Long-term monitoring of the tropospheric aerosol vertical structure and optical properties by active and passive remote- sensing at Ny-Aalesund, Svalbard M. Shiobara 1), M. Yabuki 1), R. Neuber 2), E.J. Welton 3), T.A. Berkoff 3), J.R. Campbell 3), and J.D. Spinhirne 3) 1) National Institute of Polar Research, Tokyo, Japan 2) Alfred Wegener Institute for Polar and Marine Research, Potsdam, Germany 3) NASA Goddard Space Flight Center, Greenbelt, MD, USA 8th Circumpolar Symposium on Remote Sensing of Polar Environments, 8-12 June 2004, Chamonix, France

(IPCC, 2001)

Objectives of aerosol remote sensing in the Arctic 1. Climatology of aerosol optical/physical properties in the Arctic: # Aerosol optical depth # Aerosol size distribution # Single scattering albedo # Scattering phase function 2. Aerosol-cloud interaction: # Arctic haze and arctic stratus clouds # Formation and dissipation processes of aerosol and clouds 3. Contribution to MPLNET: # Data transfer to the NASA/GSFC aerosol/cloud group # Validation of satellite retrievals from ICESat/GLAS

Ny-Alesund Location of the NIPR Arctic Observation Site

Ny-Aalesund, a unique international research site in Svalbard

NIPR Rabben Observatory is located 1.5km west of downtown Ny-Aalesund Anemometer Thermometer POSS X-band 10GHz radar All-sky camera Sky-radiometer Microwave radiometer Remote-sensing instrumentation for atmospheric research at Rabben

Sky radiometer, Prede POM-01 Specifications Wavelength 315, 400, 500, 675, 870, 940, 1020 nm Monochromator Narrow-band interference filter FWHM of filter 3 nm for 315, 10 nm for others Detector Silicon photodiode Elec. dynamic range 10 7 FOV angle 1 deg in full angle Ambient environment -30 to +35 (sensor unit) 0 to +35 (control unit) [ Analysis method ] Sky-radiance inversion method, SKYRAD ( Nakajima et al., 1996 )

( a ) 23 March 2000( b ) 17 April 2000 BackgroundHaze Volume size distribution for the haze and background days during the ASTAR 2000 campaign. The number of the smaller particles for the haze case was larger than that for the background case.

Cloud detection from all-sky images All-sky camera with a fish-eye lens All-sky image over Ny-Alesund on 30 May 2004, 13UTC

Micro-Pulse Lidar System in Ny-Alesund, Svalbard MPL operated at NIPR Rabben Observatory since March 1998 until June 2003 MPL operated at AWI Koldewey Station since June 2003 to present Micro-Pulse Lidar (MPL) Specifications Laser Diode-pumped Nd/YLF laser Wavelength 523 nm Pulse energy 8-10 J Pulse frequency 2500 Hz Detector Single photon counting APD Range resolution 30 m

Range corrected relative backscatter profile and the temporal variation over Ny-Alesund on 13 May 2004

(12:00)26 (00:00) 25 (18:00)26 (12:00)26 (06:00) Altitude (km) March 2000 Cloud formation process associated with development of a haze layer Vertical structure and temporal variation of aerosol and cloud layer observed by a Micro-Pulse Lidar at Ny-Aalesund, Svalbard

Analysis of passive/active remote sensing using sky-radiometer and MPL Analysis focuses on the difference of aerosol optical properties for the haze condition and for the background condition in the Arctic. HZ : Averaged optical thickness > 0.1 BG : Averaged optical thickness < 0.07 Sky-radiometer Size distribution Optical thickness Single scattering albedo Angstrom parameter MPL Vertical profile of the extinction coefficient S 1 parameter (Lidar ratio) τ- matching method

Angstrom parameterAerosol optical depth Single scattering albedo Results from ASTAR 2000 campaign 1. AOD: HZ>0.1, BG< Angstrom parameter: HZ>BG 3. Single scattering albedo: HZ=BG AOD of arctic haze became larger with contribution of small particles such as sulfate aerosol. Sometimes arctic haze includes absorptive aerosol such as soot.

Fig. (a): Relation between the τ(523 nm) and S 1 parameter at 523 nm. S 1 parameter has a positive correlation with the optical depth τ(523nm). The averaged S 1 parameter of the background case (BG) is 11.4 sr and that of the haze case (HZ) is 21.2 sr. Fig. (b) shows the relation between the Angstrom parameter and S 1 parameter. (a)(b) absorptive aerosol?

MPLNET Sites (From Syowa (69S, 40E) Ny-Alesund (79N, 12E) MPLNET is operated by NASA/GSFC and participating partners including NIPRs polar sites

ICESat/GLAS Ice, Cloud, and land Elevation Satellite Geoscience Laser Altimeter System Launched on 12 January 2003

ICESat/GLAS passed over Ny-Alesund on 21 May 2004, around 01:40 UTC Tracks of ICESat All-sky image MPL, Ny-Alesund ICESat/GLAS

1.Combined remote sensing with active/passive instruments is being continued at Ny-Aalesund, Svalbard for the atmospheric environment research in the Arctic. 2.Aerosol optical properties and their vertical/temporal variations are investigated for their climate impact based on long-term monitoring with Sky-Radiometer and Micro-Pulse Lidar. 3.These measurements are expected to also contribute to ground validation of satellite aerosol/cloud retrievals from space-borne active sensors such as ICESat/GLAS. Summary Acknowledgments: Operations of MPL at Rabben Station in Ny-Alesund until June 2003 were helped by the on-site engineers of Norwegian Polar Institute. Operations of MPL at Koldewey Station since June 2003 were helped by the on-site engineers of Alfred Wegener Institute for Polar and Marine Research. 8th Circumpolar Symposium on Remote Sensing of Polar Environments, 8-12 June 2004, Chamonix, France