GitHub - chrisws/redsky: Investigation into the South Australian Algal Bloom 2025 (+ 2013)

South Australian algal bloom investigation with VIIRS SST and Chlr-A data

Ocean thermal energy analysis

Mixed layer depth: 10.0m
Grid cell area: 0.5625 km²
Baseline temperature: 15.0°C

GAB:

SST: 17.50°C | Trend: -0.1213°C/yr (p=0.0000)
Heating DD/yr: 563.6 | Cooling DD/yr: 5.6
MARINE HEAT WAVES DETECTED: 9 events (88 total days) 90th percentile threshold: 20.01°C
- 2018-01-17 to 2018-01-28: 7 days, mean 21.58°C (+1.57°C), max 24.14°C (+4.14°C)
- 2018-02-05 to 2018-02-27: 12 days, mean 20.66°C (+0.65°C), max 21.45°C (+1.45°C)
- 2018-04-16 to 2018-04-21: 5 days, mean 20.37°C (+0.37°C), max 20.71°C (+0.70°C)
- 2019-02-07 to 2019-03-13: 21 days, mean 20.85°C (+0.84°C), max 21.79°C (+1.79°C)
- 2019-03-16 to 2019-03-21: 5 days, mean 20.39°C (+0.38°C), max 21.24°C (+1.23°C)
- 2020-01-26 to 2020-02-10: 10 days, mean 20.80°C (+0.80°C), max 21.45°C (+1.44°C)
- 2023-02-18 to 2023-02-25: 7 days, mean 20.65°C (+0.65°C), max 21.26°C (+1.26°C)
- 2025-01-09 to 2025-01-14: 5 days, mean 20.67°C (+0.66°C), max 21.30°C (+1.30°C)
- 2025-01-16 to 2025-02-07: 16 days, mean 20.84°C (+0.84°C), max 21.85°C (+1.84°C)

Ceduna W:

SST: 17.07°C | Trend: -0.0859°C/yr (p=0.0001)
Heating DD/yr: 403.2 | Cooling DD/yr: 14.5
MARINE HEAT WAVES DETECTED: 9 events (61 total days) 90th percentile threshold: 19.51°C
- 2018-01-18 to 2018-01-25: 5 days, mean 20.47°C (+0.97°C), max 21.49°C (+1.98°C)
- 2018-02-06 to 2018-02-17: 6 days, mean 20.40°C (+0.90°C), max 21.64°C (+2.13°C)
- 2019-01-27 to 2019-02-03: 6 days, mean 20.09°C (+0.58°C), max 20.83°C (+1.32°C)
- 2019-02-23 to 2019-03-01: 6 days, mean 20.62°C (+1.11°C), max 21.16°C (+1.65°C)
- 2019-12-28 to 2020-01-03: 5 days, mean 20.52°C (+1.01°C), max 21.03°C (+1.53°C)
- 2020-01-27 to 2020-02-12: 9 days, mean 20.51°C (+1.00°C), max 21.81°C (+2.30°C)
- 2023-02-19 to 2023-02-25: 6 days, mean 20.37°C (+0.86°C), max 21.04°C (+1.54°C)
- 2025-01-09 to 2025-01-14: 5 days, mean 19.93°C (+0.42°C), max 20.60°C (+1.09°C)
- 2025-01-16 to 2025-02-08: 13 days, mean 20.31°C (+0.80°C), max 22.38°C (+2.87°C)

Ceduna E:

SST: 16.64°C | Trend: -0.0973°C/yr (p=0.0000)
Heating DD/yr: 361.7 | Cooling DD/yr: 26.8
MARINE HEAT WAVES DETECTED: 10 events (71 total days) 90th percentile threshold: 18.85°C
- 2018-01-18 to 2018-01-25: 6 days, mean 19.78°C (+0.93°C), max 20.77°C (+1.92°C)
- 2018-02-06 to 2018-02-15: 5 days, mean 19.52°C (+0.67°C), max 21.31°C (+2.46°C)
- 2018-04-19 to 2018-04-24: 5 days, mean 19.15°C (+0.30°C), max 19.45°C (+0.60°C)
- 2019-01-22 to 2019-02-04: 11 days, mean 19.86°C (+1.01°C), max 21.53°C (+2.68°C)
- 2019-02-23 to 2019-03-05: 8 days, mean 19.87°C (+1.03°C), max 20.75°C (+1.90°C)
- 2020-02-07 to 2020-02-15: 6 days, mean 19.83°C (+0.99°C), max 21.10°C (+2.25°C)
- 2023-02-20 to 2023-02-25: 5 days, mean 20.40°C (+1.55°C), max 21.79°C (+2.94°C)
- 2025-01-07 to 2025-01-27: 13 days, mean 19.70°C (+0.86°C), max 20.83°C (+1.98°C)
- 2025-02-01 to 2025-02-08: 6 days, mean 19.14°C (+0.30°C), max 19.59°C (+0.74°C)
- 2025-02-24 to 2025-03-24: 6 days, mean 19.23°C (+0.38°C), max 19.71°C (+0.86°C)

Pt Lincoln W:

