Dataset: Optical Plankton Counter SOGLOBEC-OPC MOC
Deployment: NBP0204

The OPC data was processed into abundance spectra (N) vs. equivalent spherical diameter (ESD) of plankton in 50 size classes in the depth intervals of a correspondent MOCNESS-1 tow. The spectra calculation is based on the standard definitions in Zhou and Huntley (2007):

Definitions:

v = body volume of a zooplankter (1)
Water volume filtered (V) = OPC cross section × flow speed (2)
Abundancy sprectrum(N)= (# zooplankton in size interval delta_v)/ size interval delta_v * V (3)

Units:
ESD: mm
v: mm3
N: # mm-1 (?ESD) m-3 (water)
V: m3

Data file format:
Line 1 (header): latitude longitude date time (local, at the beginning of the deployment)
Line 2 (title): logESD dep-range1 dep-range2 ...
Line 3-52 (data): log10(ESD) log10(b) (dep 1) log10(b) (dep 2) ....

Notes:
1) Each data file represents one MOCNESS/OPC cast .The OPC failed in some MOCNESS tows.
2) The filename conventions are "CruiseName_spe_cntStationNumber.txt". The OPC cast number is same as the corresponding MOCNESS-1 cast number.
3) The depth intervals of abundance spectra are equal to the depth intervals of a corresponding MOCNESS tow.
4) The water filtered by the OPC was estimated using the flowmeter on the MOCNESS-1.
5) The size interval delta-v is evenly distributed on log(ESD) of valid OPC size range
6) The first column of the data file , represent the mid values of log10(ESD) of each size group.
7) The "-3.00" for log10(b) means 0 counts for the size group in the depth bin.
8) In some cases the OPC went through ups and downs in one depth bin, which are indicated in the depth range, for example, "25-22-75".

Reference:
Zhou, M. and M. E. Huntley, Population dynamics theory of plankton based on biomass spectra. Marine Ecology Progress Series, 157, 61-73, 1997.