scholarly journals The Onset of the Indonesian–Australian Summer Monsoon Triggered by the First-Branch Eastward-Propagating Madden–Julian Oscillation

2019 ◽  
Vol 32 (17) ◽  
pp. 5453-5470 ◽  
Author(s):  
Yongliang Duan ◽  
Hongwei Liu ◽  
Weidong Yu ◽  
Lin Liu ◽  
Guang Yang ◽  
...  
Keyword(s):  
Summer Monsoon ◽  
Heat Budget ◽  
Sea Surface ◽  
Specific Humidity ◽  
Surface Mixed Layer ◽  
Madden Julian Oscillation ◽  
Northern Australia ◽  
Surface Warming ◽  
Australian Summer Monsoon ◽  
Australian Summer

Abstract The Madden–Julian oscillation (MJO) often causes the onset of the Indonesian–Australian summer monsoon (IASM) over Indonesia and northern Australia. In the present study, a composite analysis is conducted to reveal the detailed IASM onset process and its air–sea interactions associated with the first-branch eastward-propagating MJO (FEMJO) based on 30-yr ERA-Interim data, satellite-derived sea surface temperature (SST), outgoing longwave radiation (OLR), and SODA3 ocean reanalysis. The results distinctly illustrate the phase-locked relationships among the persistent sea surface warming north of Australia, the FEMJO, and the established westerlies. It is found that the SST to the north of Australia reaches its annual maximum just before the onset of the summer monsoon. The oceanic surface mixed layer heat budget discloses that this rapid warming is primarily produced by the enhanced surface heat flux. In addition, this premonsoon sea surface warming increases the air specific humidity in the low-level troposphere and then establishes zonal moisture asymmetry relative to the FEMJO convection. This creates a more unstable atmospheric stratification southeast of the FEMJO and favors convection throughout the vicinity of northern Australia, which ultimately triggers the onset of the IASM. The results in this study thus may potentially be applicable to seasonal monsoon climate monitoring and prediction.

scholarly journals ANALISIS CUACA PADA SAAT PELAKSANAAN TMC PENANGGULANGAN BANJIR JAKARTA JANUARI FEBRUARI 2014

2015 ◽  
Vol 16 (1) ◽  
pp. 15
Author(s):  
Erwin Mulyana
Keyword(s):  
Southern Oscillation ◽  
Sea Surface ◽  
Madden Julian Oscillation ◽  
Weather Modification ◽  
Indian Ocean Dipole Mode ◽  
Monsoon Index ◽  
West Part ◽  
Cloud Development ◽  
Australian Summer Monsoon ◽  
Australian Summer

AbstrakPada tanggal 11 Januari sampai dengan 14 Februari 2014 telah dilaksanakan penerapan teknologi modifikasi cuaca (TMC) untuk menanggulangi banjir di wilayah Jakarta dan sekitarnya. Selama kegiatan tersebut fenomena ENSO dan IOD dalam kondisi normal. MJO menunjukkan aktifitas konvektif netral di wilayah Indonesia pada pertengahan Januari hingga pertengahan Februari 2014. Temperatur  permukaan laut di perairan Jawa bagian barat sekitar 28-290C. Kelembagan udara pada level 850 mb sekitar 70-80%. Pertumbuhan awan umumnya berada di sebelah barat daya, barat dan barat laut Jakarta. Indeks Monsoon Australia positif berpengaruh terhadap peningkatan pembentukan awan hujan di Jawa.Abstract Application of weather modification has carried out to reduce precipitation over Jakarta on 11 January to 14 February 2013. During this period, El Nino Southern Oscillation and Indian Ocean Dipole Mode were normal condition. The Madden Julian Oscillation shows that the convection over Indonesia region was netral condition. The sea surface temperature over west part of Java waters was 29-30 290C. The 850 mb average of relative humidity on mid January - mid February 2014 was 70-80%. Based on visual and weather radar observation, cloud development mainly over northwest to southwest of Jakarta. Positive Australian Summer Monsoon Index affected to increase precipitation over Java area.

scholarly journals The Role of Air–Sea Interaction for Prediction of Australian Summer Monsoon Rainfall

