饱和修正系数提高ZZLAS型闪烁仪测量显热通量精度
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摘要
为了研究饱和效应对大孔径闪烁仪估算区域显热通量的影响,在2014年8—9月期间进行试验,以具有抗饱和性能的双光路BLS900型闪烁仪为参考,以孔径尺寸为0.075 m(文中简记为LAS1)、0.15 m(文中简记为LAS2)的中国产ZZLAS型闪烁仪为研究对象,通过光学传播原理计算出饱和修正系数,并对ZZLAS型闪烁仪的观测结果进行饱和修正分析。结果表明:LAS1的饱和修正系数为1.034,LAS2的饱和修正系数为1.019。试验观测中LAS1饱和率为24.58%,LAS2饱和率为2.04%,进行饱和修正后,LAS1的有效饱和修正率为12.87%。与BLS900相比,LAS1修正后显热通量均方根误差变为25.67 W/m2;LAS2的饱和修正率仅为0.32%,修正前后显热通量均方根误差基本无变化。进行饱和修正前,对BLS900与LAS1观测的显热通量进行F检验,未达到显著水平(P=0.15);通过计算得出的修正系数修正后,达到极显著水平(P=0.004);而利用BLS900的实时修正系数进行修正后,接近显著水平(P=0.06)。利用试验计算得出的饱和修正系数修正后,显热通量与参考标准的误差范围为1.28~53.42 W/m2,比修正前更接近BLS900的观测结果。研究对农田、人工林下垫面条件下的观测结果采用文中的饱和修正方法进行验证,结果也表明,经饱和修正后,闪烁仪观测的显热通量更接近BLS900的观测结果。当ZZLAS型闪烁仪发生明显饱和现象时,利用光学传播原理计算得出的修正系数对饱和数据进行修正效果显著。
For the purpose of investigating the influence of saturation effect on the estimation of regional sensible heat flux by using large aperture scintillometer(LAS), a field test was conducted from August to September, 2014. The dual-optical-path BLS900 scintillometer, which possesses saturation resistance, was set as a reference, and the ZZLAS type scintillometer with aperture size of 0.075 m(LAS1) and 0.15 m(LAS2) was selected as research object. In this field test, the LAS1 was set as easily as possible to be saturated. The saturation correction coefficients calculated based on the optical propagation theory, and the real-time saturation correction coefficient calculated by BLS900 were also displayed, and the air structure parameters, heat fluxes measured from scintillometer were corrected with the coefficients in this study. Variables from LAS1 and LAS2 and that from BLS900 were compared and analyzed with fitted line, as well as root mean square error before and after correction, and F-test was also used in the test of sensible heat flux. The saturation of scintillometer is often caused by the turbulence, and the scale of turbulence is thought to the main reason. Based on the optical propagation theory, inner scale of turbulence was also taken into consideration and the saturation correction coefficient of ZZLAS scintillometer was calculated. The results from the observation were corrected, and comparisons and analysis were also made. Here are the findings. Saturation correction coefficients of LAS1 and LAS2 are 1.034 and 1.019 respectively. The real-time correction coefficients given by BLS900 range from 0.70 to 1.15 depending on the developing of turbulence. The calculated coefficient of BLS900 during 10:00-12:30 shows smaller difference with the real-time coefficients, and it is thought to be more suitable for this period. During the observation, the saturation rate of the LAS1 is 24.58% and the effective saturation correction rate is 12.87%. After correction, root mean square error of air refraction index changes from 1.003×10-13 to 9.74×10-14 m-2/3, while there is no change occurring in R2. There is no obvious change of the air structure parameters between LAS2 and BLS900 due to that the saturation rate of LAS2 is much less than LAS1. Sensible heat fluxes from ZZLAS type scintillometer are compared to the results from BLS900, and the root mean square error of LAS1 is 25.67 W/m2. By contrast, the saturation rate of LAS2 is 2.04% and the saturation correction rate is only 0.32%, and there is no significant difference for LAS2 before and after correction. It indicates that, the more pronounced the saturation phenomenon, the more pronounced the effect of saturation correction; this is consistent with the opinion that there is no need to do corrections when the saturation data are less than 5%. Sensible heat fluxes measured from LAS1 exceed 50 W/m2, the corrected fluxes are more close to the reference, and the system error decreases. Sensible heat fluxes from BLS900 and LAS1 are analyzed with F-test and the P value obtained is 0.15, which means there is much difference between the 2 datasets. The P value becomes to 0.004 when the saturation data are corrected with the calculated coefficient, while the P value changes to 0.06 when saturation data are corrected with the real-time coefficients. After correcting the saturation correction coefficient obtained by experiment, the error range of sensible heat flux with reference standard is 1.28-53.42 W/m2, which is closer to the reference standard than that before correction. The results of the observation over the farmland and plantation are also verified by the saturation correction method in the paper. Results also showed that the sensible heat flux observed by the scintillometer after saturation correction is closer to that of the BLS900. When saturation data of the ZZLAS type scintillometer exceed 20%, there is significant improvement on sensible heat flux after the correction with the correction coefficient calculated by the optical propagation theory.
