Graham Ferrier

On the Atmospheric Correction of Antarctic Airborne Hyperspectral Data

The first airborne hyperspectral campaign in the Antarctic Peninsula region was carried out by the British Antarctic Survey and partners in February 2011. This paper presents an insight into the applicability of currently available radiative transfer modelling and atmospheric correction techniques for processing airborne hyperspectral data in this unique coastal Antarctic environment. Results from the Atmospheric and Topographic Correction version 4 (ATCOR-4) package reveal absolute reflectance values somewhat in line with laboratory measured spectra, with Root Mean Square Error (RMSE) values of 5% in the visible near infrared (0.4–1 µm) and 8% in the shortwave infrared (1–2.5 µm). Residual noise remains present due to the absorption by atmospheric gases and aerosols, but certain parts of the spectrum match laboratory measured features very well. This study demonstrates that commercially available packages for carrying out atmospheric correction are capable of correcting airborne hyperspectral data in the challenging environment present in Antarctica. However, it is anticipated that future results from atmospheric correction could be improved by measuring in situ atmospheric data to generate atmospheric profiles and aerosol models, or with the use of multiple ground targets for calibration and validation.

Identifying hotspots and management of critical ecosystem services in rapidly urbanizing Yangtze River Delta Region, China

Rapid urbanization has altered many ecosystems, causing a decline in many ecosystem services, generating serious ecological crisis. To cope with these challenges, we presented a comprehensive framework comprising five core steps for identifying and managing hotspots of critical ecosystem services in a rapid urbanizing region. This framework was applied in the case study of the Yangtze River Delta (YRD) Region. The study showed that there was large spatial heterogeneity in the hotspots of ecosystem services in the region, hotspots of supporting services and regulating services aggregately distributing in the southwest mountainous areas while hotspots of provisioning services mainly in the northeast plain, and hotspots of cultural services widespread in the waterbodies and southwest mountainous areas. The regionalization of the critical ecosystem services was made through the hotspot analysis. This study provided valuable information for environmental planning and management in a rapid urbanizing region and helped improve Chinas ecological redlines policy at regional scale.

Cover: Observing estuarine currents and fronts in the Tay Estuary, Scotland, using an airborne SAR with along track interferonmetry (ATI)

Estuaries are extremely dynamic environments where large and frequent changes in bathymetry and channel locations can occur. Because estuaries are major centres of population and industry, there is an ongoing requirement to monitor and predict changes in the current fields. The tidal range, surface wind speed, atmospheric pressure, fresh water inflow and most importantly the stage of the tidal cycle affect the flow vectors. Existing boat‐based methods are unable to provide measurements of current fields with sufficient spatial and depth coverage for accurate modelling of hydrodynamic processes in estuaries. Remotely sensed data offer more extensive, synoptic, spatial coverage. However, previous studies to map the full details of the current field based on conventional optical and thermal imaging have been limited by insufficient temporal coverage and the lack of identifiable features that can be tracked. Synthetic aperture radar (SAR) imaging with along‐track interferometry (ATI) has the potential to overcome both of these limitations because it can retrieve quantitative measurements of sea surface state parameters and instantaneous surface flow from a single pass over a whole estuary. The preliminary results of ATI observations over the Tay Estuary, Scotland, validated with coincident in situ boat based observations, are presented here.