SST: 16.35°C | Trend: -0.0974°C/yr (p=0.0000)
Heating DD/yr: 285.3 | Cooling DD/yr: 25.5
MARINE HEAT WAVES DETECTED: 8 events (58 total days) 90th percentile threshold: 18.44°C
- 2018-01-16 to 2018-01-21: 5 days, mean 19.60°C (+1.15°C), max 20.85°C (+2.40°C)
- 2018-04-08 to 2018-04-14: 5 days, mean 18.80°C (+0.36°C), max 19.05°C (+0.61°C)
- 2018-04-17 to 2018-04-24: 7 days, mean 18.85°C (+0.40°C), max 19.23°C (+0.78°C)
- 2019-01-19 to 2019-01-29: 7 days, mean 19.24°C (+0.79°C), max 20.40°C (+1.96°C)
- 2019-02-23 to 2019-03-02: 6 days, mean 19.41°C (+0.96°C), max 20.31°C (+1.86°C)
- 2021-04-01 to 2021-04-08: 6 days, mean 18.76°C (+0.32°C), max 19.15°C (+0.70°C)
- 2023-02-15 to 2023-02-26: 9 days, mean 19.15°C (+0.71°C), max 20.32°C (+1.88°C)
- 2025-01-12 to 2025-02-02: 13 days, mean 19.18°C (+0.74°C), max 20.39°C (+1.95°C)

Pt Lincoln E:

SST: 16.80°C | Trend: -0.0845°C/yr (p=0.0010)
Heating DD/yr: 385.8 | Cooling DD/yr: 45.6
MARINE HEAT WAVES DETECTED: 7 events (56 total days) 90th percentile threshold: 19.96°C
- 2018-02-05 to 2018-03-10: 16 days, mean 20.85°C (+0.89°C), max 22.52°C (+2.56°C)
- 2018-04-07 to 2018-04-12: 5 days, mean 20.34°C (+0.38°C), max 20.71°C (+0.75°C)
- 2019-01-22 to 2019-02-04: 11 days, mean 20.89°C (+0.93°C), max 22.08°C (+2.12°C)
- 2019-02-20 to 2019-03-03: 8 days, mean 21.34°C (+1.38°C), max 23.45°C (+3.49°C)
- 2020-02-07 to 2020-02-18: 5 days, mean 20.39°C (+0.44°C), max 20.99°C (+1.03°C)
- 2025-02-11 to 2025-02-18: 5 days, mean 21.59°C (+1.64°C), max 22.86°C (+2.90°C)
- 2025-02-22 to 2025-03-23: 6 days, mean 21.01°C (+1.05°C), max 22.88°C (+2.92°C)

Spencer Gulf N:

SST: 17.74°C | Trend: -0.0124°C/yr (p=0.7545)
Heating DD/yr: 699.3 | Cooling DD/yr: 113.9
MARINE HEAT WAVES DETECTED: 12 events (90 total days) 90th percentile threshold: 22.62°C
- 2018-01-19 to 2018-01-26: 5 days, mean 24.03°C (+1.41°C), max 24.62°C (+2.00°C)
- 2018-02-05 to 2018-02-28: 11 days, mean 23.30°C (+0.68°C), max 25.58°C (+2.96°C)
- 2019-01-14 to 2019-01-30: 7 days, mean 23.59°C (+0.97°C), max 24.53°C (+1.90°C)
- 2019-02-02 to 2019-02-09: 6 days, mean 23.60°C (+0.98°C), max 24.33°C (+1.70°C)
- 2019-02-24 to 2019-03-03: 7 days, mean 23.85°C (+1.23°C), max 24.83°C (+2.21°C)
- 2022-01-26 to 2022-02-02: 6 days, mean 23.72°C (+1.10°C), max 24.32°C (+1.69°C)
- 2023-01-12 to 2023-01-20: 6 days, mean 23.14°C (+0.52°C), max 24.05°C (+1.43°C)
- 2023-02-20 to 2023-02-26: 5 days, mean 23.84°C (+1.21°C), max 24.72°C (+2.09°C)
- 2024-01-12 to 2024-01-25: 6 days, mean 23.29°C (+0.67°C), max 25.22°C (+2.59°C)
- 2024-02-18 to 2024-03-03: 10 days, mean 23.39°C (+0.77°C), max 23.95°C (+1.33°C)
- 2025-01-10 to 2025-01-29: 13 days, mean 23.57°C (+0.95°C), max 24.22°C (+1.60°C)
- 2025-02-06 to 2025-02-19: 8 days, mean 23.68°C (+1.06°C), max 24.76°C (+2.13°C)

Spencer Gulf C:

SST: 17.26°C | Trend: -0.0489°C/yr (p=0.1557)
Heating DD/yr: 518.5 | Cooling DD/yr: 83.0
MARINE HEAT WAVES DETECTED: 9 events (86 total days) 90th percentile threshold: 21.36°C
- 2018-01-19 to 2018-01-25: 5 days, mean 22.21°C (+0.85°C), max 23.16°C (+1.81°C)
- 2018-02-05 to 2018-02-28: 10 days, mean 21.95°C (+0.59°C), max 22.35°C (+0.99°C)
- 2018-03-04 to 2018-03-10: 5 days, mean 21.66°C (+0.31°C), max 22.02°C (+0.67°C)
- 2019-01-22 to 2019-02-12: 15 days, mean 22.07°C (+0.71°C), max 23.09°C (+1.74°C)
- 2019-02-20 to 2019-03-13: 13 days, mean 22.19°C (+0.84°C), max 23.30°C (+1.94°C)
- 2023-02-20 to 2023-02-26: 5 days, mean 22.24°C (+0.88°C), max 22.95°C (+1.59°C)
- 2024-02-08 to 2024-02-13: 5 days, mean 21.86°C (+0.50°C), max 22.33°C (+0.98°C)
- 2025-01-16 to 2025-02-03: 12 days, mean 22.36°C (+1.00°C), max 23.14°C (+1.78°C)
- 2025-02-06 to 2025-03-02: 16 days, mean 22.33°C (+0.98°C), max 23.82°C (+2.46°C)

