solar radiation treatments in snow and sea-ice
TRANSCRIPT
Solar Radiation Treatments in Snow and Sea-Ice
Charlie Zender, Cheng Dang Department of Earth System Science UC Irvine
Acknowledging:Andrew Roberts, Mark Flanner, Nicole Jeffery,
Elizabeth Hunke, Robert Pincus
On Web
ACME All-Hands MeetingPotomac, MD
June 5-7, 2017
Opportunities for Improvement1. Harmonize land/ice with sea-ice snow RT2. Re-organize spectral bands3. Optical properties update4. Physical processes
Opportunities for Improvement1. Harmonize land/ice with sea-ice snow RT2. Re-organize spectral bands3. Optical properties update4. Physical processes
Harmonize land/ice with sea-ice RT1. CICE: delta-Eddington
○ 3 bands (1 visible, 2 NIR)○ Adding/Doubling, Gaussian integration○ Melt ponds, bare ice
2. ALM: SNow-ICe-Aerosol Radiative model (SNICAR)○ 5 bands (1 visible, 4 NIR)○ Delta-Hemispheric Mean, Tri-diagonal inversion○ Needs melt ponds, bare ice
Snow: Delta-Eddington vs. SNICAR
CICE agrees with SNICAR on broadband albedo CICE absorbs ~30% more internally (spectral resolution?)
Briegleb and Light, 2007
Opportunities for Improvement1. Harmonize land/ice with sea-ice snow RT2. Re-organize spectral bands3. Optical properties update4. Physical processes
Re-organize Spectral Bands1. RRTMG computes 14 solar bands
○ Coupler: Aggregates to 2 spectral bands■ Sends 4 fluxes, receives 4 albedos■ Vis+NIR direct+diffuse■ 4 2-D fields per spectral band
2. Surface models re-bin RRTMG to 2, 3, or 5 bands○ Assumes fixed sub-bin distribution in NIR○ RRTMG band straddles 0.7 um
3. Couple all 14 RRTMG bands?4. Re-bin so RRTMGP boundary at 0.7 um?
Opportunities for Improvement1. Harmonize land/ice with sea-ice snow RT2. Re-organize spectral bands3. Optical properties update4. Physical processes
Optical Properties Update
1. Newer Melt Pond Observations (Light et al.)2. Aerosol, chlorophyll (Wang, Ogunro, Jeffery,
Burrows, Deng, Dubey)
Ice Optical Constants (Warren and Brandt, 2008)
Optical Property of Snow
Single-scattering properties of snow (Dang, Brandt, and Warren 2015)
Mie Theory
Snow radiative transfer simulationSea ice: CICE Delta Eddington methodLand and ice sheet: SNICAR
Optical Properties of Bare Ice and Ponded Ice
SHEBA 1998multi-year sea ice
ICESCAPE 2010, 2011first-year sea ice
• Sea ice interior optical properties measured at finer spectral resolution• Optical properties of first-year sea ice more suitable for the simulation of
current summer Arctic sea ice
Light et al., 2015Briegleb and Light, 2007
Opportunities for Improvement1. Harmonize land/ice with sea-ice snow RT
○ CICE delta-Eddington○ SNow-ICe-Aerosol Radiative model (SNICAR)
2. Re-organize spectral bands○ CAM-SE: RRTMG with 14 solar bands○ ALM+CICE: Two bands (visible+NIR)
3. Optical properties update○ Melt ponds○ Impurities (including algae)
4. Physical processes○ Roughness, compaction, inclination, 3D, ....○ Angular distribution
Sea Ice Algae
Lund-Hansen et al.,2015
Light absorption by BC and Chlorophyll in the Arctic Sea Ice
(Ogunro et al., 2017)Ehn and Mundy, 2013