BORIS FOMIN Central Aerological Observatory MOSCOW, RUSSIA [email protected] LBL MODELS: STATE OF THE ART AND PERSPECTIVE 11th HITRAN Conference.

BORIS FOMINCentral Aerological Observatory

MOSCOW, [email protected]

LBL MODELS: STATE OF THE ART AND PERSPECTIVE

11th HITRAN Conference

CONTENT

1. Introduction: HITRAN and progress in science2. Radiative-Transfer Modeling: state of the art

 2.1 Total atmospheric radiation  2.2 High-resolution satellite remote sensing

3. Line-by-line models at present 3.1 Current abilities of the LBL models 3.2 Spectroscopic problems

4. Line-by-line models: perspectives 4.1 Atmospheric radiation 4.2 Remote sensing 4.3 Education

5. Conclusion: some requirements to HITRAN and acknowledgements

1. HITRAN and progress in science a “human genome of gases” :-)

It is a great achievement of the modern science!!! It’s development promises a powerful impetus to geophysics as the whole, including progress in climate change prediction, satellite investigations and other fields. But…

The global average surface warming following a doubling of carbon dioxide concentration is likely to be in the range (Likely Range-> ±σ, 1/3 outside) (2 – 4.5) 0C =>IPCC, 2007 (Summary for Policymakers p.12)(1.5 – 4.5) 0C =>IPCC,

1994Carbon Dioxide , Edited by W.Bach et al.(2nd Course of the International School of Climatology, Erice,Italy,1982 !!!Углекислый газ в атмосфере (стр.8). Под редакцией В.Баха, Г.С.Голицина, И.Л.Кароля и др., «Мир», 1987

2007-1982 = 25 years !!!

The global and diurnal mean SW (red circles), LW (blue circles) and total (black diamonds) net flux deviations from the LBL code (AER for LW and libRadtran for SW) at the surface.

International comparison of

radiation codes

(CCMVal, V.Fomichev, P.Forster et al., 2010)

2.1 RTM: total atmospheric radiation

The same at the model pseudo-tropopause (200 hPa).

International comparison of

radiation codes

(CCMVal, V.Fomichev, P.Forster et al., 2010)

2.1 RTM: total atmospheric radiation

The same but for the CO2 forcing (at the pseudo-tropopause).

International comparison of

radiation codes

(CCMVal, V.Fomichev, P.Forster et al., 2010)

2.1 RTM: total atmospheric radiation

The same but for the stratospheric water vapor increase

International comparison of

radiation codes

(CCMVal, V.Fomichev, P.Forster et al., 2010)

2.1 RTM: total atmospheric radiation

GOSAT (Japan Aerospace Exploration Agency (JAXA),Jan.23, 2009)

710 715 720 725 730 735 740210

220

230

240

250

260

270270

211.096

Obs

LBRTM

FLBLM

740710

The observation results by the TANSO FTS and simulations when the satellite passed over Japan at around 1:00 p.m. on February 7, 2009 (JST). Obs, LBRTM and FLBLM – means observations and calculations obtained by the LBRTM and FLBLM

LbL models, respectively.

(Prof. Imasu provided me with the data as a part of project activities with JAXA and we have got an allowance to use the data from JAXA)

Many thanks to Prof. R. Imasu (CCSR at univ.Tokyo, Japan) for the data!

2.2 High-resolution satellite remote sensing

3.1 Current abilities of the LBL models(FLBLM – as an example)

Physical assumptions:a) Line shape modeling (continuum, form-

factors): similar to LBRTMb) Line-Coupling:

-Niro F., Von Clamann T., Jucks K., Hartmann J.M.//Spectra calculations… // J. Quant. Spectrosc. Radiat. Transfer, v. 90, p. 61-76, 2005. Many thanks to P. Sebastien (France) for his program!

