modeling the change in spectrally resolved outgoing longwave radiation

Modeling the change in spectrally resolved outgoing longwave radiation

Wing-Yee (Marie) LauAug 18, 2010

Review

Continued

Modeled AIRS (clear) – modeled IRIS (a little cloud), ozone unchanged, offset applied

Tilted

Questions about convolution code• The convolution code takes weighted average over a distance of “hw”

from the center.for i=0,lines-1,1 do begin aindex=where(abs(wn-wn[i]) le hw) wn_temp=wn(aindex) rad_temp=rad(aindex) weight_temp=1.-abs(wn_temp-wn[i])/hw rad_temp=rad_temp*weight_temp smooth_rad[i]=total(rad_temp)/total(weight_temp) endfor

• For a resolution of 2.8 cm-1, “hw” should be 1.4 cm-1. Was “hw” = 2.8 or 1.4 when convolving the measurement data?– I was told to set “hw” = 2.8.

• The convolution code does not change the number of data points, but the AIRS spectra have a uniform wavenumber step of 1.39052 cm-1. What was done besides convolution?

Too large IRIS gas profiles• All gases are order of magnitude smaller, if in unit of number density per

cubic meter• If scaled up by a factor of 10, look too large.• Check CO2 and methane, of which well accepted values are known for

1970.

Level Pressure Temp H2O CO2 O3 N2O CO CH4 O2

0 1.00E+00 299.7 6.35E+22 8.09E+20 7.03E+16 7.84E+17 3.68E+17 4.17E+18 5.12E+23

1 8.92E-01 293.7 4.35E+22 7.36E+20 7.03E+16 7.14E+17 3.24E+17 3.79E+18 4.66E+23

10 2.82E-01 237 1.67E+20 2.89E+20 4.89E+16 2.78E+17 8.71E+16 1.47E+18 1.83E+23

20 5.58E-02 206.7 5.15E+17 6.54E+19 2.77E+17 4.69E+16 2.64E+15 2.82E+17 4.14E+22

30 1.20E-02 232.3 1.52E+17 1.26E+19 3.54E+17 5.39E+15 7.59E+14 3.48E+16 7.95E+21

40 3.01E-03 254 4.52E+16 2.87E+18 6.53E+16 3.93E+14 2.70E+14 4.91E+15 1.82E+21

50 8.43E-04 270.2 1.37E+16 7.56E+17 6.41E+15 1.09E+13 1.17E+14 4.81E+14 4.79E+20

60 2.36E-04 253.1 4.11E+15 2.26E+17 7.53E+14 1.41E+12 4.76E+13 1.03E+14 1.43E+20

IRIS gas profiles converted to volume mixing ratio• Accepted concentration of CO2 in 1970: 325 ppm; Our input: 335 ppm• Accepted concentration of methane in 1970: 1.4-1.5 ppm. Our input: 1.68

ppm at ground• US standard model atmosphere provides rough estimate at a few altitude

levels only, and not for tropics. What was done besides interpolating to 101 levels?

Level Pressure Temp H2O CO2 O3 N2O CO CH4 O2

0 1.00E+00 299.7 2.563E-02 3.262E-04 2.836E-08 3.163E-07 1.483E-07 1.680E-06 2.066E-01

1 8.92E-01 293.7 1.939E-02 3.283E-04 3.134E-08 3.184E-07 1.443E-07 1.691E-06 2.079E-01

10 2.82E-01 237 4.156E-04 3.346E-04 5.071E-08 3.241E-07 1.110E-07 1.717E-06 2.120E-01

20 5.58E-02 206.7 2.638E-06 3.348E-04 9.639E-07 2.564E-07 1.572E-08 1.502E-06 2.120E-01

30 1.20E-02 232.3 3.890E-06 3.347E-04 8.936E-06 1.507E-07 1.904E-08 9.573E-07 2.120E-01

40 3.01E-03 254 5.155E-06 3.349E-04 8.187E-06 5.416E-08 2.984E-08 6.136E-07 2.120E-01

50 8.43E-04 270.2 6.061E-06 3.348E-04 3.056E-06 6.466E-09 4.906E-08 2.381E-07 2.120E-01

60 2.36E-04 253.1 6.086E-06 3.347E-04 1.233E-06 2.218E-09 6.855E-08 1.528E-07 2.120E-01

More puzzles of the simulation• My IRIS and AIRS inputs, in ppmv:

http://web.gps.caltech.edu/~mlau/IRIS_AIRS_inputs/• Original IRIS profiles from Yibo:

http://web.gps.caltech.edu/~mlau/TRP_1_MOD.100• Ozone was increased by 8% to make AIRS profile, not physical• Methane was increased by 40% to make a -6.5 K brightness temperature

difference. The true increase should be ~25%. • Does frequency shift contribute to the -8K difference at 1304 cm-1?

Simulation using profiles from Grigg’s paper• 16 altitude levels only• Source: page 17-19 of

http://web.gps.caltech.edu/~mlau/Griggs-07-IRIS-IMG-AIRS.pdf

Comments on simulation with profiles from Griggs’s• Grigg’s 1970 profiles are closer

than ours to other available sources. But her 2003 profiles are incorrect.

• Positive difference in water vapor continuum and shape inverted: they used a much smaller water profile for 2003.

Continued• Fail to simulate the ozone signal:

no significant difference in stratospheric temperature and ozone concentration in their 1970 and 2003 profiles.

• Too few levels at the stratosphere, where ozone signal is sensitive to.

Apply my scalings to Griggs’s 1970 profiles

Decision?• Set “hw” to 1.4 or 2.8 for convolution?• Recalculate all profiles from US standard model of atmosphere, or use

Griggs’s 1970 profiles and interpolate to more levels?• Keep ozone+8% and methane +40%?

Update on searching for inversion• Redoing the search for spectra with ozone band inversion, with the same

search method for both AIRS and IRIS• Finished searching among IRIS and uploaded to

http://web.gps.caltech.edu/~mlau/iris_spec_updated/.• Sample plots and statistics:

Continued

Continued

Continued• Checked every 1 in 10 among AIRS (Apr-Dec 2007, Apr-Dec 2008) for

ozone band inversion. • Uploaded to http://web.gps.caltech.edu/~mlau/airs_spec/.• Sample plots and statistics:

Continued• When searching for CO2

inversion, require the whole CO2 band centered at 670 cm-1 to be inverted, or just the Q branch at 720 cm-1?

Continued

• Thank you! I really want to, and I will, finish the exciting jobs at hand, though I’m leaving tomorrow.