35(6): 673-679. Zhao L J, Niu S J. 2012. Characteristics of interactions between radiation processes and fog microphysical structure. Trans Atmos Sci, 35(6): 673-679 (in Chinese)
Bergot T, Guedalia D. 1994. Numerical forecasting of radiation fog. Part I: Numerical model and sensitivity Tests. Mon Wea Rev, 122(6): 1218-1230
Brown R, Roach W T. 1976. The physics of radiation fog. Ⅱ: A numerical study. Quart J Roy Meteor Soc, 102(432): 335-354
Chen J Y, Carlson B E, Del Genio A D. 2002. Evidence for strengthening of the tropical general circulation in the 1990s. Science, 295(5556): 838-841
Choularton T W, Fullarton G, Latham J, et al. 1981. A field study of radiation fog in Meppen, West Germany. Quart J Roy Meteor Soc, 107(452): 381-394
Dupont J C, Haeffelin M, Protat A, et al. 2012. Stratus-fog formation and dissipation: A 6-day case study. Bound-Layer Meteor, 143(1): 207-225
Duynkerke P G. 1999. Turbulence, radiation and fog in Dutch stable boundary layers. Bound-Layer Meteor, 90(3): 447-477
Guo L J, Guo X L, Fang C G, et al. 2015. Observation analysis on characteristics of formation, evolution and transition of a long-lasting severe fog and haze episode in North China. Sci China Earth Sci, 58(3): 329-344
Haeffelin M, Bergot T, Elias T, et al. 2010. Parisfog: Shedding new light on fog physical processes. Bull Amer Meteor Soc, 91(6): 767-783
Oliver D A, Lewellen W S, Williamson G G. 1978. The interaction between turbulent and radiative transport in the development of fog and low-level stratus. J Atmos Sci, 35(2): 301-316
Pagowski M, Gultepe I, King P. 2004. Analysis and modeling of an extremely dense fog event in Southern Ontario. J Appl Meteor, 43(1): 3-16
Pilié R J, Mack E J, Rogers C W, et al. 1979. The formation of marine fog and the development of fog-stratus systems along the California coast. J Appl Meteor, 18(10): 1275-1286
Price J, Porson A, Lock A. 2015. An observational case study of persistent fog and comparison with an ensemble forecast model. Bound-Layer Meteor, 155(2): 301-327
Ramanathan V, Pitcher E J, Malone R C, et al. 1983. Response of a spectral general circulation model to refinements in radiative processes. J Atmos Sci, 40(3): 605-630
Ramanathan V. 1987. The role of earth radiation budget studies in climate and general circulation research. J Geophys Res, 92(D4): 4075-4095
Roach W T, Brown R, Caughey S J, et al. 1976. The physics of radiation fog. Ⅰ: A field study. Quart J Roy Meteor Soc, 102(432): 313-333
Roach W T. 1995. Back to basics: Fog. Part 2: The formation and dissipation of land fog. Weather, 50(1): 7-11
Stephens G L. 2005. Cloud feedbacks in the climate system: A critical review. J Climate, 18(2): 237-273
Tardif R, Rasmussen R M. 2007. Event-based climatology and typology of fog in the New York City region. J Appl Meteor Climatol, 46(8): 1141-1168
Van der Velde I R, Steeneveld G J, Wichers Schreur B G J, et al. 2010. Modeling and forecasting the onset and duration of severe radiation fog under frost conditions. Mon Wea Rev, 138(11): 4237-4253
Vehil R, Monerris J, Guedalia D, et al. 1989. Study of the radiative effects (long-wave and short-wave) within a fog layer. Atmos Res, 23(2): 179-194
Westcott N E, Kristovich D A R. 2009. A climatology and case study of continental cold season dense fog associated with low clouds. J Appl Meteor Climatol, 48(11): 2201-2214
Ye X X, Wu B G, Zhang H S. 2015. The turbulent structure and transport in fog layers observed over the Tianjin area. Atmos Res, 153: 217-234