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Help/FAQ About SST Data
5. Who uses Sea Surface Temperature data?
Sea Surface Temperature (SST) and sea colour data is used by professional fishermen and recreational anglers all over the world.
Both data sets are mostly used by anglers fishing in open waters, several kilometres from the shore. They are most useful for fishing for pelagic fish species (those that live in the water column rather than resting on the bottom).
6. Where does the data come from?
Sea Surface Temperature and Sea Colour Maps accessed through this site are produced by Earthinsite.com Pty Ltd from processed data supplied by the Western Australian Government organisation, Landgate. The raw data is received at stations in Perth, Darwin, Alice Springs, Hobart and Melbourne from the Advanced Very High Resolution Radiometer (AVHRR) sensors on-board US National Oceanic and Atmospheric Administration (NOAA) and NASA's Earth Observing System satellites Terra and Aqua which together provide global coverage many times per day. The processed data is used to produce the enhanced colour images showing current sea surface temperatures and sea colour for the entire Australian Coastline.
7. How can it tell me where fish are going to be?
It can't. What it can tell you however is where ocean currents are meeting at the surface.
The key to getting the most out of the SST and se colour observations is realising that the water temperatures are less important than changes in water temperature. The ocean is three-dimensional, and that the correlation of surface temperature (where the sun and wind play a big effect) with deep water temperature (governed by deep ocean currents) is indirect, at best.
Changes in water temperature, therefore, are a very good indicator of water activity, i.e., currents, upwellings, etc. Moving water carries nutrients, which fosters plankton growth (sea colour), which brings the baitfish, which brings other larger fish. These movements can be seen either by the temperature break, which is a sharply defined boundary between regions of two different water temperatures or lots of small scale temperature variability in a region.
8. How do I locate the area I want to fish?
When you log in to the SST Mapper, you will be presented with a series of small thumbnail images of the data sets available covering all areas of Australian waters.
When you select the data set you want to view, by either single clicking on the thumbnail or the Sea Temperature button to the right of the thumbnail, you will be taken to the SST Mapper. From here you can zoom in by drawing a box by dragging your mouse, holding the left button down, over the map to select the area you want to fish, and clicking the Zoom button.
Where there are sea colour images available from the same satellite pass there will also appear a green Sea Colour button also to the right of the thumbnail.
9. How do I find the co-ordinates of the temperature change points?
Once you have selected the area you want to fish, you can click on the Show/Hide Temperatures button and then move your curser over the screen to view the co-ordinates and the surface temperature of any point on the map.
You can download or print this map, or you can simply note down the coordinates of the most likely areas to start your fishing.
10. Why is there a white section on the image?
The satellites cannot penetrate cloud and therefore cloud cover can affect the availability of data in certain areas.
When you log in to the SST Mapper, you first select the region you are in from the map of Australia, and then you will be presented with thumbnail images of the data sets available.
When you view the larger image of these thumbnails, you may see sections of white where there is no data available. This only happens in cases of significant thick clouds.
11. Why are there large green areas in the middle of the SST satellite data?
There are two explanations for this occurring:
1. Sun Glint
Under certain conditions, water can act as a spectacular reflector, much like a mirror and as a result sun glint occurs when the sunlight is reflected from the ocean's surface back to the satellite. The sun glint can contaminate an approximately elliptical area many kilometres long and over thousands of square kilometres of the swath. Because sun glint can cause false temperature readings, it is often removed from satellite images by the processing software and thus you get large areas were no data appears. These areas can often have an elliptical shape or a rectangular shape (See Fig below)
2. Data Errors
Occasionally you get interference in the reception of the satellite data and also technical problems with the transmission of data from the satellite. This cause loss of data and usually occurs as parallel areas of green (no data) at right angles to the satellite path (see Fig below)
12. Why are there large gray areas in the middle of the Sea Colour satellite data?
This is sun glint. When it affects the sea surface temperature it looks like the images that appear above. However when it affects sea colour it appears as a gray mass.
The sun on the water can act as a giant reflector at times and affects the visible channels which are used in the Chlorophyll algorithm and products so it is masked out. In some cases it doesn't affect the SST products because they use the thermal channels so it appears alright on those images. In other cases it does and the software automatically removes it.
Click here to see an unprocessed visible image of satellite data on which you can see the sun glint areas (The light green areas).
13. Converting Latitude/Longitude GPS coordinates
For the marine and fishing industries the traditional way to show position on a GPS or a chart is in Latitude and Longitude.
Various brands of chart plotters and GPS show Lat/Long in either one of three basic ways:
a. DM.m = Degrees and Decimal Minutes (eg. 45° 22.6333')
b. D.d = Decimal Degrees (eg. 45.3772°)
c. DMS = Degrees, Minutes, Seconds (eg. 45° 22' 38")
Your GPS will usually have various options on how to show Lat/Long (Consult your manual for how to switch from one to the other).
To convert from one method to the other you first have to understand that fractions of degrees are broken down into minutes and seconds. Each minute represents 1/60th of a degree and each second represents 1/60th of a minute (or 1/3600th of a degree).
Below are some methods for converting from one display method to another:
1. Convert 45° 22' 38" to 45° 22.6333'
Divide the seconds by 60 to get decimal minutes (38/60=0.6333')
Add to minutes to decimal minutes (22+0.6333=22.6333')
2. Convert 45° 22.6333' to 45.3772°
Divide decimal minutes by 60 to get decimal degrees (22.6333/60=0.3772)
Add to degrees to get your answer in decimal degrees (45+0.3772 = 45.3772°)
3. Convert 45.3772° to 45° 22.6333'
Multiply decimal component of degrees by 60 to get minutes i.e. (0.3772*60=22.6333')
4. Convert 45° 22.6333' to 45° 22' 38"
Multiply the decimal part of the minutes by 60 to get the seconds (0.6333*60=38)
5. Convert 45° 22' 38" to 45.3772°
Divide minutes by 60 (22/60=0.3666) add seconds divided by 3600 (38/3600=0.0106 +0.3666=0.3772)
Add to degrees (45+0.3772=45.3772°)
On Seasurface.com the coordinates shown along the bottom of the image window are shown in degrees, minutes and seconds. By clicking the blue Decimal Degrees On/Off button to the left of the image window you can convert these readings to decimal degrees.
When adding a new GPS mark using the green Add/Edit GPS Marks button you can enter the Lat/Long coordinates in the appropriate boxes in degrees/minutes/seconds, or in degrees and decimal minutes or, in decimal degrees. The system knows which method you have entered.
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