During the past decade, considerable advances in satellite observing technology have been made, with satellite-derived cloud distributions, cloud/water vapor track winds, and temperature soundings making a substantial contribution to defining oceanic weather. Unfortunately, there also major limitations to satellite observations, such as the inability to provide winds below dense cloud decks and often coarse vertical resolution. Thus, some other approach is needed to collect weather observations above the oceans. Improved sampling in these areas requires a means to deploy instruments economically over large distances. Miniature autonomous aircraft, or Aerosondes, promise to meet this requirement, and similar needs in other earth sciences disciplines.
Aerosondes have sufficient range to cover much territory of interest to forecasters in North America. Even the current aircraft (handicapped by an inefficient engine and unrefined aerodynamic design) have a still-air operating radius of about 1500 km, and thus could reconnoiter large expanses of the Arctic and the Gulf of Alaska ( red circles in Figure 2). Work is underway on a new powerplant, and coupled with other improvements, should double the range of the aerosonde over the next two years (blue circles in Figure 2). Since aerosondes are relatively slow (50-100 kts still-air speed), they would generally fly with the wind. For observing the weather over the eastern Pacific, aerosondes could be sent from either Hawaii or Alaska to the west coast of North America, and recovered aerosondes could be shipped back to the origin using commercial aircraft and reused.
Aerosondes could be used in two modes over the oceans:
(1) following regular routes, depending on the wind speed or direction
and (2) being targeted to where the observations are most needed.
The latter approach, also known as "targeted observing," is a developing
technology with considerable promise. Two recent field experiments using
weather instruments dropped from manned aircraft, FASTEX (over the Atlantic)
and NORPEX (over the Pacific), have produced results suggesting the viability
of the adaptive approach. Since manned weather reconnaissance is
extremely expensive, an alternative and less expensive approach, such as
the aerosondes, is needed.
1. In support of atmospheric field experiments for studying fronts, hurricanes, cyclones, and sea breeze circulations, to name only a few.
2. To probe tropical weather systems and to determine their environment for forecasting applications.
3. To support military operations, both for improving weather model initialization and for determining weather conditions around navy ships and over coastal regions of interest.
4. For environmental observations in support of air
quality research and air pollution mitigation.
Port Hedland,-Western Australia
Tofino Trials - British Columbia