Glow from stressed ocean plants (Aqua)
What it measures. Measures the faint red glow given off by ocean phytoplankton (chlorophyll fluorescence), which rises in active blooms and can drop in stressed conditions. It also includes available light for photosynthesis.
How it's made. Computed from the MODIS ocean-color sensor on the Aqua satellite by measuring how much the water's light output rises above a baseline near that red wavelength, then mapped globally.
How & where you'd use it. Used to spot and track harmful algal blooms, find productive waters, and study the health of ocean plant life.
What's measured
Coverage & cadence
- Time span2002-07-04 → ongoing
- Measured byAqua (MODIS)
- Processing levelLevel 3
- Spatial extent-180, -90, 180, 90
- FormatsnetCDF-4
- StatusACTIVE
What you can do with it
- Watch sea-surface temperature and marine heatwaves
- Spot algal blooms and ocean-colour shifts
- Support fisheries and coastal monitoring
Official description
The Fluorescence Line Height (FLH) data suite quantifies the red chlorophyll-a fluorescence (~678–683 nm) emitted by phytoplankton, computed as the height of the measured water-leaving radiance above a spectrally interpolated baseline. FLH is widely used for HAB detection and tracking, identifying productive waters, and assessing phytoplankton physiology; values tend to be elevated in active blooms and can be reduced in complex waters. As with all ocean-color products, uncertainties increase in optically complex coastal/inland waters, so users should refer to mission/algorithm notes for details. Geophysical variables in this suite include: - nflh — Normalized Fluorescence Line Height (W m⁻² µm⁻¹ sr⁻¹) - ipar — Instantaneous Photosynthetically Available Radiation (mol photons m⁻² s⁻¹)
Get the data
import earthaccess
earthaccess.login(strategy="netrc") # free Earthdata Login
results = earthaccess.search_data(
short_name="MODISA_L3m_FLH",
version="2022.0",
bounding_box=(-122.5, 37.2, -121.8, 37.9), # your area (W,S,E,N)
temporal=("2024-01-01", "2024-12-31"), # your dates
)
files = earthaccess.open(results) # stream straight from OB_CLOUDBrowsing CMR needs no login. Downloading or streaming bytes needs a free Earthdata Login + the earthaccess package. Official links
- OPeNDAP Site for Aqua MODIS Standard Mapped Image (SMI) Product USE SERVICE API
- Earthdata Search allows users to search, discover, visualize, refine, and access NASA Earth Observation data. GET DATA
- View the version history of this product. VIEW RELATED INFORMATION
- NASA's Ocean Color Web - Data Distribution Site GET DATA
- Aqua Homepage VIEW RELATED INFORMATION
- MODIS Homepage VIEW RELATED INFORMATION
- Satellite data procesing can be difficult. We're here to help! Visit the Oceandata Help Hub to navigate learning content for accessing visualizing, and analyzing data products. VIEW RELATED INFORMATION
- Algorithm Theoretical Basis Document for Fluorescence Line Height (FLH) VIEW RELATED INFORMATION