Early Detection of Convective Echoes and Their Development Using Ka-band Radar Network

View More View Less
  • 1 Graduate School of Life and Environmental Sciences University of Tsukuba, Tsukuba, Japan
  • 2 National Research Institute for Earth Science and Disaster Resilience, Tsukuba, Japan
© Get Permissions
Restricted access

Abstract

Cumulonimbus clouds, which cause local heavy rainfall and urban floods, can develop within 20 minutes after being detected by operational centimeter-wavelength (X-, C-, or S-band) weather radars. To detect such clouds with greater lead times, Ka-band radars at a wavelength of 8.6 mm together with operational X-band radars were used in this study. The vertically averaged radar reflectivity (VAR) of convective echoes detected by the Ka-band and X-band radars were defined as mesoscale cloud echoes (MCEs) and mesoscale precipitation echoes (MPEs), respectively. The time series of each echo was analyzed by an echo tracking algorithm. On average, MCEs that developed into MPEs (denoted as developed MCEs) were detected 17 minutes earlier than the MPEs and 33 minutes earlier than the peak time of the area-averaged VAR (VARa) for MPEs. Some MCEs dissipated without developing into MPEs (denoted as non-developed MCEs). There were statistically significant differences between the developed and non-developed MCEs in terms of the maximum VARa values, maximum MCEs areas, and increase amounts of the VARa values and MCE areas for the first 6 to 12 minutes after their detection. Among these indicators, the maximum VARa for the first 9 minutes showed the most significant differences. Therefore, an algorithm for predicting MCE development using this indicator is discussed.

Corresponding author address: Syo Yoshida, Meteorological Engineering Center, Inc., 1-8-5 Kyomachibori, Nishi-ku, Osaka 550-0003, Japan. E-mail: s.yoshida@meci.jp

Abstract

Cumulonimbus clouds, which cause local heavy rainfall and urban floods, can develop within 20 minutes after being detected by operational centimeter-wavelength (X-, C-, or S-band) weather radars. To detect such clouds with greater lead times, Ka-band radars at a wavelength of 8.6 mm together with operational X-band radars were used in this study. The vertically averaged radar reflectivity (VAR) of convective echoes detected by the Ka-band and X-band radars were defined as mesoscale cloud echoes (MCEs) and mesoscale precipitation echoes (MPEs), respectively. The time series of each echo was analyzed by an echo tracking algorithm. On average, MCEs that developed into MPEs (denoted as developed MCEs) were detected 17 minutes earlier than the MPEs and 33 minutes earlier than the peak time of the area-averaged VAR (VARa) for MPEs. Some MCEs dissipated without developing into MPEs (denoted as non-developed MCEs). There were statistically significant differences between the developed and non-developed MCEs in terms of the maximum VARa values, maximum MCEs areas, and increase amounts of the VARa values and MCE areas for the first 6 to 12 minutes after their detection. Among these indicators, the maximum VARa for the first 9 minutes showed the most significant differences. Therefore, an algorithm for predicting MCE development using this indicator is discussed.

Corresponding author address: Syo Yoshida, Meteorological Engineering Center, Inc., 1-8-5 Kyomachibori, Nishi-ku, Osaka 550-0003, Japan. E-mail: s.yoshida@meci.jp
Save