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Title: The impact of the diurnal cycle on the propagation of Madden-Julian Oscillation convection across the Maritime Continent

Influences of the diurnal cycle of convection on the propagation of the Madden-Julian Oscillation (MJO) across the Maritime Continent (MC) are examined using cloud-permitting regional model simulations and observations. A pair of ensembles of control (CONTROL) and no-diurnal cycle (NODC) simulations of the November 2011 MJO episode are performed. In the CONTROL simulations, the MJO signal is weakened as it propagates across the MC, with much of the convection stalling over the large islands of Sumatra and Borneo. In the NODC simulations, where the incoming shortwave radiation at the top of the atmosphere is maintained at its daily mean value, the MJO signal propagating across the MC is enhanced. Examination of the surface energy fluxes in the simulations indicates that in the presence of the diurnal cycle, surface downwelling shortwave radiation in CONTROL simulations is larger because clouds preferentially form in the afternoon. Furthermore, the diurnal co-variability of surface wind speed and skin temperature results in a larger sensible heat flux and a cooler land surface in CONTROL compared to NODC simulations. Here, an analysis of observations indicates that the modulation of the downwelling shortwave radiation at the surface by the diurnal cycle of cloudiness negatively projects on the MJOmore » intraseasonal cycle and therefore disrupts the propagation of the MJO across the MC.« less
Authors:
 [1] ;  [2] ;  [1] ;  [1] ;  [3] ;  [2] ;  [2] ;  [4]
  1. Pacific Northwest National Lab. (PNNL), Richland, WA (United States)
  2. Univ. of Miami, Miami, FL (United States)
  3. Colorado State Univ., Fort Collins, CO (United States)
  4. Naval Research Lab., Monterey, CA (United States)
Publication Date:
Report Number(s):
PNNL-SA-118613
Journal ID: ISSN 1942-2466; KP1701000
Grant/Contract Number:
AC05-76RL01830
Type:
Accepted Manuscript
Journal Name:
Journal of Advances in Modeling Earth Systems
Additional Journal Information:
Journal Volume: 8; Journal Issue: 4; Journal ID: ISSN 1942-2466
Publisher:
American Geophysical Union (AGU)
Research Org:
Pacific Northwest National Lab. (PNNL), Richland, WA (United States)
Sponsoring Org:
USDOE
Country of Publication:
United States
Language:
English
Subject:
58 GEOSCIENCES; diurnal cycle; Madden-Julian Oscillation; Maritime Continent
OSTI Identifier:
1347866