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Feature

Watching Over New Zealand

A recent plane flight over some of the more scenic parts of New Zealand aims to give scientists a better understanding of the country's past and future.

New Zealand research institutions and the US National Aeronautics and Space Administration (NASA) have been participating in a flying visit over New Zealand of a specially modified DC-8.

Watching Over New Zealand Figure A (10KB)

The project, known as PACRIM-2, is a joint effort between NASA, and various governments and agencies throughout the Pacific Rim. It uses a modified NASA DC-8 aircraft equipped to capture images using radar of different wavelengths and orientations, as well as a sophisticated camera. The plane recently visited New Zealand to fly over the country and gather useful images with the aim of using radar to increase our knowledge of New Zealand forests, and their ability to soak up greenhouse gases, as well as to take a look at the country's geology.

Landcare Research organised the logistics of the PACRIM-2 mission while in New Zealand. Other major players included the geology and surveying departments of Otago University, the Institute of Geological and Nuclear Sciences (GNS) and Fletcher Challenge Forests, who provided substantial support.

The PACRIM-2 mission was also something of a return home for New Zealander Dr Delwyn Moller, who now works for NASA's Jet Propulsion Laboratory, and was one of five radar specialists, travelling out on the mission.

Forest Survey

Landcare Research scientists mapped out five areas for the flying laboratory to visit, including three central South Island forest sites, with the aim of producing a forest inventory to help industry groups to measure the condition of the forest. Two sites in the North Island near Taupo were also surveyed, to gain a better idea of the wood volume in a regenerating native forest.

New Zealand is a signatory to the Framework Convention for Climate Change, and must stabilise carbon dioxide emissions to the levels they were in 1990. And trees, of course, are important in soaking up these emissions. A remote-sensing scientist at Landcare Research, Stella Belliss, says radar is probably the best way of finding out how the volume of wood can vary in hard-to-access forests, and how much more forest we need to plant to avert the need to pay carbon tax, and fulfil our international obligations.

The radar images can show the bulk, shape and even the moisture content of trees. And because it can see right through clouds, radar is an excellent monitoring tool for New Zealand's changeable and often cloudy weather conditions.

Belliss says as well as helping scientists find out more about forests, the mission will help them judge the usefulness of various radar technologies. This will help New Zealand make wise investment choices in "super-satellite" technology, which will become available in a few years.

During its six-day stay, the NASA DC-8 flew over the Balmoral Forest in North Canterbury, into the Southern Alps south of Arthur's Pass, exiting the West Coast through Hokitika. Cloudy conditions and hefty head winds cleared for the North Island flight over the Kaingaroa forest north of Taupo, finishing near White Island; this line also surveyed an area along the flanks of Mt Tongariro.

Viewing Volcanoes

As well as looking at New Zealand forests, the plane flew over the country's active volcanic field, looking at White Island and active geological faults in the central North Island.

The three-dimensional topographic measurements obtained by a radar on the DC8 will help geologists understand the origin and behaviour of faults in central North Island. It is also hoped that radar and infrared images of White Island will add to the understanding of the island's volcanic activity, despite the recent activity which has seen significant amounts of ash thrown up into the atmosphere.

Using terrestrial imaging and surveying techniques, scientists have had difficulty building up an accurate picture of how repeated earthquakes have helped to shape the landscape of the central North Island.

"One hour of flying can collect the volume of information that would take many weeks of ground-based survey work to collect," GNS geologist Andy Nicol says.

"Accuracy of the NASA instruments is another benefit. It would be difficult and expensive to collect ground-based data that was accurate to one metre vertical over a large area."

Geologists are aiming to find out how repeated earthquakes over many thousands of years have combined as a major landscaping force.

"Some areas of central North Island have been subjected to hundreds of earthquakes during the past 300,000 years," says Nicol.

South of Ruapehu, the Taupo Volcanic Zone – an area of intense volcanism and geothermal activity -- appears to end abruptly and geologists are keen to find out why. It is hoped that images from NASA's "flying laboratory" will help researchers studying this area.

The DC8 can image the earth's surface through cloud and at night. To capture the images the aircraft flies at an altitude of 7 km and each sweep covers a strip10 km wide. The radar instrument collects elevation measurements every 10 metres across the landscape.

Images of White Island collected by the aircraft during its last visit, in 1996, will serve as a benchmark for scientists studying the volcano.

Watching Over New Zealand Figure B (43KB)