利用微雨雷达研究一次冷锋云系降水的垂直结构分布及演变特征
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摘要
本文利用河北邢台测站Ka波段微雨雷达(MRR)观测到的一次冷锋云系降水过程分析降水的垂直分布及演变特征。将MRR观测结果与天气雷达、地面雨滴谱仪、雨量计观测结果进行对比以检验MRR数据的可靠性。同时将MRR与雨滴谱仪和激光云高仪结合,研究了不同相对湿度阶段特征量、雨滴谱的平均垂直分布特征和降水特征量随时间、高度的演变特征。结果表明:MRR与雨量计及雨滴谱仪累计雨量结果较为接近,趋势一致。MRR 200 m雨强值与地面雨滴谱仪雨强值偏差最小,平均偏差为0.05 mm h-1,相关系数为0.93。相比雨滴谱仪,MRR观测到的小滴数浓度出现高估,大滴数浓度出现低估,中滴数浓度较为一致。降水在云内和云外受不同微物理过程影响,垂直变化特征不同。降水初期平均反射率和雨强在云底以下明显减小,小滴和中滴平均数浓度明显减小,蒸发作用影响较强。而在其余时间段在云内随高度降低平均反射率和雨强略有增加,小滴平均数浓度变化较小,中滴大滴平均数浓度增加,表明云内有云滴与雨滴间的碰并发生。而在云外低层,随高度降低平均有效直径明显增加,平均雨滴总数浓度明显减小,小滴平均数浓度显著减小,大滴平均数浓度显著增加,表明在云外低层雨滴间的碰并作用较强。
Using the micro rain radar(MRR) observations in Xingtai, Hebei Province, the vertical structure and evolution of precipitation associated with clouds along a cold front are explored. The accuracy of MRR observations has been examined by comparing with observations of the weather radar, raindrop disdrometer, and rain gauge. Combining the MRR with the disdrometer and the laser ceilometer, factors in different relative humidity ranges and average vertical distribution of the raindrop size as well as the evolution of precipitation characters with the altitude and time have been investigated. The results show that the observed cumulative rainfall and its trend are similar among different data. The difference between the rainfall intensity observed by the MRR 200 m and that observed by the disdrometer is the minimum with an average value of about 0.05 mm h-1 and the correlation coefficient is 0.93. Compared with the disdrometer, the MRR overestimated the small drop concentration and underestimated the large drop concentration.However, the medium drop concentration is consistent between observations of the MRR and the disdrometer.Precipitation is greatly affected by evaporation under low-humidity condition and affected by different microphysical processes inside and outside the clouds. The vertical variations are different. During the initial stage of precipitation, the average reflectivity(Z) and rainfall intensity(R) obviously decreased below the cloud base and the average concentration of small and medium drops decreased rapidly under the influence of evaporation. At other time, the average Z and R slightly increased and the concentration of small drops changed little. The concentration of big and medium drops increased, which indicates that coalescence processes have happened between raindrops and cloud droplets withinthe cloud. The average effective diameter increased obviously and the average total concentration of raindrops decreased with decreasing height in lower levels outside the cloud. Besides, the decreasing of small drops and increasing of big drops indicate that the coalescence processes in low levels outside the cloud are stronger.
Using the micro rain radar(MRR) observations in Xingtai, Hebei Province, the vertical structure and evolution of precipitation associated with clouds along a cold front are explored. The accuracy of MRR observations has been examined by comparing with observations of the weather radar, raindrop disdrometer, and rain gauge. Combining the MRR with the disdrometer and the laser ceilometer, factors in different relative humidity ranges and average vertical distribution of the raindrop size as well as the evolution of precipitation characters with the altitude and time have been investigated. The results show that the observed cumulative rainfall and its trend are similar among different data. The difference between the rainfall intensity observed by the MRR 200 m and that observed by the disdrometer is the minimum with an average value of about 0.05 mm h-1 and the correlation coefficient is 0.93. Compared with the disdrometer, the MRR overestimated the small drop concentration and underestimated the large drop concentration.However, the medium drop concentration is consistent between observations of the MRR and the disdrometer.Precipitation is greatly affected by evaporation under low-humidity condition and affected by different microphysical processes inside and outside the clouds. The vertical variations are different. During the initial stage of precipitation, the average reflectivity(Z) and rainfall intensity(R) obviously decreased below the cloud base and the average concentration of small and medium drops decreased rapidly under the influence of evaporation. At other time, the average Z and R slightly increased and the concentration of small drops changed little. The concentration of big and medium drops increased, which indicates that coalescence processes have happened between raindrops and cloud droplets withinthe cloud. The average effective diameter increased obviously and the average total concentration of raindrops decreased with decreasing height in lower levels outside the cloud. Besides, the decreasing of small drops and increasing of big drops indicate that the coalescence processes in low levels outside the cloud are stronger.
