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Biao Geng and Masaki Katsumata

the peak MJO date was largely induced by an ERW during its active phase. It was noted that ERWs contributed little to the variances of convective echo areas at 2 km ( Figs. 10 – 11 ). Therefore, the strong modulation of ERWs on the variances of both the 10- and 30-dB Z convective echo-top heights implies that upper-level forcing of ERWs can greatly impact the vertical development of convection within MJO events. Figure 16 shows the regressed results of the 10-dB Z stratiform echo-top heights

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Joshua Chun Kwang Lee, Anurag Dipankar, and Xiang-Yu Huang

1. Introduction The diurnal cycle is the most prominent mode of rainfall variability in the tropics. Strong solar heating and resulting energy fluxes between the land surface, adjacent seas, and the atmosphere in the afternoon often create a moist and unstable environment that is favorable for convection. Regional variations in the diurnal cycle exist and may be attributed to topography and orographic forcing ( Ohsawa et al. 2001 ; Yang and Slingo 2001 ; Qian 2008 ). For the western Maritime

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James H. Ruppert Jr. and Fuqing Zhang

; namely, their role in forcing and coupling with long-lived gravity waves. Among the most dominant drivers of weather variability in the MC is the Madden–Julian oscillation (MJO; Madden and Julian 1972 ). The MJO is a convectively coupled tropical wave that propagates slowly eastward (~5 m s −1 ) through the Indo-Pacific warm pool region, modulating deep overturning motion and moist convection on intraseasonal time scales ( Zhang 2005 ). Yet since the diurnal cycle is the primary rainfall mechanism

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Jian Ling, Yuqing Zhao, and Guiwan Chen

-propagation speed, and seasonal cycle. Hung et al. (2013) indicated only one GCM was able to simulate the observed eastward propagation of the MJO in phase 5 of the Coupled Model Intercomparison Project (CMIP5). Jiang et al. (2015) showed that only a quarter of the GCMs that participated in the MJO Task Force (MJOTF) ( Moncrieff et al. 2012 ; Waliser et al. 2012 ) and the GEWEX Atmospheric System Study (GASS) ( Petch et al. 2011 ; we refer to this by the abbreviation MJOTF/GASS in this study) could produce

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Claire L. Vincent and Todd P. Lane

maintain consistency with observed intraseasonal variability, spectral nudging toward ERA-Interim was performed for the 12-km domain only for wavelengths longer than 1000 km above the boundary layer, with an inverse nudging time scale of 0.0003 s −1 for all nudged variables. Liu et al. (2012) showed that spectral nudging achieved a better balance between maintaining consistency with large-scale forcing while allowing smaller-scale variance to develop than grid nudging, and Vincent and Hahmann (2015

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Chen Li, Jing-Jia Luo, and Shuanglin Li

layer” parameterization scheme is based on that of Lock et al. (2000) with the modifications described in Lock (2001) and Brown et al. (2008) . It is a first-order turbulence closure mixing adiabatically conserved heat and moisture variables, momentum, and tracers. For more details of the model physics, readers are referred to Walters et al. (2017) . We examine UM-GA6’s performance in the Atmospheric Model Intercomparison Project (AMIP) runs from 1982 to 2008 with observed SST forcing. The

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James H. Ruppert Jr., Xingchao Chen, and Fuqing Zhang

conspire to promote nocturnal low-level convergence, moistening, and destabilization, and hence provide explanations for the triggering and maintenance of these MCSs, though not their propagation. Yet in other regions, nocturnal propagating convective systems exist both without low-level jets and without continuous orographic forcing, as exemplified by the many examples of offshore-propagating nocturnal systems: in the Tiwi Islands ( Carbone et al. 2000 ); the Panama Bight region ( Mapes et al. 2003a

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Dongliang Yuan, Xiang Li, Zheng Wang, Yao Li, Jing Wang, Ya Yang, Xiaoyue Hu, Shuwen Tan, Hui Zhou, Adhitya Kusuma Wardana, Dewi Surinati, Adi Purwandana, Mochamad Furqon Azis Ismail, Praditya Avianto, Dirham Dirhamsyah, Zainal Arifin, and Jin-Song von Storch

represent the wind forcing in the Maluku Channel. Surface drifter trajectories are obtained from the Global Lagrangian Drifter Data of AOML/NOAA from 1979 to 2011 ( http://www.aoml.noaa.gov/envids/gld/dirkrig/parttrk_spatial_temporal.php ). The 2-Minute Gridded Global Relief Data (ETOPO2v2) of the U.S. National Geophysical Data Center are used to calculate the width of the Maluku Channel section ( https://ngdc.noaa.gov/mgg/global/etopo2.html ). The drifters released in the western Pacific Ocean during

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Xiang Li, Dongliang Yuan, Zheng Wang, Yao Li, Corry Corvianawatie, Dewi Surinati, Asep Sandra, Ahmad Bayhaqi, Praditya Avianto, Edi Kusmanto, Dirham Dirhamsyah, and Zainal Arifin

hindcast simulation forced by the NCEP–NCAR wind forcing during 2000–11 is used to form the mean velocity. The Global Ocean Forecasting System (GOFS) 3.1 operated by the Center for Ocean–Atmosphere Predictions Studies of Florida State University employs the Hybrid Coordinate Ocean Model (HYCOM) forced by the Navy Global Environmental Model (NAVGEM) atmospheric forcing and the U.S. Navy Coupled Ocean Data Assimilation system ( Cummings 2005 ; Chassignet et al. 2009 ), with a horizontal resolution of 0

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Shijian Hu, Ying Zhang, Ming Feng, Yan Du, Janet Sprintall, Fan Wang, Dunxin Hu, Qiang Xie, and Fei Chai

layer salinity in the southeastern tropical Indian Ocean is influenced by the annual cycles of the ITF and the Leeuwin Current transports, air–sea freshwater forcing, and eddy fluxes ( Zhang et al. 2016 ). Strong salinity fronts observed within the equatorial region show meridional migration associated with the intertropical convergence zone and meridional ocean currents, which may be modulated interannually by zonal advections of less saline waters from the eastern Indian Ocean related to the ITF

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