9 The Upwelling Area Off Namibia, the Northern Part of the Benguela Current System
173
9.5 Applications
The summary of applications in the region off Namibia is mainly focussed on SST
and water colour and derived products. The synoptic coverage of the entire region and
the daily repeating rate supported the capture of processes of fast spatial and temporal
variability. Hardman-Mountford et al. (2003) gave a detailed overview about the first
applications of satellite data in the Benguela region in the mid 1980s up to the end of
the 1990s. The authors used NOAA-AVHRR, CZCS and SeaWiFS data to investigate
the extent and seasonality of upwelling, to describe the distribution of chlorophyll-a,
and to develop algorithms for the retrieval of chlorophyll-a and suspended sediments
from the ocean colour satellite data (Shannon 1985; Lutjeharms and Meeuwis 1987;
Lutjeharms and Stockton 1987; Shannon et al. 1987; Shelton and Hutchings 1990;
Bailey 1991). Several publications are related to environmental conditions and fish
recruitment (Shelton and Hutchings 1990; Cole and McGlade 1998; Cole 1999).
More recent publications combined time series of NOAA-SST and SeaWiFS- derived chlorophyll-a to investigate physical and biological variability in the Namibian
upwelling area including the Angola-Benguela Front (Campillo-Campbell and Gordoa 2004; Veitch et al. 2006; Bartholomae and van der Plas 2007). Silió-Calzada et al.
(2008) improved a model approach to estimate primary productivity with MERIS
and AATSR data with application to the Benguela upwelling region. Demarcq (2009)
investigated trends in primary production, sea surface temperature and wind in upwelling systems for the period 1998–2007 including Benguela. Shutler et al. (2010)
developed an approach to identify coccolithophore blooms in other regions. Validation is based on SeaWiFS data in the period 2003–2004. A model development
(Williamson et al. 2011) contributes to the evaluation of the vertical distribution of
chlorophyll-a. Pardo et al. (2011) investigated the long-term development of SST in
eastern boundary upwelling systems.
9.5.1 Upwelling and Biological Response
Monthly mean maps of NOAA-SST were used to derive the Intense Benguela Upwelling (IBU) index during the period 1982–1999 (Hagen et al. 2001). The IBU
was calculated for the region 9–34
◦ S and 8–20
◦ E. The index was defined as the area
between the 13
◦ C isotherm and the coast. The IBU indicated a decreasing trend and
a quasi-cycle of about 27 months. Seasonality was discussed for the entire cold water
area and for the mean offshore and alongshore extent. The main upwelling season
occurred during the austral winter (July until September) with a maximum extent of
about 30 × 10
3 km
2 in August. The most intense upwelling filaments develop around
26 and 29
◦ S with a mean offshore extension of 210 and 130 km. During weak upwelling years the area decreased by a factor of two and expanded by a factor of 1.5
during strong years. Sea level changes derived from measurements at four coastal
stations (1982–1987) showed the lowest sea levels in the Lüderitz cell near 26
◦ S.
Decreasing cold water areas are accompanied by increasing sea levels and vice versa.
Mean seasonal cycles in the total cold water area has a time lag of about 1 month
behind those in the sea level along the entire south-west African coast.
173
9.5 Applications
The summary of applications in the region off Namibia is mainly focussed on SST
and water colour and derived products. The synoptic coverage of the entire region and
the daily repeating rate supported the capture of processes of fast spatial and temporal
variability. Hardman-Mountford et al. (2003) gave a detailed overview about the first
applications of satellite data in the Benguela region in the mid 1980s up to the end of
the 1990s. The authors used NOAA-AVHRR, CZCS and SeaWiFS data to investigate
the extent and seasonality of upwelling, to describe the distribution of chlorophyll-a,
and to develop algorithms for the retrieval of chlorophyll-a and suspended sediments
from the ocean colour satellite data (Shannon 1985; Lutjeharms and Meeuwis 1987;
Lutjeharms and Stockton 1987; Shannon et al. 1987; Shelton and Hutchings 1990;
Bailey 1991). Several publications are related to environmental conditions and fish
recruitment (Shelton and Hutchings 1990; Cole and McGlade 1998; Cole 1999).
More recent publications combined time series of NOAA-SST and SeaWiFS- derived chlorophyll-a to investigate physical and biological variability in the Namibian
upwelling area including the Angola-Benguela Front (Campillo-Campbell and Gordoa 2004; Veitch et al. 2006; Bartholomae and van der Plas 2007). Silió-Calzada et al.
(2008) improved a model approach to estimate primary productivity with MERIS
and AATSR data with application to the Benguela upwelling region. Demarcq (2009)
investigated trends in primary production, sea surface temperature and wind in upwelling systems for the period 1998–2007 including Benguela. Shutler et al. (2010)
developed an approach to identify coccolithophore blooms in other regions. Validation is based on SeaWiFS data in the period 2003–2004. A model development
(Williamson et al. 2011) contributes to the evaluation of the vertical distribution of
chlorophyll-a. Pardo et al. (2011) investigated the long-term development of SST in
eastern boundary upwelling systems.
9.5.1 Upwelling and Biological Response
Monthly mean maps of NOAA-SST were used to derive the Intense Benguela Upwelling (IBU) index during the period 1982–1999 (Hagen et al. 2001). The IBU
was calculated for the region 9–34
◦ S and 8–20
◦ E. The index was defined as the area
between the 13
◦ C isotherm and the coast. The IBU indicated a decreasing trend and
a quasi-cycle of about 27 months. Seasonality was discussed for the entire cold water
area and for the mean offshore and alongshore extent. The main upwelling season
occurred during the austral winter (July until September) with a maximum extent of
about 30 × 10
3 km
2 in August. The most intense upwelling filaments develop around
26 and 29
◦ S with a mean offshore extension of 210 and 130 km. During weak upwelling years the area decreased by a factor of two and expanded by a factor of 1.5
during strong years. Sea level changes derived from measurements at four coastal
stations (1982–1987) showed the lowest sea levels in the Lüderitz cell near 26
◦ S.
Decreasing cold water areas are accompanied by increasing sea levels and vice versa.
Mean seasonal cycles in the total cold water area has a time lag of about 1 month
behind those in the sea level along the entire south-west African coast.