引文
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Das S,Maitra A.2016.Vertical profile of rain:Ka band radar observations at tropical locations[J].J.Hydrol.,534:31-41.doi:10.1016/j.jhydrol.2015.12.053
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Kirankumar N V P,Kunhikrishnan P K.2013.Evaluation of performance of Micro Rain Radar over the tropical coastal station Thumba(8.5°N,76.9°E)[J].Atmos.Res.,134:56-63.doi:10.1016/j.atmosres.2013.07.018
Konwar M,Das S K,Deshpande S M,et al.2014.Microphysics of clouds and rain over the Western Ghat[J].J.Geophys.Res.,119(10):6140-6159.doi:10.1002/2014JD021606
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Sarkar T,Das S,Maitra A.2015.Assessment of different raindrop size measuring techniques:Inter-comparison of Doppler radar,impact and optical disdrometer[J].Atmos.Res.,160:15-27.doi:10.1016/j.atmosres.2015.03.001
Testud J,Oury S,Black R A,et al.2001.The concept of“normalized”distribution to describe raindrop spectra:A tool for cloud physics and cloud remote sensing[J].J.Appl.Meteor.,40(6):1118-1140.doi:10.1175/1520-0450(2001)040<1118:TCONDT>2.0.CO;2
Tokay A,Short D A.1996.Evidence from tropical raindrop spectra of the origin of rain from stratiform versus convective clouds[J].J.Atmos.Meteor.,35(3):355-371.doi:10.1175/1520-0450(1996)035<0355:EFTRSO>2.0.CO;2
Tokay A,Hartmann P,Battaglia A,et al.2009.A field study of reflectivity and Z-R relations using vertically pointing radars and disdrometers[J].J.Atmos.Oceanic Technol.,26(6):1120-1134.doi:10.1175/2008JTECHA1163.1
Ulbrich C W.1983.Natural variations in the analytical form of the raindrop size distribution[J].J.Climate Appl.Meteor.,22(10):1764-1775.doi:10.1175/1520-0450(1983)022<1764:NVITAF>2.0.CO;2
Wang H,Lei H C,Yang J F.2017.Microphysical processes of a stratiform precipitation event over eastern China:Analysis using micro rain radar data[J].Adv.Atmos.Sci.,34(12):1472-1482.doi:10.1007/s00376-017-7005-6
Wen G,Xiao H,Yang H L,et al.2017.Characteristics of summer and winter precipitation over northern China[J].Atmos.Res.,197:390-406.doi:10.1016/j.atmosres.2017.07.023
温龙,刘溯,赵坤,等.2015.两次降水过程的微降雨雷达探测精度分析[J].气象,41(5):577-587.Wen Long,Liu Su,Zhao Kunet al.2015.Precision evaluation of micro rain radar observation in two precipitation events[J].Meteorological Monthly(in Chinese),41(5):577-587.doi:10.7519/j.issn.1000-0526.2015.05.006
Zhang G,Vivekanandan J,Brandes E.2001.A method for estimating rain rate and drop size distribution from polarimetric radar measurements[J].IEEE Trans.Geosci.Remote Sens.,39(4):830-841.doi:10.1109/36.917906
Yuter S E,Houze Jr R A.Three-dimensional kinematic and microphysical evolution of Florida cumulonimbus.Part II:Frequency distributions of vertical velocity,reflectivity,and differential reflectivity[J].Mon.Wea.Rev,1995,123(7):1941-1963.doi:10.1175/1520-0493(1995)1232.0.CO;2
