Warm water had a deeper chlorophyll depth centroid in four CalCOFI samples in 1984-2020

We tested the link between surface water temperature and chlorophyll depth in two California Current regions and two periods from 1984 to 2020. Four models used 7,152 profiles with fixed depth coverage and station-month and year effects. Centroid slopes were 2.81-6.20 m per degree C. All four family 95% intervals were above zero. Positive slopes remained with stricter depth gaps, sampling controls and same-cruise comparisons. Nitrate adjustment reduced the slopes on matched records. A retention test found no clear temperature link. Exact integration changed slopes by less than 0.02 m per degree C. These are pigment associations within the upper 100 m, not causal effects of climate change or species movement. Shared ocean conditions, adaptive sampling and pigment changes per cell limit interpretation. Code, profile data, source hashes and bias checks are included.

CalCOFI · chlorophyll · temperature · vertical distribution · observation bias · nutrients · regional replication