Chapter 12
Observing the Agulhas Current With Sea
Surface Temperature and Altimetry Data:
Challenges and Perspectives
Marjolaine Krug, Paolo Cipollini and Francois Dufois
Abstract The Agulhas Current is a challenging region for satellite remote sensing
observations. Strong evaporation rates above the current core and the Retroflection
reduce the number of cloud-free observations from Infra-Red sensors, while microwave radiometers and altimeters measurements suffer from the proximity of the
current to the coast in the northern region. Infra-Red observations of the Agulhas
Current significantly improved with the launch of the Meteosat Second Generation
satellite, but Infra-Red Sea Surface Temperature datasets still suffer from inadequate
cloud masking algorithms, particularly in regions of strong temperature gradient.
Despite both Sea Surface Height and Sea Surface Temperature observations being
severely compromised in the northern Agulhas current, a synergetic use of merged
altimetry and high frequency Infra-Red Sea Surface Temperature imagery provides
a means to track deep-sea eddies, document their influence on the Agulhas Current
and helps us improve our understanding of the Agulhas Current variability.
12.1 Introduction
The Agulhas forms the western boundary current of the South Indian subtropical
gyre. It originates near the South-African/Mozambican border, at about 27
◦ S and
flows poleward to 40
◦ S, transporting large volumes of sub-tropical water towards the
southern ocean. The Agulhas Current can be divided into three regions (Fig. 12.1): the
M. Krug ()
Ecosystem Earth Observations, Council for Scientific and Industrial Research,
Cape Town, South Africa
e-mail: mkrug@csir.co.za
Also at: Nansen-Tutu Center for Marine Environmental Research, Oceanography Department,
University of Cape Town, South Africa
P. Cipollini
Marine Physics and Ocean Climate, National Oceanography Centre, Southampton, UK
F. Dufois
Oceanography Department, Mare Institute, University of Cape Town,
Cape Town, South Africa
CSIRO Marine and Atmospheric Research, Floreat, Australia
V. Barale, M. Gade (eds.), Remote Sensing of the African Seas,
233
DOI 10.1007/978-94-017-8008-7_12,
© Springer Science+Business Media Dordrecht 2014
Observing the Agulhas Current With Sea
Surface Temperature and Altimetry Data:
Challenges and Perspectives
Marjolaine Krug, Paolo Cipollini and Francois Dufois
Abstract The Agulhas Current is a challenging region for satellite remote sensing
observations. Strong evaporation rates above the current core and the Retroflection
reduce the number of cloud-free observations from Infra-Red sensors, while microwave radiometers and altimeters measurements suffer from the proximity of the
current to the coast in the northern region. Infra-Red observations of the Agulhas
Current significantly improved with the launch of the Meteosat Second Generation
satellite, but Infra-Red Sea Surface Temperature datasets still suffer from inadequate
cloud masking algorithms, particularly in regions of strong temperature gradient.
Despite both Sea Surface Height and Sea Surface Temperature observations being
severely compromised in the northern Agulhas current, a synergetic use of merged
altimetry and high frequency Infra-Red Sea Surface Temperature imagery provides
a means to track deep-sea eddies, document their influence on the Agulhas Current
and helps us improve our understanding of the Agulhas Current variability.
12.1 Introduction
The Agulhas forms the western boundary current of the South Indian subtropical
gyre. It originates near the South-African/Mozambican border, at about 27
◦ S and
flows poleward to 40
◦ S, transporting large volumes of sub-tropical water towards the
southern ocean. The Agulhas Current can be divided into three regions (Fig. 12.1): the
M. Krug ()
Ecosystem Earth Observations, Council for Scientific and Industrial Research,
Cape Town, South Africa
e-mail: mkrug@csir.co.za
Also at: Nansen-Tutu Center for Marine Environmental Research, Oceanography Department,
University of Cape Town, South Africa
P. Cipollini
Marine Physics and Ocean Climate, National Oceanography Centre, Southampton, UK
F. Dufois
Oceanography Department, Mare Institute, University of Cape Town,
Cape Town, South Africa
CSIRO Marine and Atmospheric Research, Floreat, Australia
V. Barale, M. Gade (eds.), Remote Sensing of the African Seas,
233
DOI 10.1007/978-94-017-8008-7_12,
© Springer Science+Business Media Dordrecht 2014