Monthly Chlorophyll-a Climatology for Canadian Pacific Waters (2003-2020)

18 years of satellite-derived chlorophyll-a concentration data from NASA's MODIS-Aqua instrument, processed into monthly climatological composites at 1 km resolution. The dataset provides geometric mean, geometric standard deviation factor, and data occurrence counts for each pixel, cropped to the Canadian Pacific Exclusive Economic Zone. January and December data are excluded due to low winter sun angles at high latitudes.

Use Cases

• Analyze spatial patterns of phytoplankton biomass using the monthly geometric mean chlorophyll-a concentration.
• Assess data reliability for specific ocean regions by examining the number of occurrences of valid data at each pixel.
• Model the variability in chlorophyll-a levels by incorporating the monthly geometric standard deviation factor.
• Study long-term phytoplankton trends in the Canadian Pacific Exclusive Economic Zone from 2003 to 2020.

Strengths

• Long temporal coverage spanning 18 years from 2003 to 2020.
• High spatial resolution of 1 km per pixel for detailed geographic analysis.
• Includes derived statistical measures like geometric mean and geometric standard deviation factor, accounting for the log-normal distribution of chlorophyll-a.
• Data is cropped to a defined geographic region (Canadian Pacific EEZ) and assigned a standard coordinate reference system (NAD83 EPSG:4269).

Limitations

• Missing data for January and December due to low sun angles in winter, creating a seasonal gap.
• Pixels with fewer than two valid observations over the entire 18-year period were removed, potentially reducing coverage in persistently cloudy areas.
• Uncertainties are introduced by averaging images where each pixel has a different number of observations, and short-lived events may be missed.

Provenance

Source

NASA Ocean Biology Processing Group, MODIS-Aqua Level 2 Ocean Color Data Version R2018.0.

Collection Method

Chlorophyll-a concentration retrieved from MODIS-Aqua, processed to Level-2 using the OC3/OCI method, aligned and averaged into monthly climatological composites using SeaDAS, with gaps filled via median filtering.

Time Range

2003 to 2020 (excluding January and December).

Freshness

Data covers up to 2020; metadata was last updated in March 2026.

Geography

Canadian Pacific Exclusive Economic Zone.