Atmospheric Research 2011 Technical Highlights

The 2011 Technical Highlights describes the efforts of all members of Atmospheric Research. Their dedication to advancing Earth Science through conducting research, developing and running models, designing instruments, managing projects, running field campaigns, and numerous other activities, is highlighted in this report

Satellite remote sensing of aerosols using geostationary observations from MSG-SEVIRI

Aerosols play a fundamental role in physical and chemical processes affecting regional and global climate, and have adverse effects on human health. Although much progress has been made over the past decade in understanding aerosol-climate interactions, their impact still remains one of the largest sources of uncertainty in climate change assessment. The wide variety of aerosol sources and the short lifetime of aerosol particles cause highly variable aerosol fields in both space and time. Groundbased measurements can provide continuous data with high accuracy, but often they are valid for a limited area and are not available for remote areas. Satellite remote sensing appears therefore to be the most appropriate tool for monitoring the high variability of aerosol properties over large scales. Passive remote sensing of aerosol properties is based on the ability of aerosols to scatter and absorb solar radiation. Algorithms for aerosol retrieval from satellites are used to derive the aerosol optical depth (AOD), which is the aerosol extinction integrated over the entire atmospheric column. The aim of the work described in this thesis was to develop and validate a new algorithm for the retrieval of aerosol optical properties from geostationary observations with the SEVIRI (Spinning Enhanced Visible and Infra-Red Imager) instrument onboard the MSG (Meteorological Second Generation) satellite. Every 15 minutes, MSG-SEVIRI captures a full scan of an Earth disk covering Europe and the whole African continent with a high spatial resolution. With such features MSG-SEVIRI offers the unique opportunity to explore transport of aerosols, and to study their impact on both air quality and climate. The SEVIRI Aerosol Retrieval Algorithm (SARA) presented in this thesis, estimates the AOD over sea and land surfaces using the three visible channels and one near-infrared channel of the instrument. Because only clear sky radiances can be used to derive aerosol information, a stand-alone cloud detection algorithm was developed to remove cloud contaminated pixels. The cloud mask was generated over Europe for different seasons, and it compared favorably with the results from other cloud detection algorithms - namely the cloud mask algorithm of Meteo-France for MSG-SEVIRI, and the MODIS (Moderate Resolution Imaging Spectroradiometer) algorithm. The aerosol information is extracted from cloud-free scenes using a method that minimizes the error between the measured and the simulated radiance. The signal observed at the satellite level results from the complex combination of the surface and the atmosphere contributions. The surface contribution is either parameterized (over sea), or based on a priori values (over land). The effects of atmospheric gases and aerosols on the radiance are simulated with the radiative transfer model DAK (Doubling-Adding-KNMI) for different atmospheric scenarios. The algorithm was applied for various case studies (i.e. forest fires, dust storm, anthropogenic pollution) over Europe, and the results were validated against groundbased measurements from the AERONET database, and evaluated by comparison with aerosol products derived from other space-borne instruments such as the Terra/- Aqua-MODIS sensors. In general, for retrievals over the ocean, AOD values as well as their diurnal variations are in good agreement with the observations made at AERONET coastal sites, and the spatial variations of the AOD obtained with the SARA algorithm are well correlated with the results derived from MODIS. Over land, the results presented should be considered as preliminary. They show reasonable agreement with AERONET and MODIS, however extra work is required to improve the accuracy of the retrievals based on the proposed metho

Radon: a universal baseline indicator at sites with contrasting physical settings

