Speaker
Description
Monitoring forest ecosystems using spaceborne Synthetic Aperture Radar generally relies on sun-synchronous missions that observe a given area at approximately the same local time. Consequently, the influence of the daily cycle on the radar response of vegetation remains poorly documented from space. In contrast, TeLEOS-2 operates in a near-equatorial orbit with an inclination of approximately 10°, enabling frequent observations of equatorial regions at different times of day. This distinctive configuration offers a novel opportunity to explore potential sub-daily variations in forest radar backscatter while assessing their consistency across multiple acquisition dates.
This exploratory study investigates the potential of high-resolution, fully polarimetric X-band TeLEOS-2 SAR observations for characterising the temporal variability of tropical forested areas embedded within Singapore’s urban landscape. Rather than assuming the presence of a systematic diurnal signal, the study aims to determine whether measurable and repeatable differences can be identified between acquisitions obtained at different local times. It also examines whether any observed variations can be distinguished from the effects of spatial heterogeneity, acquisition geometry, environmental conditions, and measurement uncertainty.
The analysis is based on a multi-temporal series of TeLEOS-2 images covering a range of wooded environments, including dense forest fragments and vegetated areas influenced to varying degrees by the surrounding urban landscape. Forested areas are delineated using independent land-cover information and subdivided into spatial units to evaluate the magnitude and spatial consistency of temporal variations.
For each acquisition, radiometric and polarimetric indicators are derived from the full-polarimetric observations and compared across study sites, acquisition dates, and local acquisition times. Full polarimetry provides complementary information on scattering behaviour and may help determine whether different vegetation components contribute differently to the measured temporal variability. Particular attention is paid to incidence angle, viewing geometry, radiometric stability, image noise, and spatial heterogeneity. Meteorological observations are also considered, when available, to explore possible relationships with rainfall, relative humidity, temperature, antecedent weather conditions, and vegetation water status.
This initial assessment evaluates the sensitivity and limitations of fully polarimetric X-band SAR observations for studying forest variability at rarely observed temporal scales. The findings will provide an initial methodological framework, identify the main sources of uncertainty, and help establish whether the time-diverse acquisitions enabled by the near-equatorial orbit of TeLEOS-2 can support future investigations of short-term vegetation dynamics in tropical urban environments.