周黎明,王庆,龚佃利,等.2015.山东一次暴雨过程的云降水微物理特征分析[J].气象,41(2):192-199.Zhou Liming,Wang Qing,Gong Dianliet al.2015.Microphysical properties of cloud and precipitation during a rainstorm process in Shandong Province[J].Meteorological Monthly(in Chinese),41(2):192-199.doi:10.7519/j.issn.1000-0526.2015.02.007
Chen B J,Hu W,Pu J P.2011.Characteristics of the raindrop size distribution for freezing precipitation observed in southern China[J].J.Geophys.Res.,116(D6):D06201.doi:10.1029/2010JD015305
陈聪,银燕,陈宝君.2015.黄山不同高度雨滴谱的演变特征[J].大气科学学报,38(3):388-395.Chen Cong,Yin Yan,Chen Baojun.2015.Raindrop size distribution at different altitudes in Mt.Huang[J].Transactions of Atmospheric Sciences(in Chinese),38(3):388-395.doi:10.13878/j.cnki.dqkxxb.20130223001
陈勇,刘辉志,安俊岭,等.2010.垂直指向测雨雷达的误差模拟及相互校准[J].大气科学,34(6):1114-1126.Chen Yong,Liu Huizhi,An Junlinget al.2010.Error analysis and intercalibrations of vertically pointing radars on the rainfall measurement[J].Chinese Journal of Atmospheric Sciences(in Chinese),34(6):1114-1126.doi:10.3878/j.issn.1006-9895.2010.06.07
Das S,Maitra A.2016.Vertical profile of rain:Ka band radar observations at tropical locations[J].J.Hydrol.,534:31-41.doi:10.1016/j.jhydrol.2015.12.053
Gunn R,Kinzer G D.1949.The terminal velocity of fall for water droplets in stagnant air[J].J Meteor.,6(4):243-248.doi:10.1175/1520-0469(1949)006<0243:TTVOFF>2.0.CO;2
Harikumar R,Sampath S,Kumar V S.2009.An empirical model for the variation of rain drop size distribution with rain rate at a few locations in southern India[J].Adv.Space Res..,43(5):837-844.doi:10.1016/j.asr.2008.11.001
Harikumar R,Sampath S,Sasi Kumar V.2012.Altitudinal and temporal evolution of raindrop size distribution observed over a tropical station using a K-band radar[J].Int.J.Remote Sens.,33(10):3286-3300.doi:10.1080/01431161.2010.549853
Hitschfeld W,Bordan J.1954.Errors inherent in the radar measurement of rainfall at attenuating wavelengths[J].J.Meteor,11(1):58-67.doi:10.1175/1520-0469(1954)011<0058:EIITRM>2.0.CO;2
胡子浩,濮江平,濮云涛,等.2014.南海一次海洋性对流云降水雨滴谱特征分析[J].热带气象学报,30(1):181-188.Hu Zihao,Pu Jiangping,Pu Yuntao,et al.2014.Analysis on raindrop size distribution characteristics of maritime convective cloud rain in South China Sea[J].Journal of Tropical Meteorology(in Chinese),30(1):181-188.doi:10.3969/j.issn.1004-4965.2014.01.021
Kirankumar N V P,Kunhikrishnan P K.2013.Evaluation of performance of Micro Rain Radar over the tropical coastal station Thumba(8.5°N,76.9°E)[J].Atmos.Res.,134:56-63.doi:10.1016/j.atmosres.2013.07.018
Konwar M,Das S K,Deshpande S M,et al.2014.Microphysics of clouds and rain over the Western Ghat[J].J.Geophys.Res.,119(10):6140-6159.doi:10.1002/2014JD021606
Low T B,List R.1982.Collision,coalescence and breakup of raindrops.Part II:Parameterization of fragment size distributions[J].J.Atmos.Sci.,39(7):1607-1619.doi:10.1175/1520-0469(1982)039<1607:CCABOR>2.0.CO;2
Minder J R,Letcher T W,Campbell L S,et al.2015.The evolution of lake-effect convection during landfall and orographic uplift as observed by profiling radars[J].Mon.Wea.Rev.,143(11):4422-4442.doi:10.1175/MWR-D-15-0117.1
