From email@example.com Wed Jul 17 10:39:54 1996 Date: Fri, 05 Jul 1996 10:48:41 -0700 (PDT) From: "Dr. Barry Huebert"
To: ACE-1 List Subject: Workgroup report for the C-130 REMAINING C-130 ISSUES B. Huebert, 7/4/96 The C-130 group concluded that most of the aircraft issues had been covered in earlier sessions. However, we did discuss the CAI, the comparability of data from different sampling tubes in the CAI, and plans to evaluate the CAI's efficiency. Rodney Weber noted that the UM UCN instrument often showed much more evidence of droplet shatter than Tony Clarke's (UH). When they replumbed so they could draw air from either sampling tube, the UM tube (which was apparently in the middle of the pack at the rear of the CAI), usually had much more shatter than the UH tube. This was not always the case, however, as the droplet shatter maximum moved around a bit. This suggests that some cloud droplets may penetrate to the sampling plane in a kind of jet, whose position at the sampling plane depends on aircraft yaw, sideslip, pitch, TAS, or other factors. Rodney volunteered to look into the factors which affected the shatter at each location. He will include all the CN counters on board, including Hudson's and Kok's. CAINE-2 flow measurements will also be useful in looking for nonuniformities in the CAI flow that might contribute to this phenomenon. Clearly, knowing the extent to which the CAI was able to provide similar air to many samplers is critical to interpreting differences between related measurements. We also need to know its passing efficiency vs size to see how much of the larger aerosols actually made it to our sampling devices. Some of that can be done using existing data from ACE-1. Huebert's group is now ready to compare sodium and other ions from their external sampler with that from the impactors that sampled from the CAI. They have recently measured the passing efficiency of their plumbing and impactors with monodisperse aerosols in the laboratory. This information, when combined with the internal/external differences and MASP size distributions, should permit us to make a crude estimate of the CAI size cut. The other CAI evaluation using ACE-1 data, a comparison of Baumgardner's MASP (external) and Clarke's (internal) OPC size distributions, will have to await a recalibration of Clarke's OPC, which may not be completed until the end of 1996. This comparison will require that Steve Howell use his thermodynamic model to remove the water from the MASP distribution or add it to Clarke's, since one is measured dry and the other at ambient humidity. Huebert's group is also requesting C-130 hours in the spring of 1997 (CAINE-2) to do two kinds of CAI tests. One is the measurement of velocities at a variety of points across the sampling plane and at the ends of each diffuser section in the CAI. This study, done on short flights out of Jeffco, will look for nonisokinetic conditions at the sampling plane, regions of excessive turbulence, and the possibility of jets in certain regions. The other is a set of flights in a marine location, in which the CAI will be carefully washed before sampling, exposed for 1-2 hours in the marine boundary layer, and then disassembled so that certain parts can be extracted to measure the amount of sea-salt deposited on them. An new TSI aerodynamic particle sizer (APS), which has been designed to work well on aircraft, will be used alongside a MASP to evaluate the passing efficiency vs size. ------------------------------------------------------------------------ From firstname.lastname@example.org Wed Jul 17 10:40:03 1996 Date: Fri, 05 Jul 1996 22:44:12 -1000 (HST) From: Tony Clarke To: "Dr. Barry Huebert" Cc: ACE-1 List Subject: Re: Workgroup reports for C-130 and Lagrangians Barry; A small correction to your C-130 report. Actually it is not true that nobody knows the status of the TDDR data (Valero, Bucholtz). As I reported at the meeting and indicated in my "Radiative closure" report, most of the TDDR data apears to be good and it is the expectation of Anthony Bucholtz to have this data in the data set by September. They have been busy on other field campaigns since ACE-1. Also my CN and UCN counter data should be ready in a few weeks. This will consist of files edited for shatter and files with shatter included so that others might evaluate their data (eg. Lynn Russell). Our DMA and OPC data should be out before AGU. Tony