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By Charles Rhodes, Xylene Power Ltd.
OVERVIEW OF INFRARED ABSORPTION:
For an overview of absorption of radiaion by gaseous molecules please refer
to:
CRISP
THE ROLE OF INFRARED ABSORPTION:
Recall from the Radiation Physics section that the emission temperature of an element of surface area of the earth is given by:
Ta = Te [(1 - Fr) / Ft]^.25
where the emissivity Ft is measured in the infrared spectral range and the albedo Fr is measured in the solar spectral range. Recall also that:
Ft = Integral from Z = 0 to Z = infinity of:
{Ftw(Z) [15/Pi^4] Z^3 dZ / [exp(Z) - 1]}
where Z = (H F) / (K Ta)
In order to understand Ftw(Z) it is necessary to understand the infrared absorption characteristics of the greenhouse gases and how these gases affect the infrared spectrum of the earth. The gases of most interest are water vapor, carbon dioxide, ozone, methane and nitrous oxide.
VIEW FROM OUTER SPACE:
When the earth is viewed from outer space with an infrared thermal emission spectrometer, the spectrum consists of radiation from species that will readily interact with electromagnetic radiation. Oxygen and nitrogen do not interact with photons in the thermal emission spectral range and hence are not seen. Water vapor, which interacts with photons right across the thermal emission spectrum is seen, as are carbon dioxide and ozone. High resolution thermal emission spectroscopy equipment for satelite use is being developed.
The following Tropical Clear Sky thermal emission spectrum was recorded by an IRIS instrument (Infra Red Interferometer Spectrometer) on board a Nimbus-3 or Nimbus-4 satelite over the tropical central Pacific Ocean on an exceptionally clear day when there was almost no cloud in its 100 km wide field of view. This spectrum is undated but the satelite mission records indicate that this spectrum was recorded either in the time interval April 14, 1969 to July 22, 1969 or in the time interval April 18, 1970 to January 30, 1971.
Satelite References:
IRIS Description
Spectral Range of IRIS on Nimbus 4 satelite
Nimbus 3 IRIS Operational April 14, 1969 to July 22, 1969, Nimbus 4 IRIS Operational April 8, 1970 to April 14, 1971
NIMBUS 4 IRIS data good until January 30, 1971
Nimbus 3 IRIS Spectral Resolution = 5cm^-1, Nimbus 4 IRIS Spectral Resolution = 1.4 cm^-1
High resolution thermal emission spectroscopy equipment for satelite use
Consolidation of 9268 IRIS thermal IR spectra for the equatorial ocean published in Ph.D. thesis of Xianglei Huang, April 2004, pages 3 to 6, 14, 35 and 47.
This spectrum also shows the width (575 cm^-1 to 775 cm^-1) of the main carbon dioxide absorption band over the equitorial Pacific Ocean in 1970 as seen by the overhead satelite with minimum interference by water vapor.
For wavenumbers less than 400 cm^-1 and greater than 1300 cm^-1 even a small amount of water vapor obscures everything else. The above plot also shows a dark green 255 K black body line corresponding to the temperature of high altitude water vapor.
In the wavenumber band 996 cm^-1 to 1068 cm^-1 ozone in the upper atmosphere obscures the water vapor. At wavenumbers 1029 cm^-1 and 1054 cm^-1 an overhead satelite sees radiation of an intensity corresponding to the temperature of the ozone layer.
At a wavenumber of 669 cm^-1 carbon dioxide has a much stronger absorption than water vapor. Hence, when the earth is viewed from a satelite through 669 cm^-1 bandpass filter the carbon dioxide in the upper atmosphere obscures the water vapor from the satelite's view. Since the upper atmosphere is cold (215 K), that is the effective temperature seen by the satelite at 669 cm^-1.
In the wavenumber ranges 850 cm^-1 to 980 cm^-1 and 1080 cm^-1 to 1200 cm^-1 a dense cloud of water vapor will prevent infrared radiation originating below the cloud from reaching a spacecraft above the atmosphere. Hence the spacecraft sees the temperature at the top of the cloud.
On a clear day when there is almost no cloud the remaining water vapor is almost transparent in the wavenumber range 475 cm^-1 to 1200 cm^-1. Under these circumstances within this wavenumber range the satelite can see almost down to ground level, except within the carbon dioxide and ozone absorption bands. The satelite sees condensing water vapor above the surface of the ocean. Near the equator the equivalent black body temperature seen by the satelite is in the range 265 degrees K to 285 degrees K, depending on the season. This spectral band is known as the 'water vapor window". This band allows infrared emission to space from warm water vapor regions near the warm ocean surface. This relatively high temperature thermal emission carries away most of the Earth's thermal radiant energy, thus keeping the Earth cool. Increased obstruction of the "water window" by carbon dioxide absorption leads to an increase in the Earth's surface temperature.
Careful examination of the thermal emission spectrum recorded by the IRIS instrument reveals carbon dioxide side band absorption lines at 515 cm^-1, 548 cm^-1, 800 cm^-1 and 850 cm^-1, outside the main carbon dioxide absorption band but between 475 cm^-1 and 875 cm^-1. These side bands likely arise due to rotation of the CO2 molecule. Amplitude modulation theory indicates that there will be an infinite series of such side bands with diminishing amplitude away from the center frequency. The side band absorption lines become much more important at larger carbon dioxide concentrations.
The IRIS data shows that within the wavenumber range 400 cm^-1 to 1600 cm^-1, at the present atmospheric carbon dioxide concentration, there is no significant carbon dioxide gas absorption outside the 475 cm^-1 to 875 cm^-1 band.
Laboratory measurements of infrared absorption by carbon dioxide show that the carbon dioxide absorption band consists of a central strong absorption line at 669 cm^-1 (wavelength = 15 um) and a series of side bands of diminishing amplitude. Increasing the concentration of carbon dioxide in the measurement apparatus increases the strength of the absorption sidebands and hence effectively increases the width of the carbon dioxide absorption band.
