雷暴云内电荷水平分布形式对闪电放电的影响
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摘要
为了定量探究雷暴云内电荷水平分布形式对闪电类型和先导传播行为的影响,建立了典型雷暴云电荷结构模型,引入控制电荷水平分布的参数,利用改进的随机放电参数化方案,开展二维高分辨率模拟试验。结果表明:主正电荷区电荷水平分布不均匀且向中心聚集时,产生的闪电类型多为正地闪和正极性云闪,随着电荷水平分布趋于均匀,闪电类型转变为负地闪;主负电荷区电荷水平分布趋于均匀时,闪电类型由负地闪向正极性云闪再向正地闪转变;闪电先导传播特征有较大差异,电荷分布密集不均匀时,先导被束缚在电荷高密度中心,主要在电荷区内发展,当电荷分布单一均匀时,先导能穿出电荷区并水平延伸十几至二十多千米。分析两个电荷区之间的电位分布发现,电荷区电荷水平分布趋于均匀时,位势线向电荷密度中心集中,整个位势阱水平延展,闪电触发点的初始电位值有较大差异,有利于闪电类型和先导传播行为的改变。
The charge structure of thunderstorm and its internal charge distribution is an important subject in the field of atmospheric electricity research, because it has a direct impact on characteristics of lightning discharge. Influences of different charge structures in thunderstorm on lightning discharge are studied in many aspects, such as lightning types, polarity, and scales, however, but there are few quantitative investigations on effects of the horizontal distribution. Therefore, based on the existing stochastic lightning parameterization scheme, a thundercloud model is set up based upon the work of Stolzenburg et al.(1998)revealing charge structure with four charge regions within convective updrafts in thunderstorms and a negative screening layer usually exists at the top of storms. Parameters that control the horizontal distribution of charge is introduced, and then 2-dimensional fine-resolution lighting discharge simulations are performed. Results show that horizontal distribution forms of charge in upper positive region play a key role in lightning discharge, and with forms of charge changes from dense unevenness into single uniform, lightning type changes from positive cloud-to-ground flashes to positive intra-cloud flashes, then into negative cloud-to-ground flashes, and finally into positive intra-cloud flashes in limited cases. When the distribution of charge levels in the main negative charge region tends to be uniform, the type of lightning changes from negative cloud-to-ground flashes to positive intra-cloud flashes, then to positive cloud-to-ground flashes and finally to positive intra-cloud flashes in limited cases. The horizontal distribution of space charge has a significant effect on the propagation of lightning leader. If it is dense uneven, the leader propagates in the center of the charge density, otherwise, the leader can extend more than 10 to 20 km in the horizontal direction. As the horizontal distribution of charge in the charge region tends to be uniform, potential lines between two charge regions are concentrated towards the charge density center, and the potential well extends horizontally, causing the different initial potential values of the lightning trigger points, which result in the generation of different types of lightning and far-spreading lighting leader in the horizontal direction.
The charge structure of thunderstorm and its internal charge distribution is an important subject in the field of atmospheric electricity research, because it has a direct impact on characteristics of lightning discharge. Influences of different charge structures in thunderstorm on lightning discharge are studied in many aspects, such as lightning types, polarity, and scales, however, but there are few quantitative investigations on effects of the horizontal distribution. Therefore, based on the existing stochastic lightning parameterization scheme, a thundercloud model is set up based upon the work of Stolzenburg et al.(1998)revealing charge structure with four charge regions within convective updrafts in thunderstorms and a negative screening layer usually exists at the top of storms. Parameters that control the horizontal distribution of charge is introduced, and then 2-dimensional fine-resolution lighting discharge simulations are performed. Results show that horizontal distribution forms of charge in upper positive region play a key role in lightning discharge, and with forms of charge changes from dense unevenness into single uniform, lightning type changes from positive cloud-to-ground flashes to positive intra-cloud flashes, then into negative cloud-to-ground flashes, and finally into positive intra-cloud flashes in limited cases. When the distribution of charge levels in the main negative charge region tends to be uniform, the type of lightning changes from negative cloud-to-ground flashes to positive intra-cloud flashes, then to positive cloud-to-ground flashes and finally to positive intra-cloud flashes in limited cases. The horizontal distribution of space charge has a significant effect on the propagation of lightning leader. If it is dense uneven, the leader propagates in the center of the charge density, otherwise, the leader can extend more than 10 to 20 km in the horizontal direction. As the horizontal distribution of charge in the charge region tends to be uniform, potential lines between two charge regions are concentrated towards the charge density center, and the potential well extends horizontally, causing the different initial potential values of the lightning trigger points, which result in the generation of different types of lightning and far-spreading lighting leader in the horizontal direction.