Spencer Gulf S:

SST: 16.86°C | Trend: -0.0746°C/yr (p=0.0082)
Heating DD/yr: 419.6 | Cooling DD/yr: 62.6
MARINE HEAT WAVES DETECTED: 7 events (74 total days) 90th percentile threshold: 20.33°C
- 2018-01-19 to 2018-01-25: 5 days, mean 21.26°C (+0.93°C), max 22.27°C (+1.94°C)
- 2018-02-05 to 2018-02-15: 6 days, mean 21.07°C (+0.74°C), max 21.81°C (+1.48°C)
- 2018-02-17 to 2018-03-06: 10 days, mean 20.81°C (+0.48°C), max 21.55°C (+1.22°C)
- 2019-01-22 to 2019-02-10: 13 days, mean 21.19°C (+0.86°C), max 22.19°C (+1.86°C)
- 2019-02-21 to 2019-03-07: 11 days, mean 21.45°C (+1.12°C), max 22.40°C (+2.07°C)
- 2025-01-18 to 2025-02-19: 23 days, mean 21.50°C (+1.17°C), max 22.70°C (+2.37°C)
- 2025-02-24 to 2025-03-24: 6 days, mean 20.89°C (+0.56°C), max 21.54°C (+1.21°C)

SVG - NW:

SST: 17.36°C | Trend: -0.0573°C/yr (p=0.2323)
Heating DD/yr: 418.1 | Cooling DD/yr: 91.0
MARINE HEAT WAVES DETECTED: 8 events (62 total days) 90th percentile threshold: 22.08°C
- 2018-02-05 to 2018-03-06: 7 days, mean 22.72°C (+0.64°C), max 24.52°C (+2.44°C)
- 2019-01-12 to 2019-02-10: 16 days, mean 23.35°C (+1.27°C), max 26.59°C (+4.51°C)
- 2019-02-24 to 2019-03-03: 7 days, mean 23.52°C (+1.45°C), max 24.30°C (+2.22°C)
- 2019-12-29 to 2020-01-14: 6 days, mean 22.78°C (+0.70°C), max 23.92°C (+1.84°C)
- 2023-01-09 to 2023-01-17: 5 days, mean 22.63°C (+0.55°C), max 23.01°C (+0.93°C)
- 2024-02-18 to 2024-02-27: 5 days, mean 22.69°C (+0.61°C), max 23.47°C (+1.39°C)
- 2025-01-10 to 2025-01-27: 9 days, mean 23.29°C (+1.21°C), max 24.04°C (+1.96°C)
- 2025-02-02 to 2025-02-12: 7 days, mean 23.28°C (+1.20°C), max 23.99°C (+1.91°C)

SVG - NE:

SST: 17.52°C | Trend: -0.0078°C/yr (p=0.8784)
Heating DD/yr: 421.0 | Cooling DD/yr: 86.4
MARINE HEAT WAVES DETECTED: 5 events (40 total days) 90th percentile threshold: 22.34°C
- 2019-01-14 to 2019-02-07: 12 days, mean 23.64°C (+1.30°C), max 24.63°C (+2.29°C)
- 2019-02-25 to 2019-03-03: 5 days, mean 24.10°C (+1.76°C), max 24.88°C (+2.54°C)
- 2023-01-09 to 2023-01-17: 5 days, mean 23.06°C (+0.71°C), max 23.55°C (+1.21°C)
- 2025-01-10 to 2025-01-29: 9 days, mean 23.37°C (+1.03°C), max 24.12°C (+1.78°C)
- 2025-02-02 to 2025-02-18: 9 days, mean 23.26°C (+0.92°C), max 24.36°C (+2.02°C)

SVG - SW:

SST: 16.93°C | Trend: -0.0835°C/yr (p=0.0239)
Heating DD/yr: 392.5 | Cooling DD/yr: 84.6
MARINE HEAT WAVES DETECTED: 4 events (71 total days) 90th percentile threshold: 20.92°C
- 2018-02-05 to 2018-03-16: 19 days, mean 21.42°C (+0.51°C), max 22.42°C (+1.51°C)
- 2019-01-22 to 2019-02-12: 13 days, mean 21.65°C (+0.73°C), max 22.13°C (+1.22°C)
- 2019-02-23 to 2019-03-03: 8 days, mean 22.18°C (+1.26°C), max 22.76°C (+1.84°C)
- 2025-01-10 to 2025-03-26: 31 days, mean 21.81°C (+0.89°C), max 23.20°C (+2.28°C)

SVG - SE:

SST: 17.33°C | Trend: -0.0750°C/yr (p=0.0700)
Heating DD/yr: 430.3 | Cooling DD/yr: 78.8
MARINE HEAT WAVES DETECTED: 5 events (62 total days) 90th percentile threshold: 21.54°C
- 2018-01-17 to 2018-01-25: 5 days, mean 22.41°C (+0.87°C), max 23.77°C (+2.24°C)
- 2018-02-05 to 2018-03-06: 15 days, mean 22.09°C (+0.55°C), max 23.66°C (+2.12°C)
- 2019-01-22 to 2019-02-12: 12 days, mean 22.35°C (+0.81°C), max 22.77°C (+1.24°C)
- 2019-02-23 to 2019-03-09: 10 days, mean 22.58°C (+1.04°C), max 24.04°C (+2.50°C)
- 2025-01-18 to 2025-02-22: 20 days, mean 22.49°C (+0.95°C), max 23.64°C (+2.10°C)

KI - W:

SST: 16.64°C | Trend: -0.0891°C/yr (p=0.0000)
Heating DD/yr: 317.8 | Cooling DD/yr: 19.9
MARINE HEAT WAVES DETECTED: 8 events (78 total days) 90th percentile threshold: 19.18°C
- 2018-01-16 to 2018-01-25: 5 days, mean 20.12°C (+0.94°C), max 21.19°C (+2.01°C)
- 2018-02-06 to 2018-02-15: 5 days, mean 20.08°C (+0.90°C), max 21.13°C (+1.95°C)
- 2018-02-17 to 2018-03-03: 7 days, mean 19.70°C (+0.52°C), max 20.21°C (+1.04°C)
- 2019-01-14 to 2019-02-10: 16 days, mean 20.02°C (+0.84°C), max 21.23°C (+2.05°C)
- 2019-02-19 to 2019-03-02: 9 days, mean 20.08°C (+0.90°C), max 21.28°C (+2.11°C)
- 2022-01-26 to 2022-02-02: 6 days, mean 19.58°C (+0.40°C), max 20.04°C (+0.86°C)
- 2025-01-07 to 2025-02-17: 24 days, mean 20.15°C (+0.97°C), max 21.17°C (+1.99°C)
- 2025-03-24 to 2025-03-29: 6 days, mean 19.66°C (+0.48°C), max 20.20°C (+1.02°C)

KI - E:

SST: 16.52°C | Trend: -0.0889°C/yr (p=0.0005)
Heating DD/yr: 330.2 | Cooling DD/yr: 53.7
MARINE HEAT WAVES DETECTED: 8 events (96 total days) 90th percentile threshold: 19.67°C
- 2018-01-16 to 2018-01-25: 6 days, mean 20.79°C (+1.11°C), max 21.87°C (+2.19°C)
- 2018-02-06 to 2018-02-15: 5 days, mean 20.28°C (+0.61°C), max 20.58°C (+0.91°C)
- 2018-02-26 to 2018-03-06: 7 days, mean 20.12°C (+0.45°C), max 20.60°C (+0.93°C)
- 2019-01-14 to 2019-02-13: 19 days, mean 20.54°C (+0.87°C), max 21.99°C (+2.32°C)
- 2019-02-15 to 2019-03-07: 12 days, mean 20.45°C (+0.78°C), max 21.27°C (+1.60°C)
- 2019-03-17 to 2019-03-23: 5 days, mean 20.06°C (+0.39°C), max 20.40°C (+0.72°C)
- 2023-02-20 to 2023-02-26: 5 days, mean 20.31°C (+0.64°C), max 20.89°C (+1.21°C)
- 2025-01-05 to 2025-03-25: 37 days, mean 20.61°C (+0.93°C), max 21.84°C (+2.17°C)

Victor - W:

SST: 16.20°C | Trend: -0.1045°C/yr (p=0.0001)
Heating DD/yr: 272.8 | Cooling DD/yr: 70.1
MARINE HEAT WAVES DETECTED: 6 events (63 total days) 90th percentile threshold: 19.27°C
- 2018-01-16 to 2018-01-25: 5 days, mean 20.24°C (+0.97°C), max 21.84°C (+2.56°C)
- 2019-01-12 to 2019-02-13: 16 days, mean 20.01°C (+0.74°C), max 20.95°C (+1.67°C)
- 2019-02-24 to 2019-03-02: 6 days, mean 20.42°C (+1.15°C), max 21.03°C (+1.75°C)
- 2023-02-19 to 2023-02-26: 6 days, mean 20.15°C (+0.88°C), max 20.99°C (+1.72°C)
- 2024-12-10 to 2024-12-25: 7 days, mean 19.87°C (+0.60°C), max 20.83°C (+1.56°C)
- 2025-01-08 to 2025-02-22: 23 days, mean 20.34°C (+1.07°C), max 21.41°C (+2.13°C)

Victor - E:

SST: 15.72°C | Trend: -0.0775°C/yr (p=0.0025)
Heating DD/yr: 219.5 | Cooling DD/yr: 100.6
MARINE HEAT WAVES DETECTED: 8 events (77 total days) 90th percentile threshold: 18.61°C
- 2018-01-17 to 2018-01-25: 6 days, mean 19.83°C (+1.21°C), max 21.54°C (+2.93°C)
- 2018-02-06 to 2018-02-15: 7 days, mean 19.27°C (+0.66°C), max 20.15°C (+1.54°C)
- 2019-01-22 to 2019-02-11: 12 days, mean 19.20°C (+0.59°C), max 20.44°C (+1.83°C)
- 2019-02-24 to 2019-03-09: 9 days, mean 19.52°C (+0.91°C), max 20.48°C (+1.86°C)
- 2024-12-05 to 2024-12-20: 5 days, mean 19.53°C (+0.92°C), max 20.88°C (+2.27°C)
- 2024-12-28 to 2025-02-08: 24 days, mean 19.68°C (+1.07°C), max 21.10°C (+2.49°C)
- 2025-02-11 to 2025-02-22: 9 days, mean 19.46°C (+0.85°C), max 20.40°C (+1.78°C)
- 2025-02-24 to 2025-03-23: 5 days, mean 18.99°C (+0.38°C), max 19.52°C (+0.90°C)