For the purpose of investigating the influence of saturation effect on the estimation of regional sensible heat flux by using large aperture scintillometer(LAS), a field test was conducted from August to September, 2014. The dual-optical-path BLS900 scintillometer, which possesses saturation resistance, was set as a reference, and the ZZLAS type scintillometer with aperture size of 0.075 m(LAS1) and 0.15 m(LAS2) was selected as research object. In this field test, the LAS1 was set as easily as possible to be saturated. The saturation correction coefficients calculated based on the optical propagation theory, and the real-time saturation correction coefficient calculated by BLS900 were also displayed, and the air structure parameters, heat fluxes measured from scintillometer were corrected with the coefficients in this study. Variables from LAS1 and LAS2 and that from BLS900 were compared and analyzed with fitted line, as well as root mean square error before and after correction, and F-test was also used in the test of sensible heat flux. The saturation of scintillometer is often caused by the turbulence, and the scale of turbulence is thought to the main reason. Based on the optical propagation theory, inner scale of turbulence was also taken into consideration and the saturation correction coefficient of ZZLAS scintillometer was calculated. The results from the observation were corrected, and comparisons and analysis were also made. Here are the findings. Saturation correction coefficients of LAS1 and LAS2 are 1.034 and 1.019 respectively. The real-time correction coefficients given by BLS900 range from 0.70 to 1.15 depending on the developing of turbulence. The calculated coefficient of BLS900 during 10:00-12:30 shows smaller difference with the real-time coefficients, and it is thought to be more suitable for this period. During the observation, the saturation rate of the LAS1 is 24.58% and the effective saturation correction rate is 12.87%. After correction, root mean square error of air refraction index changes from 1.003×10-13 to 9.74×10-14 m-2/3, while there is no change occurring in R2. There is no obvious change of the air structure parameters between LAS2 and BLS900 due to that the saturation rate of LAS2 is much less than LAS1. Sensible heat fluxes from ZZLAS type scintillometer are compared to the results from BLS900, and the root mean square error of LAS1 is 25.67 W/m2. By contrast, the saturation rate of LAS2 is 2.04% and the saturation correction rate is only 0.32%, and there is no significant difference for LAS2 before and after correction. It indicates that, the more pronounced the saturation phenomenon, the more pronounced the effect of saturation correction; this is consistent with the opinion that there is no need to do corrections when the saturation data are less than 5%. Sensible heat fluxes measured from LAS1 exceed 50 W/m2, the corrected fluxes are more close to the reference, and the system error decreases. Sensible heat fluxes from BLS900 and LAS1 are analyzed with F-test and the P value obtained is 0.15, which means there is much difference between the 2 datasets. The P value becomes to 0.004 when the saturation data are corrected with the calculated coefficient, while the P value changes to 0.06 when saturation data are corrected with the real-time coefficients. After correcting the saturation correction coefficient obtained by experiment, the error range of sensible heat flux with reference standard is 1.28-53.42 W/m2, which is closer to the reference standard than that before correction. The results of the observation over the farmland and plantation are also verified by the saturation correction method in the paper. Results also showed that the sensible heat flux observed by the scintillometer after saturation correction is closer to that of the BLS900. When saturation data of the ZZLAS type scintillometer exceed 20%, there is significant improvement on sensible heat flux after the correction with the correction coefficient calculated by the optical propagation theory.
