It has been another busy year for ACD personnel and I would like to take this opportunity to thank all staff for their dedication and hard work over the year. Aligned with and supportive of the NCAR mission, ACD’s mission is to understand the role of chemistry in the atmosphere and related components of the Earth system, to lead and support community endeavors in advancing scientific understanding of atmospheric chemistry, to make unbiased information in support of decision-making processes available to society, to engage society in the science behind atmospheric chemistry, and to help train the next generation of atmospheric scientists. In fiscal year 2004, ACD has made contributions in each element of this mission. 

As in previous years, ACD has been involved in a number of community field campaigns supported by NSF, NASA, and other agencies. These campaigns have ranged from the Arctic lands of Greenland to the South Pole, from Tropical rain forests to downwind of urban centers in the U.S.  Notable among these was the ACD leadership of the Antarctic Tropospheric Chemistry Investigation (ANTCI), funded by a grant provided by the National Science Foundation’s Office of Polar Programs, and of the Chemical Emission, Loss, Transformation and Interaction within Canopies in New England (CELTIC-NE) experiment.  ACD has begun preparations to lead a major community field deployment near Mexico City involving several agencies and NSF-supported university groups in early 2006; the first Megacity Impacts on Regional and Global Environments (MIRAGE) experiment will focus on the outflow and atmospheric fate of pollution from Mexico City and will combine airborne, satellite, and ground-based measurement programs. This research activity is particularly suited to ACD, as it integrates these varied ACD measurement capabilities with regional and global modeling. As we move into a new century where the human population is predicted to shift from predominantly rural to urban dwelling, the urbanization of the atmosphere will continue, making the role of megacities increasingly important to the understanding of climate change and air quality impacts. This program is important to NCAR as it integrates such diverse scientific topics as land-use change, economics, human health, urbanization, global change, and climate variability. ACD has begun and will continue to invest in instrument development, pre-deployment and deployment support of MIRAGE, and model development and simulations. The Weather Research and Forecast (WRF) model with interactive chemistry (WRF-Chem) has been implemented with typical dry season emissions in Mexico City and is being used to plan ground-site positions and aircraft flight paths. 

Another important scientific activity in ACD involves the study of the upper troposphere and lower stratosphere, which will become increasingly relevant with the availability of the NSF G-V to reach the mid-latitude lower stratosphere and the Tropical transition layer. ACD is preparing for this by contributing to the construction of a suite of chemical sensors, and ACD scientists are developing concepts for future G-V deployments, including collection and analysis of in situ and remotely- sensed measurements of the atmospheric layers near the tropopause.  Additionally, ACD scientists are performing simulations of the chemistry and dynamics of this region with several numerical models, including WACCM (the Whole Atmosphere Community Climate Model) and WRF.  In addition, development of global tropospheric chemical modeling continues. A version of the Model for Ozone and Related Chemical Tracers (MOZART) Chemistry Transport Model (CTM), with an updated and expanded chemical reaction scheme and a multi-component aerosol code, has recently been released to the community. MOZART-4 will now be frozen and future CTM development will continue within the framework of a new CTM, combining the best elements of MOZART and the Climate and Global Dynamics Division (CGD) CTM Model for Atmospheric Chemistry and Transport (MATCH). The new Community Atmosphere Model (CAM)-Chem is fully compliant with NCAR’s CCSM (Community Climate System Model) coding requirements and is capable of being run in off-line mode with either climate model or re-analysis datasets.

The Aura satellite was successfully launched in 2004, carrying the HIRDLS (High-Resolution Dynamics Limb Sounder) instrument developed collaboratively by ACD, the University of Colorado, and the University of Oxford, with joint NASA and U.K. funding. The launch was the culmination of more than a decade of dedicated work by the HIRDLS team which prepared a thoroughly-calibrated instrument and state-of-the-art data processing algorithms. Soon after launch, anomalous radiances were observed by the instrument detectors; the source and correction of these anomalous radiances is still under investigation. ACD and the community await final resolution of this anomaly and have high hopes for a successful HIRDLS science program.

