140
HF radar emplacements require electrical power for effective Tx antennae output
and to operate control modules, Rx units, computers, radio or cell data Tx/Rx communication, and climate control units as required. While these requirements are
moderate (about 3–5 kW per observation post), they are indispensable. Most units
currently installed make use of gridline power thus foregoing many favorable
deployment sites for lack of alternate power sources. A prototype Remote Power
Module (Statsewich et al. 2011), which offers the prospect of true autonomy in HF
radar emplacement, is described in Sect. 4.1 of this book. Self-powered, helicoptered
and trailered autonomous HFR systems for rapid deployment have been successfully operated in western Florida and Norway (Whelan et al. 2010).
As power availability allows, HF radar antennae are best located close to the
land-sea interface at low elevation to effectively exploit the conductive properties of
seawater that allow sensing over the horizon. Unfortunately, since the nearshore
zone is a site of intense human activity, ferromagnetic and electromagnetic anomalies are common. Massive steel structures such as ship hulls and dockside steel
works can significantly distort the resulting Rx antenna pattern, especially if in
close proximity. Likewise, large electromagnetic fields created by nearshore electric
power generators may significantly degrade antenna performance. Intermittent
interference such as that caused by ship arrivals and departures, by power generator
output variability, or by alternating power sources in close vicinity to HF radar
emplacements can confound interpretation rendering the data less accurate. Such
sites will report large errors which even after subject to statistical analysis can result
in uncertainty envelopes beyond operational usefulness. Siting alternatives should
then be explored.
Government agencies with jurisdiction over the coastal and nearshore zones,
such as those regulating natural resources, coastal navigation, and environmental
health, may require permits for fixed platform emplacement. Detailed proposals
may be required describing the platform, platform emplacement and recovery
procedures, possible environmental impact of the proposed emplacement, and the
hazards to navigation that the platform may pose.
Deployment of oceanographic and meteorological instrumentation on existing
private or government owned docks is usually straightforward requiring only radio
emission permits if contemplated. Deployment aboard existing aids-to-navigation
(pilings and buoys) requires extensive negotiation with the operator, usually the
local coast guard or equivalent body. Equipment redesign may be necessary to meet
regulatory requirements.
For moored emplacements, standard practice is to select several alternate sites
and to rank these according to desirability weighted against environmental impact
and hazard to navigation. Once a site is approved, regulatory agencies may prescribe a moratorium to actual deployment while the emplacement is charted to warn
mariners of its existence. Legal assurances must in any case be procured to cover
liability in case of damage caused to third parties. Moored buoys inadvertently set
adrift may, for instance, pose a particular hazard to navigation that must be
anticipated.
8 Planning, Implementation, and Operation of Coastal Ocean Observing Systems
HF radar emplacements require electrical power for effective Tx antennae output
and to operate control modules, Rx units, computers, radio or cell data Tx/Rx communication, and climate control units as required. While these requirements are
moderate (about 3–5 kW per observation post), they are indispensable. Most units
currently installed make use of gridline power thus foregoing many favorable
deployment sites for lack of alternate power sources. A prototype Remote Power
Module (Statsewich et al. 2011), which offers the prospect of true autonomy in HF
radar emplacement, is described in Sect. 4.1 of this book. Self-powered, helicoptered
and trailered autonomous HFR systems for rapid deployment have been successfully operated in western Florida and Norway (Whelan et al. 2010).
As power availability allows, HF radar antennae are best located close to the
land-sea interface at low elevation to effectively exploit the conductive properties of
seawater that allow sensing over the horizon. Unfortunately, since the nearshore
zone is a site of intense human activity, ferromagnetic and electromagnetic anomalies are common. Massive steel structures such as ship hulls and dockside steel
works can significantly distort the resulting Rx antenna pattern, especially if in
close proximity. Likewise, large electromagnetic fields created by nearshore electric
power generators may significantly degrade antenna performance. Intermittent
interference such as that caused by ship arrivals and departures, by power generator
output variability, or by alternating power sources in close vicinity to HF radar
emplacements can confound interpretation rendering the data less accurate. Such
sites will report large errors which even after subject to statistical analysis can result
in uncertainty envelopes beyond operational usefulness. Siting alternatives should
then be explored.
Government agencies with jurisdiction over the coastal and nearshore zones,
such as those regulating natural resources, coastal navigation, and environmental
health, may require permits for fixed platform emplacement. Detailed proposals
may be required describing the platform, platform emplacement and recovery
procedures, possible environmental impact of the proposed emplacement, and the
hazards to navigation that the platform may pose.
Deployment of oceanographic and meteorological instrumentation on existing
private or government owned docks is usually straightforward requiring only radio
emission permits if contemplated. Deployment aboard existing aids-to-navigation
(pilings and buoys) requires extensive negotiation with the operator, usually the
local coast guard or equivalent body. Equipment redesign may be necessary to meet
regulatory requirements.
For moored emplacements, standard practice is to select several alternate sites
and to rank these according to desirability weighted against environmental impact
and hazard to navigation. Once a site is approved, regulatory agencies may prescribe a moratorium to actual deployment while the emplacement is charted to warn
mariners of its existence. Legal assurances must in any case be procured to cover
liability in case of damage caused to third parties. Moored buoys inadvertently set
adrift may, for instance, pose a particular hazard to navigation that must be
anticipated.
8 Planning, Implementation, and Operation of Coastal Ocean Observing Systems