https://cdn.earthdata.nasa.gov/conduit/upload/5182/KeywordsCommunityGuide_Baseline_v1_SIGNED_FINAL.pdf 24.9 2026-09-30T10:52:06.201Z https://gcmd.earthdata.nasa.gov/KeywordViewer/scheme/instruments/b3771e7c-efaf-4867-8380-1d629f2eb66b OPC Date=2021-09-07 User Id=sritz Entity=Definition Operation=INSERT System Note=insert Definition New Value=id: null text: Optical particle counters (OPCs), photometers, Aerodynamic Particle Sizer (APS™) spectrometers, and condensation particle counters (CPCs) all measure airborne particles in real time. Each technology has a unique sensitivity to specific particle characteristics such as size, mass and refractive index. Table 1 summarizes the basic performance differences. Note in particular the size range and flow rate for each instrument as well as the upper limit of the number concentrations. Table 2 summarizes typical applications for each measurement technology. language code: en Date=2021-09-07 User Id=sritz Entity=Definition Operation=UPDATE Field=text System Note=update Definition Old Value=Optical particle counters (OPCs), photometers, Aerodynamic Particle Sizer (APS™) spectrometers, and condensation particle counters (CPCs) all measure airborne particles in real time. Each technology has a unique sensitivity to specific particle characteristics such as size, mass and refractive index. Table 1 summarizes the basic performance differences. Note in particular the size range and flow rate for each instrument as well as the upper limit of the number concentrations. Table 2 summarizes typical applications for each measurement technology. New Value=Optical particle counters (OPCs), photometers, Aerodynamic Particle Sizer (APS) spectrometers, and condensation particle counters (CPCs) all measure airborne particles in real time. Each technology has a unique sensitivity to specific particle characteristics such as size, mass and refractive index. Table 1 summarizes the basic performance differences. Note in particular the size range and flow rate for each instrument as well as the upper limit of the number concentrations. Table 2 summarizes typical applications for each measurement technology. Optical particle counters (OPCs), photometers, Aerodynamic Particle Sizer(APS) spectrometers, andcondensation particle counters (CPCs) all measure airborne particles in real time. Each technology has aunique sensitivity to specific particle characteristics such as size, mass and refractive index. Table 1summarizes the basic performance differences. Note in particular the size range and flow rate for eachinstrument as well as the upper limit of the number concentrations. Table 2 summarizes typicalapplications for each measurement technology. 2021-09-07 16:12:40.0