In the Earth's atmosphere the central absorption band is saturated, but the side bands are not. Increasing the atmospheric CO2 concentration brings more CO2 absorption side bands into play. On Earth the atmospheric CO2 pressure is about .000387 bar. Experimental evidence from the planet Venus indicates that a its atmospheric CO2 pressure of about 90 bars causes a temperature increase of about 400 degrees C.
Although the above IR spectrum reveals a lot of useful information it cannot be used for global warming calculations because it is representative of nearly ideal cloudless conditions, not average conditions, and the value of Fr is not known for these nearly ideal conditions.
INFRARED ABSORPTION DATA:
Infrared Absorbance Data for water vapor, carbon dioxide, ozone, methane and nitrous oxide is available in both graphical and numerical form from the NIST Chemistry WebBook. This data is very helpful for identifying the infrared absorption lines for each gas. For further background information it is helpful to refer to:
Content and Basic Properties of the Atmosphere and Infrared Spectroscopy
WATER VAPOR:
The physical structure of a water (H2O) molecule causes it to have a very complex families of rotational and vibrational states. The molecule is Vee shaped because the two hydrogen atoms bond to each other as well as bonding to the oxygen atom.
Chemically each of the two hydrogen atoms give up one electron to the oxygen atom, causing the oxygen atom to be negatively charged andt the hydrogen atoms to be positively charged. The mass of the hydrogen atoms is small compared to the mass of the oxygen atom, so the center of mass is located near the oxygen atom and the rotational moment of inertia is small. The moment of inertia is different in each of the three planes of rotation. Quantization of angular momentum leads to a wide range of rotational states forming absorption lines in the wavenumber range 200 cm^-1 to 600 cm^-1.(50 um to 16.6 um)
There are also vibrational states relating to the hydrogen-oxygen chemical bond. The interacion between the two hydrogen atoms massively complicates these vibrational states. These vibrational states form a broad absorption band in the frequency range start 1300 cm^-1 to 1900 cm^-1 (7.7 um to 5.2 um). This absorption band has an extremely narrow passband at about 1600 cm^-1.
Between the rotational states and the vibrational states Water vapor (H2O) has an infrared passband that extends from 600 cm^-1 to 1300 cm^-1 (20 um to 7.7 um).
The two water vopor absorption bands cut off the high wavenumber and low wavenumber ends of the infrared thermal emission spectrum emitted by the earth. Water vapor also has weak wideband absorption. Experimental data shows that increasing the water vapor concentration in the atmosphere increases the altitude at which the thermal emission occurs, and vice versa. It is possible that this wide band absorption is related to H2CO3 formed by combination of CO2 disolving in H20 cloud droplets. The exact physical mechanism of this wide band absorption remains to be resolved.
At any particular location the water vapor concentration goes through daily oscillations due to the rotation of the earth. The average water vapor concentration seeks a level that minimizes energy related to the daily water vapor concentration oscillations. The water vapor concentration adopts a level where the fluctuations in (1 - Fr) due to water vapor cancel out the fluctuations in Ft due to water vapor. Thus the temperature remains relatively constant and water is a moderating influence.
Recall that greenhouse warming is given by:
(Ta - Te) / Te = {[(1 - Fr) / Ft]^.25 - 1}
The effect of adding an increment of water vapor to the atmosphere is to increase albedo Fr and to decrease Ft. As the concentration of water vapor in the atmosphere increases the albedo increases which in turn reduces the amount of absorbed solar power, which reduces the rate of water evaporation. On average the rate of water evaporation matches the rate of precipitation. The rate of precipitation is set by the rate of infrared radiative cooling by the atmosphere. In the above equation these two effects cancel one another.
The effect of clouds is to moderate daily temperature swings because clouds reduce absorbed solar radiation during the day and trap infrared radiation during the night. When the atmospheric temperature is very low the water vapor concentration in the atmosphere is low, so there are relatively large daily temperature swings.
The concentration of water vapor in the atmosphere cannot be directly controlled by mankind. Water vapor goes through a phase change and tends to establish its own equilibrium.
Shown below is experimental relative infrared absorbance data published by NIST. The left hand column gives the wavenumber in cm^-1. The other columns give the absorbance results of ten successive experimental spectrum scans for the wavenumber range 450 cm^-1 to 2000 cm^-1. The far right column gives the average of the ten experimental runs in the spectral range of immediate interest.
