International Seminar sustainable utilization of coastal resources in tropical zone, 19-20 October,2016, Bengkulu, Indonesia

Indonesian coastlines controlling global climate Manabu D. Yamanaka*, Shin.-Ya Ogino, Pei-Ming Wu, Hamada Jun-Ichi†, Shuichi Mori, Jun Matsumoto‡ Japan Agency for Marine-Earth Science and Technology (JAMSTEC), Japan

and
 Fadli Syamsudin
 Agency for the Assessment and Application of Technology (BPPT), Indonesia

ABSTRACT

The world’s largest rainfall over the Indonesian maritime continent (IMC) sustaining the global climate has been explained often by the warmest seawater surrounding the IMC, but rainfall over the open ocean is less than over the islands in IMC. The solid land is heated easier than the liquid sea, but convective clouds generated over the true continents (Africa and South America) are less active than over the IMC. Our observations mainly for the recent two decades have revealed that the most dominant mode of weather over the IMC is diurnal-cycle rainfall and sea-land breeze circulation generated near a coastline by land-sea temperature contrast: solid land becomes hotter than liquid sea by solar heating in the afternoon, and opposite contrast appears before the sunrise. The latter is by infrared cooling at clear night in extratropics, but is by evening rainfall-induced sprinkler-like land cooling over the IMC. The diurnal cycle is almost unique mechanism to generate convective clouds systematically near the equator almost free from any cyclone activities, and tropical rainfall is a function of coastal distance (Ogino et al., 2016). Regional rainfall is roughly a function of coastal length/density, and the tropical rainfall sustaining the global climate is distributed over the total coastline length comparable to the equatorial circumference, which explains why the largest rainfall is over the IMC with the longest coastline length (Yamanaka, 2016). A climate model needs to resolve the equatorial coastlines and orography sufficiently. The intraseasonal, seasonal/annual and interannual climate variabilities appear as amplitude modulations of the diurnal cycles, and cause various societal/transboundary effects such as floods and forest fires-hazes. These features have been revealed in basically bilateral (Japan-Indonesia) meteorological collaborations, but will be studied under multinational interdisciplinary frameworks to improve both local disaster prevention and global climate prediction .

INTRODUCTION The earth’s climate system has the meridional maximum of cloud activity and rainfall amount (about 2,000 mm/year ≈ 5.5 mm/day) in the tropics along the equator (see Fig. 1(b)), as in a report of the Intergovernmental Panel on Climate Change (IPCC) (Randall et al., 2007). A basic study (Yoshida et al., 2005) used in this report has compared mean annual rainfall amounts in ten regions inside the tropics (see the right-hand side two columns of Table 1), and have shown that the Indonesian maritime continent (IMC; Ramage, 1968) is the region of the most active convective clouds producing the largest rainfall on the earth (around 2,700 mm/year ≈ 7 mm/day). The Central America region takes the second maximum of rainfall at least in numerical models. Rainfalls associated with the intertropical convergence zone (ITCZ) over the oceans and those over the true continents are weaker. The IMC has been playing the role of a “dam” for the global (from Pacific to Indian) ocean circulation, since 20 million years ago. In a glacial period the present Indonesian 11

International Seminar sustainable utilization of coastal resources in tropical zone, 19-20 October,2016, Bengkulu, Indonesia

Archipelago was connected to Asian and Australian continents, and the “dam” was almost closed. In an inter-glacier period such as the last 10,000 years, the IMC becomes a complex of large islands and inland seas, and the “dam” leaks warm water of the upper ocean to make a warm water pool in around the IMC (cf. Lucas et al., 1996; Gordon, 2005), which is often told as the cause of the most active convective clouds producing the largest amount of rainfall. However, the tropical atmosphere is conditionally unstable, and clouds cannot be generated by themselves spontaneously. Several mechanisms of so-called the conditional instability of the second kind (CISK) have been proposed to explain generations of tropical cyclones in subtropics (Ooyama, 1971; Lindzen, 1974) and intraseasonal variations (ISVs) along the equator (Madden and Julian, 1971, 1994; Hayashi and Sumi, 1986; Nakazawa, 1988; Nitta et al., 1992; Hashiguchi et al., 1995; Widiyatmi et al., 2001; Shibagaki et al., 2006; Zhang, 2005, 2013; Yoneyama et al., 2008, 2013; Hidayat and Kizu, 2010; Marzuki et al., 2013a), but these transient/traveling disturbances cannot explain the convective clouds/rainfalls over the IMC throughout a year. Otherwise an updraft must be forced externally.