Lk Alex:

SST: 16.54°C | Trend: -0.0058°C/yr (p=0.9257)
Heating DD/yr: 205.1 | Cooling DD/yr: 78.4
MARINE HEAT WAVES DETECTED: 4 events (23 total days) 90th percentile threshold: 21.20°C
- 2019-01-14 to 2019-02-05: 8 days, mean 22.52°C (+1.32°C), max 23.78°C (+2.58°C)
- 2019-02-25 to 2019-03-03: 5 days, mean 23.38°C (+2.19°C), max 24.22°C (+3.03°C)
- 2019-12-24 to 2020-01-01: 5 days, mean 21.55°C (+0.35°C), max 22.20°C (+1.01°C)
- 2024-12-05 to 2024-12-20: 5 days, mean 22.05°C (+0.86°C), max 22.85°C (+1.65°C)

Victor Harbour-Mt Gambier:

SST: 15.32°C | Trend: -0.0614°C/yr (p=0.0003)
Heating DD/yr: 176.2 | Cooling DD/yr: 109.5
MARINE HEAT WAVES DETECTED: 7 events (71 total days) 90th percentile threshold: 17.48°C
- 2018-01-05 to 2018-01-25: 15 days, mean 18.35°C (+0.87°C), max 19.53°C (+2.05°C)
- 2019-01-29 to 2019-02-04: 6 days, mean 18.25°C (+0.76°C), max 19.10°C (+1.62°C)
- 2019-02-24 to 2019-03-06: 8 days, mean 18.38°C (+0.90°C), max 18.92°C (+1.44°C)
- 2021-03-31 to 2021-04-08: 7 days, mean 17.83°C (+0.35°C), max 18.09°C (+0.61°C)
- 2022-01-25 to 2022-01-29: 5 days, mean 19.13°C (+1.65°C), max 19.86°C (+2.38°C)
- 2023-02-19 to 2023-02-24: 5 days, mean 17.78°C (+0.29°C), max 18.49°C (+1.01°C)
- 2025-01-01 to 2025-02-14: 25 days, mean 18.40°C (+0.92°C), max 20.24°C (+2.76°C)

Mt Gambier:

SST: 15.32°C | Trend: -0.0389°C/yr (p=0.0384)
Heating DD/yr: 169.1 | Cooling DD/yr: 106.4
MARINE HEAT WAVES DETECTED: 8 events (93 total days) 90th percentile threshold: 17.64°C
- 2018-01-05 to 2018-02-17: 20 days, mean 18.53°C (+0.89°C), max 20.16°C (+2.52°C)
- 2018-03-06 to 2018-03-15: 6 days, mean 18.10°C (+0.46°C), max 18.77°C (+1.13°C)
- 2019-01-10 to 2019-02-19: 21 days, mean 18.38°C (+0.74°C), max 19.09°C (+1.45°C)
- 2019-02-24 to 2019-03-07: 8 days, mean 18.62°C (+0.98°C), max 19.69°C (+2.05°C)
- 2024-02-01 to 2024-02-14: 12 days, mean 18.14°C (+0.50°C), max 18.90°C (+1.26°C)
- 2024-03-01 to 2024-03-11: 6 days, mean 18.08°C (+0.44°C), max 18.33°C (+0.69°C)
- 2025-01-11 to 2025-02-12: 13 days, mean 18.58°C (+0.94°C), max 19.81°C (+2.17°C)
- 2025-03-01 to 2025-03-29: 7 days, mean 17.88°C (+0.24°C), max 18.09°C (+0.45°C)

Pt Fairy:

SST: 15.46°C | Trend: -0.0443°C/yr (p=0.0956)
Heating DD/yr: 253.9 | Cooling DD/yr: 161.5
MARINE HEAT WAVES DETECTED: 8 events (71 total days) 90th percentile threshold: 18.81°C
- 2018-01-06 to 2018-01-11: 5 days, mean 19.11°C (+0.29°C), max 19.32°C (+0.51°C)
- 2018-01-26 to 2018-03-02: 20 days, mean 20.22°C (+1.40°C), max 25.06°C (+6.24°C)
- 2019-01-10 to 2019-01-16: 5 days, mean 19.57°C (+0.75°C), max 20.71°C (+1.89°C)
- 2019-01-20 to 2019-02-14: 15 days, mean 19.92°C (+1.10°C), max 20.81°C (+1.99°C)
- 2022-01-23 to 2022-01-29: 5 days, mean 19.68°C (+0.87°C), max 21.27°C (+2.46°C)
- 2024-02-08 to 2024-02-25: 10 days, mean 19.49°C (+0.68°C), max 20.94°C (+2.12°C)
- 2025-01-31 to 2025-02-07: 5 days, mean 19.75°C (+0.94°C), max 20.63°C (+1.82°C)
- 2025-02-11 to 2025-02-16: 6 days, mean 19.87°C (+1.05°C), max 22.17°C (+3.35°C)