引文
[1]束士杰,刘朝顺,施润和,等.基于集合卡尔曼滤波的地表水热通量同化研究[J].农业工程学报,2013,29(6):82-90.Shu Shijie,Liu Chaoshun,Shi Runhe,et al.Assimilation of surface water heat flux using Ensemble Kalman Filter[J].Transactions of the Chinese Society of Agricultural Engineering(Transactions of the CSAE),2013,29(6):82-90.(in Chinese with English abstract)
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[3]夏浩铭,李爱农,赵伟,等.遥感反演蒸散发时间尺度拓展方法研究进展[J].农业工程学报,2015,31(24):162-173.Xia Haoming,Li Ainong,Zhao Wei,et al.Review of temporal scale expansion for evapotranspiration retrieved by remote sensing data[J].Transactions of the Chinese Society of Agricultural Engineering(Transactions of the CSAE),2015,31(24):162-173.(in Chinese with English abstract)
[4]吴金胜,刘红利,张锦水.无人机遥感影像面向对象分类方法估算市域水稻面积[J].农业工程学报,2018,34(1):70-77.Wu Jinsheng,Liu Hongli,Zhang Jinshui.Paddy planting acreage estimation in city level based on UAV images and object-oriented classification method[J].Transactions of the Chinese Society of Agricultural Engineering(Transactions of the CSAE),2018,34(1):70-77.(in Chinese with English abstract)
[5]于兵,蒋磊,尚松浩.基于遥感蒸散发的河套灌区旱排作用分析[J].农业工程学报,2016,32(18):1-8.Yu Bing,Jiang Lei,Shang Songhao.Dry drainage effect of Hetao irrigation district based on remote sensing evapotranspiration[J].Transactions of the Chinese Society of Agricultural Engineering(Transactions of the CSAE),2016,32(18):1-8.(in Chinese with English abstract)
[6]曹雯,杨太明,陈金华,等.安徽省参考作物蒸散模型参数化[J].农业工程学报,2016,32(增刊2):60-68.Cao Wen,Yang Taiming,Chen Jinhua,et al.Parametrization of reference crop evapotranspiration model in Anhui Province[J].Transactions of the Chinese Society of Agricultural Engineering(Transactions of the CSAE),2016,32(Supp.2):60-68.(in Chinese with English abstract)
[7]刘春伟,曾勰婷,邱让建.用分时段修正双源模型估算南京地区冬小麦生育期蒸散量[J].农业工程学报,2016,32(增刊1):80-87.Liu Chunwei,Zeng Xieting,Qiu Rangjian.Simulated total evapotranspiration of winter wheat with modified Shuttle worth-Wallace model in different stages in Nanjing[J].Transactions of the Chinese Society of Agricultural Engineering(Transactions of the CSAE),2016,32(Supp.1):80-87.(in Chinese with English abstract)
[8]施生锦,黄彬香,刘绍民,等.大尺度水热通量观测系统的研制[J].地球科学进展,2010,25(11):1128-1138.Shi Shengjin,Huang Binxiang,Liu Shaomin,et al.Development of a measuring system for surface energy and water vapor fluxes at large scale[J].Advances in Earth Science,2010,25(11):1128-1138.(in Chinese with English abstract)
[9]李怀香,刘绍民,施生锦,等.国产光学型大孔径闪烁仪的技术性能分析[J].高原气象,2017,36(2):575-585.Li Huaixiang,Liu Shaomin,Shi Shengjin,et al.Assessing the performance of domestic optical larger aperture scintillometer under different environment conditions[J].Plateau Meteorology,2017,36(2):575-585.(in Chinese with English abstract)
[10]白洁,刘绍民,丁晓萍,等.大孔径闪烁仪观测数据的处理方法研究[J].地球科学进展,2010,25(11):1148-1167.Bai Jie,Liu Shaomin.Ding Xiaoping,et al.A study of the processing method of large aperture scintillometer observation data[J].Advances in Earth Science,2010,25(11):1148-1167.(in Chinese with English abstract)
[11]张功,张劲松,施生锦,等.ZZLAS型闪烁仪信号饱和界限的确定[J].中国农业气象,2017,38(7):426-434.Zhang Gong,Zhang Jinsong,Shi Shengjin,et al.Determination of saturation lines of ZZLAS-Type scintillometer[J].Chinese Journal of Agrometeorology,2017,38(7):426-434.(in Chinese with English abstract)
[12]Wang T,Ochs G,Clifford S.A saturation-resistant optical scintillometer to measure 2nC[J].Journal of the Optical Society of America,1978,68(3):334-338.