Fig. 1. Climatological significance of the IMC (Yamanaka, 2016). Meridional (left) and global (right) distributions of (a)(d) gravity wave momentum flux (Ogino et al., 1995; Tsuda et al., 2000), (b)(e) water and (c)(f) radiation budgets (Hartmann, 1994; Randall et al., 2007; Wallace and Hobbs, 2006). (b) shows both precipitation and evaporation, but (e) shows precipitation only (Xie and Arkin, 1997). (c) shows solar irradiance and infrared radiation, whereas (f) shows temperatures of cloud, land and sea surfaces.

Table. 1. Ten tropical regions specified in a basic study (Yoshida et al., 2005) to check the reliability of a numerical climate model used for the IPCC report (Randall et al., 2007). Land areas and coastline 12

International Seminar sustainable utilization of coastal resources in tropical zone, 19-20 October,2016, Bengkulu, Indonesia

lengths were estimated by calculating numbers of 1° longitude × 1° latitude (corresponding to 111 km × 111 km on the equator) grid points close to coastlines within 0.5°. Observed and simulated annual rainfall amounts were obtained from figures of the original paper.

We have carried out observations over the IMC for three (mainly recent two) decades (Yamanaka et al., 2008; Yamanaka, 2016). Two systematic periodical (annual and diurnal) cycles forced astronomically and the other hardly predictable components (ISVs and interannual variations) have been observed (see Fig. 2). The annual cycles of rainy (monsoon) and dry seasons are less clear in the IMC than in adjacent regions such as Indochina (Murakami and Matsumoto, 1994), and are inhomogeneous: the seasonal march in the southern hemispheric part (Jawa and Bali) has a southern-hemispheric annual cycle (a clear rainfall maximum in southern summer) (Hamada et al., 2002; Aldrian and Susanto, 2003). The equatorial and northern-hemispheric parts are semiannual (with double peaks near equinox seasons), northern-hemispheric annual (one peak in northern summer), or unclear. The semiannual cycle is reasonable if we consider that the sun passes the zenith, when the solar radiation becomes maximum, twice a year. So the rainfall over the IMC is sensitive to the solar radiation. – Is it truly all right? Why stronger solar radiation in rainy/cloudy season? Why so southern-hemispheric in low-latitude Jawa and Bali? Here we provide a brief overview (see Yamanaka, 2016, for details) on the physical climatology of the IMC reason. Section 2 shows the diurnal cycle near coastlines which is the dominant mode over the IMC. Section 3 explains why the largest rainfall appears over the IMC. Section 4 gives interdisciplinary importance of such climatological features over the IMC and brief introduction of recent observational approaches as conclusion.

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International Seminar sustainable utilization of coastal resources in tropical zone, 19-20 October,2016, Bengkulu, Indonesia

Fig. 2. Spectral analysis of 14-year hourly geostationary meteorological satellite infrared radiometer (GMS-IR) cloud top temperature (Yamanaka, 2016). Zonal wavenumber spectra (left) are for 90oE‒ 150oW longitude range at every 5o latitude around the equator. Frequency spectra (middle) are for five locations at every 20o longitude in 100o‒180oE along the equator, and are plotted geographically (right) for 6 h–2 year components.