The primary goal of World Meteorological Organisation Global Atmosphere Watch (WMO‐GAW) baseline stations is systematic global monitoring of chemical composition of the atmosphere, requiring a reliable, consistent and unambiguous approach for the identification of baseline air. Premier stations in the GAW baseline network span a broad range of physical settings, from remote marine to high‐altitude continental sites, necessitating carefully tailored site‐specific requirements for baseline sampling, data selection, and analysis. Radon‐222 is a versatile and unambiguous terrestrial tracer, widely‐used in transport and mixing studies. Since the majority of anthropogenic pollution sources also have terrestrial origins, radon has become a popular addition to the ‘baseline selection toolkit’ at numerous GAW stations as a proxy for ‘pollution potential’. In the past, detector performance and postprocessing methods necessitated the adoption of a relaxed (e.g. 100 mBq m‐3) radon threshold for minimal terrestrial influence, intended to be used in conjunction with other baseline criteria and analysis procedures, including wind speed, wind direction, particle number, outlier rejection and filtering. However, recent improvements in detector sensitivity, stability and post‐processing procedures have reduced detection limits below 10 mBq m‐3 at Cape Grim and to 25 mBq m‐3 at other baseline stations. Consequently, for suitably sensitive instruments (such as the ANSTO designed and built two‐filter dual‐flow‐loop detectors), radon concentrations alone can be used to unambiguously identify air masses that have been removed from terrestrial sources (at altitude or over ice), or in equilibrium with the ocean surface, for periods of >2‐3 weeks (radon ≤ 40 mBq m‐3). Potentially, radon observations alone can thus provide a consistent and universal (site independent) means for baseline identification. Furthermore, for continental sites with complex topography and meteorology, where true ‘baseline’ conditions may never occur, radon can be used to indicate the least terrestrially‐perturbed air masses, and provide a means by which to apply limits to the level of ‘acceptable terrestrial influence’ for a given application. We demonstrate the efficacy of the radon‐based selection at a range of sites in contrasting physical settings, including: Cape Grim (Tasmania), Cape Point (South Africa), Mauna Loa (Hawaii), Jungfraujoch (Switzerland) and Schneefernerhaus (Germany).Bureau of Meteorology and CSIRO Oceans and Atmosphere,Climate Science Centre

Development of a portable time-domain system for diffuse optical tomography of the newborn infant brain

Conditions such as hypoxic-ischaemic encephalopathy (HIE) and perinatal arterial ischaemic stroke (PAIS) are causes of lifelong neurodisability in a few hundred infants born in the UK each year. Early diagnosis and treatment are key, but no effective bedside detection and monitoring technology is available. Non-invasive, near-infrared techniques have been explored for several decades, but progress has been inhibited by the lack of a portable technology, and intensity measurements, which are strongly sensitive to uncertain and variable coupling of light sources and detector to the scalp. A technique known as time domain diffuse optical tomography (TD-DOT) uses measurements of photon flight times between sources and detectors placed on the scalp. Mean flight time is largely insensitive to the coupling and variation in mean flight time can reveal spatial variation in blood volume and oxygenation in regions of brain sampled by the measurements. While the cost, size and high power consumption of such technology have hitherto prevented development of a portable imaging system, recent advances in silicon technology are enabling portable and low-power TD-DOT devices to be built. A prototype TD-DOT system is proposed and demonstrated, with the long-term aim to design a portable system based on independent modules, each supporting a time-of-flight detector and a pulsed source. The operation is demonstrated of components that can be integrated in a portable system: silicon photodetectors, integrated circuit-based signal conditioning and time detection -- built using a combination of off-the-shelf components and reconfigurable hardware, standard computer interfaces, and data acquisition and calibration software. The only external elements are a PC and a pulsed laser source. This thesis describes the design process, and results are reported on the performance of a 2-channel system with online histogram generation, used for phantom imaging. Possible future development of the hardware is also discussed

Polarimetric Synthetic Aperture Radar

This open access book focuses on the practical application of electromagnetic polarimetry principles in Earth remote sensing with an educational purpose. In the last decade, the operations from fully polarimetric synthetic aperture radar such as the Japanese ALOS/PalSAR, the Canadian Radarsat-2 and the German TerraSAR-X and their easy data access for scientific use have developed further the research and data applications at L,C and X band. As a consequence, the wider distribution of polarimetric data sets across the remote sensing community boosted activity and development in polarimetric SAR applications, also in view of future missions. Numerous experiments with real data from spaceborne platforms are shown, with the aim of giving an up-to-date and complete treatment of the unique benefits of fully polarimetric synthetic aperture radar data in five different domains: forest, agriculture, cryosphere, urban and oceans

Study of the speckle noise effects over the eigen decomposition of polarimetric SAR data: a review

This paper is focused on considering the effects of speckle noise on the eigen decomposition of the co- herency matrix. Based on a perturbation analysis of the matrix, it is possible to obtain an analytical expression for the mean value of the eigenvalues and the eigenvectors, as well as for the Entropy, the Anisotroopy and the dif- ferent a angles. The analytical expressions are compared against simulated polarimetric SAR data, demonstrating the correctness of the different expressions.Peer ReviewedPostprint (published version

2013 GREAT Day Program

SUNY Geneseo’s Seventh Annual GREAT Day.https://knightscholar.geneseo.edu/program-2007/1007/thumbnail.jp

2018 EURēCA Abstract Book

Listing of student participant abstracts