Variations in the precipitation extremes over the Guangdong-Hong Kong-Macao Greater Bay Area in China

By using the gridded 0.25° × 0.25° observation dataset of CN05.1 provided by the China Meteorological Administration, this study investigates the variations in nine extreme precipitation indices over the Guangdong-Hong Kong-Macao Greater Bay Area (GBA) in China from 1961 to 2018. Based on trends and interannual variations, the nine kinds of extreme precipitation are classified into four categories: category 1 includes very wet days (R95P), extremely wet days (R99P), the maximum 1-day precipitation amount (RX1day), and the maximum 5-day precipitation amount (RX5day). Category 2 is the number of heavy precipitation days (R10day), the number of very heavy precipitation days (R20day), and the simple daily intensity index (SDII). Categories 3 and 4 are consecutive wet days (CWDday) and consecutive dry days (CDDday), respectively. For the extreme precipitation in category 1, the abrupt change point from fewer to more values occurs in 1991 in summer. Three abrupt change points, from fewer to more in 1972 and 2009 and from more to fewer in 1994, occur in spring. For the extreme precipitation in category 2, the abrupt change point from fewer to more values occurs in 1993 in summer. Three abrupt change points, from fewer to more in 1965 and 2010 and from more to fewer in 1990, occur in spring. Annually and seasonally, abrupt changes occur in the early 2010s for CWDday which clearly increase and for CDDday which clearly decrease. In addition, CWDday exhibit abrupt change points from fewer to more in 1966 and from more to fewer in 1983 in spring. The variations in these extreme precipitation events have significant periodic oscillations of 3–5 years, quasi-8 years, or 8–14 years. During periods 1961–1994, 1995–2009, and 2010–2018, the changes in the annual and most seasonal R95P, R99P, R10day, R20day, and SDII are consistent with those of precipitation. The values in the latter period are increasing compared with those in the former stage. The changes in RX1day, RX5day, CWDday, and CDDday have their own characteristics.