[13]饶瑞中,龚知本,王世鹏,等.激光大气闪烁饱和的孔径平均效应[J].光学学报,2001,22(1):36-40.Rao Ruizhong,Gong Zhiben,Wang Shipeng,et al.Aperture averaging of saturated scintillation of laser propagation[J].Acta Optica Sinica,2001,22(1):36-40.(in Chinese with English abstract)
[14]Clifford S F,Ochs G R,Lawrence R S.Saturation of optical scintillation by strong turbulence[J].Journal of the Optical Society of America,1974,64(2):148-154.
[15]Hill R J.Models of the scalar spectrum for turbulent advection[J].Fluid Mech,1978,88(3):541-562.
[16]Hill R J,Clifford S F.Theory of saturation of optical scintillation by strong turbulence for arbitrary refractiveindex spectra[J].Journal of the Optical Society of America,1978,71(6):675-686.
[17]Frehlich G R,Ochs R G.Effects of saturation on the optical scintillometer[J].Appl.Opt,1990,29(4):548-553.
[18]Hill R J,Frehlich R G.Onset of strong scintillation with application to remote sensing of turbulence inner scale[J].Applied Optics,1996,35(6):986-997.
[19]Kohsiek W,Meijninger W M L,Debruin,et al.Saturation of the large aperture scintllometer[J].Boundary-Layer Meteorology,2006,121(1):111-126
[20]Kleissl,Watts C.J.,Rodriguez J C,et al.Scintillometer inter-comparison study continued[J].Boundary-Layer Meteorology,2008,130(3):437-443.
[21]Beyrich,De Bruin,Meijninger,et al.Results from one year continuous operation of a large aperture scintillometer over a heterogeneous land surface[J].Boundary-Layer Meteorology,2002,105(1):85-97.
[22]Meijninger,Hartogensis O K,Kohsiek W,et al.Determination of area-averaged sensible heat fluxes with a large aperture scintillometer over a heterogeneous surfaceflevoland field experiment[J].Boundary-Layer Meteorology,2002,105(1):37-62.
[23]Kohsiek W,Meijninger W M L,Moene A F,et al.An extra-large aperture scintillometer for long range applications[J].Boundary-Layer Meteorology,2002,105(1):119-127.
[24]Kleissl,Hartogensis,Gomez.Test of scintillometer saturation correction methods using field experimental data[J].Boundary-Layer Meteorology,2010,137(2):493-507.
[25]黄印博,魏合理,梅海平,等.大气信道对红外激光通信系统性能影响的实验研究[J].光子学报,2009,38(3):646-651.Huang Yinbo,Wei Heli,Mei Haiping,et al.Effects of atmospheric channel on system performance of infrared laser communication system[J].Acta Photonica Sinica,2009,38(3):646-651.(in Chinese with English abstract)
[26]Moorhead J E,Marek G W,Colaizzi P D,et al.Evaluation of sensible heat flux and evapotranspiration estimates using a surface layer scintillometer and a large weighing lysimeter[J].Sensors,2017,17(10):2350.
[27]Beyrich F,Bange J,Hartogensis O K,et al.Towards a validation of scintillometer measurements:The LITFASS-2009 experiment[J].Boundary-Layer Meteorology,2012,144(1):83-112.
[28]Meijninger,Beyrich F,Lüdi,et al.Scintillometer-based turbulent fluxes of sensible and latent heat over a heterogeneous land surface-a contribution to LITFASS-2003[J].Boundary Layer Meteorology,2006,121(1):89-110.
[29]Hartogensis,De Bruin H A R,Van De,et al.Displaced-Beam small aperture scintillometer test partⅡ:Cases-99 stable boundary-layer experiment[J].Bound-Layer Meteorology,2002,105(3):149-176.
[30]De Bruin H.A.R.Introduction:Renaissance of scintillometry[J].Boundary-Layer Meteorology,2002,105(1):1-4.
