|GLAR 2. juni 2007, 22:14
PACDEX Chefen til sine medarbejdere på første togt med verdens mest avancerede Gulfstream-V med Global climate måleudstyr ombord. Lidt selvrosende men også alarmerende. De har funden koncentrationer på mere end 400 PPM CO2
Dear PACDEX folks,
Now that the airborne field deployment has been completed, Ram and I want to thank all of the participants for their hard work. A number of you worked long hours during this project to make it a success and we had good fortune in having dust events that we could sample. The project not only achieved its major data collection objectives, but the number of successful sampling events exceeded our expectations. The G-V proved to be a capable platform for long-range, multi-altitude sampling. Some of the major accomplishments of this field deployment are:
1. It appears that we were successful at sampling a moderate dust event from the Western Pacific to the East Pacific in three 8-9 hour flights that occurred over about a 4 day transit time from Japan. This event was tracked by the models for mission planning and they also provided guidance in real time via a satellite link to the aircraft. This required a great deal of ground support and mission-specific information. The dust altitudes ranged from above 30 thousand feet to below 10 thousand feet. Multi-hour sampling in this dust plume during these missions allowed for extensive sampling of aerosols, such as Ice Nuclei.
2. Paul DeMott has already commented on the success that he had in sampling Ice Nuclei under various ranges of temperature and super saturation. This sampling included studies in both the heterogeneous and homogeneous freezing regimes.
3. Three extra tropical cyclonic storms were sampled at multiple altitudes over traverses that often extended on both sides of frontal regions (and air mass characteristics). Droplet and ice particles were collected through the CVI and sampled by the SP2 for black carbon, by the CSU CFDC for IN, and captured for chemical analysis by Jim Anderson. Concurrent measurements of the cloud particle size distributions and the liquid and total condensed water were made. These data should make excellent case studies of the interaction of dust and pollution with major large-scale weather systems in the Pacific.
4. Conditions that were sampled included very clean conditions, (e.g. CCN below 10 per cc), and polluted conditions (e.g. CO concentrations over 400 ppbv). Clouds were encountered during a number of these extreme conditions. This offers an excellent opportunity to examine cloud particle size distributions and the cloud residue (via CVI sampling) for black carbon, IN, and aerosol composition, under a wide range of ambient conditions and in high, middle, and low clouds.
5. At various points during the campaign we sampled aerosols below the cloud base and then sampled in the cloud at the cloud base. This occurred on about a dozen occasions at various locations in the Pacific, and at different levels of pollution. CCN concentrations at two super saturations were measured along with the other aerosol measurements. Cloud droplet size distributions were collected near the cloud base, along with vertical wind and other data (e.g. liquid and condensed water). Vertical profiles of the clouds were made occasionally. These data should provide a unique survey of cloud base conditions and their relationship to sub cloud aerosol in various plume locations.
6. All indications are that the spectral irradiance and part of the actinic flux measurements were successful during each flight, which will provide the in situ radiative context for future studies. Other instruments such as CO, CVI, CCN, worked well for nearly the entire project.
7. The black carbon instrument seemed to perform well, providing measurements in and out of cloud over the whole Pacific campaign. This will be an especially interesting set of data. I have probably missed a few points (and a few instruments), so feel free to add your own comments. Next, we will be setting up an archival process for the data sets, and we will be planning for a science meeting later this year. This summer, we will setup a conference call or two to plan this meeting and to discuss data archives and processing issues, etc. with you.
Ram and I are trying to gather some early results that illustrate what was done during the project by the investigators. For example, Greg Kok has provided an interesting example of his data on Black Carbon. There are a few uses for this information.
First, there are two conferences where we are planning to present an overview of PACDEX, such as the IUGG conference in Perugia, Italy (early July), and the European Aerosol Conference (September). We will likely add some other future conferences to this list.
Second, we would like to share some of the early results with the NSF. If you would be willing to provide me with a power point slide or two illustrating your data/early results from PACDEX, we would try and include it in some of these presentations (depending on how many responses we get and how much material we have to work with, of course). In these please include a text box or other method that contains the proper credits (e.g. your name and sponsor, preliminary data notice if needed, etc.), so that we can be sure to acknowledge the contribution properly. If I could get these in the next two weeks (before about June 15), it would be most helpful.
Thanks again for the hard work that so many of you did to make the field project a success. I look forward to working with you as we put together the results from this project.
Jeff Stith <email@example.com>