Yearly mean values (chlr-a)

| Group      |      GAB |   Ceduna W |   Ceduna E |   Pt Lincoln W |   Pt Lincoln E |   Spencer Gulf N |   Spencer Gulf C |   Spencer Gulf S |   SVG - NW |   SVG - NE |   SVG - SW |   SVG - SE |   KI - W |   KI - E |   Victor - W |   Victor - E |   Lk Alex |   Victor Harbour-Mt Gambier |   Mt Gambier |   Pt Fairy |
|:-----------|---------:|-----------:|-----------:|---------------:|---------------:|-----------------:|-----------------:|-----------------:|-----------:|-----------:|-----------:|-----------:|---------:|---------:|-------------:|-------------:|----------:|----------------------------:|-------------:|-----------:|
| 2012       | 0.395075 |   0.704127 |   0.62447  |       0.424389 |       0.479383 |          2.09308 |         0.526196 |         0.512825 |    2.37877 |    4.18012 |   0.711444 |   0.742047 | 0.282815 | 0.540881 |     0.585828 |     0.682859 |  nan      |                    0.467531 |     0.332491 |   0.784586 |
| 2013       | 0.47089  |   0.775856 |   0.706796 |       0.437607 |       0.490458 |          2.33492 |         0.611009 |         0.608825 |    2.75805 |    4.55311 |   0.792129 |   0.87921  | 0.289305 | 0.555602 |     0.444416 |     0.51717  |   10.7002 |                    0.447544 |     0.315183 |   0.730188 |
| 2014       | 0.359467 |   0.786139 |   0.809266 |       0.555249 |       0.529739 |          2.25154 |         0.528562 |         0.583451 |    2.58515 |    4.72018 |   0.785615 |   0.730013 | 0.333831 | 0.606861 |     0.470669 |     0.617708 |  nan      |                    0.520572 |     0.301768 |   0.653584 |
| 2017       | 0.420358 |   0.719711 |   0.750979 |       0.472473 |       0.477375 |          2.16509 |         0.55729  |         0.553885 |    2.55451 |    3.80648 |   0.758223 |   0.804488 | 0.294448 | 0.562252 |     0.505473 |     0.511924 |   24.6263 |                    0.440204 |     0.317932 |   0.765035 |
| 2018       | 0.374212 |   0.676656 |   0.616501 |       0.393879 |       0.416414 |          1.93521 |         0.548518 |         0.505213 |    2.14749 |    3.28013 |   0.712456 |   0.764651 | 0.269927 | 0.522626 |     0.394739 |     0.463087 |   23.5477 |                    0.387717 |     0.288127 |   0.581171 |
| 2019       | 0.375582 |   0.691767 |   0.633042 |       0.451581 |       0.484225 |          2.00372 |         0.560138 |         0.499253 |    2.25286 |    3.86962 |   0.683958 |   0.703383 | 0.279634 | 0.477494 |     0.358079 |     0.428672 |   23.8018 |                    0.391544 |     0.277845 |   0.612534 |
| 2020       | 0.427576 |   0.775579 |   0.724257 |       0.493186 |       0.476527 |          2.04482 |         0.530192 |         0.50209  |    2.48055 |    4.08964 |   0.664259 |   0.693749 | 0.297335 | 0.495834 |     0.384684 |     0.497005 |   19.7804 |                    0.52211  |     0.395027 |   0.695104 |
| 2021       | 0.334956 |   0.597513 |   0.581799 |       0.446657 |       0.433315 |          1.74886 |         0.5243   |         0.488959 |    2.19237 |    3.42195 |   0.614813 |   0.610256 | 0.275859 | 0.483064 |     0.385646 |     0.50852  |   16.2773 |                    0.43047  |     0.300323 |   0.702936 |
| 2022       | 0.357808 |   0.671229 |   0.603623 |       0.389092 |       0.450971 |          1.96852 |         0.531655 |         0.529475 |    2.24708 |    3.66757 |   0.60951  |   0.656991 | 0.279882 | 0.484602 |     0.581118 |     0.678748 |  nan      |                    0.461897 |     0.340982 |   0.791325 |
| 2023       | 0.366831 |   0.693477 |   0.628672 |       0.459894 |       0.509031 |          1.94362 |         0.547301 |         0.597199 |    2.38479 |    3.63854 |   0.831204 |   0.755583 | 0.333343 | 0.678843 |     0.82325  |     0.795522 |  nan      |                    0.513577 |     0.286142 |   0.680048 |
| 2024Q1     | 0.454326 |   1.15619  |   1.81511  |       2.28553  |       0.770145 |          2.1871  |         0.581775 |         0.794668 |    2.63438 |    3.39618 |   0.724994 |   0.694829 | 0.716583 | 0.786435 |     0.532364 |     1.09447  |   30.723  |                    1.55208  |     0.463185 |   0.816965 |
| 2024Q2     | 1.3662   |   1.82643  |   1.88289  |       1.34329  |       0.859269 |          2.07278 |         0.751773 |         0.864611 |    2.3182  |    3.31705 |   0.878533 |   0.797009 | 0.476847 | 0.960647 |     1.13285  |     1.28257  |   32.9429 |                    0.706783 |     0.391611 |   0.837316 |
| 2024Q3     | 0.483385 |   1.15536  |   1.35677  |       0.842483 |       0.683304 |          1.80349 |         0.655805 |         0.902387 |    1.69659 |    3.89979 |   0.74611  |   0.717173 | 0.410024 | 0.763577 |     0.837046 |     1.14057  |   27.4474 |                    0.674633 |     0.379422 |   1.05563  |
| 2024Q4     | 0.311394 |   0.696075 |   0.593906 |       0.405704 |       0.373535 |          1.52252 |         0.422686 |         0.466826 |    2.0938  |    3.1447  |   0.562048 |   0.463881 | 0.234204 | 0.476275 |     0.390396 |     0.595555 |  nan      |                    0.422824 |     0.294721 |   0.622021 |
| 2025Q1     | 0.376193 |   0.712626 |   0.604254 |       0.432756 |       0.536578 |          2.21596 |         0.580119 |         0.591788 |    2.69539 |    3.32973 |   0.824022 |   0.692935 | 0.297852 | 0.673126 |     0.474917 |     0.505771 |  nan      |                    0.472143 |     0.271055 |   0.634368 |
| 2025Q2     | 0.586443 |   0.91306  |   0.768801 |       0.590395 |       0.810694 |          2.18309 |         0.84232  |         1.24034  |    4.36114 |    4.38811 |   2.59219  |   1.40029  | 0.656925 | 1.32357  |     0.91589  |     0.962905 |   21.0486 |                    0.566423 |     0.367223 |   0.921352 |
| 2025Q3     | 0.343732 |   0.637652 |   0.699562 |       0.476294 |       0.757779 |          2.77171 |         0.651085 |         0.589823 |   13.2696  |   11.8667  |   2.27952  |   3.32532  | 0.319275 | 0.649195 |     0.56203  |     0.614875 |  nan      |                    0.419024 |     0.343666 |   0.627906 |
| 2025Q4     | 0.285594 |   0.519815 |   0.431246 |       0.288273 |       0.339615 |          2.32145 |         0.527534 |         0.489277 |    4.52746 |    5.29383 |   0.957656 |   1.26867  | 0.231938 | 0.488529 |     0.378762 |     0.442039 |  nan      |                    0.341309 |     0.28596  |   0.433947 |
| 2026Q1     | 0.367615 |   0.768359 |   0.698767 |       0.661008 |       0.632367 |          2.56882 |         0.609019 |         0.903001 |    2.4988  |    3.03735 |   0.762023 |   0.677932 | 0.435135 | 0.653237 |     0.44506  |     0.374268 |  nan      |                    0.46914  |     0.258508 |   0.461609 |
| Grand Mean | 0.414969 |   0.77942  |   0.75259  |       0.540277 |       0.534577 |          2.09429 |         0.577177 |         0.61876  |    2.75722 |    4.0269  |   0.834469 |   0.81829  | 0.33528  | 0.616569 |     0.526272 |     0.627531 |   22.101  |                    0.503517 |     0.323175 |   0.690753 |

