Intro 1. Part 1. Black Carbon in Arctic snow: concentrations and effect on surface albedo Tom Grenfell & Steve Warren University of Washington Tony Clarke (University of Hawaii) Vladimir Radionov (AARI, St. Petersburg) Other UW participants: Dean Hegg, Richard Brandt,
Part 1. Black Carbon in Arctic snow:
concentrations and effect on surface albedo
Tom Grenfell & Steve Warren
University of Washington
Tony Clarke (University of Hawaii)Vladimir Radionov (AARI, St. Petersburg)
Other UW participants:
Dean Hegg, Richard Brandt,
Sarah Doherty, Steve Hudson,
Mike Town, Hyun-Seung Kim,
Lora Koenig, Ron Sletten (ESS)
Jamie Morison, Andy Heiberg, Mike Steele (APL)
Project website: www.atmos.washington.edu/sootinsnow
Soot in snow 1983-4 (Clarke & Noone) Most amounts are 5-50 parts per billion.
Warren & Wiscombe (1985);
Soot contents from Clarke & Noone (1985)
Difficulties in the use of remote sensing to determine BC's effect on snow albedo
1. It's hard to distinguish snow from clouds-over-snow, which hide the surface. Thin near-surface layers of atmospheric ice crystals ("diamond-dust") are common in the Arctic.
2. The bidirectional reflectance (BRDF) is affected by:
a. small-scale surface roughness: ripples, sastrugi, suncups, pressure-ridges. (The effects of sastrugi on BRDF are different at different wavelengths, because they depend on the ratio of sastrugi width to flux-penetration depth.)
b. when thin surface-fog (or diamond-dust layer) covers the rough snow, the forward peak is enhanced and the nadir view is darker. This darkening at nadir could be mistaken for BC contamination.
c. Grain shape
3. Albedo reduction by BC in snow can be mimicked by:- thin snow. Sooty snow has the same spectral signature as thin snow.
- increase of grain size with depth (common situation) preferentially reduces visible albedo - sub-grid-scale leads in the Arctic Ocean. - BC in the atmosphere above the snow (Arctic haze).
Our 4-year project (begun
in spring 2006): a
comprehensive surface-based survey
of BC in Arctic snow,
to repeat and extend Clarke & Noone’ssurvey from 1983/4.
Filters are compared to standard calibration filters. They will be scanned with a spectrophotometer to quantify BC, dust, & other components – different spectral absorption curves.
BC in snow (ppb)
K. Steffen automatic
weather stations +
BC in Snow (ppb)
M. Sturm (CRREL)
T. Grenfell and Steve Hudson, Western Arctic Russia March-May 2007
Permissions were granted to enter restricted border areas;
International Polar Year (IPY) has prominence in Russia.
IPY News Information Bulletin June 2007
Stephen Hudson (left), a graduate student at the University of Washington, traveling up the Khatanga River
*strong haze event
(1) Do particles collect at the surface as the snow melts?
Greenland (Dye-2) August 2007, melting snow:
surface 9 ppb, subsurface 3 ppb
(2) Snow grain size increases markedly with spring melt onset magnifying the effect of a given soot load – accelerating
melt. Δ(albedo) changes from -0.01 to -0.03 for 35 ngC/g
January: Artificial snowpack to quantify effect of soot on snow albedo with homogeneous grain size and known BC loading - (Rich Brandt, Steve Warren – Adirondacks)
March-May: Snow sampling in Eastern Siberia (Grenfell & Warren)
April: Albedo & BC intercomparison with Norwegian Polar Institute
April-May: Redistribution of BC during melt (Sanja Forsstrøm at Tromsø)
July: Greenland melting-snow zone: redistribution study - fine vertical BC sampling of top 20 cm; spectral albedo (Brandt & Warren)
Calibrate new spectrophotometer; quantify BC, dust, other components (Sarah Doherty, Tom Grenfell); further comparisons with SP2 (Joe McConnell, Tony Clarke)
Scanning Electron Microscope and chemical analysis of samples to investigate source signatures (Hegg, Grenfell, Warren)
for inspiring us to take on this project
Clean Air Task Force and NSF Arctic Program
This project has benefited from the increased scientific activity in the Arctic, 2007-9.
Norwegian Polar Institute (Svalbard) Sebastian Gerland
Danish Polar Center (Northeast Greenland) Carl-Egede Bøggild
Arctic and Antarctic Research Institute (Russia) Vladimir Radionov
Volunteers who have collected snow for this project in 2007:
Konrad Steffen & Thomas Phillips (Univ. Colorado). Automatic weather stations in Greenland
Matthew Sturm (U.S. Army Cold Regions Lab, Fairbanks, Alaska).
Snowmobile traverse of Arctic Alaska and Canada
Jacqueline Richter-Menge (U.S. Army Cold Regions Lab, Hanover, NH).
Snow on sea ice in the Beaufort Sea
Jamie Morison, Andy Heiberg & Mike Steele (UW Applied Physics Lab).
North Pole Environmental Observatory and Switchyard Expt, Arctic Ocean.
Matt Nolan (Univ. Alaska). McCall Glacier, northern Alaska
Von Walden (Univ. Idaho). Ellesmere Island, Canada
Shawn Marshall (Univ. Calgary). Devon Island Ice Cap, Canada.
a. Anions – ion chromatography
b. Hydrocarbons – liquid chromatography, mass spectrometer detection
c. Elements – ICP-OES (inductively coupled plasma with optical emission spectroscopy)
Levoglucosan is not simply correlated with BC but is identified by the factor analysis.
PMF (Positive matrix factorization) model results (tentative) for available data base. The five most significant factors explained 90% of variance.
90 % of the mass of BC is associated with this and the next factor.
90 % of the mass of BC is associated with this and the previous factor.