The multination, high-resolution field study of Meteorology And Diffusion Over Non-Uniform Areas (MADONA) was conducted by scientists from the United States, the United Kingdom, Germany, Denmark, Sweden, and the Netherlands at Porton Down, Salisbury, Wiltshire, United Kingdom, during September and October 1992. The host of the field study was the Chemical and Biological Defence Establishment (CBDE, now part of Defence Evaluation and Research Agency) at Porton Down. MADONA was designed and conducted for high-resolution meteorological data collection and diffusion experiments using smoke, sulphurhexaflouride (SF₆), and propylene gas during unstable, neutral, and stable atmospheric conditions in an effort to obtain terrain-influenced meteorological fields, dispersion, and concentration fluctuation measurements using specialized sensors and tracer generators. Thirty-one days of meteorological data were collected during the period 7 September–7 October and 27 diffusion experiments were conducted from 14 to 23 September 1992. Puffs and plumes of smoke and SF₆ were released simultaneously for most of the experiments to gauge the resultant diffusion and concentration behavior. Some 44 meteorological and aerosol sensors and four source generators were used during each day of the field study. This array of sensors included 14 towers of wind cups and vanes, 10 sonic anemometer/thermometers, one boundary layer sonde, two lidar, one ion sensor, the CBDE Weather Station, and several one-of-a-kind sensors. Simulations of airflow and diffusion over the MADONA topography (a 9 km by 7.5 km area) were made with a variety of models. Wind fields and wind-related parameters were simulated with several high-resolution (microalpha scale) wind flow models. A tally of the various data-gathering activities indicates that the execution of MADONA was highly successful. Preliminary use of the datasets shows the high quality and depth of the MADONA database. This well-documented database is suitable for the evaluation and validation of short-range/near-field wind and diffusion models/codes. The database was originally placed on CD-ROM in a structured way by CBDE, Porton Down. The database is now available from the Risø National Laboratory, Denmark.

The Climate Absolute Radiance and Refractivity Observatory (CLARREO) mission will provide a calibration laboratory in orbit for the purpose of accurately measuring and attributing climate change. CLARREO measurements establish new climate change benchmarks with high absolute radiometric accuracy and high statistical confidence across a wide range of essential climate variables. CLARREO's inherently high absolute accuracy will be verified and traceable on orbit to Système Internationale (SI) units. The benchmarks established by CLARREO will be critical for assessing changes in the Earth system and climate model predictive capabilities for decades into the future as society works to meet the challenge of optimizing strategies for mitigating and adapting to climate change. The CLARREO benchmarks are derived from measurements of the Earth's thermal infrared spectrum (5–50 μm), the spectrum of solar radiation reflected by the Earth and its atmosphere (320–2300 nm), and radio occultation refractivity from which accurate temperature profiles are derived. The mission has the ability to provide new spectral fingerprints of climate change, as well as to provide the first orbiting radiometer with accuracy sufficient to serve as the reference transfer standard for other space sensors, in essence serving as a “NIST [National Institute of Standards and Technology] in orbit.” CLARREO will greatly improve the accuracy and relevance of a wide range of space-borne instruments for decadal climate change. Finally, CLARREO has developed new metrics and methods for determining the accuracy requirements of climate observations for a wide range of climate variables and uncertainty sources. These methods should be useful for improving our understanding of observing requirements for most climate change observations.

A first-of-a-kind, extended-term cloud aircraft campaign was conducted to obtain an in situ statistical characterization of continental boundary layer clouds needed to investigate cloud processes and refine retrieval algorithms. Coordinated by the Atmospheric Radiation Measurement (ARM) Aerial Facility (AAF), the Routine AAF Clouds with Low Optical Water Depths (CLOWD) Optical Radiative Observations (RACORO) field campaign operated over the ARM Southern Great Plains (SGP) site from 22 January to 30 June 2009, collecting 260 h of data during 59 research flights. A comprehensive payload aboard the Center for Interdisciplinary Remotely-Piloted Aircraft Studies (CIRPAS) Twin Otter aircraft measured cloud microphysics, solar and thermal radiation, physical aerosol properties, and atmospheric state parameters. Proximity to the SGP's extensive complement of surface measurements provides ancillary data that support modeling studies and facilitates evaluation of a variety of surface retrieval algorithms. The five-month duration enabled sampling a range of conditions associated with the seasonal transition from winter to summer. Although about twothirds of the flights during which clouds were sampled occurred in May and June, boundary layer cloud fields were sampled under a variety of environmental and aerosol conditions, with about 77% of the cloud flights occurring in cumulus and stratocumulus. Preliminary analyses illustrate use of these data to analyze aerosol– cloud relationships, characterize the horizontal variability of cloud radiative impacts, and evaluate surface-based retrievals. We discuss how an extended-term campaign requires a simplified operating paradigm that is different from that used for typical, short-term, intensive aircraft field programs.