VIIRS Pixel Coverage Summary


GAB {'lat_km': 100.18799999999983, 'lon_km': 236.14039282935244, 'area_km2': 23658.43367678712, 'expected_pixels': 1478.652104799195}
Ceduna W {'lat_km': 100.18799999999983, 'lon_km': 84.45069361866571, 'area_km2': 8460.946092266866, 'expected_pixels': 528.8091307666791}
Ceduna E {'lat_km': 200.37599999999966, 'lon_km': 93.3608076236846, 'area_km2': 18707.26518840339, 'expected_pixels': 1169.204074275212}
Pt Lincoln W {'lat_km': 178.11200000000014, 'lon_km': 73.48130770267028, 'area_km2': 13087.902677538019, 'expected_pixels': 817.9939173461262}
Pt Lincoln E {'lat_km': 200.37599999999966, 'lon_km': 73.39338185392326, 'area_km2': 14706.272282361702, 'expected_pixels': 919.1420176476064}
Spencer Gulf N {'lat_km': 155.84799999999984, 'lon_km': 139.4028962077236, 'area_km2': 21725.662568181284, 'expected_pixels': 1357.8539105113302}
Spencer Gulf C {'lat_km': 66.79200000000016, 'lon_km': 110.22196155400673, 'area_km2': 7361.945256115235, 'expected_pixels': 460.1215785072022}
Spencer Gulf S {'lat_km': 77.92399999999952, 'lon_km': 109.35870090910547, 'area_km2': 8521.667409641082, 'expected_pixels': 532.6042131025677}
SVG - NW {'lat_km': 77.92399999999952, 'lon_km': 38.55462068911782, 'area_km2': 3004.3302625787987, 'expected_pixels': 187.77064141117492}
SVG - NE {'lat_km': 77.92399999999952, 'lon_km': 44.062423644703465, 'area_km2': 3433.520300089852, 'expected_pixels': 214.59501875561574}
SVG - SW {'lat_km': 66.79200000000016, 'lon_km': 40.98439194469068, 'area_km2': 2737.4295067697863, 'expected_pixels': 171.08934417311164}
SVG - SE {'lat_km': 66.79200000000016, 'lon_km': 40.98439194468809, 'area_km2': 2737.4295067696135, 'expected_pixels': 171.08934417310084}
KI - W {'lat_km': 100.18799999999983, 'lon_km': 90.23076422948498, 'area_km2': 9040.039806623625, 'expected_pixels': 565.0024879139766}
KI - E {'lat_km': 100.18799999999983, 'lon_km': 90.23076422948498, 'area_km2': 9040.039806623625, 'expected_pixels': 565.0024879139766}
Victor - W {'lat_km': 89.05599999999968, 'lon_km': 63.121684790097184, 'area_km2': 5621.364760666875, 'expected_pixels': 351.33529754167967}
Victor - E {'lat_km': 89.05599999999968, 'lon_km': 71.95634710042403, 'area_km2': 6408.144447375339, 'expected_pixels': 400.5090279609587}
Lk Alex {'lat_km': 44.52799999999984, 'lon_km': 45.37001311025132, 'area_km2': 2020.2359437732637, 'expected_pixels': 126.26474648582898}
Victor Harbour-Mt Gambier {'lat_km': 211.50799999999984, 'lon_km': 132.56279752558572, 'area_km2': 28038.092179041563, 'expected_pixels': 1752.3807611900977}
Mt Gambier {'lat_km': 111.32, 'lon_km': 174.23988004162143, 'area_km2': 19396.383446233296, 'expected_pixels': 1212.273965389581}
Pt Fairy {'lat_km': 111.32, 'lon_km': 174.23988004162143, 'area_km2': 19396.383446233296, 'expected_pixels': 1212.273965389581}

