oxygen in the water), creating ecosystems with high carbon reservoirs called tropical
peatlands.
The Indonesian Maritime Continent (IMC) The IMC was one of the most
important regions for hydroclimate studies of the Monsoon Asian
HydroÀAtmosphere Scientific Research and Prediction Initiative (MAHASRI;
2006–2016) and the Asian Monsoon Years (AMY; 2007–2012) program in the
World Climate Research Programme (WCRP) (Matsumoto et al. 2016, 2017;
Yamanaka et al. 2016) (Fig. 6.4). This is simply because the IMC has the world’s
largest regional rainfall but has no sufficiently reliable observation network.
Geographical rainfall distributions with meridional peaks of approximately
2000 mm/year in the tropics are also estimated from satellite cloud observations
and simulated by numerical climate models. For example, Fig. 6.4 (right) shows a
simulated rainfall map from a report by the Intergovernmental Panel on Climate
Change (IPCC) (Randall et al. 2007), although the peak values displayed are
somewhat larger than the direct rainfall observations from rain gauges and radars.
A study related to the IPCC report (Yoshida et al. 2005) compared these estimates
and simulations (the Community Climate System Model version 3 (CCSM3);
Collins et al. 2006) of the mean annual rainfall in various regions, 10 of which are
in the tropics. The IMC is the region with the most active convective clouds,
producing the largest regional rainfall on earth (approximately 2700 mm/year %
7 mm/day). The second highest regional rainfall is found in Central America.
The world’s largest regional rainfall, which occurs over the IMC, has often been
explained in terms of the seawater surrounding the IMC, which is the warmest
(Fig. 6.4, right); this seawater functions similarly to a dam for the global movement
of Indonesian throughflow from the Pacific to the Indian Oceans (e.g., Lukas et al.
1996; Gordon 2005). However, the amount of rainfall over the open ocean, including the ITCZ, is less than that over the islands in the IMC. The tropical atmosphere is
conditionally unstable; convection is developed only when clouds appear, whereas
clouds are generated when convection develops. This paradoxical situation may be
overcome over the open ocean by conditional instability of the second kind (CISK),
which generates tropical cyclones in the subtropics and intraseasonal variations
(ISVs) along the equator (Ooyama 1971; Lindzen 1974; Hayashi and Sumi 1986).
Tropical cyclones generally appear outside the IMC.
El Niño–Southern Oscillation (ENSO) and Indian Ocean Dipole (IOD) Mode It
is assumed that the Maritime Continent is one of the key meteorological elements
that form tropical peatlands in Southeast Asia. The boundary of the Maritime
Continent is usually the tropical warm pool (TWP); however, when El Niño events
occur, with a warm ocean current off the coast of Peru, the ocean temperature in the
Maritime Continent decreases due to the rising cool sublayer currents, causing
evaporation from the seawater to decrease drastically (Fig. 6.4, left). The boundary
of the Maritime Continent is 2000 km off the coast of Peru; however, it is hypothesized that the Maritime Continent boundary and the area off the coast of Peru are
directly linked. This is generally confirmed by the decrease in the precipitation rate
6 Natural Capital-Based Societies in the Tropics
201
peatlands.
The Indonesian Maritime Continent (IMC) The IMC was one of the most
important regions for hydroclimate studies of the Monsoon Asian
HydroÀAtmosphere Scientific Research and Prediction Initiative (MAHASRI;
2006–2016) and the Asian Monsoon Years (AMY; 2007–2012) program in the
World Climate Research Programme (WCRP) (Matsumoto et al. 2016, 2017;
Yamanaka et al. 2016) (Fig. 6.4). This is simply because the IMC has the world’s
largest regional rainfall but has no sufficiently reliable observation network.
Geographical rainfall distributions with meridional peaks of approximately
2000 mm/year in the tropics are also estimated from satellite cloud observations
and simulated by numerical climate models. For example, Fig. 6.4 (right) shows a
simulated rainfall map from a report by the Intergovernmental Panel on Climate
Change (IPCC) (Randall et al. 2007), although the peak values displayed are
somewhat larger than the direct rainfall observations from rain gauges and radars.
A study related to the IPCC report (Yoshida et al. 2005) compared these estimates
and simulations (the Community Climate System Model version 3 (CCSM3);
Collins et al. 2006) of the mean annual rainfall in various regions, 10 of which are
in the tropics. The IMC is the region with the most active convective clouds,
producing the largest regional rainfall on earth (approximately 2700 mm/year %
7 mm/day). The second highest regional rainfall is found in Central America.
The world’s largest regional rainfall, which occurs over the IMC, has often been
explained in terms of the seawater surrounding the IMC, which is the warmest
(Fig. 6.4, right); this seawater functions similarly to a dam for the global movement
of Indonesian throughflow from the Pacific to the Indian Oceans (e.g., Lukas et al.
1996; Gordon 2005). However, the amount of rainfall over the open ocean, including the ITCZ, is less than that over the islands in the IMC. The tropical atmosphere is
conditionally unstable; convection is developed only when clouds appear, whereas
clouds are generated when convection develops. This paradoxical situation may be
overcome over the open ocean by conditional instability of the second kind (CISK),
which generates tropical cyclones in the subtropics and intraseasonal variations
(ISVs) along the equator (Ooyama 1971; Lindzen 1974; Hayashi and Sumi 1986).
Tropical cyclones generally appear outside the IMC.
El Niño–Southern Oscillation (ENSO) and Indian Ocean Dipole (IOD) Mode It
is assumed that the Maritime Continent is one of the key meteorological elements
that form tropical peatlands in Southeast Asia. The boundary of the Maritime
Continent is usually the tropical warm pool (TWP); however, when El Niño events
occur, with a warm ocean current off the coast of Peru, the ocean temperature in the
Maritime Continent decreases due to the rising cool sublayer currents, causing
evaporation from the seawater to decrease drastically (Fig. 6.4, left). The boundary
of the Maritime Continent is 2000 km off the coast of Peru; however, it is hypothesized that the Maritime Continent boundary and the area off the coast of Peru are
directly linked. This is generally confirmed by the decrease in the precipitation rate
6 Natural Capital-Based Societies in the Tropics
201