MFRSR Hardware Improvements

Description

Two projects are underway that will have significant impact on all ARM MFRSRs and MFRs. The current sensor configuration includes one open (unfiltered/broadband) silicon detector, and six narrowband silicon detectors. ENG0001218 is documenting the replacement of the unfiltered detector with 1625 nm InGaAs filterdetectors. The addition of a near-IR channel will allow improved retrievals of aerosol and cloud properties. The longer wavelength, sensitive to larger particles, will help constrain the size distribution of coarse-mode aerosol particles, allowing for more accurate retrievals of aerosol optical properties. We also expect to improve cloud optical depth and mean effective cloud particle size retrievals using a combination of this near-IR wavelength and a mid-visible one. When implemented for up- and down-pointing paired MFRSR and MFR units, the longer wavelength will better constrain spectral surface albedo estimates, especially for vegetation with a strong spectral dependence across the visible and near-IR. The second project is a redesign of the linear heater controller board used to keep MFRSR/MFR sensors at a stable temperature. This is being tracked in ENG0001024. ARM began deploying redesigned MFRSR logging and instrument control systems in 2007, and the new systems have proven to be very robust with the exception of the heater controller board. The board was custom designed by ARM, and uses a Wavelength Electronics HTC3000 chip for controlling temperature. This chip is the board component that most often fails. By far, the heater controller board is the system component most prone to failure. We would like to replace the current controller with either an off-the-shelf unit or a redesigned custom board, or a combination of the two. Updates of these two projects are presented, along with a sidebar on some recent issues and system changes to the 2cNFOV and SGP NIMFR systems.