ALBERT

Description: The changes in the occurrence and intensity of precipitation have been widely observed around the world. However, exploring the causes of changes in precipitation remains challenging. To better explore the causes of precipitation changes, the evaporation sources of such precipitation were identified. The region from which evaporative sources contribute to precipitation in a sink region is called the precipitationshed. Based on the ERA5 reanalysis data, we identified the seasonal precipitationshed in the Pearl River Delta (PRD), one of the most densely urbanized regions in the world, using the Water Accounting Model-2layers (WAM-2layers). The precipitationshed in the PRD has larger variation in summer and autumn, and differences in the responses of different types of precipitation to the change in the precipitationshed were identified. In autumn, results show that light precipitation increases when the evaporation contribution from the south is enhanced while heavy precipitation increases when the evaporation contribution from the northeast is enhanced in the PRD. The precipitationshed is influenced by natural climate variability. The identified differences in the response of different types of precipitation to the change in the precipitationshed further help us to better understand the influence of natural climate variability on precipitation. The influences of El Niño Southern Oscillation (ENSO), Indian Ocean Dipole (IOD), and North Atlantic Oscillation (NAO) on different types of seasonal precipitation were investigated. For example, results show that more heavy precipitation is expected in the PRD in summer when the positive phase of IOD and the negative phase of ENSO occur simultaneously.

Description: Low-frequency oscillation plays a vital role in interpreting sea-level change and its acceleration. This presentation designed a novel objective analyzing scheme based on non-uniform time series processing methods and analyzed low-frequency sea-level change signals (〉10yr) on a global scale from tide gauge records. According to the frequency distribution and the average amplitude spectrum, a significant oscillation of about 60 years is verified to exist at many tide gauges. The spatial distribution of the signal's amplitude and phase was drawn and found to be in moderate agreement with the newly proposed theoretical formula. Through analysis of a great number of long-term geophysical time series, we support the conclusion that this 60yr oscillation is more likely from the Earth's internal motion than the sun and spread into global climate systems by angular momentum exchange.