Diurnal hydrologic cycle around coastlines The most dominant periodicity of the solar radiation is diurnal, and sea-land heat capacity contrasts enforce local diurnal variations in wind, clouds and rainfall, which have been known in Batavia (now Jakarta) since a century ago (van Bemmelen, 1922). We have confirmed them everywhere along coastal zones of larger islands (Sumatera, Kalimantan, Jawa, Sulawesi, and Papua) of the IMC, based on wind profilers (including raindrop measurements) (Hashiguchi et al., 1995; Renggono et al., 2001; Hadi et al., 2002; Murata et al., 2002; Araki.et al., 2006; Marzuki et al., 2009; Tabata et al., 2011), weather radars (Kawashima et al., 2006, 2011; Wu et al., 2007, 2013; Sakurai et al., 2009, 2011; Mori et al., 2011; Kamimera et al., 2012), a satellite-borne weather radar (Mori et al., 2004; Wu et al., 2008a), and GPS (precipitable water or moisture) (Wu et al., 2003, 2008b), and infrared (cloud-top temperature) observation satellite (Hendon and Woodberry, 1993; Nitta and Sekine, 1994; Ohsawa et al., 2001; Sakurai et al., 2005; Hamada et al., 2008).

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International Seminar sustainable utilization of coastal resources in tropical zone, 19-20 October,2016, Bengkulu, Indonesia

Fig. 3. Hovmӧller diagrams along the direction shown in (a), concerning diurnal-cycle migrations of rainfalls by (b) 3-year TRMM observation (Mori et al., 2004) and by (c) a global high-resolution numerical model simulation (Arakawa and Kitoh, 2005).

Fig. 4. Observations of development of a convective cloud system at the western coast of Sumatera shown in (a). (b) Horizontal and (c) vertical displays of rainfalls (contours) and winds (arrows) observed with dual X-band Doppler radars installed at Tiku and MIA indicated in (b) (Sakurai et al., 2011), and (d) strong gust observed with surface anemometer (Kawashima et al., 2011).

Based on radar observations in Sumatera and Jawa (e.g., Wu et al., 2007, 2013; Sakurai et al., 2009, 2011), the rainfall intensity with a typical precipitating cloud system is stronger than 10 mm/h only in a small migrating area of (10 km) 2, which has an echo top 15

International Seminar sustainable utilization of coastal resources in tropical zone, 19-20 October,2016, Bengkulu, Indonesia

of about 10 km and covers a station only within an hour. Thus the liquid water content of such a developed cloud system is estimated very roughly as 1ton/m3 ×[10mm×(10km)2]/(10km)3 ≈ 1×10–6 ton/m3 ≈ 1g/m3, which is somewhat larger than typical values (0.5 g/m3) for oceanic convective clouds. For a broader area around it, however, rainfall intensities are around 1 mm/h, and such weaker rainfalls are observed at a station for about 10 hours from evening until next morning, or a daily rainfall amount of about 10 mm/day, which is close to the regional-mean annual-mean value 2,700 mm/year ≈ 7 mm/day. Therefore, the annual rainfall amount over the IMC in average is almost explained by such typical diurnal-cycle clouds generated along the coastlines every day. We may consider a very rapid water cycle near the IMC coastline (Fig. 5(a)), although such a hydrologic cycle is considered to be balanced in annual time scale in middle and high latitudes. If so, a liquid water transport by river from land to sea should be approximately balanced with water vapor transport by sea breeze from sea to land. As shown in Fig. 5(b), we have confirmed that Ciliwung river in West Jawa has a diurnal cycle (Sulistyowati et al., 2014). Furthermore, as shown in Fig. 5(c) for example, we have found a diurnal cycle also in the biosphere and humanosphere, which are also concentrated near the coastline.

