Research Interests

My research interests concern the application of Synthetic Aperture Radar (SAR) to the modelling of forests. The work of Woodhouse(Relevant Paper), Meitte, Papathanassiou (Relevant Presentation), Treuhaft (Relevant Research) and Cloude (Relevant Presentation and Paper)appear to be the most relevant work to my field. More forest related research is provided by West, Brown, Enqvist and Niklas.

The Outline of my projected project is as follows:

Radar bakcscatter modelling of forests using a macroecological approach

Supervisors: Dr. Iain H Woodhouse, Prof Maurizio Mencucini

This project will make the novel link between a generic plant structure model and a
microwave backscatter model. In so doing, we aim to improve understanding of the
sensitivity of radar backscatter to forest biomass density and explore the potential
additional information obtainable from other modes of data acquisition, such as multifrequency
or canopy height from interferometry.

This work establishes a framework for improved exploitation of new data from
current and planned satellite radar imagers and will provide input to the design of
future radar instrument configurations for monitoring global vegetation biomass. By
adapting and modifying an existing plant structure model to improve its description of
tree canopy architecture while simultaneously accommodating the requirements of
existing backscatter models we will:

1. provide a direct link between the plant biology and the radar observations,
hence improving the ability of such observations to provide information on plant
processes,

2. reduce the uncertainty of forest parameter estimation, especially biomass,
from radar measurements,

3. help determine optimum observational strategies for forest monitoring,

4. improve the retrieval of canopy height from interferometry, and

5. help researchers plan future measurement campaigns (both in situ and remote)
by characterising the main forest variables that influence the radar response.
The project will aim to (a) modify the existing plant model for use with backscatter
models; and (b) predict the sensitivity of radar retrieved parameters to biophysical
parameters such as biomass density and tree height for various instrument
configurations.
The novelty of this project lies in its exploration of a subject where macroecology,
biogeography, remote sensing and microwave scattering come together, and thus has
the potential to forge new synergies among these disciplines.

If you were wondering............

What is Synthetic Aperture Radar?

Environmental monitoring, earth-resource mapping, and military systems require broad-area imaging at high resolutions. Many times the imagery must be acquired in inclement weather or during night as well as day. Synthetic Aperture Radar (SAR) provides such a capability. SAR systems take advantage of the long-range propagation characteristics of radar signals and the complex information processing capability of modern digital electronics to provide high resolution imagery. Synthetic aperture radar complements photographic and other optical imaging capabilities because of the minimum constraints on time-of-day and atmospheric conditions and because of the unique responses of terrain and cultural targets to radar frequencies.

Synthetic aperture radar technology has provided terrain structural information to geologists for mineral exploration, oil spill boundaries on water to environmentalists, sea state and ice hazard maps to navigators, and reconnaissance and targeting information to military operations. There are many other applications or potential applications. Some of these, particularly civilian, have not yet been adequately explored because lower cost electronics are just beginning to make SAR technology economical for smaller scale uses.

How does Synthetic Aperture Radar work?

A detailed description of the theory of operation of SAR is complex and beyond the scope of this document. Instead, this page is intended to give the reader an intuitive feel for how synthetic aperture radar works.

Consider an airborne SAR imaging perpendicular to the aircraft velocity as shown in the figure below. Typically, SARs produce a two-dimensional (2-D) image. One dimension in the image is called range (or cross track) and is a measure of the "line-of-sight" distance from the radar to the target. Range measurement and resolution are achieved in synthetic aperture radar in the same manner as most other radars: Range is determined by precisely measuring the time from transmission of a pulse to receiving the echo from a target and, in the simplest SAR, range resolution is determined by the transmitted pulse width, i.e. narrow pulses yield fine range resolution.

Synthetic Aperture Radar Imaging Concept

The other dimension is called azimuth (or along track) and is perpendicular to range. It is the ability of SAR to produce relatively fine azimuth resolution that differentiates it from other radars. To obtain fine azimuth resolution, a physically large antenna is needed to focus the transmitted and received energy into a sharp beam. The sharpness of the beam defines the azimuth resolution. Similarly, optical systems, such as telescopes, require large apertures (mirrors or lenses which are analogous to the radar antenna) to obtain fine imaging resolution. Since SARs are much lower in frequency than optical systems, even moderate SAR resolutions require an antenna physically larger than can be practically carried by an airborne platform: antenna lengths several hundred meters long are often required. However, an airborne radar could collect data while flying this distance and then process the data as if it came from a physically long antenna. The distance the aircraft flies in synthesizing the antenna is known as the synthetic aperture. A narrow synthetic beamwidth results from the relatively long synthetic aperture, which yields finer resolution than is possible from a smaller physical antenna.

Achieving fine azimuth resolution may also be described from a doppler processing viewpoint. A target's position along the flight path determines the doppler frequency of its echoes: Targets ahead of the aircraft produce a positive doppler offset; targets behind the aircraft produce a negative offset. As the aircraft flies a distance (the synthetic aperture), echoes are resolved into a number of doppler frequencies. The target's doppler frequency determines its azimuth position.