Diss-length: Difference between revisions
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This is the length of data over which one estimate of dissipation rate is made for each shear probe. Using our recommended fft processing, each [[Fft-length|FFT-length]] segment will have 1.9 degrees of freedom (dof). | This is the length of data over which one estimate of dissipation rate is made for each shear probe. Using our recommended fft processing, each [[Fft-length|FFT-length]] segment will have 1.9 degrees of freedom (dof). | ||
'''As a general rule, we recommend a diss-length of minimum 3 fft-lengths.''' | '''As a general rule, we recommend a diss-length of minimum 3 fft-lengths.''' Similar to FFT-length, Diss-length should be a power of 2, converted in time and saved in the metadata. | ||
Five fft-lengths is desirable. It may sometimes, however, be desirable to achieve high temporal (or spatial) resolution in dissipation profiles and/or the user chooses not to apply [[the Goodman algorithm]]. In those cases the user may choose single diss-length = fft-length, with the caveat of the poor statistical reliability of the dissipation estimate. A single fft-length as diss-length is ill-advised and has poor statistical reliability. | Five fft-lengths is desirable. It may sometimes, however, be desirable to achieve high temporal (or spatial) resolution in dissipation profiles and/or the user chooses not to apply [[the Goodman algorithm]]. In those cases the user may choose single diss-length = fft-length, with the caveat of the poor statistical reliability of the dissipation estimate. A single fft-length as diss-length is ill-advised and has poor statistical reliability. | ||
Latest revision as of 19:11, 6 June 2024
This is the length of data over which one estimate of dissipation rate is made for each shear probe. Using our recommended fft processing, each FFT-length segment will have 1.9 degrees of freedom (dof).
As a general rule, we recommend a diss-length of minimum 3 fft-lengths. Similar to FFT-length, Diss-length should be a power of 2, converted in time and saved in the metadata.
Five fft-lengths is desirable. It may sometimes, however, be desirable to achieve high temporal (or spatial) resolution in dissipation profiles and/or the user chooses not to apply the Goodman algorithm. In those cases the user may choose single diss-length = fft-length, with the caveat of the poor statistical reliability of the dissipation estimate. A single fft-length as diss-length is ill-advised and has poor statistical reliability.
Choosing the length of data, in units of meters, for the estimation of dissipation rates makes this choice fairly platform and vehicle independent, and allows it to be mainly driven by the science one wishes to accomplish.
return to Flow chart for shear probes
