The San Diego County Sheriff's Department and the California Department of Forestry and Fire Protection airlift replacement sensors for HPWREN real-time weather alerts

HPWREN weather alerts have paged firefighters in San Diego County many times since their implementation was originally described at /news/041106.html. While some of the meteorological sensors can be run for several years without regular maintenance, others require more attention. For example, the fuel sticks require an annual replacement.

Fuel sticks emulate fire response characteristics of the brush vegetation to measure moisture and temperature, which are usually different from the temperature and relative humidity measured in the air.

The sensor data is available at /Sensors.

HPWREN's current main fuel sensor for real-time alerts, managed and operated in collaboration with San Diego State University's Field Station Programs, is at an HPWREN backbone site at Lyons Peak in San Diego County. Access to the site has been difficult lately due to some easement dispute on the access road with a local property owner. This situation made it impossible to undertake the annual fuel sensor replacement so CDF and USFS get reliable pager alarms from the system.

During a recent meeting between HPWREN Principal Investigator Hans-Werner Braun and CDF Captain Steve Shoemaker at the Helitack base at Gillespie Field, collaborations regarding data networking technology for both the station and the aircraft were discussed. CDF's real-time data needs would fit nicely into the agenda of the current NSF HPWREN award. The Lyons Peak situation came up in a discussion with Steve Shoemaker and San Diego Sheriff Department's pilot Dan Megna. This also included expressing CDF Division Chief Randy Lyle's interest to get the fuel sticks replaced. Chief Lyle was the CDF officer who parameterized the weather alert data for the HPWREN sensors. Dan Megna then suggested an aerial approach, which everyone agreed to as being the right thing to solve the problem quickly.

HPWREN PI Hans-Werner Braun is ready for the flight. CDF rules require wearing fire protecting Nomex clothing and a flight helmet. Dan Megna, the Sheriff Department's pilot, inspects the helicopter prior to takeoff.

Dan Megna pilots the helicoptor across San Diego County on its way to Lyons Peak.

The approach to Lyons Peak is difficult due the fact that there is no helicopter landing spot, with remaining flat areas being used up with tower facilities or power wires. Eventually a landing spot further down the mountain was picked, requiring hiking up to the tower to replace the fuel sticks.

These two images show the replaced fuel sticks, and compare them to a fairly new one. The long stick measures fuel moisture, while the short one measures the fuel temperature via a probe contained after an installation. The dark sticks are the ones installed in August 2004, and show the wear during a year of sun exposure and last winter's rain. Information from the Campbell Scientific web site: The CS505 Fuel Moisture sensor measures the moisture content of a ponderosa pine dowel that is fabricated to USFS specifications. The dowels have the same 1/2" diameter, 20" long dimensions as those used on the traditional weighing fuel moisture racks. The dowels have undergone two additional sorts to optimize probe-to-probe repeatability and to allow probe interchangeability without individual calibration.

After successfully replacing the fuel sticks, the landing at Gillespie Field shows one of the new firefighting helicopters in the background that are jointly operated by the CDF and the Sheriff's Department.

Additional photos can be found at: /Photos/20050717