Fig. 5. (a) Schematic diurnal hydrologic cycle near the coastline of the IMC (Yamanaka, 2016), based on rainfall observations in Sumatera (Mori et al., 2004; Wu et al., 2009) and Kalimantan (Wu et al., 2008a). (b) Diurnal cycle observed at a river in west Jawa (Sulistyowati et al., 2014). (c) Diurnal cycle of flying animals (probably bats, according to late Prof. Inoue of Kyoto University) observed as non-atmospheric echoes of a wind profiler at Serpong (analized by a Singaporean student as his BEng thesis at Kyoto University) for dry and rainy seasons.

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International Seminar sustainable utilization of coastal resources in tropical zone, 19-20 October,2016, Bengkulu, Indonesia

Why Indonesia has world’s largest rainfall The predominance of diurnal cycles in the tropical coastal zones is reasonable, because they are almost unique systematic mechanism to generate convective clouds near the equator free from any cyclone activities. In middle and high latitudes a diurnal cycle dominates only on clear days, whereas in the IMC and probably many other tropical regions this cycle dominates in the rainy season. Such a tropical diurnal cycle is the life (or migration) cycle of cloud systems generated over mountain slopes hotter than coastal plains in the afternoon, developed on (or migrated toward) the plain in the evening, and extinguished (or displaced beyond the coastline) after strong rainfall before sunrise. The land surface and air are cooled by the strong rainfall in the night. In the morning the sky is very clear over the land, and strong solar radiation due to the highest solar elevation (occurring in the rainy season) heats up the land surface, which re-generates the active convective cloud system in the subsequent afternoon. Radar and satellite observations have shown that the characteristic horizontal scale of the diurnal cycle areas is of the order of some hundreds of kilometers (Figs. 2−4), which looks somewhat broader than typical values in middle latitudes. Clouds and precipitation are concentrated in a narrower updraft/convergence zone of the sea-land breeze circulation cell, but their daylong migrations provide rainfall in each place over the whole diurnal-cycle area at different local time: mainly on land in the evening, and on the sea in the morning. As shown in Fig. 6 (left lower panel), local rainfall is a function of coastal distance: 25% of the total tropical rainfall and all of areas with > 3,000 mm/year are distributed within 300 km from coastline (Ogino et al., 2016). The characteristic scale 300 km is also found in the spectral analysis of cloud activity (see the left panel of Fig. 2), suggesting a sink of energy/enstrophy (cf. Gage and Nastrom, 1986) if it is related to horizontal flow field (e.g., convergence below the cloud bottom). For an island smaller than this horizontal scale, the diurnal cycle of sea-land circulations along the coastline is suppressed, which is consistent with theoretical and numerical studies (cf. Niino et al., 2006; Takasuka et al., 2015, for local and global models, respectively). In smaller islands neighboring larger islands within about 100 km, such as Siberut near Sumatera (Wu et al., 2003; Kamimera et al., 2012) and Biak near Papua (Tabata et al., 2011b) there are two peaks due to diurnal cycles of both islands (night and morning by small and large islands, respectively) .

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International Seminar sustainable utilization of coastal resources in tropical zone, 19-20 October,2016, Bengkulu, Indonesia

Fig. 6. Geographical distributions of local AM-PM differences of about 13-year TRMM-PR rainfall data over tropical regions (upper three panels), and histograms of rainfall amount plotted as a function of coastline distance (bottom left) (Ogino et al., 2016). The right bottom panel shows a relationship between coastline length (divided by land area, in 100 km resolution) and observed/simulated rainfall for the ten low-latitude regions listed in Table 1 (Yamanaka, 2016).

