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Moisture Origin and Transport for Extreme Precipitation over Indonesia's New Capital City, Nusantara in August 2021
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  • Anis Purwaningsih,
  • Sandro W Lubis,
  • Eddy Hermawan,
  • Teguh Harjana,
  • Dian Nur Ratri,
  • Akas Pinaringan Sujalu,
  • Ainur Ridho,
  • Dita Fatria Andarini,
  • Risyanto Risyanto
Anis Purwaningsih
Research Center for Climate and Atmosphere (PRIMA), National Research and Innovation Agency (BRIN)

Corresponding Author:[email protected]

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Sandro W Lubis
Rice University
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Eddy Hermawan
Research Center for Climate and Atmosphere (PRIMA), National Research and Innovation Agency (BRIN)
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Teguh Harjana
Research Center for Climate and Atmosphere (PRIMA), National Research and Innovation Agency (BRIN)
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Dian Nur Ratri
Meteorological Climatological and Geophysical Agency
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Akas Pinaringan Sujalu
Universitas 17 Agustus 1945 Samarinda
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Ainur Ridho
Cerdas Antisipasi Risiko Bencana Indonesia (CARI)
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Dita Fatria Andarini
Research Center for Climate and Atmosphere (PRIMA), National Research and Innovation Agency (BRIN)
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Risyanto Risyanto
Research Center for Climate and Atmosphere (PRIMA)
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Abstract

Nusantara, the Indonesia’s New Capital City, experienced a rare extreme rainfall event on 27 to 28 August 2021. This unusual heavy rainfall occurred during the dry season and caused severe flooding and landslides. To better understand the underlying mechanisms for such extreme precipitation events, we investigated the moisture sources and transport processes using the Lagrangian model HYSPLIT. Our findings revealed that moisture was mostly transported to Nusantara along three major routes, namely from Borneo Island (BRN, 53.73%), the Banda Sea, and its Surroundings (BSS, 32.03%), and Sulawesi Island (SUL, 9.05%). Overall, BRN and SUL acted as the main sources of terrestrial moisture, while the BSS was the main oceanic moisture origin having a lower contribution than that of its terrestrial counterpart. The terrestrial moisture transport from BRN was mainly driven by the large-scale high vortex flow, while the moisture transport from the SUL was driven by the circulations induced by boreal summer intraseasonal oscillation (BSISO) and low-frequency variability associated with La Niña. The near-surface oceanic moisture transport from BSS is mainly associated with prevailing winds due to the Australian Monsoon system. These insights into moisture sources and pathways can potentially improve skill in predictions of summer precipitation extremes in Indonesia’s New Capital City, Nusantara, and benefit natural resource managers in the region.