Bright Band Identification from CINRAD-SA/SB

Zhang Lejian; Cheng Minghu; Tao Lan

Vol.21, NO.2, 2010

Article Contents

Article Navigation > Journal of Applied Meteorological Science > 2010 > 21(2): 171-179

Zhang Lejian, Cheng Minghu, Tao Lan. Bright band identification from CINRAD-SA/SB. J Appl Meteor Sci, 2010, 21(2): 171-179.

Citation:

Zhang Lejian, Cheng Minghu, Tao Lan. Bright band identification from CINRAD-SA/SB. J Appl Meteor Sci, 2010, 21(2): 171-179.

Zhang Lejian, Cheng Minghu, Tao Lan. Bright band identification from CINRAD-SA/SB. J Appl Meteor Sci, 2010, 21(2): 171-179.

Citation:

Zhang Lejian, Cheng Minghu, Tao Lan. Bright band identification from CINRAD-SA/SB. J Appl Meteor Sci, 2010, 21(2): 171-179.

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Bright Band Identification from CINRAD-SA/SB

1.
Chinese Academy of Meteorological Sciences, Beijing 100081
2.
Nan jing University of Information Science & Technology, Nanjing 210044
3.
Meteorological Observation Center of CMA, Beijing 100081
4.
Shanghai Meteorological Center, Shanghai 200030

Received Date: 2009-04-15
Rev Recd Date: 2010-02-04
Publish Date: 2010-04-30

Abstract

Abstract

The bright band caused by aggregated snow melting has increased the uncertainties in radar based quantitative precipitation estimation. However, the height of the bright band can indicate the 0℃ isotherm and can be useful in identifying areas of potential icing for aviation and in the data assimilation for numerical weather predictions. Furthermore, the region of the bright band can also indicate the region of transition from convective to stratiform cloud which is useful for meso scale weather analysis. Based on extensive analysis, an automated method to identify bright band with CINRAD SA/SB Doppler radar based on vertical profile of reflectivity (VPR) and 3 dimension characteristics (horizontal, reflectivity gradient and vertical reflectivity lapse) of radar (3DVPR BBID) is developed. The 3DVPR BBID algorithm can determine from a volume scan mean VPR and a background freezing level height from soundings if a bright band exists. To evaluate the performance of the 3DVPR BBID, radar data from 22 June to 11 July 2003 and from 1 to 31 July 2007 in Hefei and from 1 to 30 June 2008 in Guangzhou are utilized, and a method which identifies bright band based only on VPR is also implemented for comparison. The results show that 3DVPR BBID can identify the existence of bright band exactly and give the height of 0℃ isotherm. The accuracy rate for VPR of bright band with 3DVPR BBID is higher than that with VPR BBID. The probabilities of identification between VPR BBID and 3DVPR BBID are 94.0% and 95.7% from 22 June to 11 July 2003 separately, 85.4% and 92.3% in July 2007, 81.0% and 89.8% in June 2008. The height of 0℃ isotherm derived from 3DVPR BBID and VPR BBID are close to the sounding observation. Furthermore, the performance of 3DVPR BBID is better than VPR BBID. In most cases, the evaluation of 3DVPR BBID is better than VPR BBID based on mean absolute error (MAE) of different distance from radar. Since the time interval of soundings is longer, the algorithm can give higher time resolution data of the 0℃ isotherm. When calculating the height of bright band with radar data, it's estimated that radar wave transmits with the standard atmosphere refraction. Another limitation is that VPR can only be used in certain parts of the radar detected regions. And there are some uncertainties with VPR in the distance far away from radar.
- Doppler weather radar;
- bright band;
- 3 dimension characteristics of radar echoes;
- vertical profile of reflectivity

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References(17)

Figures and Tables

图 1 反射率因子垂直廓线亮带概念模型

Fig. 1 The bright band model of vertical profile of reflectivity

DownLoad: Full-Size Img PowerPoint

图 2 合肥雷达站2007年7月8日07：03(北京时，下同)3km高度反射率因子图 (a)，降水类型分类图 (b) 及对流云降水VPR图 (c)

(CON表示对流云降水，BB表示包含零度层亮带的层状云降水，STR表示一般性层状云降水)

Fig. 2 The image of Heifei radar reflectivity at the height of 3 km at 07:03 8 July 2007 (a), the precipitation type field (b) and the VPR of convective precipitation (c)

(the CON, BB and STR represent the convective precipitation, bright band and stratiform precipitation)

DownLoad: Full-Size Img PowerPoint

图 3 广州雷达站2008年6月6日08：033km高度反射率因子图 (a) 及降水类型分类图 (b) 及包含零度层亮带的VPR图 (c)(其他说明同图 2)

Fig. 3 The image of Guangzhou radar reflectivity at the height of 3 km at 08:03 6 June 2008 (a), the precipitation type tield (b) and the VPR of bright band (c) (the others same as in Fig. 2)

DownLoad: Full-Size Img PowerPoint

图 4 广州雷达站2008年6月13日20：013km高度反射率因子图 (a)、降水类型分类图 (b)、对流云降水VPR图 (c) 及包含零度层亮带的VPR图 (d)(其他说明同图 2)

Fig. 4 The image of Guangzhou radar reflectivity at the height of 3 km at 20:01 13 June 2008 (a), the precipitation type field (b), the VPR of convective precipitation (c) and bright band (d)(the others same as in Fig. 2)

DownLoad: Full-Size Img PowerPoint

图 5 广州雷达站2008年6月25日11：543km高度反射率因子图 (a)、降水类型分类图 (b)、对流云降水VPR图 (c) 及包含零度层亮带的VPR图 (d)(其他说明同图 2)

Fig. 5 The image of Guangzhou radar reflectivity at the height of 3 km at 11: 54 25 June 2008 (a), the precipitation type field (b), the VPR of convective precipitation (c) and bright band (d)(the others same as in Fig. 2)

DownLoad: Full-Size Img PowerPoint

图 6 广州雷达站2008年6月25日11：54降水类型分类图 (a)、对流云降水VPR图 (b) 及包含零度层亮带的VPR图 (c)(其他说明同图 2)

Fig. 6 The image of the precipitation type field at the height of 3 km at 11; 54 25 June 2008 (a), the VPR of convective precipitation (b) and bright band (c) (the others same as in Fig. 2)

DownLoad: Full-Size Img PowerPoint

图 7 探空观测、VPR-BBID和3DVPR-BBID确定的零度层高度 (a)2003年6月22日—7月11日合肥雷达，(b)2007年7月合肥雷达，(c)2008年6月广州雷达

Fig. 7 The height of 0℃ isotherm derived from observation, VPR-BBID and 3DVPR-BBID (a) Heifti radar from 22 June to 11 July 2003, (b) Heifti radar from 1 to 31 July 2007, (c) Guangzhou radar from 1 to 30 June 2008

DownLoad: Full-Size Img PowerPoint

图 8 距离雷达站不同径向距离段内的平均绝对误差图 (a)2003年6月22日—7月11日合肥雷达，(b)2007年7月合肥雷达，(c)2008年6月广州雷达

Fig. 8 The mean absolute error of different distance from radar (a) Heiffi radar from 22 June to 11 July 2003, (b) Heiffi radar from 1 to 31 July 2007, (c) Guangzhou radar from 1 to 30 June 2008

DownLoad: Full-Size Img PowerPoint

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