Cresswell et al., 1993; Hirst and Godfrey, 1993;
MacDonald, 1993; Toole and Warren, 1993;
Molcard et al., 1994, 1996, 2001; Miyama et al.,
1995; Godfrey, 1996; Gordon et al., 1997, 1999a;
Potemra et al., 1997; Shriver and Hurlburt, 1997;
Gordon and McClean, 1999; Gordon and Susanto,
1999; Potemra, 1999).
As part of the US–Indonesian Arlindo programme, velocity and temperature were measured
at various depths at two moorings within a 45-km
wide constriction of the Makassar Strait near 3°S
between December 1996 and June 1998 (Gordon
et al., 1998a, 1999a; Gordon and Susanto, 1999;
Ffield et al., 2000). The 1997 average southward
transport with Makassar Strait is 9.3 Sv, with a
range of about <2.5 Sv depending on how the
surface flow is taken into account (Gordon et al.,
1999a). Temperature and salinity data obtained
during the Arlindo cruises (five cruises from 1991
to 1998) indicate there is no return to the Pacific
Ocean of Makassar North Pacific-derived thermocline water along a route east of Sulawesi Island
(Gordon and Fine, 1996; A. Gordon and R. Fine,
personal communication; in fact during the La
Niña condition of December 1996, a time of
strong ITF, see Section 4.7.3.4, additional North
Pacific thermocline water may enter the Banda Sea
from the north).
Measurements in the Lombok Strait (Murray
and Arief, 1988; Murray et al., 1989) from January 1985 to January 1986 show an average transport of 1.7 Sv, with a maximum of 4.0 Sv towards
the Indian Ocean during July and August, and less
than 1 Sv from December 1985 to January 1986.
The mean transport between the sea surface and
1250 m in the Timor Passage (between Timor and
Australia) measured from March 1992 to April
1993 is 4.3 Sv (Molcard et al., 1996). Cresswell
et al. (1993) using CTD and ADCP sections
obtained in October 1987 and March 1988 across
Timor Passage find 7 Sv flowing towards the
Indian Ocean. Molcard et al. (2001) find a range
of transport within Ombai Strait (north of Timor,
between Timor and Alor Island) during 1996
(December 1995 to December 1996) of 3–6 Sv,
depending on the assumed cross-strait shear.
While caution is urged as these time series measurements were made at different times and ENSO
phases, Makassar Strait transport is comparable to
the transport sum of 10.5 Sv through the passages
of the Lesser Sunda Island chain.
The various streams of the ITF merge to enter
the South Equatorial Current of the Indian Ocean.
Within the upper 400 m passing across a section
between Java and Australia, the ITF is estimated
from 1983 to 1989 XBT data (Meyers et al., 1995;
Meyers, 1996) to be 5 Sv, with a 12 Sv August–
September maximum, and near zero transport in
May–June and again in October–November.
Quadfasel et al. (1996) find that of the 22 Sv transport within the upper 470 m of the South Equatorial Current in the eastern Indian Ocean in October
1987, approximately 9 Sv is derived from the ITF.
Gordon et al. (1997), using five meridional WOCE
sections in the Indian Ocean, find that the Indian
Ocean South Equatorial Current transfers on average 9 Sv of Indonesian Throughflow water westward within the Indian Ocean. Fieux et al. (1994,
1996) find 18 Sv passing into the Indian Ocean
between Java and Australia in August 1989 and
2.6 Sv headed eastward in February 1992. The
Indian Ocean South Equatorial Current estimates
support an ITF transport of 10 Sv.
Inverse (and related) solutions also suggest mean
values for the ITF transport. Piola and Gordon
(1984) find 14 Sv, while Toole and Warren (1993)
deduce a throughflow of 6.7 Sv. Robbins and
Toole (1997), using the same data as Toole and
Warren but with a silica constraint, find a ITF
transport of 9.9 Sv. MacDonald and Wunsch
(1996) arrive at a ITF of 7 Sv with a global inverse
solution. de las Heras and Schlitzer (1999) calculate the ITF as 13.2 Sv. Ganachaud (1999) finds a
ITF of 15<3 Sv.
4.7.3.3 ITF and ENSO
Observational and model studies suggest the ITF
transport sways in tune with ENSO: larger transport during La Niña condition, smaller transport
during El Niño (Kindle et al., 1989; Bray et al.,
1996; Fieux et al., 1996; Gordon and Fine, 1996;
Meyers, 1996; Potemra et al., 1997). The highresolution POP model (Gordon and McClean, 1999)
yields a 12 Sv annual average during La Niña and
4 Sv average during El Niño. The Arlindo mooring
observations within the Makassar Strait, which
span the entire cycle of the strong 1997/1998 El
Niño, find a correlation (r:0.73) between Makassar transport and ENSO (Gordon et al., 1999a;
though the time-series is far too short to say this
with assurance). During the El Niño months
December 1997 to February 1998 the transport
SECTION 4 THE GLOBAL FLOW FIELD
308
MacDonald, 1993; Toole and Warren, 1993;
Molcard et al., 1994, 1996, 2001; Miyama et al.,
1995; Godfrey, 1996; Gordon et al., 1997, 1999a;
Potemra et al., 1997; Shriver and Hurlburt, 1997;
Gordon and McClean, 1999; Gordon and Susanto,
1999; Potemra, 1999).
