Satellite data inputs
The Bureau of Meteorology generates IMOS L3S AVHRR sea surface temperature (SST) products daily. The SST product used in ReefTemp Next Generation is comprised of 1-day night-only SST from multiple NOAA satellites (NOAA-11, 12, 14, 15, 16, 17, 18, 19) at a grid resolution of 0.02° x 0.02° (~2x2 km).
In cases where SST cannot be calculated due to cloud cover, the grid cell is left blank (white in web plots, transparent in Google Earth) to indicate missing data.
Climatology
Average monthly temperatures were calculated from IMOS L3S 1-day night-only SST data for each month for the period 2002–2011. For comparison, the CSIRO 1993–2003 climatology used in ReefTemp V1 was also used to construct products. All products, with the exception of SST, are referenced to monthly climatologies.
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Temperature metrics
- Sea Surface Temperature (SST) - 1 day
- The IMOS 1-day L3S night-only SST product. The temperature range visualised is from
20–35°C. - Sea Surface Temperature (SST) - 14 day mosaic
- A 14-day mosaic SST product, based on the IMOS L3S 1-day product, is also created within the ReefTemp Next Generation system. This product is created by filling any missing data pixels in today's SST data with the most recent available 1-day data from up to 14 days ago. The temperature range visualised is from 20–35°C.
The 14 day SST mosaic product was developed to mimic the legacy Bureau SST mosaic product that underpinned ReefTemp V1, to assist reef mangers to transition smoothly to the ReefTemp Next Generation system. It is important to note that whilst a more complete SST image is available using the 14 day mosaic method, it can be spatially inhomogeneous. - Sea Surface Temperature Anomaly (SSTA)
- SSTA is the difference between SST values and climatology, the monthly long term mean SST. Two climatologies are used to produce products. The first is an IMOS climatology for 2002–2011, constructed for each month using IMOS L3S 1-day night-only SST products in that period. The second climatology used is the CSIRO 1993–2003 climatology that the ReefTemp V1 system utilised. The use of both climatologies allows for comparisons of products based on different reference periods. All SSTA values appear in the range -4°C to 4°C.
- Degree Heating Days (DHD)
- Degree Heating Days (DHD) are the accumulation of positive SSTA values over the summer (1 December to 31 March ) at each grid cell. If no data is available, DHDs are not accumulated and remain the same as the previous day. The visualisation range for DHD values is 0–240 °C days. This product is only available between December and March inclusive.
- Degree Heating Day Count (DHDC)
- The number of days in which temperatures have exceeded the long-term average (when data was available) at each grid cell i.e. positive SSTA values observed. This product is only available between December and March inclusive.
- Mean Positive Summer Anomaly (MPSA)
- Mean Positive Summer Anomaly (MPSA; formerly known as Heating Rate), calculated as the number of Degree Heating Days (DHD) divided by the Degree Heating Day Count (DHDC). The visualisation range for MPSA values is 0-5 °C. This product is only available between December and March inclusive.
Quality metrics
Each grid cell has some visualised quality metrics to help assess data accuracy.
- Data Error Bias
- Data Error Bias indicates the errors (deg C) in the input IMOS L3S 1-day night-only SST data at each pixel due to proximity to cloud, instrumentation errors and the like.
- Data Quality Level (QL)
- Data Quality Level (QL) indicates the quality level of the input IMOS L3S 1-day night-only SST data where 3 = low quality, 4 = acceptable quality and 5 = best quality. Quality levels are determined using the data error for each pixel.
- Missing Data Persistence
- Missing Data Persistence indicates the number of days since there was data available at a given pixel in the input IMOS L3S 1-day night-only SST data. Missing data is generally due to presence of cloud or failure to receive data in real-time.
- 14-day Mosaic Pixel Age (Pixel Age)
- 14-day Mosaic Pixel Age indicates the age of the data which comprises the 14-day Mosaic SST product at each pixel, up to a maximum of 14 days.
Abbreviations
- Advanced Very High Resolution Radiometer (AVHRR)
- The Advanced Very High Resolution Radiometer (AVHRR) is a space-borne sensor embarked on the National Oceanic and Atmospheric Administration (NOAA) family of polar orbiting platforms.
- Integrated Marine Observation System (IMOS)
- IMOS is designed to be a fully integrated national array of observing equipment to monitor the open oceans and coastal marine environment around Australia, covering physical, chemical and biological variables. All IMOS data is freely and openly available through the IMOS Ocean Portal for the benefit of Australian marine and climate science as a whole.
- L3S
- L3S data is gridded data taken from multiple satellite sensors, across multiple swaths.
- National Oceanic and Atmospheric Administration (NOAA)
- The National Oceanic and Atmospheric Administration (NOAA) is a scientific agency within the United States Department of Commerce focused on the conditions of the oceans and the atmosphere. NOAA provides a coral reef watch satellite monitoring service.