Furthermore we hypothesize that the annual rainfall amount for a region may be approximately given by the number of clouds along the coastline, that is, the length of coastline divided by 100 km. Although it has been known that the coastline length is dependent on the resolution of measurement (Mandelbrot, 1967), we have measured the lengths of coastlines for the ten regions listed in Table 1 with a resolution of 100 km or 1° in latitude (and also in longitude near the equator), and the land area surrounded by such smoothed coastlines. The results are shown in columns on centered two columns of Table 1. Plotting the data in a diagram of annual rainfall amounts vs. coastline length divided by land area (see right lower panel of Fig. 6), we obtain a roughly linear relationship: Annual rainfall [mm/year]
≈ 2000 [mm/year · 102 km] × Coastline length [102 km] / Land area [104 km2] at least for eight regions except for Amazonia and Central Africa. The factor 2000 mm/year looks somewhat larger than the coastline peak 1300 mm/year in the TRMM analysis (left lower panel of Fig. 6), which should be reconsidered after analyzing the regional rainfalls from the TRMM data. Note that 2000 mm/year ≈ 5.5 mm/day, which is very close to the zonal-mean value around the equator (see Fig. 1(b)), suggesting that major rainfalls in the equatorial region occurs near the coastlines. Steep slopes between high mountain ranges and low swampy basins also may produce diurnal variations with mountain-valley breeze-like circulations. In the IMC mountains of 18

International Seminar sustainable utilization of coastal resources in tropical zone, 19-20 October,2016, Bengkulu, Indonesia

major islands are not so low (reaching 3,000 m or higher) but close to the coastlines, so that the mountain-valley breezes are not separated from the sea-land breezes. However, inland regions of the true continents may have diurnal cycles of mountain-valley type completely separated from the coastlines. Thus, if we take such steep slope effects into account and correct the coastline length by adding the lengths of contour lines of appropriate altitudes, we may obtain a corrected result in which the data plots for Amazonia and Central Africa also approach to the linear relationship. Detailed local rainfall variability due to orography over the IMC has been started with dense mesoscale rain gauge network with daily-pentad (so no diurnal-cycle resolvable) sampling (Hamada et al., 2008), and raindrop size disdrometers (Marzuki et al., 2013b) or wind profilers (Tabata et al., 2011a,b) with high time resolutions at almost isolated stations. For local orographic effects on the diurnal-cycle rainfalls (and winds) we need to analyze meteorological Doppler radar data (including many BMKG operational stations) more precisely in the next step. The results described here suggest that a numerical model need to resolve the equatorial coastlines in a sufficiently high resolution (<< 100 km). A high resolution model (20 km mesh) has been used to show diurnal cycles over the IMC at present and in future, suggesting that they will be weakened mainly due to nighttime land temperature increase associated with global warming (Kitoh and Arakawa, 2005). Another much higher resolution model (7 and 3.5 km grids) has shown a precise simulation on equatorial cloud behaviors causing a flood in the Malay Peninsula adjacent to the IMC (Miura et al., 2007).

CONCLUSION Interactions of the multi-scale (diurnal and other) phenomena often work to generate extreme weathers causing disasters such as floods and droughts. The IMC modifies larger-scale phenomena to lead abnormal weathers affecting societies over the world. A typical example is El Niño which causes less rainfall (because lower sea surface temperature makes morning maritime convection weaker) (Hamada et al., 2002, 2012; Aldrian and Susanto, 2003; Hashiguchi et al., 2006; Lestari et al., 2016; As-syakur et al., 2016) and forest fires over IMC, and they induce transboundary haze and global abnormal climate. In the opposite phase La Niña Jakarta had large rainfalls and floods, when monsoon (clod surge) and/or ISV enhanced the diurnal cycle (Wu et al., 2007, 2013). The long historical meteorological records of Indonesia have been started to be analyzed by Indonesian scientists (Siswanto et al., 2016; Yanto et al., 2016; Supari et al., 2016), which will clarify features and mechanisms of the multi-scale interactions more clearly. Agricultural applications of climatological studies (Hidayat et al., 2016; Marjuki et al., 2016) are requested strongly from the Indonesian government and society. Interdisciplinary studies with hydrology and oceanography are also being grown, although we do not describe them in this article. The importance of diurnal cycle described in this paper has been established in two bilateral (Japan-Indonesia) collaboration projects constructing a radar network called 19

International Seminar sustainable utilization of coastal resources in tropical zone, 19-20 October,2016, Bengkulu, Indonesia

Hydrometeorological Array for Interaseasonal Variation-Monsoon Automonitoring (HARIMAU; 2005-10; Yamanaka et al., 2008) and a prototype institute called Maritime Continent Center of Excellence (MCCOE; 2009-14). Now we understand that such high-resolution observations/models over IMC are truly necessary in order to improve both local disaster prevention and global climate prediction. In the next step called Years of the Maritime Continent (YMC; 2017-9) Indonesia as a G20 country should keep observations under more completely multinational framework (see YMC websites).