引文
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[14]赵中阔,郄秀书,张廷龙,等.一次单体雷暴云的穿云电场探测及云内电荷结构.科学通报,2009,54(22):3532-3536.
[15]谭涌波,张冬冬,周博文,等.地闪近地面形态特征的数值模拟.应用气象学报,2015,26(2):211-220.
[16]Qie X,Zhang T,Chen C,et al.The lower positive charge center and its effect on lightning discharges on the Tibetan Plateau.Geophys Res Lett,2005,32(5):215-236.
[17]谭涌波,张鑫,向春燕,等.建筑物上侧击雷电的三维数值模拟.应用气象学报,2017,28(2):227-236.
[18]Nag A,Rakov V A.Some inferences on the role of lower positive charge region in facilitating different types of lightning.Geophys Res Lett,2009,36(5):126-127.
[19]武斌,张广庶,文军,等.闪电初始预击穿过程辐射脉冲特征及电流模型.应用气象学报,2017,28(5):555-567.
[20]郑栋,张义军,孟青,等.一次雹暴的闪电特征和电荷结构演变研究.气象学报,2010,68(2):248-263.
[21]谭涌波,梁忠武,师正,等.雷暴云底部正电荷区对闪电类型影响的数值模拟.中国科学(地球科学),2014(12):2743-2752.
[22]Mansell E R,Macgorman D R,Ziegler C L,et al.Charge structure and lightning sensitivity in a simulated multicell thunderstorm.Journal of Geophysical Research:Atmospheres,200,110(D12):1545-1555.
[23]Tessendorf S A,Rutledge S A,Wiens K C.Radar and lightning observations of normal and inverted polarity multicellular storms from STEPS.Mon Wea Rev,2007,135(11):3682-3706.
[24]Krehbiel P R,Riousset J A,Pasko V P,et al.Upward electrical discharges from thunderstorms.Nature Geoscience,2008,1(4):233-237.
[25]Shao X M,Krehbiel P R.The spatial and temporal development of intracloud lightning.Journal of Geophysical Research:Atmospheres,1996,101(D21):26641-26668.
[26]董万胜,刘欣生.利用闪电宽带干涉仪系统对地闪先导-回击过程的观测研究.中国科学(地球科学),2002,32(1):81-88.
[27]Pilkey J T,Uman M A,Hill J D,et al.Rocket-triggered lightning propagation paths relative to preceding natural lightning activity and inferred cloud charge.Journal of Geophysical Research:Atmospheres,2015,119(23):13427-13456.
[28]Riousset J A,Pasko V P,Krehbiel P R,et al.Three-dimensional fractal modeling of intracloud lightning discharge in a New Mexico thunderstorm and comparison with lightning mapping observations.Journal of Geophysical Research:Atmospheres,2007,112(D15):0996.
[29]谭涌波,梁忠武,师正,等.空间电荷分布特征对云闪传播行为的影响.高原气象,2015,34(5):1502-1510.
[30]Wang H,Guo F,Zhao T,et al.A numerical study of the positive cloud-to-ground flash from the forward flank of normal polarity thunderstorm.Atmos Res,2016,169(4):183-190.
[31]谭涌波,陶善昌,祝宝友,等.雷暴云内闪电双层、分枝结构的数值模拟.中国科学(地球科学),2006,36(5):486-496.
