Monitoring Algal Blooms#

Introduction#

Monitoring algal blooms is something more easily done from space, given there is standardised data covering a wide area at regular periods over a long period of time. We can also look at related data at the same places, to understand ecological dynamics, the impact of climate change on marine ecosystems, and whether algae growth can be an indicator of larger-scale climate events. For our study, we focused on the following satellites:

  • Landsat

  • Sentinel-2

  • MODIS

Our use of this data#

Landsat, Sentinel-2, and MODIS offer complementary advantages for monitoring algal blooms. Landsat’s extensive historical archive is invaluable for long-term studies, Sentinel-2 provides the spatial detail needed for more localised investigations, and MODIS is unbeatable for observing large-scale trends over short time periods.

MODIS Level-3 Data Products#

Ocean Temperature Maps#

Ocean temperature plays a crucial role in the growth and spread of algae. Warmer waters can facilitate the rapid multiplication of algae, leading to blooms that could potentially become harmful.

The MODIS Ocean Temperature Maps provide sea surface temperature measurements on various temporal scales (daily, weekly, monthly, etc.) and spatial scales (down to 1 km resolution). These data are critical for understanding how temperature variations contribute to algae dynamics and can be used in conjunction with other parameters to model and predict algal blooms.

Ocean Chlorophyll Maps#

Chlorophyll is the pigment responsible for the green colour in algae, and its concentration in the ocean serves as a direct indicator of algal presence. Higher levels of chlorophyll usually correspond to increased algal activity, making this data vital for identifying and monitoring blooms.

MODIS Ocean Chlorophyll Maps offer measurements of chlorophyll-a concentration at the ocean’s surface. These are generally available on various temporal scales (daily, weekly, monthly, etc.) and spatial resolutions (usually 4 km). The data are often colour-coded, making it easy to identify areas of high algal concentration.