ACKNOWLEDGMENTS We thank Dr. Kunio Yoneyama for his supervision and encouragement concerning researches toward the YMC and on our submission of this paper to the international seminar at Bengkulu on October 19-20, 2016. The YMC websites at BMKG and JAMSTEC are maintained/updated by Ms. Nurhayati and Dr. Yoneyama, respectively.

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https://www.researchgate.net/publication/29624770 Sakurai, N., F. Murata, M. D. Yamanaka, H. Hashiguchi, S. Mori, J.-I. Hamada, Y.-I. Tauhid, T. Sribimawati and B. Suhardi, 2005: Diurnal cycle of migration of convective cloud systems over Sumatera Island. J. Meteor. Soc. Japan, 83, 835– 850. http://doi.org/10.2151/jmsj.83.835 Sakurai, N., M. Kawashima, Y. Fujiyoshi, H. Hashiguchi, T. Shimomai, S. Mori, Hamada J.-I., F. Murata, M. D. Yamanaka, Y. I. Tauhid, T. Sribimawati, and B. Suhardi, 2009: Internal structures of migratory cloud systems with diurnal cycle over Sumatera Island during CPEA-I campaign. J. Meteor. Soc. Japan, 87, 157-170. http://doi.org/10.2151/jmsj.87.157 Sakurai, N., S. Mori, M. Kawashima, Y. Fujiyoshi, J-I. Hamada, S. Shimizu, H. Fudeyasu, Y. Tabata, W. Harjupa, H. Hashiguchi, M. D. Yamanaka, J. Matsumoto, Emrizal and F. Syamsudin, 2011: Migration process and 3D wind field of precipitation systems associated with a diurnal cycle in west Sumatera: Dual Doppler radar analysis during the HARIMAU2006 campaign. J. Meteor. Soc. Japan, 89, 341-361. http://doi.org/10.2151/jmsj.2011-404 Shibagaki, Y., T. Shimomai, T. Kozu, S. Mori, Y. Fujiyoshi, H. Hashiguchi, M. K. Yamamoto, S. Fukao and M. D. Yamanaka, 2006: Multi-scale convective systems associated with an intraseasonal oscillation over the Indonesian maritime continent. Mon. Wea. Rev., 134, 1682–1696. http://dx.doi.org/10.1175/MWR3152.1 Siswanto, S., G. J. van Oldenborgh, G. van der Schrier, R. Jilderda and B. van den Hurk, B., 2016: Temperature, extreme precipitation, and diurnal rainfall changes in the urbanized Jakarta city during the past 130 years. Int. J. Climatol., 36, 3207–3225. https://www.researchgate.net/publication/284723104 Sulistyowati, R., R. I. Hapsari, F. Syamsudin, S. Mori, S. T. Oishi and M. D. Yamanaka, 2014: Rainfall-driven diurnal variations in the Ciliwung River, West Jawa, Indonesia. SOLA, 10, 141−144. http://doi.org/10.2151/sola.2014-029 Supari, F. Tangang, L. Juneng and E. Aldrian, 2016: Observed changes in extreme temperature and precipitation over Indonesia. Int. J. Climatol.. doi: 10.1002/joc.4829 http://onlinelibrary.wiley.com/doi/10.1002/joc.4829/full Tabata, Y., H. Hashiguchi, M. K. Yamamoto, M. Yamamoto, M. D. Yamanaka, S. Mori, F. Syamsudin and T. Manik, 2011a: Lower tropospheric horizontal wind over Indonesia: A comparison of wind-profiler network observations with global reanalyses. J. Atmos. Solar Terr. Phys., 73, 986−995. https://www.researchgate.net/publication/235222454 Tabata, Y., H. Hashiguchi, M. K. Yamamoto, M. Yamamoto, M. D. Yamanaka, S. Mori, F. Syamsudin, and T. Manik, 2011b: Observational study on diurnal precipitation cycle in equatorial Indonesia using 1.3-GHz wind profiling radar network and TRMM precipitation radar, J. Atmos. Solar Terr. Phys., 73, 1031−1042. https://www.researchgate.net/publication/229377917 Takasuka, D., T. Miyakawa, M. Satoh and H. Miura, 2015: Topographical effects on internally produced MJO-like disturbances in an aqua-planet version of NICAM. SOLA, 11, 170-176. http://doi.org/10.2151/sola.2015-038 Tsuda, T., M. Nishida, C. Rocken and R. H. Ware, 2000: A global morphology of gravity wave activity in the stratosphere revealed by the GPS occultation data (GPS/MET). J. Geophys. Res., 105, 7257–7273. http://nldr.library.ucar.edu/repository/assets/osgc/OSGC-000-000-001-369.pdf van Bemmelen, W., 1922: Land- und seebrise in Batavia. Beitr. Phys. Frei. Atmos., 10, 169-177. http://aoe.scitec.kobe-u.ac.jp/~mdy/library/papers/vanBemmelen1922BPfA.pdf 24