Particularly noteworthy among an array of impressive results this year include observation of emissions from biomass burning events encountered over Amazonia that far exceed conventional model emission inventories. ACD scientists have also been investigating anomalous chemistry at the South Pole, and, in particular, the unique observation of changes in fast photochemical radical chemistry during the time of a solar eclipse. 

Change continues to be the only constant of the research landscape and ACD staff have adapted and remained flexible in the face of uncertainty. However, with change come new opportunities, most significantly, the new laboratory office facility for ACD and the new NSF research aircraft. 

An ACD landmark occurred in the fall of 2004: the ground-breaking for the new, custom-built chemistry laboratory to house ACD experimental, remote sensing, and modeling activities, which will reunite ACD staff for the first time since 1990. This 21^st-century building will implement modern laboratory safety protocols and equipment, including state-of-the-art air handling.  These considerations will improve efficiency and enable enhanced scientific interactions, provide improved opportunities for community collaborations both within the laboratory setting and more generally, and will help the new building (FL0) become a hub for interdisciplinary science at NCAR.  All ACD staff have had many opportunities to review and provide input to the draft plans for the new facility.  This process has led to a design that will enhance both laboratory and office functions, which in turn improves staff investment.

Another significant landmark is expected in the next few weeks, when a modified Gulfstream-V (G-V) research aircraft will be delivered to NCAR. ACD scientists and research engineers are building several state-of-the-science community instruments to be deployed on the G-V. This work is supported through a combination of special funding from NSF and the NCAR Director, augmented with  ACD core funds.  Additionally, ACD scientists will assist NCAR’s Earth Observing Laboratory (EOL) in the management of several chemistry instruments being developed in the community.

And, finally, in 2004 NCAR has reorganized at two levels, creating three new interdisciplinary institutes and organizing existing divisions into five interdisciplinary laboratories.  The new institutes are the Institute for Mathematics Applied to Geosciences (IMAGe), the Institute for the Study of Society and Environment (ISSE), and The Institute for Multidisciplinary Earth Studies (TIMES).  ACD scientists contribute significantly to the scientific program of TIMES through support of the Biogeosciences and Wildfire initiatives.

NCAR’s reorganization into five laboratories will more closely align the organizational structure with components of the NCAR mission. ACD, along with NCAR’s Mesoscale & Microscale Meteorology (MMM) Division, High Altitude Observatory (HAO) Division, CGD, and TIMES, collectively comprise the Earth and Sun Systems Laboratory (ESSL). The intent of this new laboratory is to increase the affinities between the disciplinary activities represented by the NCAR divisions, and to enable integrative science to arise and be more easily fostered. This will be achieved by reducing the administrative barriers to divisional interactions.  This will occur under guidance by the Division Directors, who will operate under the leadership of the Laboratory Associate Directors, who, in turn, will have a special role in promoting affinities between the laboratories via their service on the NCAR Executive Committee.

ACD is well-poised to take scientific advantage of this new configuration. The WACCM model provides a bridge between ACD, HAO, and CGD. This new structure will enable ACD to work more effectively with MMM on WRF, and ACD has already forged strong links to TIMES through participation in the Wildfire and Biogeosciences Initiatives. Meanwhile, ACD will continue to strengthen ties to the new Earth Observing Laboratory (EOL) through support of community instrumentation and field campaigns and will explore opportunities to study environmental and societal impacts of atmospheric composition changes through collaborations with the Institute for the Study of Society and Environment (ISSE).  More information on NCAR’s re-organization may be found at www.ncar.ucar.edu/directorate/Reorg/.

As we look ahead and plan for the future, this Annual Scientific Report reflects the commitment, energy, and accomplishments of all ACD staff during this past fiscal year.  We are pleased to play important roles in the reorganized NCAR. 

I invite you to read this report, and, if you have any questions or comments, please contact me, Daniel McKenna, or any of our scientific or administrative staff.

Yours sincerely,

Daniel McKenna