Peters G,Fischer B,Andersson T.2002.Rain observations with a vertically looking Micro Rain Radar(MRR)[J].Boreal Environ.Res.,7:353-362
Peters G,Fischer B,Andersson T.Rain observations with a vertically looking Micro Rain Radar(MRR)[J].Boreal environment research,2002,7(4):353-362
Peters G,Fischer B,Münster H,et al.2005.Profiles of raindrop size distributions as retrieved by micro rain radars[J].J.Appl.Meteor.,44(12):1930-1949.doi:10.1175/JAM2316.1
Sarkar T,Das S,Maitra A.2015.Assessment of different raindrop size measuring techniques:Inter-comparison of Doppler radar,impact and optical disdrometer[J].Atmos.Res.,160:15-27.doi:10.1016/j.atmosres.2015.03.001
Testud J,Oury S,Black R A,et al.2001.The concept of“normalized”distribution to describe raindrop spectra:A tool for cloud physics and cloud remote sensing[J].J.Appl.Meteor.,40(6):1118-1140.doi:10.1175/1520-0450(2001)040<1118:TCONDT>2.0.CO;2
Tokay A,Short D A.1996.Evidence from tropical raindrop spectra of the origin of rain from stratiform versus convective clouds[J].J.Atmos.Meteor.,35(3):355-371.doi:10.1175/1520-0450(1996)035<0355:EFTRSO>2.0.CO;2
Tokay A,Hartmann P,Battaglia A,et al.2009.A field study of reflectivity and Z-R relations using vertically pointing radars and disdrometers[J].J.Atmos.Oceanic Technol.,26(6):1120-1134.doi:10.1175/2008JTECHA1163.1
Ulbrich C W.1983.Natural variations in the analytical form of the raindrop size distribution[J].J.Climate Appl.Meteor.,22(10):1764-1775.doi:10.1175/1520-0450(1983)022<1764:NVITAF>2.0.CO;2
Wang H,Lei H C,Yang J F.2017.Microphysical processes of a stratiform precipitation event over eastern China:Analysis using micro rain radar data[J].Adv.Atmos.Sci.,34(12):1472-1482.doi:10.1007/s00376-017-7005-6
Wen G,Xiao H,Yang H L,et al.2017.Characteristics of summer and winter precipitation over northern China[J].Atmos.Res.,197:390-406.doi:10.1016/j.atmosres.2017.07.023
温龙,刘溯,赵坤,等.2015.两次降水过程的微降雨雷达探测精度分析[J].气象,41(5):577-587.Wen Long,Liu Su,Zhao Kunet al.2015.Precision evaluation of micro rain radar observation in two precipitation events[J].Meteorological Monthly(in Chinese),41(5):577-587.doi:10.7519/j.issn.1000-0526.2015.05.006
Zhang G,Vivekanandan J,Brandes E.2001.A method for estimating rain rate and drop size distribution from polarimetric radar measurements[J].IEEE Trans.Geosci.Remote Sens.,39(4):830-841.doi:10.1109/36.917906
Yuter S E,Houze Jr R A.Three-dimensional kinematic and microphysical evolution of Florida cumulonimbus.Part II:Frequency distributions of vertical velocity,reflectivity,and differential reflectivity[J].Mon.Wea.Rev,1995,123(7):1941-1963.doi:10.1175/1520-0493(1995)1232.0.CO;2
周黎明,王庆,龚佃利,等.2015.山东一次暴雨过程的云降水微物理特征分析[J].气象,41(2):192-199.Zhou Liming,Wang Qing,Gong Dianliet al.2015.Microphysical properties of cloud and precipitation during a rainstorm process in Shandong Province[J].Meteorological Monthly(in Chinese),41(2):192-199.doi:10.7519/j.issn.1000-0526.2015.02.007