Abstract
AbstractThe Indonesian sea is the only low-latitude pathway connecting two tropical oceans, which plays an important role in the coupled ocean-atmosphere mode in the Indo-Pacific sector. A small change in the sea surface temperature (SST) in the Indonesian sea has a significant influence on the precipitation and air-sea heat flux. During the past 33 years, the SST in the Indonesian sea has indicated a warming trend on the average of 0.19 ± 0.04 decade−1, which is larger than global SST warming trend. Moreover, the warming trend indicates seasonal variations, in which maximum trend occurred during boreal summer season. Investigation on the potential driver for this warming trend, namely, the net surface heat flux, resulted in an opposite trend (cooling trend), while the Ekman pumping and the wind mixing only play a minor role on the SST warming. Here, we proposed the upper layer process associated with an increasing trend in precipitation and decreasing trend in mixed layer depth (MLD) for the SST warming within the Indonesian seas. Shoaling of MLD gives a favorable condition for the surface heat flux to warm the surface ocean. However, shoaling of MLD could not solely explain the total SST warming within the Indonesian seas. The seasonal dependence in the warming trend, highest during boreal summer, was significantly related to the Indo-Pacific climate modes, namely the negative Indian Ocean Dipole (IOD) and La Niña events. Higher warming trend observed in the south of Makassar Strait and in the eastern Indonesian seas, in the vicinity of the Maluku Sea and the northeastern part of the Banda Sea, was significantly associated with the La Niña event. Meanwhile, strong warming trend observed in the Karimata Strait and Java Sea, and in the Flores Sea south of Sulawesi Island seems to be enhanced by the negative IOD event. Our rough quantitative estimate of the possible mechanism leading to the SST warming suggests that other mechanism might be at work in warming the SST within the Indonesian seas. Horizontal heat advection associated with an increasing trend of the heat transport from the Pacific into the Indian Ocean by the Indonesian Throughflow (ITF) might play a role in causing the warming trend within the Indonesian seas. However, to what extend this heat advection could modulate the SST warming is still unresolved in the present study. Further study based on realistic model output as well as long-term observational records is necessary to describe the dynamics underlying the warming trend within the Indonesian seas.
Funder
Kementerian Riset, Teknologi dan Pendidikan Tinggi
Publisher
Springer Science and Business Media LLC
Subject
General Earth and Planetary Sciences
Reference27 articles.
1. Aldrian E, Susanto RD (2003) Identification of three dominant rainfall regions within indonesia and their relationship to sea surface temperature. Int J Climatol 23(12):1435–1452
2. Alory G, Wijffels S, Meyers G (2007) Observed temperature trends in the Indian Ocean over 1960-1999 and associated mechanisms. Geophys Res Lett 34(2):2–7
3. Banzon V, Smith TM, Chin TM, Liu C, Hankins W, Centers N, et al. A long-term record of blended satellite and in situ sea-surface temperature for climate monitoring , modeling and environmental studies. 2016;(8):165–76.
4. Cahyarini SY, Pfeiffer M, Nurhati IS, Aldrian E, Dullo W-C, Hetzinger S (2014) Twentieth century sea surface temperature and salinity variations at Timor inferred from paired coral d18O and Sr/Ca measurements. J Geophys Res Ocean 119:4593–4604
5. Dayem KE, Noone DC, Molnar P (2007) Tropical western Pacific warm pool and maritime continent precipitation rates and their contrasting relationships with the Walker Circulation. J Geophys Res Atmos 112(6):1–12