DefinePK

Abstract

Hainan Island, as the biggest island in the tropical region of China, the daily extremes of temperature and precipitation may cause serious regional and global consequences, but observation-based research in Hainan is scarce. In this paper, recent annual changes of daily temperature and precipitation extremes at 7 meteorological observing stations in Hainan Island from 1975 to 2012 were studied. Twelve extreme temperature and 11 extreme precipitation indices are selected referring to the CCI/CLIVAR/JCOMM Expert Team on Climate Change Detection and Indices. The results indicated that changes indeed occur in daily temperature and precipitation extremes in Hainan Island, but the changes are not uniform at different locations in the region. Over Hainan Island, coldest night (TNn), coldest day (TXn), cool days (TX10p), warmest night (TNx), warmest day (TXx), warm nights (TN90p), warm days (TX90p), warm spell duration indicator (WSDI) showed warming trends, whereas cool nights (TN10p), cold spell duration indicator (CSDI) and diurnal temperature range (DTR) showed cooling trends between 1975 and 2012. Additionally, the magnitude of trends for indices of TN10p, TN90p, TX90p, WSDI are more pronounced than those of TXx, TNn, TXn, TX10p, CSDI, TNx and DTR. All the regional annual series for the indices in precipitation over Hainan Island have an upward tendency during 1975-2012. Annual total wet-day precipitation, maximum 1-day and 5-day precipitation, very wet and extremely wet day precipitation, annual count of days when Pt≥10mm, Pt≥25mm and Pt≥50mm in the study area generally showed growing patterns. It is noteworthy that the shifts of the probability distribution function (PDF) curves of TN90p, TX90P, TNx, TXx and TX10P are less evident in 2005-2012 during the past four decades. While the shift of the PDF curves of precipitation extremes are more evident than those of temperature. The PDF curves of P10mm, P25mm, P95 and P99 were the most evident in 1985-1994.