Effects of topographic smoothing on the simulation of winter precipitation in High Mountain Asia

Details

• Journal Title:
  Journal of Geophysical Research: Atmospheres
• Personal Author:
  Cannon, Forest ; Carvalho, Leila M. V. ; Jones, Charles ; Norris, Jesse ; Bookhagen, Bodo ; Kiladis, George N.
• NOAA Program & Office:
  OAR (Oceanic and Atmospheric Research) ; ESRL (Earth System Research Laboratory) ; PSL (Physical Sciences Laboratory)
• Description:
  Numerous studies have projected future changes in High Mountain Asia water resources based on temperature and precipitation from global circulation models (GCMs) under future climate scenarios. Although the potential benefit of such studies is immense, coarse grid‐scale GCMs are unable to resolve High Mountain Asia's complex topography and thus have a biased representation of regional weather and climate. This study investigates biases in the simulation of physical mechanisms that generate snowfall and contribute to snowpack in High Mountain Asia in coarse topography experiments using the Weather Research and Forecasting model. Regional snowpack is event driven, thus 33 extreme winter orographic precipitation events are simulated at fine atmospheric resolution with 6.67 km resolution topography and smoothed 1.85° × 1.25° GCM topography. As with many modified topography experiments performed in other regions, the distribution of precipitation is highly dependent on first‐order orographic effects, which dominate regional meteorology. However, we demonstrate that topographic smoothing enhances circulation in simulated extratropical cyclones, with significant impacts on orographic precipitation. Despite precipitation reductions of 28% over the highest ranges, due to reduced ascent on windward slopes, total precipitation over the study domain increased by an average of 9% in smoothed topography experiments on account of intensified extratropical cyclone dynamics and cross‐barrier moisture flux. These findings identify an important source of bias in coarse‐resolution simulated precipitation in High Mountain Asia, with important implications for the application of GCMs toward projecting future hydroclimate in the region.
• Keywords:
  Mathematical Models Rain And Rainfall Mathematical Models Rain And Rainfall
• Source:
  JGR Atmospheres 122(3): 1456-1474, 2017
• DOI:
  https://doi.org/10.1002/2016JD026038
• Document Type:
  Journal Article
• Place as Subject:
  Asia
• Rights Information:
  Other
• Compliance:
  Submitted
• Main Document Checksum:
  urn:sha256:1aadfe1f5804380583bc09df5b6d72b50d2e47885095e8056086b04b702df6f5
• Download URL:
  https://repository.library.noaa.gov/view/noaa/28080/noaa_28080_DS1.pdf
• File Type:
  [PDF - 17.21 MB ]