[32]Kasemir H W.A contribution to the electrostatic theory of a lightning discharge.J Geophys Res,1960,65(7):187 3-1878.
[33]Tao S,Tan Y,Zhu B,et al.Fine-resolution simulation of cloud-toground lightning and thundercloud charge transfer.Atmos Res,2009,91(2):360-370.
[34]Vonnegut B,Moore C B,Espinola R P,et al.Electric Potential Gradients above Thunderstorms.J Atmos Sci,1966,23(6):764-770.
[35]Marshall T C,David R W,Winn W P,et al.Electrical structure in two thunderstorm anvil clouds.J Geophys Res,1989,94(D2):2171-2181.
[36]Bell T F,Pasko V P,Inan U S.Runaway electrons as a source of red sprites in the mesosphere.Geophys Res Lett,1995,22(16):2127-2130.
[37]Marshall T C,Maribeth S.Estimates of cloud charge densities in thunderstorms.Journal of Geophysical Research:Atmospheres,1998,1031(D16):19769-19776.
[38]Tan Y,Tao S,Liang Z,et al.Numerical study on relationship between lightning types and distribution of space charge and electric potential.Journal of Geophysical Research:Atmospheres,2014,119(2):1003-1014.
[2]张义军,徐良韬,郑栋,等.强风暴中反极性电荷结构研究进展.应用气象学报,2014,25(5):513-526.
[3]张义军,孟青,吕伟涛,等.两次超级单体雷暴的电荷结构及其地闪特征.科学通报,2005,50(23):2663-2675.
[4]Tan Y,Tao S,Zhu B.Fine-resolution simulation of the channel structures and propagation features of intracloud lightning.Geophys Res Lett,2006,33(9):499-505.
[5]Tan Y,Tao S,Zhu B,et al.A simulation of the effects of intra-cloud lightning discharges on the charges and electrostatic potential distributions in a thundercloud.Chinese J Geophys Res,2007,50(4):916-930.
[6]任晓毓,张义军,吕伟涛,等.闪电先导随机模式的建立与应用.应用气象学报,2011,22(2):194-202.
[7]Akita M,Yoshida S,Nakamura Y,et al.Effects of charge distribution in thunderstorms on lightning propagation paths in Darwin,Australia.J Atmos Sci,2011,68(4):719-726.
[8]李俊,吕伟涛,张义军,等.一次多分叉多接地的空中触发闪电过程.应用气象学报,2010,21(1):95-100.
[9]刘恒毅,董万胜,徐良韬,等.闪电起始过程时空特征的宽带干涉仪三维观测.应用气象学报,2016,27(1):16-24.
[10]Stolzenburg M,Rust W D,Smull B F,et al.Electrical structure in thunderstorm convective regions:1.Mesoscale convective systems.Journal of Geophysical Research:Atmospheres,1998,103(D12):14097-14108.
[11]Coleman L M,Marshall T C.Effects of charge and electrostatic potential on lightning propagation.Journal of Geophysical Research:Atmospheres,2003,108(D9):1601-1612.
[12]Rust W D,Macgorman D R,Bruning E C.Inverted-polarity electrical structures in thunderstorms in the Severe Thunderstorm Electrification and Precipitation Study(STEPS).Atmos Res,2005,76(1):247-271.
[13]郑栋,张义军,孟青,等.北京地区雷暴过程闪电与地面降水的相关关系.应用气象学报,2010,21(3):287-297.
[14]赵中阔,郄秀书,张廷龙,等.一次单体雷暴云的穿云电场探测及云内电荷结构.科学通报,2009,54(22):3532-3536.
[15]谭涌波,张冬冬,周博文,等.地闪近地面形态特征的数值模拟.应用气象学报,2015,26(2):211-220.
[16]Qie X,Zhang T,Chen C,et al.The lower positive charge center and its effect on lightning discharges on the Tibetan Plateau.Geophys Res Lett,2005,32(5):215-236.