[2]张宝忠,许迪,刘钰,等.多尺度蒸散发估测与时空尺度拓展方法研究进展[J].农业工程学报,2015,31(6):8-16.Zhang Baozhong,Xu Di,Liu Yu,et al.Review of multi-scale evapotranspiration estimation and spatio-temporal scale expansion[J].Transactions of the Chinese Society of Agricultural Engineering(Transactions of the CSAE),2015,31(6):8-16.(in Chinese with English abstract)
[3]夏浩铭,李爱农,赵伟,等.遥感反演蒸散发时间尺度拓展方法研究进展[J].农业工程学报,2015,31(24):162-173.Xia Haoming,Li Ainong,Zhao Wei,et al.Review of temporal scale expansion for evapotranspiration retrieved by remote sensing data[J].Transactions of the Chinese Society of Agricultural Engineering(Transactions of the CSAE),2015,31(24):162-173.(in Chinese with English abstract)
[4]吴金胜,刘红利,张锦水.无人机遥感影像面向对象分类方法估算市域水稻面积[J].农业工程学报,2018,34(1):70-77.Wu Jinsheng,Liu Hongli,Zhang Jinshui.Paddy planting acreage estimation in city level based on UAV images and object-oriented classification method[J].Transactions of the Chinese Society of Agricultural Engineering(Transactions of the CSAE),2018,34(1):70-77.(in Chinese with English abstract)
[5]于兵,蒋磊,尚松浩.基于遥感蒸散发的河套灌区旱排作用分析[J].农业工程学报,2016,32(18):1-8.Yu Bing,Jiang Lei,Shang Songhao.Dry drainage effect of Hetao irrigation district based on remote sensing evapotranspiration[J].Transactions of the Chinese Society of Agricultural Engineering(Transactions of the CSAE),2016,32(18):1-8.(in Chinese with English abstract)
[6]曹雯,杨太明,陈金华,等.安徽省参考作物蒸散模型参数化[J].农业工程学报,2016,32(增刊2):60-68.Cao Wen,Yang Taiming,Chen Jinhua,et al.Parametrization of reference crop evapotranspiration model in Anhui Province[J].Transactions of the Chinese Society of Agricultural Engineering(Transactions of the CSAE),2016,32(Supp.2):60-68.(in Chinese with English abstract)
[7]刘春伟,曾勰婷,邱让建.用分时段修正双源模型估算南京地区冬小麦生育期蒸散量[J].农业工程学报,2016,32(增刊1):80-87.Liu Chunwei,Zeng Xieting,Qiu Rangjian.Simulated total evapotranspiration of winter wheat with modified Shuttle worth-Wallace model in different stages in Nanjing[J].Transactions of the Chinese Society of Agricultural Engineering(Transactions of the CSAE),2016,32(Supp.1):80-87.(in Chinese with English abstract)
[8]施生锦,黄彬香,刘绍民,等.大尺度水热通量观测系统的研制[J].地球科学进展,2010,25(11):1128-1138.Shi Shengjin,Huang Binxiang,Liu Shaomin,et al.Development of a measuring system for surface energy and water vapor fluxes at large scale[J].Advances in Earth Science,2010,25(11):1128-1138.(in Chinese with English abstract)
[9]李怀香,刘绍民,施生锦,等.国产光学型大孔径闪烁仪的技术性能分析[J].高原气象,2017,36(2):575-585.Li Huaixiang,Liu Shaomin,Shi Shengjin,et al.Assessing the performance of domestic optical larger aperture scintillometer under different environment conditions[J].Plateau Meteorology,2017,36(2):575-585.(in Chinese with English abstract)
[10]白洁,刘绍民,丁晓萍,等.大孔径闪烁仪观测数据的处理方法研究[J].地球科学进展,2010,25(11):1148-1167.Bai Jie,Liu Shaomin.Ding Xiaoping,et al.A study of the processing method of large aperture scintillometer observation data[J].Advances in Earth Science,2010,25(11):1148-1167.(in Chinese with English abstract)
[11]张功,张劲松,施生锦,等.ZZLAS型闪烁仪信号饱和界限的确定[J].中国农业气象,2017,38(7):426-434.Zhang Gong,Zhang Jinsong,Shi Shengjin,et al.Determination of saturation lines of ZZLAS-Type scintillometer[J].Chinese Journal of Agrometeorology,2017,38(7):426-434.(in Chinese with English abstract)
[12]Wang T,Ochs G,Clifford S.A saturation-resistant optical scintillometer to measure 2nC[J].Journal of the Optical Society of America,1978,68(3):334-338.
