Archbold Biological Station – a day in the field
Amartya Saha, Ecohydrologist/Instrumentation Specialist, Archbold Biological Station
While summer in Florida means beaches, watermelons and swimming pools, it also routinely sees stormy weather that often reaches hurricane/cyclone/typhoon intensity. With wind gusting routinely at 200 – 250 kmph (125 – 150 mph or more), hurricanes are a concern for eddy flux tower scientists and technicians, given the high cost of sensors and presence of large solar panels that act as sails and fly off with the wind. Hence, an annual summer ritual is for a lab to go through a hurricane preparation checklist. This checklist includes the locations of towers and details about what to do to ensure the safety of expensive and sophisticated flux tower equipment. The action ramps up when a hurricane is projected to arrive.
Now hurricane path projections and time of arrivals have a lot of uncertainty. Hurricanes have been often seen to completely change tracks, even with a 12-hour window of expected landfall or arrival, given that they swell up and strengthen over the open extremely warm seas that surround Florida. Securing one tower typically takes 2 – 4 hrs for a crew of 3 – 4 people. We have 5 towers across the landscape, so it usually takes 5 – 6 hours total for two separate crews.
Once a hurricane is imminent to arrive within 24 hours, teams are decided, tools distributed the day before (to avoid driving an hour and finding that special Allen key wrench is not there), trucks gassed and all kept ready. At Archbold Biological Station we have 5 towers, so two teams of 3 – 4 people – some familiar with the tower, others not. Being the wet season, the approach to these towers is through flooded pastures and ditches, taking care not to get stuck!!
On arrival at a tower, first step, take photos of all connections – documentation is key for putting things back together later on! Then power the tower down, to avoid short circuiting when disassembling panels and sensors. A pair of folks go to work taking off solar panels, while others take down the EC system. Prior training in the lab ensures that all crew members follow good practices of working with unplugging cables, unwiring sensors, etc. to avoid damage done under the hurried working conditions.
The solar panels are taken off the stands and transported back to the lab, if there is time and roads passable, else laid down flat on the ground, stacked solar side up to prevent water entry into the cable/diode box, covered with tarpaulin and ratchet-strapped to T-posts. The decision of how many sensors to take down is usually decided by time available and cost of sensors – in our case it’s just the CH4, CO2/H2O sensors, sonic anemometer and maybe the PhenoCam if time permits. The meteorological tower instruments are much smaller. We leave the datalogger box as they are, with fresh desiccant to maintain low humidity. Sometimes we leave a small solar panel and charge controller to power a met tower, just to measure wind gust speeds.
Finally, we race back to the lab, to secure that – unplug computers and instruments to avoid being fried by a power surge, shift fragile equipment away from windows that may blow in, stuff off the floor to prevent flooding damage, securing loose items that can projectile and cause damage, etc. Then rush to evacuate and reach a zone of safety.
Once the hurricane has passed, and the field area accessible (our site was completely flooded with a foot of water for 3 weeks after Hurricane Irma passed by in 2017), the task is to put the towers back online. This is a good time to clean and maintain sensors that are in the lab and go out, put them back in a more relaxed manner, put the panels up, flip the power switch hoping all is well, eyes glued on the solar charge controller. Sometimes the battery bank may be below 10V, due to some leaks, and they have to be jumpstarted from the truck 12V battery, just to get the Outback solar charge controller to come back on – a weird feature, as it may be a bright sunny day, with panels pushing loads of amps, but if the battery bank is below 10V, the controller remains silent.
Oftentimes Florida gets 2 or even 3 major hurricanes in a single season. If circumstances pull in a second hurricane to the same area, the process would need to be repeated. So far, we have been lucky to have just one major hurricane per year.
Archbold Biological Station – https://www.archbold-station.org/
US-ABa – https://ameriflux.lbl.gov/sites/siteinfo/US-ABa; US-ABb – https://ameriflux.lbl.gov/sites/siteinfo/US-ABb; US-ABc – https://ameriflux.lbl.gov/sites/siteinfo/US-ABc; US-ABd – https://ameriflux.lbl.gov/sites/siteinfo/US-ABd; US-ABe – https://ameriflux.lbl.gov/sites/siteinfo/US-ABe
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