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Topic Frequently Asked Questions / Data Products & Algorithms FAQ / Raw to geophysical values (locked)
What are the equations to convert pixel values to geophysical values?
The scaling equation, the slope, and intercept are found in the metadata of the file.
With this information you can calculate the actual data values for a particular product. To view the metadata, a command such as this will work (used on a Level 3 Monthly SST file for example):
ncdump -h A20040012004031.L3m_MO_SST_9KM |more
The output of interest is this:
:Scaling = "linear" ;
:Scaling_Equation = "(Slope*l3m_data) + Intercept = Parameter value" ;
:Slope = 0.15000001f ;
:Intercept = -2.f ;
:Data_Minimum = -1.799999f ;
:Data_Maximum = 35.25f
Please note that this info will vary according to product and file type (Level 2, Level 3). Information for each of the products, including the scaling info can be found here: Ocean Color Products and clicking on the "product specifics" links.
The scaling equation, the slope, and intercept are found in the metadata of the file.
With this information you can calculate the actual data values for a particular product. To view the metadata, a command such as this will work (used on a Level 3 Monthly SST file for example):
ncdump -h A20040012004031.L3m_MO_SST_9KM |more
The output of interest is this:
:Scaling = "linear" ;
:Scaling_Equation = "(Slope*l3m_data) + Intercept = Parameter value" ;
:Slope = 0.15000001f ;
:Intercept = -2.f ;
:Data_Minimum = -1.799999f ;
:Data_Maximum = 35.25f
Please note that this info will vary according to product and file type (Level 2, Level 3). Information for each of the products, including the scaling info can be found here: Ocean Color Products and clicking on the "product specifics" links.
Topic Frequently Asked Questions / Data Products & Algorithms FAQ / Raw to geophysical values (locked)