NIST INFRARED ABSORPTION DATA FOR WATER VAPOR WAVENUMBER(cm^-1) ABSORBANCE AVERAGE 450.0 97 1808 4679 1749 1382 2926 3112 759 1423 1682 1961.7 490.0 1555 1702 629 2741 1616 1569 1561 3208 1300 1338 1721.9 530.0 808 573 990 321 1352 1070 761 533 514 614 753.6 570.0 900 1242 898 1368 791 1050 508 1035 612 602 900.6 610.0 220 635 512 580 896 348 858 752 769 322 water window 589.2 650.0 460 377 458 476 213 791 325 454 201 615 water window 437.0 690.0 564 696 528 474 586 409 409 321 364 306 water window 465.7 730.0 400 259 373 476 535 310 480 340 241 418 water window 383.2 770.0 280 396 282 465 236 363 363 455 405 309 water window 355.4 810.0 467 235 399 256 405 228 340 359 277 349 water window 331.5 850.0 314 485 239 403 298 371 258 379 326 281 water window 335.4 890.0 377 310 370 247 443 294 376 306 405 324 water window 930.0 314 408 298 377 270 447 259 381 328 368 Water window 970.0 334 338 405 268 389 301 406 271 396 340 water window 1010.0 336 368 349 383 258 415 308 401 282 436 water window 1050.0 327 355 383 356 388 317 445 295 409 312 water window 1090.0 427 314 371 405 348 400 314 451 282 427 water window 1130.0 331 401 388 375 411 324 440 338 434 308 water window 1170.0 457 446 406 377 435 446 298 491 325 423 water window 1210.0 345 594 355 420 589 363 411 320 619 355 water window 1250.0 485 326 595 563 692 1090 542 496 478 893 water window 1290.0 862 883 547 522 324 1074 1519 2362 1220 678 1330.0 600 532 3686 2833 728 790 704 1606 2872 2101 1370.0 1377 3107 2174 943 2379 2016 3150 4455 2166 1526 1410.0 2525 403 6621 2679 3121 1234 4221 3423 1319 1350 1450.0 2363 3847 7480 3681 2250 2293 6614 4690 716 3528 1490.0 6097 2708 4544 3680 7523 10000 6087 7143 9633 5270 1530.0 5613 4122 6153 9560 7220 3325 4233 8971 5018 2175 1570.0 2909 2683 1973 2028 0 1274 540 1556 447 1294 narrow passband 1610.0 1430 989 3843 1317 3926 208 3423 3912 1967 2813 1650.0 6727 6477 2700 1834 2373 3100 5484 1568 5970 6742 1690.0 3409 2173 7444 6751 4878 1930 4049 7816 2728 905 1730.0 3154 7275 3233 2933 4399 5718 3197 3042 3036 1605 1770.0 3910 4492 1879 2542 2083 2709 3470 2649 3801 1188 1810.0 1606 1831 813 1478 2069 2935 1620 638 2226 3508 1850.0 1629 298 798 777 1724 3134 871 425 497 790 1890.0 1363 1145 687 515 662 846 1050 1188 1942 711 1930.0 350 506 369 1454 1081 345 379 527 277 951 1970.0 636 325 280 296 206 1183 1035 404 252 328 2010.0 176 524 878 526 267 310 129 403 563 352 Note the water window from 600 cm^-1 to 1300 cm^-1 and the very narrow passband between 1570 cm^-1 and 1610 cm^-1. The width of this passband is less than the 40 cm^-1 incrementation of the digitized spectrum.
CARBON DIOXIDE:
From a global warming point of view the most important gas is carbon dioxide. Its laboratory measured relative transmittance versus:
Wavenumber= F / C
for five experimental runs is tabulated below using data from NIST. The claimed resolution is 4 cm^-1.
FREQUENCY (cm^-1) TRANSMITTANCE #1 #2 #3 #4 #5 458.879000 0.9730 0.9730 0.9720 0.9720 0.9720 463.551912 0.9720 0.9730 0.9730 0.9730 0.9730 468.224824 0.9750 0.9750 0.9760 0.9760 0.9780 472.897735 0.9780 0.9780 0.9790 0.9790 0.9790 477.570647 0.9790 0.9790 0.9780 0.9780 0.9760 482.243559 0.9760 0.9750 0.9750 0.9750 0.9750 486.916471 0.9750 0.9750 0.9750 0.9750 0.9750 491.589383 0.9750 0.9750 0.9750 0.9730 0.9730 496.262295 0.9730 0.9730 0.9730 0.9730 0.9710 500.935206 0.9710 0.9710 0.9690 0.9690 0.9690 505.608118 0.9690 0.9680 0.9660 0.9660 0.9660 510.281030 0.9650 0.9630 0.9630 0.9630 0.9620 514.953942 0.9620 0.9620 0.9620 0.9630 0.9630 Weak Sideband 515 = 669-(3X51.3) 519.626854 0.9650 0.9650 0.9660 0.9660 0.9660 524.299766 0.9660 0.9660 0.9660 0.9650 0.9650 528.972677 0.9650 0.9650 0.9650 0.9650 0.9650 533.645589 0.9650 0.9650 0.9650 0.9650 0.9650 538.318501 0.9650 0.9660 0.9660 0.9660 0.9650 542.991413 0.9650 0.9650 0.9630 0.9630 0.9630 547.664325 0.9620 0.9620 0.9620 0.9620 0.9620 Weak Sideband 548 = 650 -(2X51) 552.337236 0.9620 0.9630 0.9630 0.9650 0.9650 557.010148 0.9660 0.9660 0.9680 0.9690 0.9690 561.683060 0.9710 0.9710 0.9720 0.9720 0.9730 566.355972 0.9730 0.9730 0.9730 0.9750 0.9750 571.028884 0.9750 0.9750 0.9760 