[17]谭涌波,张鑫,向春燕,等.建筑物上侧击雷电的三维数值模拟.应用气象学报,2017,28(2):227-236.
[18]Nag A,Rakov V A.Some inferences on the role of lower positive charge region in facilitating different types of lightning.Geophys Res Lett,2009,36(5):126-127.
[19]武斌,张广庶,文军,等.闪电初始预击穿过程辐射脉冲特征及电流模型.应用气象学报,2017,28(5):555-567.
[20]郑栋,张义军,孟青,等.一次雹暴的闪电特征和电荷结构演变研究.气象学报,2010,68(2):248-263.
[21]谭涌波,梁忠武,师正,等.雷暴云底部正电荷区对闪电类型影响的数值模拟.中国科学(地球科学),2014(12):2743-2752.
[22]Mansell E R,Macgorman D R,Ziegler C L,et al.Charge structure and lightning sensitivity in a simulated multicell thunderstorm.Journal of Geophysical Research:Atmospheres,200,110(D12):1545-1555.
[23]Tessendorf S A,Rutledge S A,Wiens K C.Radar and lightning observations of normal and inverted polarity multicellular storms from STEPS.Mon Wea Rev,2007,135(11):3682-3706.
[24]Krehbiel P R,Riousset J A,Pasko V P,et al.Upward electrical discharges from thunderstorms.Nature Geoscience,2008,1(4):233-237.
[25]Shao X M,Krehbiel P R.The spatial and temporal development of intracloud lightning.Journal of Geophysical Research:Atmospheres,1996,101(D21):26641-26668.
[26]董万胜,刘欣生.利用闪电宽带干涉仪系统对地闪先导-回击过程的观测研究.中国科学(地球科学),2002,32(1):81-88.
[27]Pilkey J T,Uman M A,Hill J D,et al.Rocket-triggered lightning propagation paths relative to preceding natural lightning activity and inferred cloud charge.Journal of Geophysical Research:Atmospheres,2015,119(23):13427-13456.
[28]Riousset J A,Pasko V P,Krehbiel P R,et al.Three-dimensional fractal modeling of intracloud lightning discharge in a New Mexico thunderstorm and comparison with lightning mapping observations.Journal of Geophysical Research:Atmospheres,2007,112(D15):0996.
[29]谭涌波,梁忠武,师正,等.空间电荷分布特征对云闪传播行为的影响.高原气象,2015,34(5):1502-1510.
[30]Wang H,Guo F,Zhao T,et al.A numerical study of the positive cloud-to-ground flash from the forward flank of normal polarity thunderstorm.Atmos Res,2016,169(4):183-190.
[31]谭涌波,陶善昌,祝宝友,等.雷暴云内闪电双层、分枝结构的数值模拟.中国科学(地球科学),2006,36(5):486-496.
[32]Kasemir H W.A contribution to the electrostatic theory of a lightning discharge.J Geophys Res,1960,65(7):187 3-1878.
[33]Tao S,Tan Y,Zhu B,et al.Fine-resolution simulation of cloud-toground lightning and thundercloud charge transfer.Atmos Res,2009,91(2):360-370.
[34]Vonnegut B,Moore C B,Espinola R P,et al.Electric Potential Gradients above Thunderstorms.J Atmos Sci,1966,23(6):764-770.
[35]Marshall T C,David R W,Winn W P,et al.Electrical structure in two thunderstorm anvil clouds.J Geophys Res,1989,94(D2):2171-2181.
[36]Bell T F,Pasko V P,Inan U S.Runaway electrons as a source of red sprites in the mesosphere.Geophys Res Lett,1995,22(16):2127-2130.
[37]Marshall T C,Maribeth S.Estimates of cloud charge densities in thunderstorms.Journal of Geophysical Research:Atmospheres,1998,1031(D16):19769-19776.
[38]Tan Y,Tao S,Liang Z,et al.Numerical study on relationship between lightning types and distribution of space charge and electric potential.Journal of Geophysical Research:Atmospheres,2014,119(2):1003-1014.