Technical Notes

VIIRS Sensor Capabilities:

Operational: 2011-present (Suomi-NPP), 2017-present (NOAA-20)
Resolution: 750m (superior to MODIS 1000m)
Calibration: Stable, no orbital drift (unlike aging MODIS)
Algorithm: Standard NASA OC3 chlorophyll-a retrieval
Validation: Well-established for coastal waters globally

Not Benthic Reflectance:

Upper Spencer Gulf depth: 20-40m (adequate for ocean color sensing)
Gulf St Vincent North depth: 15-30m (adequate for ocean color sensing)
VIIRS algorithm corrects for shallow-water reflectance
13-year temporal stability rules out bottom-type changes
Southern regions (similar depths) show low stable values
Spike events (9.11 mg/m³) impossible from benthic reflectance

Not Cloud/Atmospheric Artifacts:

13-year consistent pattern (thousands of clear-sky observations)
Multiple independent overpasses (NPP + NOAA-20)
Standard atmospheric correction applied
Pattern matches known circulation (counter-clockwise GSV)
Independent validation: In-situ sampling during 2025 crisis confirmed satellite values

What is Chlorophyll-a?

Chlorophyll-a is the green pigment found in all photosynthetic algae and plants. In ocean water, measuring chlorophyll-a tells us how much algae (phytoplankton) is present. It's the standard indicator used worldwide to monitor algal blooms.

Understanding the Measurements (mg/m³)

Chlorophyll-a Level	Interpretation	Water Quality
0.1 - 1.0 mg/m³	Normal oceanic levels	🟢 Healthy
1.0 - 2.0 mg/m³	Slightly elevated	🟡 Acceptable
2.0 - 5.0 mg/m³	Moderate bloom conditions	🟠 Concerning
5.0 - 10.0 mg/m³	Severe bloom	🔴 Harmful
> 10.0 mg/m³	Extreme bloom / toxic potential	🔴 Crisis

What Causes High Chlorophyll?

Algae need nutrients (primarily nitrogen and phosphorus) to grow. Excessive nutrients from:

Wastewater discharge
Agricultural fertilizer runoff
Industrial waste
Urban stormwater
Waste management facilities

Nitrogen Isotope Fingerprinting

Sample seagrass/algae tissue from north-south transects
δ15N signatures differentiate: organic waste (+8 to +20‰), treated sewage (+15 to +22‰), natural marine (+3 to +7‰)
Definitive source apportionment
For details, see: https://pubmed.ncbi.nlm.nih.gov/23602260/

Lake Alexandrina

Refer to the "Chlorophyll-a Time Series Viewer" for an alternative visualisation
This uses a merged dataset from two satellites (still VIIRS, but NRT) for improved gap filling
Or just drive down Point Sturt road and see for yourself :)

Last updated: Sun 15 Mar 2026 08:19:18 ACDT

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South Australian algal bloom investigation with VIIRS SST and Chlr-A data

Ocean thermal energy analysis

GAB:

Ceduna W:

Ceduna E:

Pt Lincoln W:

Pt Lincoln E:

Spencer Gulf N:

Spencer Gulf C:

Spencer Gulf S:

SVG - NW:

SVG - NE:

SVG - SW:

SVG - SE:

KI - W:

KI - E:

Victor - W:

Victor - E:

Lk Alex:

Victor Harbour-Mt Gambier:

Mt Gambier:

Pt Fairy:

Yearly mean values (chlr-a)

VIIRS Pixel Coverage Summary

Technical Notes

VIIRS Sensor Capabilities:

Not Benthic Reflectance:

Not Cloud/Atmospheric Artifacts:

What is Chlorophyll-a?

Understanding the Measurements (mg/m³)

What Causes High Chlorophyll?

Nitrogen Isotope Fingerprinting

Lake Alexandrina

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