0.9760 0.9760 575.701796 0.9780 0.9780 0.9780 0.9780 0.9760 580.374707 0.9760 0.9750 0.9750 0.9730 0.9730 585.047619 0.9730 0.9730 0.9720 0.9710 0.9690 589.720531 0.9690 0.9680 0.9650 0.9630 0.9620 594.393443 0.9600 0.9590 0.9580 0.9560 0.9470 599.066355 0.9290 0.9080 0.9080 0.9290 0.9420 Sideband 599 = 650 - 51 603.739266 0.9400 0.9390 0.9360 0.9340 0.9340 608.412178 0.9330 0.9320 0.9330 0.9340 0.9360 613.085090 0.9360 0.9360 0.9390 0.9420 0.9450 617.758002 0.9430 0.9288 0.4711 0.4650 0.5749 Narrow 618 = 669 - 51 622.430914 0.9443 0.9470 0.9470 0.9261 0.9141 627.103826 0.9030 0.8850 0.8740 0.8560 0.8380 631.776737 0.8061 0.7781 0.7631 0.7441 0.7231 636.449649 0.7020 0.6800 0.6570 0.6340 0.6120 641.122561 0.5891 0.5671 0.5401 0.5340 0.5181 645.795473 0.5080 0.4979 0.4460 0.4010 0.3520 650.468385 0.3031 0.3030 0.3608 0.3550 0.3490 STRONG SIDEBAND 650 = 669 - 9 655.141297 0.3450 0.3420 0.3430 0.3480 0.3490 659.814208 0.3560 0.3620 0.3680 0.3750 0.3780 664.487120 0.3850 0.4200 0.4660 0.4630 0.1993 Relative Minimum Absorption 669.160032 0.1341 0.0692 0.1797 0.2737 0.2939 MAXIMUM ABSORPTION 669 673.832944 0.2990 0.2940 0.2900 0.2860 0.2810 Relative Minimum Absorption 678.505856 0.2800 0.2800 0.2810 0.2900 0.2990 Strong Sideband 678 = 669 + 9 683.178767 0.3060 0.3150 0.3230 0.3260 0.3350 687.851679 0.3430 0.3540 0.3670 0.3799 0.3949 692.524591 0.4110 0.4290 0.4450 0.4620 0.4790 697.197503 0.4950 0.5100 0.5359 0.5490 0.5819 701.870415 0.6110 0.6310 0.6630 0.6800 0.6970 706.543327 0.7130 0.7389 0.7520 0.7610 0.7829 711.216238 0.8090 0.8330 0.8490 0.8560 0.8690 715.889150 0.8770 0.8900 0.9109 0.9210 0.9300 720.562062 0.8149 0.7099 0.5790 0.3332 0.3330 Narrow Sideband 720 = 669 +51 725.234974 0.9578 0.9580 0.9550 0.9460 0.9430 729.907886 0.9390 0.9360 0.9330 0.9320 0.9300 734.580797 0.9290 0.9290 0.9270 0.9270 0.9260 739.253709 0.9260 0.9260 0.9240 0.9230 0.9210 Sideband 739 = 669 + 51 + 9 743.926621 0.9230 0.9370 0.9460 0.9580 0.9600 748.599533 0.9630 0.9650 0.9680 0.9690 0.9730 753.272445 0.9760 0.9780 0.9790 0.9810 0.9820 757.945357 0.9820 0.9840 0.9840 0.9850 0.9860 762.618268 0.9860 0.9880 0.9890 0.9890 0.9890 767.291180 0.9890 0.9890 0.9890 0.9890 0.9890 771.964092 0.9910 0.9910 0.9910 0.9910 0.9910 776.637004 0.9910 0.9910 0.9910 0.9910 0.9920 781.309916 0.9920 0.9910 0.9910 0.9890 0.9890 785.982828 0.9890 0.9890 0.9890 0.9890 0.9890 Weaker 790.655739 0.9890 0.9890 0.9890 0.9890 0.9890 Weaker 795.328651 0.9890 0.9890 0.9890 0.9890 0.9880 Weaker 800.001563 0.9880 0.9860 0.9860 0.9860 0.9860 Weak Sideband 800 804.674475 0.9880 0.9880 0.9880 0.9880 0.9880 Weaker 809.347387 0.9890 0.9890 0.9890 0.9890 0.9890 Weaker 814.020298 0.9890 0.9910 0.9910 0.9910 0.9910 818.693210 0.9910 0.9910 0.9910 0.9910 0.9910 823.366122 0.9910 0.9910 0.9910 0.9910 0.9920 828.039034 0.9920 0.9920 0.9920 0.9910 0.9910 832.711946 0.9910 0.9920 0.9920 0.9920 0.9920 837.384858 0.9920 0.9920 0.9920 0.9920 0.9940 842.057769 0.9940 0.9940 0.9940 0.9940 0.9940 846.730681 0.9940 0.9940 0.9940 0.9940 0.9950 851.403593 0.9950 0.9940 0.9940 0.9940 0.9940 856.076505 0.9940 0.9940 0.9940 0.9950 0.9940 weak sideband 856 860.749417 0.9940 0.9940 0.9940 0.9940 0.9940 865.422328 0.9940 0.9940 0.9950 0.9950 0.9950 870.095240 0.9950 0.9950 0.9950 0.9950 0.9950 874.768152 0.9950 0.9950 0.9950 0.9950 0.9950 879.441064 0.9950 0.9950 0.9950 0.9950 0.9950 884.113976 0.9970 0.9970 0.9950 0.9950 0.9950 888.786888 0.9950 0.9950 0.9940 0.9940 0.9940 weak sideband 893.459799 0.9950 0.9950 0.9950 0.9950 0.9950 weak sideband 898.132711 0.9970 0.9950 0.9950 0.9950 0.9950 weak 902.805623 0.9950 0.9950 0.9950 0.9970 0.9970 907.478535 0.9970 0.9980 0.9980 0.9980 1.0000 912.151447 1.0000 1.0010 1.0010 1.0010 1.0010 916.824359 1.0010 1.0010 1.0010 1.0010 1.0020 921.497270 1.0020 1.0020 1.0020 1.0020 1.0020 926.170182 1.0020 1.0020 1.0040 1.0040 1.0040 930.843094 1.0040 1.0040 1.0040 1.0040 1.0040 935.516006 1.0040 1.0040 1.0050 1.0050 1.0050 940.188918 1.0050 1.0050 1.0050 1.0050 1.0050 944.861829 1.0050 1.0050 1.0050 1.0050 1.0050 949.534741 1.0050 1.0050 1.0050 1.0050 1.0050 954.207653 1.0050 1.0050 1.0050 1.0050 