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Wallace, J. M., and Hobbs, P. V., 2006: Atmospheric Science: An Introductory Survey (2nd Ed.). Academic Press, 483pp. http://www.iiserpune.ac.in/~p.subramanian/Atmospheric_Science-Wallace_Hobbs. pdf Widiyatmi, I., H. Hashiguchi, S. Fukao, M. D. Yamanaka, S.-Y. Ogino, K. S. Gage, S. W. B. Harijono, S. Diharto and H. Djojodihardjo, 2001: Examination of 3-6 day disturbances over equatorial Indonesia based on boundary layer radar observations during 1996-1999 at Serpong, Biak and Bukittinggi. J. Meteor. Soc. Japan, 79, 317-331. http://doi.org/10.2151/jmsj.79.317 Wu, P.-M., J.-I. Hamada, S. Mori, Y. I. Tauhid, M. D. Yamanaka and F. Kimura, 2003: Diurnal variation of precipitable water over a mountaneous area in Sumatera Island. J. Appl. Meteor., 42, 1107-1115. http://dx.doi.org/10.1175/1520-0450(2003)042<1107:DVOPWO>2.0.CO;2 Wu, P.-M., M. Hara, H. Fudeyasu, M. D. Yamanaka, J. Matsumoto, F. Syamsudin, R. Sulistyowati and Y. S. Djajadihardja, 2007: The impact of trans-equatorial monsoon flow on the formation of repeated torrential rains over Java Island. SOLA, 3, 93-96. http://doi.org/10.2151/sola.2007-024 Wu, P.-M., M. D. Yamanaka and J. Matsumoto, 2008a: The formation of nocturnal rainfall offshore from convection over western Kalimantan (Borneo) Island. J. Meteor. Soc. Japan, 86A, 187-203. http://doi.org/10.2151/jmsj.86A.187 Wu, P.-M., S. Mori, J.-I. Hamada, M. D. Yamanaka, J. Matsumoto and F. Kimura, 2008b: Diurnal variation of rainfall and precipitable water over Siberut Island off the western coast of Sumatera Island. SOLA, 4, 125–128. http://doi.org/10.2151/sola.2008-032 Wu, P.-M., M. Hara, J.-I. Hamada, M. D. Yamanaka and F. Kimura, 2009: Why heavy rainfall occurs frequently over the sea in the vicinity of western Sumatera Island during nighttime. J. Appl. Meteor. Climatol., 48, 1345–1361. https://www.researchgate.net/publication/235222352 Wu, P.-M., A. A. Arbain, S. Mori, Hamada J.-I., M. Hattori, F. Syamsudin and M. D. Yamanaka, 2013: The effects of an active phase of the Madden-Julian oscillation on the extreme precipitation event over western Jawa Island in January 2013. SOLA, 9, 79-83. http://doi.org/10.2151/sola.2013-018 Xie, P., and P. A. Arkin, 1997: Global precipitation: A 17-year monthly analysis based on gauge observations, satellite estimates, and numerical model outputs. Bull. Amer. Meteor. Soc., 78, 2539–2558. http://dx.doi.org/10.1175/1520-0477(1997)078<2539:GPAYMA>2.0.CO;2 Yamanaka, M. D., 2016: Physical climatology of Indonesian maritime continent: An outline to comprehend observational studies. Atmos. Res., 178-179, 231-259. http://doi.org/10.1016/j.atmosres.2016.03.017 Yamanaka, M. D., S. Mori, Wu P.-M., Hamada J.-I., N. Sakurai, H. Hashiguchi, M. K. Yamamoto, Y. Shibagaki, M. Kawashima, Y. Fujiyoshi, T. Shimomai, T. Manik, Erlansyah, W. Setiawan, B. Tejasukmana, F. Syamsudin, Y. S. Djajadihardia, and J. T. Anggadiredja, 2008: HARIMAU radar-profiler network over Indonesian maritime continent: A GEOSS early achievement for hydrological cycle and disaster prevention. J. Disaster Res., 3, 78–88. https://www.researchgate.net/publication/235009524 Yanto, B. Rajagopalan and E. Zagona, 2016: Space–time variability of Indonesian rainfall at inter-annual and multi-decadal time scales. Clim. Dyn., first online: 30 January 2016. http://link.springer.com/article/10.1007/s00382-016-3008-8. Yoneyama, K., Y. Masumoto, Y. Kuroda, M. Katsumata, K. Mizuno, Y. N. Takayabu, M. 25

