TY - JOUR
T1 - Relating the radar bright band and its strength to surface rainfall rate using an automated approach
AU - Lin, Dongqi
AU - Pickering, Ben
AU - Neely, Ryan R.
N1 - Funding Information:
The authors would like to thank the staff of the NERC Facility for Atmospheric and Radar Research (NFARR) at the Chilbolton Observatory. Without their daily vigilance and support, this work would not have been possible. We especially thank Dr. Chris J. Walden for his guidance and comments on the use of the radar data.
Publisher Copyright:
© 2020 American Meteorological Society.
PY - 2020/2
Y1 - 2020/2
N2 - In radar observations of hydrometeors, the 0°C isotherm in the atmosphere (i.e., the freezing level) usually appears as a region of enhanced reflectivity. This region is known as the bright band (BB). In this study, observations over 12 months from a vertically pointing 35-GHz radar and a collocated disdrometer at the Natural Environment Research Council (NERC) Facility for Atmospheric and Radio Research (NFARR) are used to identify and compare microphysical differences between BB and non-brightband (NBB) periods. From these observations, the relationship between radar reflectivity Z and rainfall intensity R is found to be Z = 772R0.57 for BB periods and Z = 108R0.99 for NBB periods. Additionally, the brightband strength (BBS) was calculated using a novel method derived from the Michelson contrast equation in an attempt to explain the observed variability in BB precipitation. A series of Z–R relationships are computed with respect to BBS. The coefficients increase with increasing BBS from 227 to 926, while the exponents decrease with increasing BBS from 0.85 to 0.38. The results also indicate that NBB periods identified in the presence of a 0°C isotherm in other studies may be misclassified due to their inability to identify weak brightband periods. As such, it is hypothesized that NBB periods are solely due to warm rain processes.
AB - In radar observations of hydrometeors, the 0°C isotherm in the atmosphere (i.e., the freezing level) usually appears as a region of enhanced reflectivity. This region is known as the bright band (BB). In this study, observations over 12 months from a vertically pointing 35-GHz radar and a collocated disdrometer at the Natural Environment Research Council (NERC) Facility for Atmospheric and Radio Research (NFARR) are used to identify and compare microphysical differences between BB and non-brightband (NBB) periods. From these observations, the relationship between radar reflectivity Z and rainfall intensity R is found to be Z = 772R0.57 for BB periods and Z = 108R0.99 for NBB periods. Additionally, the brightband strength (BBS) was calculated using a novel method derived from the Michelson contrast equation in an attempt to explain the observed variability in BB precipitation. A series of Z–R relationships are computed with respect to BBS. The coefficients increase with increasing BBS from 227 to 926, while the exponents decrease with increasing BBS from 0.85 to 0.38. The results also indicate that NBB periods identified in the presence of a 0°C isotherm in other studies may be misclassified due to their inability to identify weak brightband periods. As such, it is hypothesized that NBB periods are solely due to warm rain processes.
UR - http://www.scopus.com/inward/record.url?scp=85082177934&partnerID=8YFLogxK
U2 - 10.1175/JHM-D-19-0085.1
DO - 10.1175/JHM-D-19-0085.1
M3 - Article
AN - SCOPUS:85082177934
SN - 1525-755X
VL - 21
SP - 335
EP - 353
JO - Journal of Hydrometeorology
JF - Journal of Hydrometeorology
IS - 2
ER -