1.0050 958.880565 1.0050 1.0050 1.0050 1.0050 1.0050 963.553477 1.0050 1.0050 1.0050 1.0070 1.0070 968.226389 1.0070 1.0070 1.0070 1.0070 1.0070 972.899300 1.0070 1.0070 1.0070 1.0070 1.0080 977.572212 1.0080 1.0070 1.0070 1.0070 1.0070 982.245124 1.0070 1.0070 1.0070 1.0070 1.0070 986.918036 1.0070 1.0070 1.0070 1.0080 1.0080 991.590948 1.0080 1.0080 1.0100 1.0100 1.0100 996.263860 1.0100 1.0080 1.0080 1.0080 1.0080 1000.936771 1.0080 1.0070 1.0070 1.0050 1.0050 1005.609683 1.0040 1.0040 1.0040 1.0050 1.0070 absorption 1005 1010.282595 1.0080 1.0080 1.0100 1.0100 1.0100 1014.955507 1.0100 1.0110 1.0110 1.0110 1.0130 1019.628419 1.0130 1.0140 1.0140 1.0140 1.0140 1024.301330 1.0140 1.0140 1.0140 1.0140 1.0140 1028.974242 1.0140 1.0150 1.0150 1.0150 1.0150 1033.647154 1.0150 1.0150 1.0150 1.0150 1.0150 1038.320066 1.0150 1.0140 1.0140 1.0130 1.0130 1042.992978 1.0110 1.0110 1.0110 1.0110 1.0140 absorption 1042 1047.665890 1.0150 1.0150 1.0140 1.0050 1.0020 absorption 1047 1052.338801 1.0040 1.0140 1.0150 1.0150 1.0130 1057.011713 1.0130 1.0130 1.0140 1.0140 1.0140 1061.684625 1.0130 1.0130 1.0130 1.0130 1.0110 1066.357537 1.0110 1.0110 1.0100 1.0080 1.0050 1071.030449 1.0050 1.0040 1.0040 1.0040 1.0040 1075.703360 1.0040 1.0050 1.0050 1.0080 1.0080 1080.376272 1.0100 1.0110 1.0110 1.0110 1.0130 1085.049184 1.0130 1.0130 1.0140 1.0140 1.0140 1089.722096 1.0140 1.0140 1.0140 1.0150 1.0150 1094.395008 1.0150 1.0150 1.0150 1.0170 1.0170 1099.067920 1.0170 1.0170 1.0170 1.0170 1.0170 1103.740831 1.0170 1.0170 1.0170 1.0170 1.0170 1108.413743 1.0170 1.0170 1.0170 1.0170 1.0170 1113.086655 1.0180 1.0180 1.0180 1.0180 1.0180 1117.759567 1.0180 1.0180 1.0180 1.0180 1.0180 1122.432479 1.0180 1.0180 1.0180 1.0180 1.0180 1127.105391 1.0170 1.0170 1.0170 1.0170 1.0150 1131.778302 1.0140 1.0140 1.0140 1.0130 1.0130 1136.451214 1.0130 1.0130 1.0110 1.0110 1.0110 1141.124126 1.0110 1.0110 1.0130 1.0130 1.0140 1145.797038 1.0140 1.0150 1.0150 1.0150 1.0150 1150.469950 1.0170 1.0170 1.0180 1.0180 1.0180 1155.142861 1.0180 1.0180 1.0180 1.0180 1.0180 1159.815773 1.0180 1.0180 1.0180 1.0180 1.0180 1164.488685 1.0180 1.0180 1.0180 1.0180 1.0180 1169.161597 1.0180 1.0180 1.0180 1.0180 1.0180 1173.834509 1.0170 1.0150 1.0140 1.0140 1.0130 1178.507421 1.0110 1.0100 1.0100 1.0110 1.0140 1183.180332 1.0170 1.0170 1.0180 1.0180 1.0200 1187.853244 1.0200 1.0200 1.0210 1.0210 1.0230 1192.526156 1.0230 1.0230 1.0230 1.0230 1.0230 1197.199068 1.0230 1.0230 1.0230 1.0230 1.0230 1201.871980 1.0230 1.0230 1.0230 1.0230 1.0230 1206.544891 1.0230 1.0230 1.0230 1.0230 1.0230 1211.217803 1.0230 1.0230 1.0230 1.0230 1.0230 1215.890715 1.0230 1.0230 1.0230 1.0230 1.0230 1220.563627 1.0210 1.0210 1.0210 1.0210 1.0200 1225.236539 1.0200 1.0200 1.0200 1.0200 1.0200 1229.909451 1.0200 1.0210 1.0200 1.0200 1.0180 1234.582362 1.0180 1.0170 1.0150 1.0150 1.0140 1239.255274 1.0130 1.0100 1.0100 1.0080 1.0080 1243.928186 1.0080 1.0070 1.0070 1.0050 1.0050 1248.601098 1.0050 1.0040 1.0040 1.0020 1.0020 1253.274010 1.0010 1.0010 1.0010 1.0010 1.0010 1257.946922 1.0010 1.0010 1.0010 1.0010 1.0000 1262.619833 1.0000 1.0000 1.0000 1.0000 1.0000 1267.292745 1.0000 1.0000 1.0000 1.0000 1.0000 1271.965657 0.9980 0.9980 0.9980 0.9980 0.9980 1276.638569 0.9980 0.9980 0.9980 0.9980 0.9970 1281.311481 0.9970 0.9970 0.9970 0.9970 0.9970 1285.984392 0.9970 0.9970 0.9970 0.9950 0.9950 1290.657304 0.9940 0.9940 0.9940 0.9940 0.9940 1295.330216 0.9940 0.9940 0.9940 0.9940 0.9940 1300.003128 0.9940 0.9940 0.9940 0.9940 0.9940 1304.676040 0.9950 0.9950 0.9950 0.9950 0.9950 1309.348952 0.9950 0.9950 0.9950 0.9950 0.9950 1314.021863 0.9940 0.9940 0.9940 0.9920 0.9940 1318.694775 0.9940 0.9940 0.9940 0.9940 0.9940 1323.367687 0.9940 0.9950 0.9950 0.9950 0.9950 1328.040599 0.9950 0.9950 0.9950 0.9950 0.9950 1332.713511 0.9950 0.9950 0.9950 0.9950 0.9950 1337.386422 0.9950 0.9950 0.9950 0.9950 0.9950 1342.059334 0.9950 0.9950 0.9950 0.9950 0.9970 1346.732246 0.9970 0.9950 0.9950 0.9940 0.9940 1351.405158 0.9920 0.9910 0.9890 0.9880 0.9860 1356.078070 0.9860 0.9850 0.9850 0.9840 0.9840 1360.750982 0.9840 0.9840 0.9850 0.9850 0.9850 