As part of the US–Indonesian Arlindo programme, velocity and temperature were measured
at various depths at two moorings within a 45-km
wide constriction of the Makassar Strait near 3°S
between December 1996 and June 1998 (Gordon
et al., 1998a, 1999a; Gordon and Susanto, 1999;
Ffield et al., 2000). The 1997 average southward
transport with Makassar Strait is 9.3 Sv, with a
range of about <2.5 Sv depending on how the
surface flow is taken into account (Gordon et al.,
1999a). Temperature and salinity data obtained
during the Arlindo cruises (five cruises from 1991
to 1998) indicate there is no return to the Pacific
Ocean of Makassar North Pacific-derived thermocline water along a route east of Sulawesi Island
(Gordon and Fine, 1996; A. Gordon and R. Fine,
personal communication; in fact during the La
Niña condition of December 1996, a time of
strong ITF, see Section 4.7.3.4, additional North
Pacific thermocline water may enter the Banda Sea
from the north).
Measurements in the Lombok Strait (Murray
and Arief, 1988; Murray et al., 1989) from January 1985 to January 1986 show an average transport of 1.7 Sv, with a maximum of 4.0 Sv towards
the Indian Ocean during July and August, and less
than 1 Sv from December 1985 to January 1986.
The mean transport between the sea surface and
1250 m in the Timor Passage (between Timor and
Australia) measured from March 1992 to April
1993 is 4.3 Sv (Molcard et al., 1996). Cresswell
et al. (1993) using CTD and ADCP sections
obtained in October 1987 and March 1988 across
Timor Passage find 7 Sv flowing towards the
Indian Ocean. Molcard et al. (2001) find a range
of transport within Ombai Strait (north of Timor,
between Timor and Alor Island) during 1996
(December 1995 to December 1996) of 3–6 Sv,
depending on the assumed cross-strait shear.
While caution is urged as these time series measurements were made at different times and ENSO
phases, Makassar Strait transport is comparable to
the transport sum of 10.5 Sv through the passages
of the Lesser Sunda Island chain.
The various streams of the ITF merge to enter
the South Equatorial Current of the Indian Ocean.
Within the upper 400 m passing across a section
between Java and Australia, the ITF is estimated
from 1983 to 1989 XBT data (Meyers et al., 1995;
Meyers, 1996) to be 5 Sv, with a 12 Sv August–
September maximum, and near zero transport in
May–June and again in October–November.
Quadfasel et al. (1996) find that of the 22 Sv transport within the upper 470 m of the South Equatorial Current in the eastern Indian Ocean in October
1987, approximately 9 Sv is derived from the ITF.
Gordon et al. (1997), using five meridional WOCE
sections in the Indian Ocean, find that the Indian
Ocean South Equatorial Current transfers on average 9 Sv of Indonesian Throughflow water westward within the Indian Ocean. Fieux et al. (1994,
1996) find 18 Sv passing into the Indian Ocean
between Java and Australia in August 1989 and
2.6 Sv headed eastward in February 1992. The
Indian Ocean South Equatorial Current estimates
support an ITF transport of 10 Sv.
Inverse (and related) solutions also suggest mean
values for the ITF transport. Piola and Gordon
(1984) find 14 Sv, while Toole and Warren (1993)
deduce a throughflow of 6.7 Sv. Robbins and
Toole (1997), using the same data as Toole and
Warren but with a silica constraint, find a ITF
transport of 9.9 Sv. MacDonald and Wunsch
(1996) arrive at a ITF of 7 Sv with a global inverse
solution. de las Heras and Schlitzer (1999) calculate the ITF as 13.2 Sv. Ganachaud (1999) finds a
ITF of 15<3 Sv.
4.7.3.3 ITF and ENSO
Observational and model studies suggest the ITF
transport sways in tune with ENSO: larger transport during La Niña condition, smaller transport
during El Niño (Kindle et al., 1989; Bray et al.,
1996; Fieux et al., 1996; Gordon and Fine, 1996;
Meyers, 1996; Potemra et al., 1997). The highresolution POP model (Gordon and McClean, 1999)
yields a 12 Sv annual average during La Niña and
4 Sv average during El Niño. The Arlindo mooring
observations within the Makassar Strait, which
span the entire cycle of the strong 1997/1998 El
Niño, find a correlation (r:0.73) between Makassar transport and ENSO (Gordon et al., 1999a;
though the time-series is far too short to say this
with assurance). During the El Niño months
December 1997 to February 1998 the transport
SECTION 4 THE GLOBAL FLOW FIELD
308