#  Special ClimaTea 

 



####  calendar\_today Date and Time 

 **June 12, 2019** 

 12:00PM - 12:00PM EDT 

####  pin\_drop Location 

 **HUCE Seminar Room MCZ 440**  



 

 



 

 Speaker: [Associate Professor Koh Tieh Yong from SUSS ](https://www.suss.edu.sg/about-suss/faculty-and-staff/detail/associate-professor-koh-tieh-yong)

 Title: ***"MULTI-SCALE CONVECTION IN THE TROPICS: MODELLING AND OBSERVATIONS"***

 Abstract: The Weather Research and Forecasting (WRF) model was used to dynamically downscale 27 years of the Climate Forecast System Reanalysis (CFSR) in a tropical belt configuration at 36 km horizontal grid spacing. A key parameter controlling the moisture reference profile in the Betts-Miller-Janjic convective adjustment scheme was adjusted and a Precipitating Convective Cloud scheme was developed to address the prior model deficiencies so as to obtain a good rainfall climatology as observed by the Tropical Rainfall Measuring Mission (TRMM). The representation of conventional and Modoki-type El Niño-Southern Oscillation (ENSO) and the Indian Ocean Dipole (IOD) in the model were confirmed by linear regression. Madden-Julian Oscillation (MJO) and Boreal Summer Intra-seasonal Oscillation (BSISO) were also well-simulated. However, WRF does not capture well the diurnal cycle of precipitation over the Maritime Continent, highlighting the crucial role of the TRMM dataset in the study of multi-scale interactions involving the diurnal cycle.

 The WRF simulation shows that in the boreal summer, conventional ENSO modifies the MJO amplitude while Modoki-type ENSO and IOD impacts are MJO-phase dependent; in boreal winter, these inter-annual variations have little impact on MJO amplitude.

 The TRMM observations show that in the Maritime Continent, a moderate El Nino event accentuates MJO’s influence on diurnal cycle amplitude (whether strengthening or weakening) with little change in phase; whereas a moderate La Nina event has the anti-symmetric effect of countering MJO’s influence on the diurnal cycle. A strong ENSO leads to non-linear impacts where the diurnal cycle’s amplitude tends to be enhanced with large changes in its phase across all MJO phases, regardless of the ENSO-phase.[Paper 1](https://eps.harvard.edu/files/eps/files/gmd-8-2915-2015.pdf), [paper 2](https://eps.harvard.edu/files/eps/files/koh_et_al-2016-quarterly_journal_of_the_royal_meteorological_society.pdf), [paper 3](https://eps.harvard.edu/files/eps/files/fonseca2019_article_multi-scaleinteractionsinahigh.pdf)



 

 



 

 See also:- [ ClimaTea ](/type-event/climatea-lecturejournal-club)
 
 

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