Tonkov M.V., Filippov N.N., Timofeev Yu.M., Polyakov A.V. (1996) “A simple model of the line mixing effect for atmospheric application: Theoretical background and comparison with experimental profiles”, JQSRT 56, 783-795

c) LTE and Non-LTE

0 1000 2000 3000 4000 5000 6000 7000200

220

240

260

280

300

CHANNEL NUMBER

BR

IGH

TN

ES

S

TE

MP

ER

AT

UR

E

[K]

298.57

209.58

0

1

10

78401 N

Algorithms : Molecular absorption and cloud/aerosol scattering (shortwave and longwave) by means of the Monte Carlo method.

Brightness temperatures in the IASI channels (LOS= 60O) for tropical atmosphere. Upper (red) line 0- clear-sky atmosphere; middle (blue) 1 and lower (pink) 10- for cloud of optical thickness 1.0 and 10.0 (Disregard of scattering -> error up to 4 K).

3.1 Current abilities of the LBL models(FLBLM – as an example)

3.2 Spectroscopic problems(different LC models)

660 661 662 663 664 665 666 667 668 669 67010

100

1 103

1 104

5 .42 103

13 .032

L C

C b0P 6

C b0P 8

670660

Absorption spectrum at P=1 atm, T=283.72. LC– means calculations with the Line-Coupling model by [Niro et al.], VOIGT and Cb0P6, Cb0P8 mean calculations using the Line-Coupling model by [Tonkov et al.] with Cb = 0.6 and Cb = 0.8, respectively.

660 661 662 663 664 665 666 667 668 669 67010

100

1 103

1 104

5 .42 103

10 .997

L C

L B R T M

V O IG T

670660

Absorption spectrum at P=1 atm, T=283.72. LC– means calculations with the Line-Coupling model (Niro et al.), VOIGT and LBRTM mean calculations with the pure Voigt and corrected (as in LBRTM) profiles.

3.2 Spectroscopic problems(line shape correction)

Table 4Errors in calculations with different approximations of the line-mixing effect-------------------------------------------------------------------------------------------- Upward Fluxes (W/m2) Downward Fluxes (W/m2)5km 13 m 20km 104km 0km 5km 13km 20km Approximation 0 0 0 0.03 0 -0.01 -0.01 -0.03 ‘1-order’ 0.66 2.13 2.37 2.33 -1.60 -2.35 -0.39 -0.18 ‘Voigt’ 0.01 0.10 0.13 0.12 -0.02 -0.14 -0.09 -0.11 ‘LBRTM’ 0.05 0.25 0.23 0.16 -0.01 -0.26 -0.22 -0.28 ‘Kunde-

Maguire’--------------------------------------------------------------------------------------------

3.2 Spectroscopic problems (total radiation)

4. Line-by-line models: perspectives

4.1 Atmospheric radiationCurrent situation with accuracy of the radiation codes for Global Circulation Models (GCMs) is unacceptable. But this problem can be solved by means of the LBL models if to apply a new k-distribution technique [Fomin, B.A. (2004), 1.FKDM, fast k-distribution model …, J. Geophys. Res., 109, D02110, doi:10.1029/2003JD003802.]

4.2 Remote sensingDue to progress in hardware the LBL models can be faster in 100 and more times if to apply processors for parallel calculations (e.g. video cards, using CUDA).

4.3 Education At present, we must admit that it is the “human factor” that impedes essentially the progress in geophysics. The fast, precise, flexible and user friendly LbL models can play the key role in the training process of a new generation of researches.

5. Conclusion: some requirements to HITRAN and acknowledgements.

1. At present the main problems in the radiative transfer modeling are related to the line shape theory. It will be very useful to find in HITRAN the current L-C and continuum models as well as the correction form-factors to the Voigt profile. In other words all information for the LBL models.

Thanks to everybody for your attention!

AcknowledgementsThis work has been supported by the RFBR (grants 10-0108099-3, 08-01-00024 and 09-01-00071).

2. The high-resolution remote sensing needs very high calculation accuracy (up to ~ 0.2 K in brightness temperature). So it will be very useful to find in HITRAN a set of exact experimental spectra for the LBL validation (similar to the cross-section data). These spectra can be also used as the PT-tables in the problem spectral region.