17 Basic Ecosystem Dynamics in the Red Sea as Seen by Sundry . . .
339
Given the peculiar name of the basin (where “Red”—a term coming from antiquity and recurring in all languages spoken in the region—may refer to the recurrence
of red-coloured cyanobacteria blooms
1 or, according to other sources, to the ancient designation of cardinal points according to a geo-chromatic code, red being
associated with south), it would seem rather appropriate to investigate the Red Sea
ecosystem by virtue of optical observations. However, althought widely applied
for the characterization of other Eurasian enclosed seas (see e.g. various authors in
Barale and Gade 2008), satellite observations, particularly in the visible and near
infrared spectral range, have not been used extensively for basin-scale studies of the
Red Sea. Kirby et al. (1993) considered Coastal Zone Colour Scanner (CZCS) data
over a 2-year period (1979–1980) to describe the basin surface optical properties and
to determine their seasonality due to the monsoon cycle. Barale (2007) used a 9-year
time series (1998–2006) generated by the Sea-viewing Wide Field-of-view Sensor
(SeaWiFS) to look at the space-time monthly variability of chl patterns, as well as
interannual anomalies and other irregular features of the pigment field, occurring
over monthly to seasonal scales.
More frequently, it has been the northern part of the basin, and primarily the Gulf
of Aqaba, that has been the subject of in-depth investigations of bio-optical properties, from both satellite and in situ measurements (Labiosa et al. 2003; Stambler
2005), or of site-specific algorithms for their derivation from RS radiance measurements (Iluz et al. 2003; Sokoletsky et al. 2003, 2004). Acker et al. (2008), finally,
used seven years of SeaWiFS data (1998–2004), coupled to concurrent 2003–2004
Sea Surface Temperature (SST) data collected by the Moderate Resolution Imaging Spectroradiometer (MODIS), on the Aqua orbital platform, to observe seasonal
phytoplankon dynamics, local impacts of coastal features such as coral reefs, and
surface circulation patterns described by optical tracers, primarily in the northern
Red Sea, between 21.5
◦ N and 27.5
◦ N.
In the limited scientific literature available, much attention is devoted to the link
between sea surface bio-optical environment and atmospheric processes, as related
chiefly to the monsoon cycle (see Fig. 17.1 for a schematic representation of wind
patterns). Marked seasonal variations of the local wind field, controlled by the largescale monsoon wind system, are indeed the key features of the basin (Edwards
1987). During the Southwest (SW) Monsoon, in boreal summer, winds over the
Arabian Sea are southwesterly, changing to north-northwesterly over the southern
Red Sea. During the Northeast (NE) Monsoon, in boreal winter, winds over the
Arabian Sea are northeasterly, changing to south-southeasterly over the southern
Red Sea. Conversely, in the northern Red Sea, the prevailing winds (linked to the
eastern Mediterranean weather systems) are north-northwesterly year-round (Morcos
1970). Thus, the region north of 20
◦ N is not markedly affected by the monsoons,
while the region south of 20
◦ N is subject to a monsoon-driven seasonal wind reversal
(Sheppard et al. 1992).
1 see e.g. the spatial and temporal distribution of Trichodesmium spp. in the Gulf of Aqaba as
reported by Post et al. (2002).
339
Given the peculiar name of the basin (where “Red”—a term coming from antiquity and recurring in all languages spoken in the region—may refer to the recurrence
of red-coloured cyanobacteria blooms
1 or, according to other sources, to the ancient designation of cardinal points according to a geo-chromatic code, red being
associated with south), it would seem rather appropriate to investigate the Red Sea
ecosystem by virtue of optical observations. However, althought widely applied
for the characterization of other Eurasian enclosed seas (see e.g. various authors in
Barale and Gade 2008), satellite observations, particularly in the visible and near
infrared spectral range, have not been used extensively for basin-scale studies of the
Red Sea. Kirby et al. (1993) considered Coastal Zone Colour Scanner (CZCS) data
over a 2-year period (1979–1980) to describe the basin surface optical properties and
to determine their seasonality due to the monsoon cycle. Barale (2007) used a 9-year
time series (1998–2006) generated by the Sea-viewing Wide Field-of-view Sensor
(SeaWiFS) to look at the space-time monthly variability of chl patterns, as well as
interannual anomalies and other irregular features of the pigment field, occurring
over monthly to seasonal scales.
More frequently, it has been the northern part of the basin, and primarily the Gulf
of Aqaba, that has been the subject of in-depth investigations of bio-optical properties, from both satellite and in situ measurements (Labiosa et al. 2003; Stambler
2005), or of site-specific algorithms for their derivation from RS radiance measurements (Iluz et al. 2003; Sokoletsky et al. 2003, 2004). Acker et al. (2008), finally,
used seven years of SeaWiFS data (1998–2004), coupled to concurrent 2003–2004
Sea Surface Temperature (SST) data collected by the Moderate Resolution Imaging Spectroradiometer (MODIS), on the Aqua orbital platform, to observe seasonal
phytoplankon dynamics, local impacts of coastal features such as coral reefs, and
surface circulation patterns described by optical tracers, primarily in the northern
Red Sea, between 21.5
◦ N and 27.5
◦ N.
In the limited scientific literature available, much attention is devoted to the link
between sea surface bio-optical environment and atmospheric processes, as related
chiefly to the monsoon cycle (see Fig. 17.1 for a schematic representation of wind
patterns). Marked seasonal variations of the local wind field, controlled by the largescale monsoon wind system, are indeed the key features of the basin (Edwards
1987). During the Southwest (SW) Monsoon, in boreal summer, winds over the
Arabian Sea are southwesterly, changing to north-northwesterly over the southern
Red Sea. During the Northeast (NE) Monsoon, in boreal winter, winds over the
Arabian Sea are northeasterly, changing to south-southeasterly over the southern
Red Sea. Conversely, in the northern Red Sea, the prevailing winds (linked to the
eastern Mediterranean weather systems) are north-northwesterly year-round (Morcos
1970). Thus, the region north of 20
◦ N is not markedly affected by the monsoons,
while the region south of 20
◦ N is subject to a monsoon-driven seasonal wind reversal
(Sheppard et al. 1992).
1 see e.g. the spatial and temporal distribution of Trichodesmium spp. in the Gulf of Aqaba as
reported by Post et al. (2002).