scholarly journals EVALUASI PERFORMA INDEKS MONSUN AUSMI DAN WNPMI DI WILAYAH INDONESIA

2021 ◽  
Vol 22 (2) ◽  
pp. 61-70
Author(s):  
Adi Mulsandi ◽  
Ardhasena Sopaheluwakan ◽  
Akhmad Faqih ◽  
Rahmat Hidayat ◽  
Yonny Koesmaryono

Intisari Iklim di wilayah Indonesia sangat dipengaruhi oleh aktivitas monsun Asia-Australia. Variabilitas kedua sistem monsun tersebut dapat direpresentasikan dengan baik masing-masing oleh indeks monsun Australian Summer Monsoon Index (AUSMI) dan Western North Pacific Monsoon Index (WNPMI). Saat ini, BMKG secara operasional menggunakan indeks AUSMI dan WNPMI untuk memonitor aktivitas monsun di wilayah Indonesia sebagai bahan prakiraan musim. Meskipun banyak literatur menyatakan bahwa wilayah Indonesia merupakan bagian dari sistem monsun Asia-Australia, namun kondisi topografi lokal yang kompleks berpotensi memodifikasi sirkulasi monsun sehingga perlu dikaji performa kedua indeks tersebut sebelum digunakan secara operasional. Penelitian ini dilakukan untuk menguji performa indeks monsun AUSMI dan WNPMI dalam menggambarkan variasi antartahunan (interannual), variasi dalam musim (intraseasonal), dan siklus tahunan (annual cycle) hujan monsun Indonesia. Hasil penelitian mengungkapkan bahwa kedua indeks memiliki performa yang sangat baik hanya di wilayah dimana indeks tersebut didefinisikan namun kurang baik untuk wilayah Indonesia seperti yang ditunjukan oleh nilai koefisien korelasi yang tidak signifikan dari hasil uji statistik antara kedua indeks dengan curah hujan dari Global Precipitation Climatology Project (GPCP) pada periode 1981-2010. Selain itu, kedua indeks juga memperlihatkan karakteristik siklus tahunan yang berbeda dengan karakteristik siklus tahunan hujan wilayah Jawa sebagai wilayah kunci monsun Indonesia. Hasil ini mengindikasikan perlunya pendefinisian indeks sendiri untuk memonitor aktivitas monsun di wilayah Indonesia.    Abstract  The climate of Indonesia is strongly affected by the Asian-Australian monsoon system. The variability of the two monsoon systems can be well represented by the Western North Pacific Monsoon Index (WNPMI) and the Australian Summer Monsoon Index (AUSMI) respectively. For producing seasonal forecast, BMKG uses the WNPMI and AUSMI monsoon index to monitor monsoon activity in Indonesia. Although most literature states that the Indonesian region is part of the Asian-Australian monsoon system, the complex local topography may modify the monsoon circulation. Hence, it is necessary to assess the performance of the two indices before they are operationally used. This study was conducted to evaluate the performance of the AUSMI and WNPMI monsoon indices in describing the annual cycle, intraseasonal and interannual variability of the Indonesian monsoon rainfall. The results revealed that the two indices only performed very well in the areas where the index was defined but lack of skill for the Indonesian region because of insignificant linear correlation based on a statistical significance test between the two indices and the Global Precipitation Climatology Project (GPCP) rainfall in the 1981-2010 period. In addition, both monsoon indices and Java rainfall showed different characteristics of the annual cycle. These results indicate that it is necessary to define a specific index for monitoring monsoon activity in Indonesia.

2015 ◽  
Vol 16 (1) ◽  
pp. 15
Author(s):  
Erwin Mulyana

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.


MAUSAM ◽  
2021 ◽  
Vol 51 (2) ◽  
pp. 127-154
Author(s):  
KSHUDIRAM SARA ◽  
SURANJANA SARA

Climatological fields of several meteorological variables associated with the Australian summer monsoon, as revealed by NCEP/NCAR reanalysis, are reviewed in the context of observed weather and climate over the continent and surrounding regions. Inter-hemispheric distributions of pressure, temperature and circulation features suggest a see-saw relationship of the Australian monsoon with the monsoons of Asia during both summer and winter. Computed values of cross-equatorial fluxes of air appear to lend credence to this hypothesis.


