Trends in downscaled projected precipitation across Queensland indicate a wetter summer with higher intensity events and drier winter with prolonged dry spells — Australian Meteorological and Oceanographic Society

Trends in downscaled projected precipitation across Queensland indicate a wetter summer with higher intensity events and drier winter with prolonged dry spells (#177)

Ralph Trancoso 1 , Jozef Syktus 1
  1. Global Change Institute, University of Queensland, Brisbane, QLD, Australia

Projected changes in regional precipitation is highly uncertain. Climate models simulate drivers of rainfall variability differently. While some models suggest a dryer future, others point out a wetter future. This work uses trend analysis to answer the following three questions: (i) Are there long-term wetting and drying trending patterns on seasonal precipitation? (ii) To what extent these patterns are influenced by model spatial resolution? (iii) How precipitation is projected to change (frequency, duration and intensity)? We calculated non-parametric trends (Mann-Kendall and Sen-Slope tests) in projected future rainfall from 11 CMIP5 models downscaled to 10km and 50 km pixel-size and native resolution (~200km). We assess trends in both annual and seasonal (summer and winter) totals and extreme precipitation indices (Simple Daily Intensity, Consecutive Dry Days, Maximum 1-day Precipitation, Very Wet Day Precipitation, Number of wet days and Extremely Wet Day Precipitation) in the period 1980-2099. Trend analysis of projected precipitation from multiple models and spatial resolutions reveal a consistent reduction of future annual rainfall across Queensland seaboard. In addition, high resolution models point out an increase of annual rainfall on inland regions. While large uncertainty still remains on annual future rainfall totals, wetting and drying trend patterns are much clearer across summer and winter with substantial agreement among downscaled models (50 km and 10 km). These spatial trending patterns over seasons are generally consistent across spatial scales (coarse, moderate and high-resolution models). Trend analysis of extreme precipitation indices suggest that the wetting pattern during summer seems associated with changes in rainfall frequency and duration, whereas the drying pattern during winter is associated to reduction in rainfall frequency, duration and intensity. Our results, for the first time, reveal a consistent changing pattern in projected seasonal precipitation using robust continuous approach with strong implication for water resource management and climate change adaptation.

 

 

 

 

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