2012 ◽  
Vol 25 (4) ◽  
pp. 1278-1290 ◽  
Author(s):  
Harry H. Hendon ◽  
Eun-Pa Lim ◽  
Guo Liu
Keyword(s):  
Summer Monsoon ◽  
Coupled Model ◽  
Intrinsic Property ◽  
Forecast Model ◽  
Forecast Skill ◽  
Northern Australia ◽  
The North ◽  
Australian Summer Monsoon ◽  
Sst Anomalies ◽  
Australian Summer

Abstract Forecast skill for seasonal mean rainfall across northern Australia is lower during the summer monsoon than in the premonsoon transition season based on 25 years of hindcasts using the Predictive Ocean Atmosphere Model for Australia (POAMA) coupled model seasonal forecast system. The authors argue that this partly reflects an intrinsic property of the monsoonal system, whereby seasonally varying air–sea interaction in the seas around northern Australia promotes predictability in the premonsoon season and demotes predictability after monsoon onset. Trade easterlies during the premonsoon season support a positive feedback between surface winds, SST, and rainfall, which results in stronger and more persistent SST anomalies to the north of Australia that compliment the remote forcing of Australian rainfall from El Niño in the Pacific. After onset of the Australian summer monsoon, this local feedback is not supported in the monsoonal westerly regime, resulting in weaker SST anomalies to the north of Australia and with lower persistence than in the premonsoon season. Importantly, the seasonality of this air–sea interaction is captured in the POAMA forecast model. Furthermore, analysis of perfect model forecasts and forecasts generated by prescribing observed SST results in largely the same conclusion (i.e., significantly lower actual and potential forecast skill during the monsoon), thereby supporting the notion that air–sea interaction contributes to intrinsically lower predictability of rainfall during the monsoon.

scholarly journals Interannual Variability of Sea Surface Temperature off Java and Sumatra in a Global GCM*

2008 ◽  
Vol 21 (11) ◽  
pp. 2451-2465 ◽  
Author(s):  
Yan Du ◽  
Tangdong Qu ◽  
Gary Meyers
Keyword(s):  
Indian Ocean ◽  
Surface Temperature ◽  
Sea Surface Temperature ◽  
Mixed Layer ◽  
Heat Budget ◽  
Sea Surface ◽  
Surface Mixed Layer ◽  
Horizontal Advection ◽  
Cold Anomaly ◽  
Sst Anomalies

Abstract Using results from the Simple Ocean Data Assimilation (SODA), this study assesses the mixed layer heat budget to identify the mechanisms that control the interannual variation of sea surface temperature (SST) off Java and Sumatra. The analysis indicates that during the positive Indian Ocean Dipole (IOD) years, cold SST anomalies are phase locked with the season cycle. They may exceed −3°C near the coast of Sumatra and extend as far westward as 80°E along the equator. The depth of the thermocline has a prominent influence on the generation and maintenance of SST anomalies. In the normal years, cooling by upwelling–entrainment is largely counterbalanced by warming due to horizontal advection. In the cooling episode of IOD events, coastal upwelling–entrainment is enhanced, and as a result of mixed layer shoaling, the barrier layer no longer exists, so that the effect of upwelling–entrainment can easily reach the surface mixed layer. Horizontal advection spreads the cold anomaly to the interior tropical Indian Ocean. Near the coast of Java, the northern branch of an anomalous anticyclonic circulation spreads the cold anomaly to the west near the equator. Both the anomalous advection and the enhanced, wind-driven upwelling generate the cold SST anomaly of the positive IOD. At the end of the cooling episode, the enhanced surface thermal forcing overbalances the cooling effect by upwelling/entrainment, and leads to a warming in SST off Java and Sumatra.

scholarly journals The steady enhancement of the Australian Summer Monsoon in the last 200 years

2017 ◽  
Vol 7 (1) ◽  
Author(s):  
David Gallego ◽  
Ricardo García-Herrera ◽  
Cristina Peña-Ortiz ◽  
Pedro Ribera
Keyword(s):  
Summer Monsoon ◽  
Australian Summer Monsoon ◽  
Australian Summer
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