Report - working group on C-130 aerosol characterization
The C-130 aerosol characterization group (including some gas phase representation) met to assess issues on the C-130 and identify some working objectives for data analysis.
Considerable time was expended in discussing the issue of aerosol shatter on the community aerosol inlet [CAI]. Both Clarke and Weber demonstrated that this was pronounced and increasing as liquid water content increased. However, their detectors did not always identify this effect at the same time unless they were connected to the same outlet port of the CAI. In view of the number of individuals counting particles of the CAI, it was decided that a carefull intercomparison of concurrent counters (Hudson, Clarke, Mcmurry) be carried out, including one not on the CAI (Kok) in order to determine whether operational, flight or environmental conditions could be isolated and used to interpret inlet behavior. Rodney Weber agreed to combine the data set and explore these issues. Results would also be used to identify times when other measurments might be suspect when using the CAI.
LOCAL C-130 CLOSURE OPPORTUNITIES:
A variety of measurements are suitable to address elements of closure on the C-130.
Although full mass closure was not attempted on the C-130 a closure attempt will be carried out for:
Sea-salt size/mass - OPC volatility (Clarke); single particle
(Anderson); bulk analysis with IC (Huebert)
Fine particle size/mass - same appproach
CN and UCN - integral counts and DMA derived counts can be tested against each other including the number in the 3 to 10 nm range (difference in TSI 3025 and 3010 counts). (Clarke, Russell, Mcmurry)
CCN - compare measured CCN to those expected from modeled DMA size/composition data and to selected droplet spectra from the external probes (eg. FSSP) [Hudson]
Comparison of internal "dry" size data and external "wet" size data after allowing for RH growth etc. [Clarke, Baumgardner, Huebert]
Various Raditive Closure issues were separately addressed in the C-130 Column Closure working group.
CN Instrumentation [Clarke, Hudson, Mcmurry, Kok]
Radiometers (Air/Ground,ship) [Baumgardner, Valero, Porter]
CCN (Cape Grim, Maquerie Island) - [Hudson, Gras, Harvey, Kriedenweiss]
DMA [Russell, Wiedensholer, Covert, Clarke, Kriedenweiss]
CO&O3 [Kok, Johnson, CSIRO]
NH3&NO (ship, Cape grim, C-130) Scott
Becuase the C-130 poses greater difficulty for data collection with the
DMA that include inlet particle shatter issues and flow fluctuations
with pressure changes, it was decided to intercompare C-130 DMA's
(Russell, Clarke) over preferred periods before including these data for
coordinated comparisons with the surface measurements.
IDENTIFIED TIME PERIODS OF INTEREST
Efforts will be made to assemble these times for combined analysis.
Cloud Outflow - nucleation periods-up to 10 min needed for single part. anal. Cloud Inflow/Outflow -- contrast/process studies
Platform Intercomparison Periods
Radiative Closure Periods
Vertical Profiles - gradients, mixing, inversion, radiative transfer etc.
Horizontal sampling legs
Between strato-cumulus layers (high OH)
Possible C-130 exhaust encounters
SOME QUESTIONS IN ADDITON TO OUR STATED OBJECTIVES:
How does a detraining air mass evolve? (tracers? dynamics?)
Can we describe cloud processing in light of our measurements?
Can we understand the fundamentals of droplet shatter on our inlet?
Can we use our observations to help assess inlet losses?
The above outline was proposed as a way of focusing our activites on the huge volume of three dimensional data collected on the C-130. Tasks will be further refined as preliminary data organization and "clean up" is completed during the next several months.