An objective definition of summer monsoon onset in the northwestern maritime continent

Research output: Contribution to journalArticle

Abstract

Unlike in other parts of the Asian Monsoon region, the summer monsoon in the Northwestern Maritime Continent (NwMC) is relatively dry. Hence, an objective definition is needed in order to determine the arrival of the dry season in this particular sub-region. Criteria for the objective definition of summer monsoon onset in the NwMC were defined based on reanalysis data from the National Centers for Environment Prediction (NCEP) and Global Precipitation Climatology Project (GPCP) databases. Considering the Matsuno-Gill theoretical relationship between tropical precipitation and low-level winds, the summer monsoon onset date can be determined objectively based on the commencement of the sustained 850-hPa zonal winds averaged over the area from 5° to 10°N and from 100° to 115°E. The establishment of steady westerly/southwesterly winds over the NwMC region is consistent with the abrupt shift of rainfall from the equatorial region (5°S–5°N) to areas north of the equator. The onset is also associated with the northeastward propagation of anomalous convection from the western equatorial Indian Ocean on an intraseasonal time scale. In view of its representation of large-scale circulation and objectiveness, this new monsoon onset index will provide a useful metric with which to predict NwMC summer monsoon onset and for studying the interannual variation in monsoon onset. A simple lead–lag correlation shows the monsoon onset in NwMC has a close relationship with ENSO. Generally an early (late) monsoon onset can be expected when cold (warm) ENSO event occurred in the preceding summer.

Original languageEnglish
JournalInternational Journal of Climatology
DOIs
Publication statusPublished - 1 Jan 2019

Fingerprint

monsoon
summer
El Nino-Southern Oscillation
precipitation (climatology)
continent
zonal wind
westerly
annual variation
dry season
convection
timescale
rainfall
prediction

Keywords

  • Asian summer monsoon
  • interannual variability
  • monsoon onset
  • northwestern maritime continent

ASJC Scopus subject areas

  • Atmospheric Science

Cite this

@article{d20dc6ee9fd141fe83028adbb7e08f4d,
title = "An objective definition of summer monsoon onset in the northwestern maritime continent",
abstract = "Unlike in other parts of the Asian Monsoon region, the summer monsoon in the Northwestern Maritime Continent (NwMC) is relatively dry. Hence, an objective definition is needed in order to determine the arrival of the dry season in this particular sub-region. Criteria for the objective definition of summer monsoon onset in the NwMC were defined based on reanalysis data from the National Centers for Environment Prediction (NCEP) and Global Precipitation Climatology Project (GPCP) databases. Considering the Matsuno-Gill theoretical relationship between tropical precipitation and low-level winds, the summer monsoon onset date can be determined objectively based on the commencement of the sustained 850-hPa zonal winds averaged over the area from 5° to 10°N and from 100° to 115°E. The establishment of steady westerly/southwesterly winds over the NwMC region is consistent with the abrupt shift of rainfall from the equatorial region (5°S–5°N) to areas north of the equator. The onset is also associated with the northeastward propagation of anomalous convection from the western equatorial Indian Ocean on an intraseasonal time scale. In view of its representation of large-scale circulation and objectiveness, this new monsoon onset index will provide a useful metric with which to predict NwMC summer monsoon onset and for studying the interannual variation in monsoon onset. A simple lead–lag correlation shows the monsoon onset in NwMC has a close relationship with ENSO. Generally an early (late) monsoon onset can be expected when cold (warm) ENSO event occurred in the preceding summer.",
keywords = "Asian summer monsoon, interannual variability, monsoon onset, northwestern maritime continent",
author = "Diong, {Jeong Yik} and {Tangang @ Tajudin Mahmud}, Fredolin and Liew, {Ju Neng}",
year = "2019",
month = "1",
day = "1",
doi = "10.1002/joc.6075",
language = "English",
journal = "International Journal of Climatology",
issn = "0899-8418",
publisher = "John Wiley and Sons Ltd",

}

TY - JOUR

T1 - An objective definition of summer monsoon onset in the northwestern maritime continent

AU - Diong, Jeong Yik

AU - Tangang @ Tajudin Mahmud, Fredolin

AU - Liew, Ju Neng

PY - 2019/1/1

Y1 - 2019/1/1

N2 - Unlike in other parts of the Asian Monsoon region, the summer monsoon in the Northwestern Maritime Continent (NwMC) is relatively dry. Hence, an objective definition is needed in order to determine the arrival of the dry season in this particular sub-region. Criteria for the objective definition of summer monsoon onset in the NwMC were defined based on reanalysis data from the National Centers for Environment Prediction (NCEP) and Global Precipitation Climatology Project (GPCP) databases. Considering the Matsuno-Gill theoretical relationship between tropical precipitation and low-level winds, the summer monsoon onset date can be determined objectively based on the commencement of the sustained 850-hPa zonal winds averaged over the area from 5° to 10°N and from 100° to 115°E. The establishment of steady westerly/southwesterly winds over the NwMC region is consistent with the abrupt shift of rainfall from the equatorial region (5°S–5°N) to areas north of the equator. The onset is also associated with the northeastward propagation of anomalous convection from the western equatorial Indian Ocean on an intraseasonal time scale. In view of its representation of large-scale circulation and objectiveness, this new monsoon onset index will provide a useful metric with which to predict NwMC summer monsoon onset and for studying the interannual variation in monsoon onset. A simple lead–lag correlation shows the monsoon onset in NwMC has a close relationship with ENSO. Generally an early (late) monsoon onset can be expected when cold (warm) ENSO event occurred in the preceding summer.

AB - Unlike in other parts of the Asian Monsoon region, the summer monsoon in the Northwestern Maritime Continent (NwMC) is relatively dry. Hence, an objective definition is needed in order to determine the arrival of the dry season in this particular sub-region. Criteria for the objective definition of summer monsoon onset in the NwMC were defined based on reanalysis data from the National Centers for Environment Prediction (NCEP) and Global Precipitation Climatology Project (GPCP) databases. Considering the Matsuno-Gill theoretical relationship between tropical precipitation and low-level winds, the summer monsoon onset date can be determined objectively based on the commencement of the sustained 850-hPa zonal winds averaged over the area from 5° to 10°N and from 100° to 115°E. The establishment of steady westerly/southwesterly winds over the NwMC region is consistent with the abrupt shift of rainfall from the equatorial region (5°S–5°N) to areas north of the equator. The onset is also associated with the northeastward propagation of anomalous convection from the western equatorial Indian Ocean on an intraseasonal time scale. In view of its representation of large-scale circulation and objectiveness, this new monsoon onset index will provide a useful metric with which to predict NwMC summer monsoon onset and for studying the interannual variation in monsoon onset. A simple lead–lag correlation shows the monsoon onset in NwMC has a close relationship with ENSO. Generally an early (late) monsoon onset can be expected when cold (warm) ENSO event occurred in the preceding summer.

KW - Asian summer monsoon

KW - interannual variability

KW - monsoon onset

KW - northwestern maritime continent

UR - http://www.scopus.com/inward/record.url?scp=85063643970&partnerID=8YFLogxK

UR - http://www.scopus.com/inward/citedby.url?scp=85063643970&partnerID=8YFLogxK

U2 - 10.1002/joc.6075

DO - 10.1002/joc.6075

M3 - Article

AN - SCOPUS:85063643970

JO - International Journal of Climatology

JF - International Journal of Climatology

SN - 0899-8418

ER -