1365.423893 0.9850 0.9860 0.9860 0.9850 0.9840 1370.096805 0.9820 0.9820 0.9820 0.9810 0.9810 1374.769717 0.9790 0.9790 0.9790 0.9790 0.9780 1379.442629 0.9730 0.9660 0.9630 0.9620 0.9600 1384.115541 0.9620 0.9620 0.9630 0.9660 0.9690 1388.788453 0.9730 0.9790 0.9850 0.9890 0.9890 1393.461364 0.9910 0.9910 0.9920 0.9920 0.9940 1398.134276 0.9950 0.9950 0.9950 0.9950 0.9950 1402.807188 0.9950 0.9950 0.9950 0.9940 0.9950 1407.480100 0.9950 0.9950 0.9950 0.9950 0.9950 1412.153012 0.9950 0.9970 0.9970 0.9970 0.9980 1416.825923 0.9980 0.9970 0.9970 0.9950 0.9950 1421.498835 0.9950 0.9950 0.9950 0.9950 0.9950 1426.171747 0.9950 0.9950 0.9950 0.9950 0.9970 1430.844659 0.9970 0.9940 0.9940 0.9920 0.9920 1435.517571 0.9920 0.9910 0.9910 0.9920 0.9920 1440.190483 0.9920 0.9920 0.9920 0.9920 0.9920 1444.863394 0.9920 0.9920 0.9920 0.9920 0.9920 1449.536306 0.9920 0.9910 0.9910 0.9910 0.9890 1454.209218 0.9890 0.9880 0.9880 0.9880 0.9860 1458.882130 0.9860 0.9860 0.9880 0.9880 0.9890 1463.555042 0.9890 0.9890 0.9890 0.9890 0.9910 1468.227954 0.9910 0.9910 0.9910 0.9910 0.9910 1472.900865 0.9910 0.9910 0.9910 0.9910 0.9920 1477.573777 0.9910 0.9890 0.9890 0.9880 0.9860 1482.246689 0.9860 0.9860 0.9860 0.9860 0.9860 1486.919601 0.9860 0.9860 0.9880 0.9880 0.9890 1491.592513 0.9880 0.9880 0.9880 0.9880 0.9880 1496.265424 0.9880 0.9890 0.9890 0.9890 0.9880 1500.938336 0.9880 0.9880 0.9880 0.9880 0.9880 1505.611248 0.9880 0.9880 0.9890 0.9890 0.9890 1510.284160 0.9910 0.9890 0.9890 0.9890 0.9880 1514.957072 0.9880 0.9880 0.9880 0.9880 0.9880 1519.629984 0.9860 0.9860 0.9850 0.9860 0.9860 1524.302895 0.9860 0.9860 0.9860 0.9880 0.9880 1528.975807 0.9880 0.9880 0.9890 0.9890 0.9890 1533.648719 0.9890 0.9890 0.9880 0.9880 0.9880 1538.321631 0.9880 0.9860 0.9860 0.9860 0.9880 1542.994543 0.9860 0.9860 0.9860 0.9860 0.9880 1547.667454 0.9880 0.9880 0.9880 0.9890 0.9910 1552.340366 0.9910 0.9910 0.9910 0.9890 0.9880 1557.013278 0.9880 0.9880 0.9880 0.9880 0.9880 1561.686190 0.9880 0.9890 0.9880 0.9880 0.9880 1566.359102 0.9890 0.9890 0.9890 0.9890 0.9890 1571.032014 0.9880 0.9880 0.9880 0.9860 0.9860 1575.704925 0.9880 0.9860 0.9860 0.9860 0.9860 1580.377837 0.9860 0.9860 0.9860 0.9880 0.9880 1585.050749 0.9880 0.9890 0.9890 0.9910 0.9890 1589.723661 0.9890 0.9890 0.9890 0.9910 0.9890 1594.396573 0.9890 0.9890 0.9890 0.9890 0.9890 1599.069485 0.9890 0.9890 0.9890 0.9890 0.9880 1603.742396 0.9880 0.9890 0.9890 0.9890 0.9890 1608.415308 0.9890 0.9890 0.9890 0.9890 0.9880 1613.088220 0.9880 0.9880 0.9890 0.9890 0.9890 1617.761132 0.9890 0.9890 0.9890 0.9880 0.9860 1622.434044 0.9860 0.9880 0.9880 0.9890 0.9910 1627.106955 0.9910 0.9910 0.9910 0.9920 0.9910 1631.779867 0.9910 0.9910 0.9910 0.9920 0.9920 1636.452779 0.9940 0.9940 0.9940 0.9940 0.9950 1641.125691 0.9970 0.9970 0.9970 0.9980 0.9980 1645.798603 0.9980 0.9970 0.9970 0.9950 0.9950 1650.471515 0.9950 0.9940 0.9920 0.9920 0.9920 1655.144426 0.9920 0.9910 0.9890 0.9890 0.9890 1659.817338 0.9890 0.9890 0.9890 0.9890 0.9890 1664.490250 0.9890 0.9890 0.9890 0.9890 0.9880 1669.163162 0.9880 0.9880 0.9880 0.9880 0.9880 1673.836074 0.9880 0.9880 0.9890 0.9890 0.9880 1678.508985 0.9880 0.9860 0.9860 0.9910 0.9920 1683.181897 0.9920 0.9920 0.9920 0.9910 0.9910 1687.854809 0.9890 0.9890 0.9880 0.9860 0.9860 1692.527721 0.9860 0.9860 0.9860 0.9860 0.9860 1697.200633 0.9850 0.9850 0.9850 0.9850 0.9850 1701.873545 0.9850 0.9850 0.9850 0.9850 0.9850 1706.546456 0.9850 0.9850 0.9850 0.9860 0.9860 1711.219368 0.9880 0.9880 0.9860 0.9860 0.9860 1715.892280 0.9860 0.9860 0.9850 0.9850 0.9850 1720.565192 0.9850 0.9850 0.9840 0.9840 0.9840 1725.238104 0.9840 0.9840 0.9840 0.9840 0.9840 1729.911016 0.9840 0.9840 0.9840 0.9850 0.9850 1734.583927 0.9860 0.9860 0.9860 0.9860 0.9860 1739.256839 0.9860 0.9860 0.9850 0.9850 0.9850 1743.929751 0.9840 0.9850 0.9850 0.9850 0.9850 1748.602663 0.9850 0.9850 0.9850 0.9850 0.9850 1753.275575 0.9850 0.9850 0.9850 0.9850 0.9850 1757.948486 0.9850 0.9850 0.9850 0.9850 0.9850 1762.621398 0.9850 0.9850 0.9850 0.9850 0.9860 1767.294310 0.9860 0.9860 0.9860 0.9860 0.9860 1771.967222 0.9860 0.9860 0.9860 0.9860 