2007 ◽  
Vol 25 (9) ◽  
pp. 1929-1933 ◽  
Author(s):  
J.-Y. Yu ◽  
M. A. Janiga

Abstract. This study examines the decadal changes in the in-phase relationship between Indian summer monsoon and the subsequent Australian summer monsoon using observational data from 1950–2005. The in-phase relationship is the tendency for a strong Indian summer monsoon to be followed by a strong Australian summer monsoon and vice versa. It is found that the in-phase relationship was weak during the late 1950s and early 1960s, strengthened to a maximum in the early 1970s just before the 1976/77 Pacific climate shift, then declined until the late 1990s. Pacific SST anomalies are noticed to have strong persistence from boreal to austral summer, providing the memory to connect the Indian and subsequent Australian summer monsoon. The simultaneous correlation between the Pacific SST anomalies and the Indian summer monsoon is always strong. It is the weakening and strengthening of the simultaneous correlation between the Australian summer monsoon and the Pacific SST anomalies that contributes to the decadal variations of the in-phase monsoon relation. This study suggests that the interaction between the Australian monsoon and the Pacific Ocean is crucial to tropical climate variability and has experienced significant changes over the past five decades.


2012 ◽  
Vol 25 (12) ◽  
pp. 4304-4322 ◽  
Author(s):  
Brant Liebmann ◽  
Ileana Bladé ◽  
George N. Kiladis ◽  
Leila M. V. Carvalho ◽  
Gabriel B. Senay ◽  
...  

Abstract A precipitation climatology of Africa is documented using 12 years of satellite-derived daily data from the Global Precipitation Climatology Project (GPCP). The focus is on examining spatial variations in the annual cycle and describing characteristics of the wet season(s) using a consistent, objective, and well-tested methodology. Onset is defined as occurring when daily precipitation consistently exceeds its local annual daily average and ends when precipitation systematically drops below that value. Wet season length, rate, and total are then determined. Much of Africa is characterized by a single summer wet season, with a well-defined onset and end, during which most precipitation falls. Exceptions to the single wet season regime occur mostly near the equator, where two wet periods are usually separated by a period of relatively modest precipitation. Another particularly interesting region is the semiarid to arid eastern Horn of Africa, where there are two short wet seasons separated by nearly dry periods. Chiefly, the summer monsoon spreads poleward from near the equator in both hemispheres, although in southern Africa the wet season progresses northwestward from the southeast coast. Composites relative to onset are constructed for selected points in West Africa and in the eastern Horn of Africa. In each case, onset is often preceded by the arrival of an eastward-propagating precipitation disturbance. Comparisons are made with the satellite-based Tropical Rainfall Measuring Mission (TRMM) and gauge-based Famine Early Warning System (FEWS NET) datasets. GPCP estimates are generally higher than TRMM in the wettest parts of Africa, but the timing of the annual cycle and average onset dates are largely consistent.


2021 ◽  
Vol 13 (2) ◽  
pp. 254 ◽  
Author(s):  
Jie Hsu ◽  
Wan-Ru Huang ◽  
Pin-Yi Liu ◽  
Xiuzhen Li

The Climate Hazards Group InfraRed Precipitation with Station data (CHIRPS), which incorporates satellite imagery and in situ station information, is a new high-resolution long-term precipitation dataset available since 1981. This study aims to understand the performance of the latest version of CHIRPS in depicting the multiple timescale precipitation variation over Taiwan. The analysis is focused on examining whether CHIRPS is better than another satellite precipitation product—the Integrated Multi-satellitE Retrievals for Global Precipitation Mission (GPM) final run (hereafter IMERG)—which is known to effectively capture the precipitation variation over Taiwan. We carried out the evaluations made for annual cycle, seasonal cycle, interannual variation, and daily variation during 2001–2019. Our results show that IMERG is slightly better than CHIRPS considering most of the features examined; however, CHIRPS performs better than that of IMERG in representing the (1) magnitude of the annual cycle of monthly precipitation climatology, (2) spatial distribution of the seasonal mean precipitation for all four seasons, (3) quantitative precipitation estimation of the interannual variation of area-averaged winter precipitation in Taiwan, and (4) occurrence frequency of the non-rainy grids in winter. Notably, despite the fact that CHIRPS is not better than IMERG for many examined features, CHIRPS can depict the temporal variation in precipitation over Taiwan on annual, seasonal, and interannual timescales with 95% significance. This highlights the potential use of CHIRPS in studying the multiple timescale variation in precipitation over Taiwan during the years 1981–2000, for which there are no data available in the IMERG database.


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

Author(s):  
Arnold Gruber ◽  
Bruno Rudolf ◽  
Mark M. Morrissey ◽  
Toshiyuki Kurino ◽  
John E. Janowiak ◽  
...  

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