Scholarlink

<p>This study investigates the spatiotemporal variability and trends in annual and seasonal rainfall, as well as the intensity and frequency of heavy rainfall events, across Southeast Asia (SEA) from 1980 to 2019, using the high-resolution (~ 0.1°) Multi-Source Weighted-Ensemble Precipitation daily gridded observational dataset. Heavy rainfall is defined as daily precipitation exceeding the 95th percentile of the baseline distribution at each grid cell over the study period, and trends are assessed using linear regression with statistical significance evaluated by a two-tailed Student’s t-test (<i>p</i> &lt; 0.05). Extending beyond previous studies that focus on specific countries or seasons, this study provide a comprehensive regional assessment of long-term and decadal variability (1980–1999 and 2000–2019) across SEA and its subregions: Northeast (NE), Northwest (NW), Southeast (SE), and Southwest (SW) for all seasons (DJF, MAM, JJA, SON). The influence of El Niño Southern Oscillation (ENSO) and the Indian Ocean Dipole (IOD) on rainfall metrics is also examined. Results reveal strong spatial heterogeneity in rainfall trends across, with contrasting patterns observed among regions and seasons. For the 1980–2019 period, area-averaged analysis shows a significant increase in annual rainfall only over NE. Seasonal rainfall increased significantly in NE across all seasons and in NW during DJF. Heavy rainfall magnitude and frequency also increased significantly over SEA (DJF, JJA); NE (DJF, MAM); NW (DJF); and SE (DJF, MAM, JJA). In the 2000–2019 period, seasonal rainfall, along with heavy rainfall magnitude and frequency, increased significantly over SEA and NW during JJA and SON, but declined during MAM; in SW, declines were observed during MAM, JJA, and SON. Composite analysis indicates ENSO and IOD strongly modulate rainfall: positive IOD enhances MAM but suppresses SON rainfall, while El Niño causes wet anomalies in DJF (NE/NW) but widespread drying in MAM/SON.</p>

错误：搜索内容不能为空，请输入英文关键词
错误：关键词超出字数限制，请精简
高级检索

Quantifying long-term variability and extremes in Southeast Asia’s rainfall: a 40-year observational study (1980–2019)

  • 期刊论文

  • 发表日期：

    2025年7月9日

查看全文
  • Alugula Boyaj,
  • Srivatsan Vijayaraghavan

摘要

This study investigates the spatiotemporal variability and trends in annual and seasonal rainfall, as well as the intensity and frequency of heavy rainfall events, across Southeast Asia (SEA) from 1980 to 2019, using the high-resolution (~ 0.1°) Multi-Source Weighted-Ensemble Precipitation daily gridded observational dataset. Heavy rainfall is defined as daily precipitation exceeding the 95th percentile of the baseline distribution at each grid cell over the study period, and trends are assessed using linear regression with statistical significance evaluated by a two-tailed Student’s t-test (p < 0.05). Extending beyond previous studies that focus on specific countries or seasons, this study provide a comprehensive regional assessment of long-term and decadal variability (1980–1999 and 2000–2019) across SEA and its subregions: Northeast (NE), Northwest (NW), Southeast (SE), and Southwest (SW) for all seasons (DJF, MAM, JJA, SON). The influence of El Niño Southern Oscillation (ENSO) and the Indian Ocean Dipole (IOD) on rainfall metrics is also examined. Results reveal strong spatial heterogeneity in rainfall trends across, with contrasting patterns observed among regions and seasons. For the 1980–2019 period, area-averaged analysis shows a significant increase in annual rainfall only over NE. Seasonal rainfall increased significantly in NE across all seasons and in NW during DJF. Heavy rainfall magnitude and frequency also increased significantly over SEA (DJF, JJA); NE (DJF, MAM); NW (DJF); and SE (DJF, MAM, JJA). In the 2000–2019 period, seasonal rainfall, along with heavy rainfall magnitude and frequency, increased significantly over SEA and NW during JJA and SON, but declined during MAM; in SW, declines were observed during MAM, JJA, and SON. Composite analysis indicates ENSO and IOD strongly modulate rainfall: positive IOD enhances MAM but suppresses SON rainfall, while El Niño causes wet anomalies in DJF (NE/NW) but widespread drying in MAM/SON.