0.9860 1776.640134 0.9860 0.9860 0.9860 0.9860 0.9860 1781.313046 0.9850 0.9860 0.9860 0.9860 0.9860 1785.985957 0.9860 0.9860 0.9860 0.9860 0.9860 1790.658869 0.9860 0.9860 0.9860 0.9860 0.9860 1795.331781 0.9860 0.9860 0.9860 0.9860 0.9860 1800.004693 0.9860 0.9860 0.9860 0.9860 0.9860 1804.677605 0.9860 0.9880 0.9880 0.9880 0.9880 1809.350516 0.9880 0.9880 0.9880 0.9880 0.9880 1814.023428 0.9880 0.9880 0.9880 0.9880 0.9880 1818.696340 0.9880 0.9880 0.9880 0.9880 0.9880 1823.369252 0.9880 0.9880 0.9880 0.9880 0.9880 1828.042164 0.9880 0.9880 0.9880 0.9880 0.9880 1832.715076 0.9880 0.9880 0.9880 0.9880 0.9880 1837.387987 0.9880 0.9880 0.9880 0.9880 0.9880 1842.060899 0.9880 0.9880 0.9880 0.9880 0.9880 1846.733811 0.9880 0.9880 0.9880 0.9880 0.9880 1851.406723 0.9880 0.9880 0.9880 0.9880 0.9880 1856.079635 0.9880 0.9880 0.9880 0.9880 0.9880 1860.752547 0.9880 0.9880 0.9880 0.9880 0.9880 1865.425458 0.9860 0.9860 0.9860 0.9860 0.9860 1870.098370 0.9860 0.9860 0.9860 0.9860 0.9860 1874.771282 0.9860 0.9860 0.9860 0.9860 0.9860 1879.444194 0.9860 0.9860 0.9860 0.9860 0.9860 1884.117106 0.9860 0.9860 0.9860 0.9860 0.9860 1888.790017 0.9860 0.9860 0.9860 0.9860 0.9860 1893.462929 0.9860 0.9860 0.9860 0.9860 0.9860 1898.135841 0.9860 0.9860 0.9860 0.9860 0.9860 1902.808753 0.9860 0.9860 0.9880 0.9880 0.9880 1907.481665 0.9860 0.9860 0.9860 0.9860 0.9860 1912.154577 0.9860 0.9860 0.9860 0.9860 0.9860 1916.827488 0.9860 0.9860 0.9860 0.9880 0.9880 1921.500400 0.9880 0.9880 0.9880 0.9880 0.9880 1926.173312 0.9880 0.9880 0.9880 0.9880 0.9880 1930.846224 0.9880 0.9880 0.9880 0.9880 0.9880 1935.519136 0.9880 0.9880 0.9860 0.9860 0.9860 1940.192047 0.9860 0.9860 0.9850 0.9840 0.9840 1944.864959 0.9840 0.9840 0.9840 0.9840 0.9850 1949.537871 0.9850 0.9850 0.9850 0.9850 0.9840 1954.210783 0.9820 0.9790 0.9780 0.9780 0.9790 1958.883695 0.9840 0.9860 0.9880 0.9880 0.9860 1963.556607 0.9880 0.9880 0.9890 0.9890 0.9890 1968.229518 0.9890 0.9890 0.9880 0.9890 0.9890 1972.902430 0.9890 0.9890 0.9890 0.9910 0.9910 1977.575342 0.9890 0.9890 0.9890 0.9890 0.9890 1982.248254 0.9890 0.9890 0.9890 0.9890 0.9890 1986.921166 0.9890 0.9890 0.9890 0.9890 0.9890 1991.594078 0.9890 0.9890 0.9890 0.9890 0.9890 1996.266989 0.9890 0.9890 0.9890 0.9890 0.9890 2000.939901 0.9890 0.9890 0.9890 0.9890 0.9890
Note that the absorbance of carbon dioxide contains multiple absorption lines (side bands) of diminishing strength around the main translational absorption wave number= 669 cm^-1. At higher carbon dioxide concentrations these sidebands play a major role in global warming. The main absorptin wavenumber 669 cm^-1 appears to be amplitude modulated by 9 cm^-1 and 51 cm^-1 signals, probably due to molecular rotation states.
The infrared absorption spectrum of carbon dioxide (CO2) recorded by the IRIS instrument in 1970 has a strong absorption band centered at 669 cm^-1 (15 um). The main absorption band clearly extends from 575 cm^-1 to 775 cm^-1 (17.39 um to 12.9 um). The IRIS instrument shows other smaller absorption bands on both sides of the main absorption band. The origin of these sidebands cannot be determined from the IRIS data alone. However, comparison of the IRIS data with the NIST data shows that the absorptions visible at 515 cm^-1, 548 cm^-1 and 800 cm^-1 on the IRIS data are all due to carbon dioxide.
At the central portion of the 15 um carbon dioxide absorption band only the temperature of the cold upper atmosphere is visible from outer space. At this wavelength the carbon dioxide in the lower atmosphere is opaque. Increasing the carbon dioxide concentration increases the absorption by side bands, making these sideband wavenumbers opaque as well. Thus, increasing the carbon dioxide concentration increases the apparent width of the main carbon dioxide absorption band, which decreases Ft and hence increases global warming. Note that the area of the main absorption band, if the carbon dioxide concentration is less than 16 times its present value, is bounded by 475 cm^-1, 875 cm^-1, the 215K black body line, the 290 K line and the water vapor absorption in the absence of carbon dioxide.
