Auxiliary material for:
Monsoon oscillations regulate fertility of the Red Sea
Dionysios E. Raitsos1,2, Xing Yi2, Trevor Platt1, Marie-Fanny Racault1, Robert J.W. Brewin1,
Yaswant Pradhan3, Vassilis P. Papadopoulos4, Shubha Sathyendranath1, Ibrahim Hoteit2
1 - Plymouth Marine Laboratory (PML), Prospect Place, Plymouth, PL1 3DH, United
Kingdom
2 - King Abdullah University for Science and Technology (KAUST), Thuwal, 23955-6900,
Kingdom of Saudi Arabia
3 - Met Office, FitzRoy Road, Exeter, EX1 3PB, United Kingdom
4 - Hellenic Centre for Marine Research, Anavissos, 190 13, Greece
Submitted to Geophysical Research Letters
INTRODUCTION
The supporting material contains: A) 3 supplementary figures (Figure S1, S2, S3) and B)
Supplementary text01 (Supplementary methods).
A)
-Figure S1: The legend is below:
Figure S1. Topography of Africa and Arabian Peninsula that surrounds the Red Sea and Gulf
of Aden. The Red Sea is meridionally elongated (2250km), lying between the African and the
Asian continental shelves. A deep trench stretches from north to south along the axis of the
entire sea reaching maximum depth of about 2500m. At its northern end the Red Sea
connects with the Mediterranean Sea through the Suez Canal. The southern region of the Red
Sea connects with the Gulf of Aden via the strait of Bab-el-Mandeb, and exchanges its waters
with the Arabian Sea and Indian Ocean. The prevailing winds in the northern half of the Red
Sea do not exhibit significant seasonal variations (general direction remains southward during
every season). However, a noticeable change in both wind speed and wind direction
(northward) is observed during the autumn-winter period in the southern half of the Red Sea
[Patzert 1974]. During this period, these strong south-easterly winds are the key drivers
responsible for the intrusion of nutrient-rich waters from the Gulf of Aden [Murray and
Johns, 1997; Johns and Sofianos, 2012; Churchill et al., 2014; Triantafyllou et al., 2014].
The high mountains (dark brown colour) constrain the winter monsoon winds to blow parallel
to the longitudinal axis of the Red Sea [Patzert 1974]. The orography channels the northward
propagation of the nutrient-rich water masses from the Gulf of Aden.
References of supplementary Figure S1
Churchill, J. H., A. S. Bower, D. C. McCorkle, and Y. Abualnaja (2014-In press). The
Transport of Nutrient-Rich Indian Ocean Water through the Red Sea and into Coastal Reef
Systems. In press: J. of Mar. Res.
Johns, W. E., and S. S. Sofianos (2012), Atmospherically Forced Exchange through the Bab
el Mandeb Strait, J. Phys. Oceanogr., 42, 1143–1157.
Murray, S. P., and W. Johns (1997), Direct observations of seasonal exchange through the
Bab el Mandab strait. Geoph Res Let 24:2557–2560.
Patzert, W. C. (1974), Wind-induced reversal in Red Sea circulation, Deep-Sea Res., 21,
109–121.
Triantafyllou, G. et al. (2014), Exploring the Red Sea seasonal ecosystem functioning using a
three
dimensional
biophysical
doi:10.1002/2013JC009641.
model.
J.
Geophys.
Res.,
119,
1791–1811.
-Figure S2: The legend is below:
Figure S2. Monthly values, averaged over 1999-2004 period, of satellite-derived meridional
component of net surface current (cv, cm/s) at different latitudinal transects (represented by
the solid lines) from 14°N to 17°N in the Red Sea. The dashed line represents the ensemble
mean of cv within 14-17N band. Positive/negative sign indicates northward/southward
direction while the magnitude represents the strength of the cv. It is evident that during the
winter time (Oct-Apr), in the southern part of the Red Sea, the currents have a strong mean
northward component, which abruptly changes in May and remain southward through to
September. The prolonged northward winter currents in the southern Red Sea are believed to
transport nutrient-rich waters from the Gulf of Aden through the Bab-el-Mandeb strait.
-Figure S3: The legend is below:
Figure S3. Satellite-derived meridional component of net surface current (cv, cm/s) averaged
seasonally (winter: Oct-Apr, and summer: May-Sep) during the two consecutive periods of
negative (1999-2001) and positive (2002-2004) MEI phases. The red dashes represent
seasonal average cv at different latitudinal transects from 14°N to 17°N in the Red Sea during
the positive MEI period, while the black dashes represent the seasonal averages during the
negative MEI phase. During winter, cv is mostly northward and its magnitude is found to be
more than twice as strong during the positive MEI phase as compared to the negative one. In
contrast, the difference in the pattern between the two MEI phases was smaller during
summer. Therefore, this suggests that the northward (winter) component of the surface flow
in the southern Red Sea is intensified during the MEI + phase, which play a key role in
supplying the nutrient-rich waters from Gulf of Aden.
B)
B) Supplementary text01 (Supplementary methods):
Simple methods to estimate volume transport and net surface flow in the ocean from satellite
observations