D.G. BARBER, A. THOMAS, AND T.N. PAPAKYRIAKOU
3.S
Conclusions and Future Directions
In this chapter we have introduced the notion that microwave energy interacts within
the marine cryosphere as a function of the surface energy balance. Our long-term goal
in this work is to develop a better understanding of how processes operate within the
ocean-sea ice-atmosphere interface. To achieve this end we require spatially and temporally contiguous observations of both the energy balance and the physical characteristics of this interface. As these tools evolve we intend to use them to develop an
understanding of the linkages, feedback mechanisms and potential anthropogenic
effects on the dynamic and thermodynamic nature of the marine cryosphere.
In this chapter we partitioned the problem of estimating surface energy balance variables from the temporal evolution of the microwave scattering coefficient 0"0 into its
constituent parts. In Sect. 3.2 we explored the nature of the interrelationships amongst
the geophysical, electrical and microwave scattering properties of the snow-covered sea
ice. We showed that there are sound physical reasons to suggest that transfer functions
exist which would allow the estimation of energy balance variables from 0"0 due to the
fact that both respond to the seasonal dynamics of the physical and electrical properties of the marine cryosphere. In Sect. 3.3 we investigated the nature of these transfer
functions by using exploratory univariate and multivariate statistical analyses. Our
objective here was to determine which components of the energy balance explained a
statistically significant amount of the observed seasonal variability in 0"0. We found that
the shortwave flux and the conductive flux at the snow/ice interface consistently
accounted for a significant amount of observed variation in the seasonal evolution of
0"0. In Sect. 3.4 we began to exploit our knowledge of the "energy balance-physical property-microwave scattering" relationship through the development of image products.
These image products, although still experimental, represent a significant step forward
in the development of energy flux fields at a scale (in space and time) appropriate for
studying marine cryosphere processes.
In the near term the work described here will evolve on two interrelated fronts:
I. Development of RADARS AT image products. Canada's RADARSAT is now operational
and offers significant advantages over the ERS and JERS SAR satellites currently in operation. The payload instrument on board RADARSAT is a C-band, HH polarized SAR.
RADARSAT offers a variety of mission-selectable resolutions, image swath widths, and
incidence angle parameters. Orbit and image modes have been specified to allow maximum national and global coverage. In ScanSAR mode, RADARSAT will provide daily
coverage of polar regions above 7SoN (Ramsay et al. 1993). Two ScanSAR modes are
offered by RADARSAT. The first mode alternates between two wide swath beams to
image a 300-km swath with a so-m pixel spacing. The second mode uses a four beam
coverage to image a soo-km swath at a 100-m pixel spacing. A variety of research questions will be addressed with RADARSAT data to evaluate how well the principles developed here apply to the unique beam modes, polarization differences and increased temporal resolution of RADARSAT.
2. Forward and inverse electromagnetic interaction modelling. The Office of Naval
Research (ONR) is nearing the end of a s-year Accelerated Research Initiative (ARI)
which is directed towards the development of forward and inverse modelling of various electromagnetic frequencies with snow-covered sea ice. The goals of this project
3.S
Conclusions and Future Directions
In this chapter we have introduced the notion that microwave energy interacts within
the marine cryosphere as a function of the surface energy balance. Our long-term goal
in this work is to develop a better understanding of how processes operate within the
ocean-sea ice-atmosphere interface. To achieve this end we require spatially and temporally contiguous observations of both the energy balance and the physical characteristics of this interface. As these tools evolve we intend to use them to develop an
understanding of the linkages, feedback mechanisms and potential anthropogenic
effects on the dynamic and thermodynamic nature of the marine cryosphere.
In this chapter we partitioned the problem of estimating surface energy balance variables from the temporal evolution of the microwave scattering coefficient 0"0 into its
constituent parts. In Sect. 3.2 we explored the nature of the interrelationships amongst
the geophysical, electrical and microwave scattering properties of the snow-covered sea
ice. We showed that there are sound physical reasons to suggest that transfer functions
exist which would allow the estimation of energy balance variables from 0"0 due to the
fact that both respond to the seasonal dynamics of the physical and electrical properties of the marine cryosphere. In Sect. 3.3 we investigated the nature of these transfer
functions by using exploratory univariate and multivariate statistical analyses. Our
objective here was to determine which components of the energy balance explained a
statistically significant amount of the observed seasonal variability in 0"0. We found that
the shortwave flux and the conductive flux at the snow/ice interface consistently
accounted for a significant amount of observed variation in the seasonal evolution of
0"0. In Sect. 3.4 we began to exploit our knowledge of the "energy balance-physical property-microwave scattering" relationship through the development of image products.
These image products, although still experimental, represent a significant step forward
in the development of energy flux fields at a scale (in space and time) appropriate for
studying marine cryosphere processes.
In the near term the work described here will evolve on two interrelated fronts:
I. Development of RADARS AT image products. Canada's RADARSAT is now operational
and offers significant advantages over the ERS and JERS SAR satellites currently in operation. The payload instrument on board RADARSAT is a C-band, HH polarized SAR.
RADARSAT offers a variety of mission-selectable resolutions, image swath widths, and
incidence angle parameters. Orbit and image modes have been specified to allow maximum national and global coverage. In ScanSAR mode, RADARSAT will provide daily
coverage of polar regions above 7SoN (Ramsay et al. 1993). Two ScanSAR modes are
offered by RADARSAT. The first mode alternates between two wide swath beams to
image a 300-km swath with a so-m pixel spacing. The second mode uses a four beam
coverage to image a soo-km swath at a 100-m pixel spacing. A variety of research questions will be addressed with RADARSAT data to evaluate how well the principles developed here apply to the unique beam modes, polarization differences and increased temporal resolution of RADARSAT.
2. Forward and inverse electromagnetic interaction modelling. The Office of Naval
Research (ONR) is nearing the end of a s-year Accelerated Research Initiative (ARI)
which is directed towards the development of forward and inverse modelling of various electromagnetic frequencies with snow-covered sea ice. The goals of this project