Joint AMWGCVWG Workshop

1
Improvements in Radiation ProcessesBill Collins
www.cgd.ucar.edu/wcollinsAndrew Conley, David
Fillmore, Julia Lee-Taylor, Phil RaschNational
Center for Atmospheric Research

• Inclusion of diagnostic aerosols
• Improvements in near-infrared absorption by H2O
• Update to longwave to incorporate new H2O
  continuum

2
Radiative Forcing by Diagnostic Aerosols
3
Global Aerosol Assimilation Climatology
1995-2000
Aerosol Assimilation
AVHRR
Analysis
Aerosol Forcing
Analysis
NCAR CAM
Climate Impacts
4
?Annual Mean Aerosol Mass
5
?Optical Depths for Each Species
6
Clear-sky Forcing, by Species
7
Clear-sky Forcing, by Species (cont)
8
Clear-sky Radiative Forcing, All Aerosols
TOA
9
Aerosol Forcing on the Atmosphere
10
?Shortwave Heating Rates
11
Change in Atmospheric Temperatures
T (2m)
T (850 mb)
Aerosol - Control
Aerosol - Control
99 Significance
12
Change in Temperature Profiles
13
Change in Boundary Layer Height
99 Significance
14
?Change in Residual Surface Energy Flux
99 Significance
15
?Change in Net Surface Longwave Flux
99 Significance
16
?Change in Sensible Heat Flux
99 Significance
17
?Change in Latent Heat Flux
99 Significance
18
?Perturbation to Precipitation Rates
Annual
DJF
95 Significance
19
?Change in Atmospheric Vertical Velocity
20
?Conclusions

• Characteristics of global aerosol climatology
• Visible Optical Depth 0.11
• Atmospheric Forcing 2.81 Wm-2
• Atmospheric response to aerosol forcing
• Increased zonal-mean vertical velocity
• Increased stability of boundary layer
• Large decreases in latent and sensible heat
• Statistically significant shifts in precipitation
  patterns
• Future work response of coupled climate system

21
Modifications to Clear-sky Shortwave

• Update interaction of SW radiation with H2O
• New H2O line data (updates since 1982 database
  used in CAM2)
• New treatments of H2O continuum absorption (no
  continuum treatment in CAM2)
• Benchmark calculations for verification
• Spectral absorption from GENLN3
• Radiative transfer by DISORT2
• Improved procedures for parameterization

22
Path to Updated Shortwave Parameterization
GENLN3 Line by line model
Parallel Radiation Code
Near-IR Absorption Spectra
Parameterization
Benchmark Heating Rates
Updated Parameterization
Error Analysis
23
Benchmark Absorption
2.7 ?m
?
?
?
???
24
Benchmark Absorption (detail)
25
Benchmark Scattering
26
Benchmark Solar Spectrum
27
Benchmark Heating Rates Tropics
28
Benchmark Heating Rates High Latitude
29
Benchmark Heating Rates Mid Latitude
30
Benchmark Heating Rates
31
Absorption Cross-Section of H2O
32
Absorption Cross-Section of H2O
CAM Bands
33
Fitting Procedure
34
Fitting Procedure (cont).
35
Fitting Procedure (cont).
36
Variation of Absorption with Atmospheric State
CAM2
CAM2x
37
Path to Updated LW Parameterization

• Objective update to latest H2O Continuum

GENLN3 Line by line model
New Absorptivity Emissivity Tables
Benchmark Heating Rates
Updated Parameterization
Error Analysis
38
Cooling with Old/New H2O Continua
39
Sensitivity to H2O Continua
40
Cooling with Old/New H2O Line Data
41
Sensitivity to H2O Line Data