3.2.3. Aerosol Optical Depth Remote Sensing
Current aerosol optical depth activities include the filterwheel normal incidence phyrheliometer (FWNIP) project, the MLO Physikalisch-Meteorologisches Observatorium Davos (PMOD) sunphotometer, a small group of hand-held instruments used for special projects, and a group of multifilter rotating shadowband radiometers (MFRSRs). The FWNIP project has been discussed in earlier reports. In the near future the analysis and processing of data from the FWNIP will be upgraded to utilize a new radiative transfer model, MODTRAN 4.0. The PMOD photometer continues to collect data at MLO as it has for the past 15 years. However, the operation of the astronomical dome and the data acquisition system was updated in late 1995 and new data processing was initiated, but no newly analyzed data are available for preliminary release at this time. The hand-held instrument calibrations were conducted at MLO and in the mountains west of Boulder, Colorado. These hand-held instruments were used in the Aerosol Characterization Experiment (ACE)I and ACEII field programs as well as in the arctic and antarctic.
MFRSRs were deployed at Bermuda (February 1996), Kwajalein (April 1996), and BAO (November 1996) in conjunction with the BSRN program. The main goal of this program is to obtain a spectral optical depth time series and to maintain calibrations using Langley analysis. Data are currently downloaded from the sites and archived automatically.