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The EvK2 Pyramid and the AERONET network “Atmospheric Brown Cloud" Characterization via Sunphotometer Observations G.P. Gobbi, F. Barnaba, and F. Angelini CNR, Istituto di Scienze dell'Atmosfera e del Clima, Roma contact: g.gobbi@isac.cnr.it.
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The EvK2 Pyramid and the AERONET network “Atmospheric Brown Cloud" Characterization via Sunphotometer Observations G.P. Gobbi, F. Barnaba, and F. Angelini CNR, Istituto di Scienze dell'Atmosfera e del Clima, Roma contact: g.gobbi@isac.cnr.it Mountains, Witnesses of Global Changes: SHARE-Asia Project, Rome, November 16-17, 2005
Terra/MODIS, December 17, 2004: Thick haze and smoke along the Ganges Basin from fires and large cities. EvK2
MODIS Dec-Feb 2001, 2002 and 2003 550nm Aerosol Optical Thickness The Aerosol Optical Thickness at wavelength w (AOTw) quantifies the extinction introduced by atmospheric aerosols on extraterrestrial solar radiation I0 before reaching the ground: I=I0 exp-(AOTw)
Courtesy of Y. Kaufman et al. NASA GSFC
Ground-based measurements of AOT are more accurate than satellite ones, particularly at sites with high surface albedo; Furthermore, sky-scanning sunphotometers can provide extended information on aerosol optical properties (Nakajima et al. [AO,1983, AO 1996]; Dubovik and King, [JGR, 2000] and Dubovik et al. [JGR, 2000]) At the beginning of 2006, we plan to install at the EvK2 Pyramid a robotized Sunphotometer Cimel CE 318N The Laboratory is located at 5050 m asl, 27º57’31’’ N – 86º48’48’’ E, at the foot of the Nepali side of Mt. Everest.
The sunphotometer will operate in the framework of AERONET, the NASA AERosol RObotic NETwork SPECIFICATIONS: CE 318-N : sun-tracking and sky-scanning sunphotometer with 5 filters centered at 440, 670, 870, 936,1020 nm Bandwidth: 10 nm at full width half maximum Operating temperature: -30 to +60°C Data transfer via GOES satellite link to NASA GSFC Further details: Optical head with 2 collimators 1.2° FOV: Sun tracking method by a 4-quadrant detector, Accuracy better than 0.1° Power requirements: 12 V – 10 Ah battery rechargeable by solar panel Data Storage in EPROM readable on a PC
AERONET, the Aerosol Robotic Network (http://aeronet.gsfc.nasa.gov) • The AERONET program is a federation of ground-based remote sensing aerosol stations. • The goal is to assess aerosol optical properties and validate satellite aerosol retrievals. • The network imposes standardization of instruments, calibration, and processing. • Data provides globally distributed observations of spectral aerosol optical depths, inversion products, and precipitable water in geographically diverse aerosol regimes. • Three levels of data are available from this website: Level 1.0 (unscreened), Level 1.5 (cloud-screened), and Level 2.0 (Cloud-screened and quality-assured).
AERONET, “quasi-real time” products available on the web site: http://aeronet.gsfc.nasa.gov
Further analysis will address the annual evolution of size-dependent aerosol properties from direct AOT measurements (Kaufman, Gobbi & Koren, in preparation 2005)
The Indo-Gangean plan of AERONET Courtesy of B. Holben
Conclusions: • In the framework of the SHARE – ASIA project these observations are therefore expected to contribute answering the following questions: • Which is the climatology of aerosol physical, chemical, and optical properties at this remote, high altitude station? • How do aerosols radiative properties change as a consequence of transport of ABC or other type of air masses? • What are the ABC effects on formation and lifetime of clouds? • How good are satellite retrievals of aerosol AOT over this region? THANK YOU VERY MUCH FOR YOU ATTENTION Mountains, Witnesses of Global Changes: SHARE-Asia Project, Rome, November 16-17, 2005