A North American Arctic Aerosol Climatology using Ground-based Sunphotometry

The Arctic is known as a key area for the detection of climate changes and atmospheric pollution on a global scale. In this paper we describe a new Canadian sunphotometer network called AEROCAN, whose primary mandate is to establish a climatology of atmospheric aerosols. This network is part of AERONET, the worldwide federated sunphotometer network managed by the NASA Goddard Space Flight Center. The potential of sunphotometer data from the AERONET/AEROCAN network for monitoring of Arctic aerosols is illustrated, using examples of the multiyear variation of aerosol optical properties and atmospheric precipitable water vapour content at some stations, and in particular at Bonanza Creek, Alaska since 1994. Despite its sparse spatial density, the network represents an important tool for monitoring the spatio-temporal variation of Arctic aerosols. It also represents an important source of independent aerosol data, which we feel should be further developed in northern areas to improve our understanding of how atmospheric aerosols influence global climate.L'Arctique est reconnu comme une région clé pour la détection des changements climatiques et de la pollution atmosphérique à l'échelle planétaire. Cet article présente un nouveau réseau canadien de photomètres solaires (AEROCAN) dont le mandat principal est d'établir une climatologie des aérosols atmosphériques. Ce réseau est intégré au réseau fédéré mondial de photomètres solaires AERONET géré par le Centre des vols spatiaux Goddard de la NASA. Le potentiel des données héliophotométriques générées par le réseau AERONET/AEROCAN pour la surveillance des aérosols dans l'Arctique est illustré à l'aide d'exemples de la variation pluriannuelle des paramètres optiques des aérosols et du contenu en vapeur d'eau atmosphérique précipitable à diverses stations, en particulier à Bonanza Creek (Alaska) depuis 1994. Malgré sa faible densité spatiale, le réseau représente un outil important pour la surveillance de la variation spatio-temporelle des aérosols arctiques. Il représente en outre une source majeure de données indépendantes sur les aérosols, données dont la provenance devrait, selon nous, englober les régions boréales afin que nous ayons une meilleure compréhension de l'influence des aérosols atmosphériques sur le climat de la planète

Maritime aerosol network as a component of AERONET - First results and comparison with global aerosol models and satellite retrievals

The Maritime Aerosol Network (MAN) has been collecting data over the oceans since November 2006. Over 80 cruises were completed through early 2010 with deployments continuing. Measurement areas included various parts of the Atlantic Ocean, the Northern and Southern Pacific Ocean, the South Indian Ocean, the Southern Ocean, the Arctic Ocean and inland seas. MAN deploys Microtops hand-held sunphotometers and utilizes a calibration procedure and data processing traceable to AERONET. Data collection included areas that previously had no aerosol optical depth (AOD) coverage at all, particularly vast areas of the Southern Ocean. The MAN data archive provides a valuable resource for aerosol studies in maritime environments. In the current paper we present results of AOD measurements over the oceans, and make a comparison with satellite AOD retrievals and model simulations

Job Search Mechanism and Individual Behaviour

job-search, human capital, social network, epidemic processes,

Synchronus starphotometry and lidar measurements at Eureka in High Canadian Arctic

We present recent progress related to the night-time retrievals of aerosol and cloud optical depth using starphotometry over the PEARL (Polar Environmental Atmospheric Research Laboratory) station at Eureka (Nunavut, Canada) in the High Arctic (80° N, 86° W). In the spring of 2011 and 2012, the SPSTAR starphotometer was employed to acquire aerosol optical depth (AOD) measurements while vertical aerosol and cloud backscatter coefficient profiles were acquired using the CANDAC Raman Lidar (CRL). Several events were detected and characterized using starphotometry-lidar synergy: aerosols (short term aerosol events on 9 and 10 March 2011); a potential multi-night aerosol event across three polar nights (13–15 March 2012), a thin cloud event (21 February 2011) and a very low altitude ice crystals (10 March 2011). Using a simple backscatter coefficient threshold criterion we calculated fine and coarse (sub and super-micron) mode AODs from the vertically integrated CRL profiles. These were compared with their starphotometry analogues produced from a spectral deconvolution algorithm. The process-level analysis showed, in general, good agreement in terms of the physical coherence between high frequency starphotometry and lidar data. We argue that R2 (coefficient of determination) is the most robust means of comparing lidar and starphotometer data since it is sensitive to significant optico-physical variations associated with these two independent data sources while being minimally dependent on retrieval and calibration artifacts. Differences between the fine and course mode components of the starphotometry and lidar data is clearly also useful but is more dependent on such artifacts. Studying climatological seasonal aerosol trends necessitates effective cloud-screening procedures: temporal and spectral cloud screening of starphotometry data was found to agree moderately well with temporal cloud screening results except in the presence of thin homogeneous cloud. We conclude that better screening conditions can be implemented to arrive at a robust method for combined temporal/spectral cloud-screening of starphotometer (and possibly sunphotometer) data. In general, as our understanding of process-level details increases with growing datasets, we will inevitably have more confidence in bulk climatological analyses of ground-based and satellite retrievals of aerosol parameters where conditions are less than ideal because of the weakness of the polar winter aerosol signal

An Emerging Ground-Based Aerosol Climatology. Aerosol Optical Depth from AERONET.

Abstract not availableJRC.(SAI)-Space Application Institut