Operational usage-oriented evaluation of millimeter radar’s observations in Shanghai

1.Shanghai Ecological Forecasting and Remote Sensing Center;2.Baoshan Meteorological Service;3.Meteorological Observation Center of CMA,China Meteorological Administration;4.Shanghai Meteorological Information and Technology Support Centre;5.Shanghai by Weather Technology Co., Ltd.

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Fund Project:

National Key R&D Program of China(2017YFC1501902,2017YFC1501701),The National Natural Science Foundation of China(41905007);Shanghai Sailing Program(20YF1443400)

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    The observational stability, observational ability, and rationality of both base data and products of millimeter cloud radar (MCR for short) installed at Shanghai Meteorological Service during “The study and experiment of vertical integrated meteorological observation technology in mega-cities” (MCME for short) have been evaluated using observations from ground-based Lidar distrometer, micro-rain radar, radiosonde, FY-4A’s products as well as surface rain gage. The results show that: the observational stability of MCR is considerably high that only one-time software failure happened during the MCME and the data acquisition rate is larger than 95%. The minimal detectable reflectivity of MCR is generally distributed within -40 to -20 dBZ and has an exponential distribution in the vertical direction which fits well with the theory. The minimal detectable reflectivity of MCR changes little (smaller than 2 dB for heights lower than 9 km) during the MCME. A false “No Cloud” region will be seen in the MCR’s observation when the rain rate is larger than 4-5 mm/h. Although the raw data of the two MCRs have certain differences, the pattern of reflectivity in the time-height cross-section is highly reasonable indicated by the comparisons between the reflectivity from MCR’s observation, the reflectivity calculated with Lidar distrometer’s observation, and the reflectivity from micro-rain radar’s observation. The cloud top height and cloud base height retrieved by MCR are also evaluated by the cloud top/base height calculated by radiosonde and cloud top height retrieved by FY-4A satellite, and the results show certainly a degree of consistency among the three observations. The inconsistency of reflectivity due to the merge of multiple pulses with different pulse widths used in MCR’s base data processing and the false “clear sky area” due to the strong attenuation are two obvious issues that may have significant impacts on the operational usage of MCR. The advice on how to improve the current MCR from the perspective of the demand for the development of the Shanghai Meteorological Service has been given at the end of the paper.

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  • Received:June 23,2022
  • Revised:August 09,2022
  • Adopted:August 27,2022
  • Online: September 01,2022
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