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CLAMS Home

The CLAMS Supplemental Observations Page is intended to be a location where information regarding the use of other surface observations can be posted and reviewed.

In Situ Aerosol Sampling

Folks, We went out the the lighthouse on Friday and retrieved the last week's worth of data from the in situ sampling instruments. The attached Power-Point file shows times series plots of the parameters that we record. The nephelometer data (total scattering coefficients at 450, 550, and 650 nm) looks particularly good and should be useful, when combined with soundings of boundary layer depth, to you in your validation effort. The soot absorption measurement is noisy at times, but can be improved if we increase the flow rate on the instrument...we set it quite low to reduce the number of times per day that the sample filter has to be changed. Its data combined with that from the nephelometer can be used to calculate single scattering albedo (see Figure 5). The total aerosol concentration measurement is noisy because the only instrument we had available was one that had fallen off a truck as it was being returned from the TRACE-P mission. It works fine 75% of the time, but drops out occasionally for no reason. We have several other instruments we can replace that one with when they are returned from being calibrated. As can be seen in Figures 6 and 7 of the attachment, the CN data is very useful for identifying pollution episodes.
Bruce Anderson   (Power point document: clams_insitu_data.ppt)

NASA Langley Research Center: Sunphotometers (pdf).

NASA Langley Research Center: Downwelling spectral flux and near IR aerosol optical depth. COVE Site Scientist Ken Rutledge will deploy the high resolution ASD Field Spectrometer (0.4-2.20 um) for downwelling spectral irradiance at the COVE sea platform during CLAMS.
Greg Schuster will conduct an experiment to measure near IR aerosol optical thickness at 1.240 and 1.558 micrometers by specially orienting the ASD during a portion of its observation cycle.

Water Leaving Radiances, Chlorophyll, and Absorption Spectra.

A suite of measurements are being made informally by Prof. Glenn Cota's group at the Center for Coastal Physical Oceanography (www.ccpo.odu.edu/~orca), Old Dominion University. A SAS III (SeaWiFS Airborne Sensor - made by Satlantic) with 13 channels (380-865nm) measures water leaving radiance at 40 deg from nadir, sky radiance at 40 deg from zenith, and downwelling irradiance each day. Discrete water samples yield chlorophyll concentration (mg/m3) and absorption spectra (/m) at 1 nm resolution (280-850 nm). Automated optical observations coincide with daily overpasses of SeaWiFS and/or MODIS at the COVE sea platform from July through August with weekly water collections. During the CLAMS campaign more frequent observations are planned.

Ground Based Aerosol Sampling.

Jose Vanderlei Martins from the Climate and Radiation Branch of NASA Goddard Space Flight Center is collecting aerosol particle samples on filters for chemical composition analysis at the COVE site and Wallops Island. These setups will give information on the near-surface concentrations of fine and coarse particle mass, black carbon, inorganic trace elements and water-soluble compounds. This is a joint project between NASA GSFC, University of Maryland Baltimore County and University of Sao Paulo, Brazil.

Directional Scans for Upwelling SW Spectral Radiances.

Ken Rutledge has re-activated the SP1-A Spectral Photometer to scan for upwelling radiances in 4 channels (450, 500, 675, and 862nm) for a BRDF program by Wenying Su (w.su@larc.nasa.gov) and Tom Charlock. Every 5 minutes, the scan covers 180 deg of azimuth using steps of 10 deg in elevation. Observations will continue after CLAMS. Contact W. Su for possible brief scans in other wavelengths and/or with polarizing filters.