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NDACC News and Highlights
2015 NDACC News and Highlights
2015 NDACC News and Highlights
This section highlights significant items of interest within NDACC, with updates at least annually following the NDACC Steering Committee meeting.
With help from the NDACC Data Host Facility, the Theory and Analysis Working Group has uploaded model support files to the NDACC data archive. There are two types of content, one customized for the FTIR group and the other for the Lidar, Dobson, and Sonde working groups. File content is based on each group’s request for constituent and meteorological fields. The support files were created from a Hindcast simulation produced by the NASA Global Modeling Initiative (GMI) chemistry transport model integrated with MERRA (reanalysis) meteorology. Individual station data files, each containing 1 year of model output, are available for years 1992 to 2014. The files are written in netCDF format.
The files written for the Lidar, Dobson, and Sonde stations contain hourly vertical profiles of O3, NO2, H2O, temperature, pressure, and potential vorticity on a geometric altitude coordinate with 1 km resolution. The FTIR station files consist of daily profile and column quantities for 10 atmospheric species, including O3, N2O, CH4, and HCl. Basic meteorological quantities are also included. The FTIR species are reported on 72 pressure levels between the surface and 0.01 hPa. Details of each file type’s content can be found in a ‘readme’ file in the model data subdirectory of the NDACC data archive.
The GMI chemistry transport model integrated with MERRA meteorology produces realistic simulations of the atmospheric composition of the recent past. The GMI output can be used to determine the effects of irregular temporal sampling at a station. When used in combination with the full, 3D GMI simulation, differences between station data and the zonal mean indicate the representativeness of a station. This is particularly relevant for the attribution and interpretation of long-term trends. The GMI simulation builds a bridge between the irregular space/time sampling of ground-based measurements and the global perspective.
Left panel: The GMI simulation captures the observed seasonal, interannual, and decadal variability column HCl
measured at Harestua, Norway (60N, 10E). Right panel: Scatterplot of the points in the left panel, demonstrating
excellent agreement. Similar agreement is found at midlatitudes. The colors indicate different seasons.
The annual meeting of the international Steering Committee (SC) for NDACC was held from October 12 to 15 at the Scripps Institution of Oceanography in La Jolla, CA, a research site for the AGAGE Cooperating Network. A detailed report from the NDACC Data Host Facility (DHF) on data archiving status and data utilization was followed by reports from the various NDACC Instrument Working Group (WG) Representatives. As in the past, these reports highlighted WG activities and/or meetings during the past year, summarized NDACC measurement and analysis activities, described proposals (pending and received) seeking NDACC affiliation, and outlined possible new sites for consideration. Over the next several weeks, the WG Representatives will work with the DHF representative to bring any delinquent data archiving up to date.
Subsequent reports from representatives of the Satellite and Theory and Analysis working groups and from the NDACC Cooperating Networks focused on new activities and initiatives pertinent to NDACC interests and to possible future collaborations. In particular, the Theory and Analysis WG will be providing simulated data to begin the process of examining station variability and representativeness, thereby better informing network expansion priorities.
Representatives from the Water Vapor Theme Group summarized a first draft of an NDACC water vapor measurement strategy. While focusing initially on the use of frost point sondes (a recently accepted NDACC measurement capability), this strategy has expanded to include lidar, microwave, and FTIR measurement capabilities. A preliminary report from the Theme Group for Combining Trace Gas Data from NDACC and its Cooperating Networks was also presented. Both Theme Groups will continue their activities over the next year and report their progress at the next SC meeting.
A number of miscellaneous business discussions followed covering such items as NDACC involvement in various international projects, improved NDACC communications, future strategies and implementation, and the scheduling of future SC meetings. The venue for the 2016 SC meeting is yet to be determined. One candidate is Buenos Aires, Argentina, followed by an optional site visit to Rio Gallegos; another option is in Europe. Following the close of the meeting, many SC members visited the JPL Table Mountain Observatory in Wrightwood, CA and the NASA Aircraft Facility in Palmdale, CA.
Researchers from Karlsruhe Institute of Technology (KIT, Karlsruhe, Germany) have for the first time used several mobile Fourier Transform Spectrometers for detecting the CO2 emitted by a large metropolitan region in solar absorption spectra. The campaign was performed in June and July 2014 around Berlin, Germany, using five EM27SUN spectrometers (this type of spectrometer has been developed in a collaboration between researchers at KIT and Bruker Optics GmbH, Ettlingen). The results have been published recently and are currently accessible in AMTD (Frey et al., 2015, Hase et al., 2015). The advantage of this novel approach is to directly measure the column-averaged abundances that are insensitive to assumptions on vertical exchange as opposed to eg. high precision surface in-situ measurements. However, due to the long atmospheric lifetime of CO2 the expected column-averaged CO2 enhancements are small compared to the background abundance, therefore the precision, instrument-to-instrument consistency and stability requirements are very high. The results prove the first successful demonstration of this novel approach. The KIT researchers now plan to initiate the new spectrometer type for highly accurate and precise observations of CO2 and CH4 around the globe by joining with other international collaborations. The emerging network is named COCCON (Collaborative Carbon Column Observing Network) and will complement the established TCCON network with stations in remote areas and through dedicated campaigns. It is foreseen to associate COCCON with the FTIR activities in NDACC’s Infrared Working Group.