Arctic Radiative Environment CANDAC Theme

Thomas J. Duck, Glen Lesins, Line Bourdages, Graeme Nott, Matthew Coffin, Jonathan Doyle Kim Strong Jim Sloan Jim Whiteway Bruce McArthur Norm O’Neill Ed Eloranta Von Walden Instrumentation

• SEARCH AHSR Lidar - operational • SEARCH PAERI - operational • RMR lidar - current installation • Tropospheric ozone lidar - installed (status?) • MM radar - operational • CANDAC PAERI - under construction • BSRN - partially operational (data status?) • AMS - operational • Sun photometers - operational • Star photometer - broken camera Summertime Sea Extent

17 September 2007

http://www.nsidc.org/ August Decline 9

8

7

Extent (million sq km) 6

5 1978 1982 1986 1990 1994 1998 2002 2006 Year Surface Temperature Change July 2005-1955

GISS Surface Temperature Analysis http://data.giss.nasa.gov/gistemp/maps/ Surface Temperature Change January 2005-1955

GISS Surface Temperature Analysis http://data.giss.nasa.gov/gistemp/maps/ January Average Temperatures at Eureka -25

-30

-35 emperatures (C) T -40

-45 1960 1970 1980 1990 2000 Year Correlation between surface pressure and NAO 0.0 (monthly averages)

-0.2 ficient -0.4

-0.6 Correlation Coef -0.8

-1.0 0 2 4 6 8 10 12 Month Eureka Monthly Averages (1953-2005) 2 5 (Jan) 2 (Feb) 0

1 5

1 0 (Jul)

Surface wind speed (km/h) 5

0 -50 -40 -30 -20 -10 0 10 Temperature (C)

➡ surface temperatures are influenced by wind induced mixing January Mean Temperatures (1991-2005) 20

15

10 Altitude (km)

5

0 -70 -60 -50 -40 -30 -20 Temperature (C) Radiative Transfer • 24 h sunlight in , darkness in winter • High albedo due to and sea ice • Very cold and dry: cooling to space via 20 micron window • Atmosphere is insulated from relatively warm ocean by sea ice

➡ Has the Arctic reached a tipping point?

May 6, 2007 1 AUGUST 2004 I N T R I E R I A N D S H U P E 2953

Characteristics and Radiative Effects of Diamond Dust over the Western Arctic Ocean Region

JANET M. INTRIERI NOAA/Environmental Technology Laboratory, Boulder, Colorado

MATTHEW D. SHUPE Science and Technology Corporation, NOAA/Environmental Technology Laboratory, Boulder, Colorado

(Manuscript received 28 August 2003, in final form 19 February 2004)

ABSTRACT Atmospheric observations from active remote sensors and surface observers, obtained in the western Arctic Ocean between November 1997 and May 1998, were analyzed to determine the physical characteristics and to assess the surface radiative contribution of diamond dust. The observations showed that diamond dust contributed only a negligible radiative effect to the sea ice surface. Surface radiative fluxes and radiative forcing values during diamond dust events were similar in magnitude when compared to observed clear-sky periods. Combined information from lidar, radar, and surface observers showed that diamond dust occurred ϳ13% of the time between November and mid-May over the Arctic Ocean and was not observed between mid-May and October. Diamond dust vertical depths, derived from lidar measurements, varied between 100 and 1000 m but were most often observed to be about 250 m. Lidar and radar measurements were analyzed to assess if from boundary layer was present during times when surface observers reported diamond dust. This analysis revealed that surface observers had incorrectly coded diamond dust events ϳ45% of the time. The miscoded events occurred almost exclusively under conditions with limited or no illumination (December–March). In 95% of the miscoded reports, lidar measurements revealed the presence of thin liquid clouds precipitating down to the surface. Journal of , 2004 1. Introduction and background monly termed ‘‘diamond dust,’’ has been hypothesized to have a significant effect on the radiative balance at Unraveling the effects of clouds on the surface energy the Arctic surface (e.g., Gotaas and Benson 1965; Curry budget of the Arctic has seen recent advancement. These et al. 1990, 1993; Wilson et al. 1993). As part of the advances can be attributed to 1) an increased research Shupe and Intrieri cloud–radiation study, diamond dust emphasis precipitated by climate-warming concerns at high latitudes and 2) the resulting long-needed obser- was found to provide only a negligible surface radiative vational information gathered from newly acquired oce- contribution. Since diamond dust information is sparse, anic, ice, and atmospheric datasets. For example, year- we present additional remote sensing and surface ob- long cloud measurements, collected over the Beaufort servations to provide further details on the frequency and Chukchi Seas during 1997/98, provided key infor- of occurrence and physical, microphysical, and radiative mation for compiling an annual cycle of Arctic cloud- properties of this polar phenomena. iness statistics (Intrieri et al. 2002b) and for quantifying Observations of diamond dust are scarce because of an annual cycle of cloud radiative forcing over the Arc- the difficulties encountered when making measurements tic surface (Intrieri et al. 2002a). This same Arctic cloud in the harsh polar environment, and suspect because dataset has been analyzed by Shupe and Intrieri (2004) surface observations are notoriously difficult due to the to assess which cloud types are radiatively important poor visibility during the dark winter when di- and which individual cloud properties most affect the amond dust is most prevalent (Hahn et al. 1995). Ad- surface longwave and shortwave radiation. ditionally, satellite observations are not especially use- Cloudless ice crystal precipitation (ICP), more com- ful in detecting or characterizing diamond dust since there is little thermal or visible contrast between it and the underlying snow- and ice-covered surface. Diamond Corresponding author address: Dr. Janet M. Intrieri, NOAA/En- dust is not explicitly included in classic cloud clima- vironmental Technology Laboratory, 325 Broadway, R/E/ET2, Boul- der, CO 80305. tologies, so long-term statistics of its occurrence are not E-mail: [email protected] available. Even more rare are microphysical and radi- Statistics of Diamond Dust Events at Eureka

Month in Number of Diamond DD events 2006 observations dust events with clouds

January 748 550 (74%) 270 (36%) February 674 460 (68%) 249 (37%) March 746 270 (36%) 225 (34%) April 715 311 (44%) 263 (37%) May 731 6 (1%) 6 (1%) June 760 0 (0%) 0 (0%) July 799 0 (0%) 0 (0%) August 794 0 (0%) 0 (0%) September 821 1 (0%) 1 (0%) October 738 29 (4%) 28 (4%) November 723 335 (46%) 279 (39%) December 737 401 (54%) 245 (33%) AHSR Lidar

PAERI

http://lidar.ssec.wisc.edu/

Model - measurement comparison

Gray - AERI 6 Feb 2007

m/sr) Black - SBDART μ /

2 Diamond Dust (21:50 - 22:10 Z) Clear Sky (14:30 - 15:00 Z) ound Radiance (W/m Zenith Gr

Wavelength (microns) Submitted to GRL

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• RMR lidar tropospheric temperatures, water vapour • Tropospheric ozone lidar measurements • PAERI with extended range • BSRN broadband irradiances • Star photometer OD measurements