부산대학교 도서관

Based on the precipitation data of 43 national meteorological stations in Fujian during 1980-2011, we revealed the spatial-temporal distribution of the Annual Maximum Precipitation with the Short Duration of 5 to 1440 Minutes in Fujian. We also explored the impacts of the solar radiation at daytime, cloud-radiation at nighttime, local position and topography on the distributions of diurnal and monthly variations of annual maximum precipitation occurrences. Using the NCEP/NCAR height and wind data, the synoptic situations for the annual maximum precipitation with the duration of 45 minutes in inland stations during 2000-2011 are reveled, the possible mechanisms of the unmatched phenomenon between monthly precipitation frequency and amount for the annual maximum precipitation with 5-60 minutes over inland stations are also researched. Possible causes related to the decadal changes of the precipitation intensity are discussed according to sampling synoptic chart and reference findings. The effects of different configurations of terrain and synoptic systems on the spatial distribution of annual maximum precipitation are also discussed. Finally, Synoptic backgrounds that may cause rainfall intensity record-broken are reviewed based on above analyses and reference researches. The main conclusions are shown as follows: 1. The annual maximum precipitation shows remarkable multi-time scale characteristics. (1) For diurnal distributions, the events with the duration less than 90min mainly occur at the period during 13:00 to 18:00 Beijing time, and the precipitation diurnal peak time delays from coastal areas to inland stations. The regional differences of the precipitation diurnal peak time are closely related to the diurnal variation of solar radiation at daytime; the diurnal peak time of precipitation frequency lags behind 1.5-2 hours to that of temperature. Even in the same reign, the diurnal variation of the annual maximum precipitation varies with seasons. The diurnal peak time over the coastal and inland stations (middle stations) in summer is 30min-1h earlier (30min later) than in Meiyu season. Due to favorable thermal condition at summer afternoon, the occurrence frequency of the annual maximum precipitation during afternoon to evening in summer is more than in Meiyu season for all regions, meanwhile, the occurrence frequency of the annual maximum precipitation during midnight to morning (0:00-8:00 Beijing time) in the stations over central Fujian and inland areas in Meiyu season is more than that in summer for the favorable conditions as cloud radiation and weak cold flow in the Meiyu season. However, the coastal stations show opposite features due to more typhoon cases and coastal rainstorms at summer night reinforced by the land-breeze convergence line. (2)For monthly distributions, the events are concentrated from May to September. At coastal stations, the precipitation occurrence frequency with the duration of 5-1440min shows double peak pattern with a primary peak in August and a secondary peak in June. At inland stations, the monthly occurrence frequency of the precipitation with the duration of less than 60min (more than 60min) shows double peak pattern with one in June and the other in August, (single peak with peak in June). At middle stations, the precipitation occurrence frequency with the duration less than 180min (more than 180min) shows single peak in August (double peaks with one in June and the other in August). Huanan quasi- stationary front being active in June and subtropical system being active in August lead to the double peak pattern over the coastal stations. The characteristic of Huanan quasi- stationary front also results in the precipitation frequency peak in June over the inland stations. Another peak in August of the precipitation with the durations of 5-60min over the inland stations is mainly due to the high precipitation efficiency caused by mixed cumulus, cold cumulus, and thick warm clouds. In the coastal stations, the precipitation frequency in September is comparable to that in June and is more than that in May obviously. However, in the inland stations, the precipitation frequency in May is more than that in Jul-Sep. (3) For the decadal distributions, the decadal variation of the annual maximum precipitation in Fujian may be divided into four patterns as Strengthen-pattern, Weaken-pattern, Stabilized-pattern, and Polarized-pattern. The annual maximum rainfall with the duration more than 45min over most stations located at south to Mingjiang and east to mountain belt of central Fujian Province, or near the tributaries of upper Reaches of Mingjiang shows Strengthen-pattern. The station proportions of other patterns (Weaken-pattern and Stabilized-pattern and Polarized pattern) are less and mainly located in inland and middle areas of Fujian and seldom located in coastal regions. The climatic background of the decadal strengthening may be related to the decadal variations of the Australia anticyclone, Mascarene anticyclone and the vertical structure of Somalia cross-equatorial flow. 2. The spatial distributions of the annual maximum rainfall intensity are distinct.(1) Mean value of the annual maximum precipitation with the duration of 10-1440min shows the pattern of high in east and low in west with high (low) values mainly located at coastal areas (regions west to mountain belt of central Fujian Province). In addition, for the stations located in the regions east to mountain-belt of central Fujian Province, stations close to coastline show higher values than the stations far from the coastline. However, for precipitation with the duration of 5min, higher values are mainly located at regions north to Mingjiang River.(2) For spatial distribution of extreme maximum values, higher values for the precipitation with the duration of 5-min are mainly located at the regions north to Mingjiang River, which is similar to that of mean values; higher values for the precipitation with the duration of 30-240min are located at regions east to mountain belt of central Fujian Province and regions south to the upper reaches of Mingjiang, however, lower values are located at Northwest Fujian; the distribution of the precipitation with the duration of 360- 1440min shows a pattern of ‘quasi south-north’ with higher values in east and west regions than that in the middle region and the highest values are mainly located at bell mouthed terrain with entrance toward south or southeast.(3)Factors affecting the spatial distributions of annual maximum rainfall intensity include weather system, topography, and configuration of terrain and synoptic system. Mountain belt of central Fujian Province is the main factor of topography. For the regions east to Mountain belt of central Fujian Province, new historical record might be caused by typhoon circulation together with multiple factors as dry line at 500-700hPa levels, weak cold flow in boundary layer, and sea-land breeze convergence line, thus, the synoptic background as above should be focused on. However, for the regions west to the Mountain belt of central Fujian Province, new historical record might be caused by quasi- stationary front together with low pressure disturbance at the leeward slope, which is formed by southwest warm wet flow of levels from surface to boundary layer being blocked by Wuyi Mountain, thus the synoptic background should also be focused on.