International Seminar sustainable utilization of coastal resources in tropical zone, 19-20 October,2016, Bengkulu, Indonesia

Yoshizaki, A. Shareef, Y. Fujiyoshi, M. J. McPhaden, V. S. N. Murty, R. Shirooka, K. Yasunaga, H. Yamada, N. Sato, T. Ushiyama, Q. Moteki, A. Seiki, M. Fujita, K. Ando, H. Hase, I. Ueki, T. Horii, C. Yokoyama and T. Miyakawa, 2008: MISMO field experiment in the equatorial Indian Ocean. Bull. Amer. Meteor. Soc., 89, 1889-1903. http://www.jamstec.go.jp/res/ress/yoneyamak/PDFs/Yoneyama-etal_2008_BAMS. pdf Yoneyama, K., C. Zhang and C. N. Long, 2013: Tracking pulses of the Madden–Julian oscillation. Bull. Amer. Meteor. Soc., 94, 1871– 1891. http://www.jamstec.go.jp/res/ress/yoneyamak/PDFs/Yoneyama-etal_2013_BAMS. pdf Yoshida, Y., K. Maruyama, J. Tsutsui, N. Nakashiki, F. O. Bryan, M. Blackmon, B. A. Boville and R. D. Smith, 2005: Multi-century ensemble global warming projections using the Community Climate System Model (CCSM3). J. Earth Simulator, 3, 2-10. http://www.jamstec.go.jp/esc/publication/journal/jes_vol.3/pdf/JES3-21yoshida.pdf YMC (Years of the Maritime Continent) websites: http://www.bmkg.go.id/ymc/ http://www.jamstec.go.jp/ymc/ Zhang, C., 2005: Madden-Julian oscillation. Rev. Geophys., 43, RG2003, doi:10.1029/2004RG000158. https://www.rsmas.miami.edu/users/czhang/publications/MJOrev.pdf
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