[13]饶瑞中,龚知本,王世鹏,等.激光大气闪烁饱和的孔径平均效应[J].光学学报,2001,22(1):36-40.Rao Ruizhong,Gong Zhiben,Wang Shipeng,et al.Aperture averaging of saturated scintillation of laser propagation[J].Acta Optica Sinica,2001,22(1):36-40.(in Chinese with English abstract)
[14]Clifford S F,Ochs G R,Lawrence R S.Saturation of optical scintillation by strong turbulence[J].Journal of the Optical Society of America,1974,64(2):148-154.
[15]Hill R J.Models of the scalar spectrum for turbulent advection[J].Fluid Mech,1978,88(3):541-562.
[16]Hill R J,Clifford S F.Theory of saturation of optical scintillation by strong turbulence for arbitrary refractiveindex spectra[J].Journal of the Optical Society of America,1978,71(6):675-686.
[17]Frehlich G R,Ochs R G.Effects of saturation on the optical scintillometer[J].Appl.Opt,1990,29(4):548-553.
[18]Hill R J,Frehlich R G.Onset of strong scintillation with application to remote sensing of turbulence inner scale[J].Applied Optics,1996,35(6):986-997.
[19]Kohsiek W,Meijninger W M L,Debruin,et al.Saturation of the large aperture scintllometer[J].Boundary-Layer Meteorology,2006,121(1):111-126
[20]Kleissl,Watts C.J.,Rodriguez J C,et al.Scintillometer inter-comparison study continued[J].Boundary-Layer Meteorology,2008,130(3):437-443.
[21]Beyrich,De Bruin,Meijninger,et al.Results from one year continuous operation of a large aperture scintillometer over a heterogeneous land surface[J].Boundary-Layer Meteorology,2002,105(1):85-97.
[22]Meijninger,Hartogensis O K,Kohsiek W,et al.Determination of area-averaged sensible heat fluxes with a large aperture scintillometer over a heterogeneous surfaceflevoland field experiment[J].Boundary-Layer Meteorology,2002,105(1):37-62.
[23]Kohsiek W,Meijninger W M L,Moene A F,et al.An extra-large aperture scintillometer for long range applications[J].Boundary-Layer Meteorology,2002,105(1):119-127.
[24]Kleissl,Hartogensis,Gomez.Test of scintillometer saturation correction methods using field experimental data[J].Boundary-Layer Meteorology,2010,137(2):493-507.
[25]黄印博,魏合理,梅海平,等.大气信道对红外激光通信系统性能影响的实验研究[J].光子学报,2009,38(3):646-651.Huang Yinbo,Wei Heli,Mei Haiping,et al.Effects of atmospheric channel on system performance of infrared laser communication system[J].Acta Photonica Sinica,2009,38(3):646-651.(in Chinese with English abstract)
[26]Moorhead J E,Marek G W,Colaizzi P D,et al.Evaluation of sensible heat flux and evapotranspiration estimates using a surface layer scintillometer and a large weighing lysimeter[J].Sensors,2017,17(10):2350.
[27]Beyrich F,Bange J,Hartogensis O K,et al.Towards a validation of scintillometer measurements:The LITFASS-2009 experiment[J].Boundary-Layer Meteorology,2012,144(1):83-112.
[28]Meijninger,Beyrich F,Lüdi,et al.Scintillometer-based turbulent fluxes of sensible and latent heat over a heterogeneous land surface-a contribution to LITFASS-2003[J].Boundary Layer Meteorology,2006,121(1):89-110.
[29]Hartogensis,De Bruin H A R,Van De,et al.Displaced-Beam small aperture scintillometer test partⅡ:Cases-99 stable boundary-layer experiment[J].Bound-Layer Meteorology,2002,105(3):149-176.
[30]De Bruin H.A.R.Introduction:Renaissance of scintillometry[J].Boundary-Layer Meteorology,2002,105(1):1-4.