关键词: 年降水量, 趋势, Mann-Kendall检验, 小波分析, 周期, 突变

Abstract: Based on the annual precipitation data of Tianjin urban area from 1890 to 2022 for 133 years, P-Ⅲ frequency analysis, linear trend, 5-year moving average, cumulative anomaly, Mann-Kendall test, and wavelet analysis were used to analyze the statistical characteristics, evolutionary trends variation rule and mutation of precipitation. Results showed that:（1）Annual precipitation in Tianjin urban area was mainly lower than the annual average 545.8 mm, but some precipitation data was far greater than the average value; the overall trend was increasing, but not significant; the extreme value ratio was 4.82, with uneven interannual distribution.（2）Results of 5-year moving average method showed 7 periods of decrease and 4 periods of increase for precipitation. Results of cumulative anomaly method showed 11 periods with excessive annual precipitation, totaling 41 years; 7 periods with insufficient precipitation, totaling 44 years. From 2019 to 2022, the cumulative anomaly of precipitation was on the rise, with excessive precipitation.（3）According to the M-K mutation test, 5 periods with a total of 68 years of precipitation showed a downward trend; since 1953, the overall trend was on the rise. 7 mutation points were obtained, and validated by the cumulative anomaly method. After removing pseudo points, the retained mutation points were 1948, 1979, 1984, and 2019.（4）According to wavelet analysis, there were four time-scales of periodic variation patterns for precipitation, including 5-6a, 12-13a, 32-34a, and 48-52a, and the most significant was 48-52a scale, with 51a as the first main period. It is speculated that in the following about 8 years after 2018, precipitation will still be relatively high. This achievement has reference value for the prevention of drought and flood disasters in Tianjin.

Key words: annual precipitation, trend, Mann-Kendall test, wavelet analysis, period, mutation