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Title: Calibration of a convective parameterization scheme in the WRF model and its impact on the simulation of East Asian summer monsoon precipitation

Reasonably modeling the magnitude, south-north gradient and seasonal propagation of precipitation associated with the East Asian Summer Monsoon (EASM) is a challenging task in the climate community. In this study we calibrate five key parameters in the Kain-Fritsch convection scheme in the WRF model using an efficient importance-sampling algorithm to improve the EASM simulation. We also examine the impacts of the improved EASM precipitation on other physical process. Our results suggest similar model sensitivity and values of optimized parameters across years with different EASM intensities. By applying the optimal parameters, the simulated precipitation and surface energy features are generally improved. The parameters related to downdraft, entrainment coefficients and CAPE consumption time (CCT) can most sensitively affect the precipitation and atmospheric features. Larger downdraft coefficient or CCT decrease the heavy rainfall frequency, while larger entrainment coefficient delays the convection development but build up more potential for heavy rainfall events, causing a possible northward shift of rainfall distribution. The CCT is the most sensitive parameter over wet region and the downdraft parameter plays more important roles over drier northern region. Long-term simulations confirm that by using the optimized parameters the precipitation distributions are better simulated in both weak and strong EASM years.more » Due to more reasonable simulated precipitation condensational heating, the monsoon circulations are also improved. Lastly, by using the optimized parameters the biases in the retreating (beginning) of Mei-yu (northern China rainfall) simulated by the standard WRF model are evidently reduced and the seasonal and sub-seasonal variations of the monsoon precipitation are remarkably improved.« less
Authors:
 [1] ;  [1] ;  [2] ;  [1] ;  [3]
  1. Nanjing Univ., Nanjing (China)
  2. Pacific Northwest National Lab. (PNNL), Richland, WA (United States)
  3. Pacific Northwest National Lab. (PNNL), Richland, WA (United States); Lanzhou Univ., Lanzhou (China)
Publication Date:
OSTI Identifier:
1194289
Report Number(s):
PNNL-SA--101192
Journal ID: ISSN 0930-7575; KP1703010
Grant/Contract Number:
AC05-76RL01830
Type:
Accepted Manuscript
Journal Name:
Climate Dynamics
Additional Journal Information:
Journal Volume: 44; Journal Issue: 5-6; Journal ID: ISSN 0930-7575
Publisher:
Springer-Verlag
Research Org:
Pacific Northwest National Laboratory (PNNL), Richland, WA (United States)
Sponsoring Org:
USDOE
Country of Publication:
United States
Language:
English
Subject:
54 ENVIRONMENTAL SCIENCES convective parameterization; WRF model; simulation; East Asian Summer Monsoon precipitation; EASM; precipitation; parameter calibration