Poster Session 2, Tuesday, October 4, 10:40–12:40
An in situ and remote sensing evaluation of the impacts of wildfire ash on apparent and inherent optical properties
In recent years, wildfires around the globe have grown in frequency, severity, and scale. Many coastal regions have a history of wildfires that are getting larger and more intense (e.g., Australia, Brazil, the western United States, etc.). Wildfires can affect the coastal ocean via smoke production and deposition of ash. However, the effects of wildfires on marine ecology and biogeochemistry have been studied infrequently. Most existing studies assess the impacts of wildfire ash on lakes or in laboratory incubations; studies examining the potential effects of wildfires on marine ecosystems in situ are rare. Increasingly, remote sensing measurements are used to study the impacts of wildfires on marine ecosystems through optical proxies, such as chlorophyll-a from remote sensing reflectance (Rrs). Here, we evaluate the potential and limitations of remote sensing measurements to describe the impacts of wildfires on optics and phytoplankton observations. Using samples collected in the Santa Barbara Channel (California, USA) during the Thomas Fire in December 2017, we consider the impact of wildfire smoke and ash particles on chlorophyll-a retrievals from in situ Rrs vs. from satellites. We also compare the spectral shapes and magnitudes of inherent optical properties (IOPs) derived from inversions of in situ and satellite Rrs vs. the IOPs measured in situ. We expect that satellites will remain an important tool to measure the impacts of wildfires on marine ecosystems: this analysis helps to quantify the impact of ash on remote sensing observations for studying changes in ocean ecology and biogeochemistry from wildfires.
Kelsey Bisson, Oregon State University, [email protected], 0000-0003-4230-3467
Catherine Mitchell, Bigelow Laboratory for Ocean Sciences, [email protected], 0000-0001-9932-3050