It is possible that carbon dioxide in the atmosphere combines with condensed water vapor droplets to form H2CO3, a wide band absorbing species. When there are no clouds there is no H2CO3, and hence this wide band absorption disappears. However, this wide band absorption may be negligible compared to water vapor absorption.Reference:Carbonic acid production in H2O:CO2 ices
As the concentration of carbon dioxide increases, Ftw(Z) decreases at all the CO2 absorption lines (475 cm^-1 to 875 cm^-1) causing Ft to decrease. This decrease in Ft forces the temperature Ta to increase, and is the direct cause of global warming due to carbon dioxide.
OZONE:
A reference summarizing the absorption bands of ozone is:
Absorption band.
A reference summarizing ozone chemistry in the atmosphere is:
Stratospheric Ozone Chemistry
Recall that greenhouse warming is given by:
(Ta - Te) / Te = {[(1 - Fr) / Ft]^.25 - 1}
The effect of adding ozone (O3) to the atmosphere is to decrease Ft. Hence adding ozone has the effect of increasing greenhouse warming. However, ozone is kept in a constant equilibrium maintained by solar radiation. This equilibrium is in balance provided that there are no catalysts present such as chlorine atoms that destroy ozone. The total amount of ozone present is so small that only the main absorption band has any practical effect. The other absorption lines are too weak.
The main absorption band of appears to have rounded edges. There is a rounded edge in the range 963 cm^-1 to 996 cm^-1. There strong absorptions at 1029 cm^-1 and 1056 cm^-1. There is another rounded edge in the range 1067 cm^-1 to 1080 cm^-1.
Ozone is catalyticly destroyed by chloro-fluorocarbon gases in the atmosphere. Due to the earth's magnetic field holes in the ozone layer tend to occur near the earth's magnetic poles. These holes allow more solar UV energy to reach the ground, contributing to melting of polar ice.
Ozone is not evenly distributed through the atmosphere. Ozone is concentrated in the upper atmosphere where it is made by interaction of UV light with oxygen. Since the total amount of ozone in the atmosphere is very small, its weak broad band absorption lines have little effect on Ft.
NIST INFRARED TRANSMITTANCE DATA FOR OZONE Wavenumber(cm^-1) Transmittance 402.089000 0.9630 0.9630 0.9630 0.9610 0.9590 408.616431 0.9590 0.9560 0.9560 0.9540 0.9540 415.143863 0.9520 0.9520 0.9480 0.9420 0.9400 421.671294 0.9380 0.9360 0.9340 0.9320 0.9320 428.198726 0.9300 0.9240 0.9220 0.9200 0.9200 434.726157 0.9150 0.9130 0.9130 0.9110 0.9090 441.253588 0.9050 0.9050 0.9050 0.9050 0.9050 447.781020 0.9030 0.9030 0.9010 0.9010 0.9010 454.308451 0.9010 0.9010 0.8990 0.8990 0.8970 460.835882 0.8950 0.8950 0.8950 0.8970 0.8970 460 weak absorption 467.363314 0.8990 0.8990 0.8990 0.8990 0.8990 473.890745 0.9010 0.9030 0.9030 0.9090 0.9090 480.418177 0.9090 0.9110 0.9110 0.9110 0.9110 486.945608 0.9130 0.9150 0.9180 0.9200 0.9200 493.473039 0.9200 0.9220 0.9220 0.9300 0.9340 500.000471 0.9340 0.9360 0.9360 0.9360 0.9360 506.527902 0.9380 0.9400 0.9420 0.9420 0.9440 513.055333 0.9440 0.9460 0.9460 0.9480 0.9500 519.582765 0.9520 0.9540 0.9560 0.9560 0.9590 526.110196 0.9590 0.9610 0.9630 0.9670 0.9710 532.637628 0.9730 0.9750 0.9770 0.9770 0.9790 539.165059 0.9830 0.9850 0.9870 0.9890 0.9910 545.692490 0.9930 1.0040 1.0060 1.0080 1.0080 552.219922 1.0100 1.0100 1.0120 1.0120 1.0160 558.747353 1.0180 1.0180 1.0180 1.0200 1.0220 565.274785 1.0220 1.0220 1.0240 1.0240 1.0240 571.802216 1.0260 1.0260 1.0260 1.0260 1.0260 578.329647 1.0260 1.0260 1.0280 1.0280 1.0280 584.857079 1.0260 1.0260 1.0260 1.0260 1.0260 591.384510 1.0260 1.0260 1.0260 1.0280 1.0280 597.911941 1.0280 1.0280 1.0280 1.0280 1.0260 604.439373 1.0260 1.0280 1.0280 1.0260 1.0260 610.966804 1.0240 1.0220 1.0220 1.0140 1.0080 617.494236 1.0060 1.0060 1.0060 1.0060 1.0060 624.021667 1.0040 1.0040 1.0020 1.0020 1.0000 630.549098 1.0000 1.0000 0.9970 0.9930 0.9890 637.076530 0.9810 0.9770 0.9750 0.9710 0.9670 643.603961 0.9610 0.9590 0.9481 0.9381 0.9320 650.131392 0.9300 0.9280 0.9240 0.9220 0.9200 656.658824 0.9200 0.9200 0.9200 0.9180 0.9180 663.186255 0.9130 0.9030 0.8950 0.8850 0.8790 669.713687 0.8750 0.8750 0.8830 0.8830 0.8174 676.241118 0.7950 0.7930 0.7930 0.7930 0.7930 676 absorption 682.768549 0.7930 0.7930 0.7930 0.7950 0.7970 689.295981 0.8050 0.8050 0.8110 0.8130 0.8150 695.823412 0.8230 0.8270 0.8360 0.8440 0.8460 702.350843 0.8500 0.8520 0.8520 0.8520 0.8520 708.878275 0.8520 0.8520 0.8520 0.8520 0.8520 715.405706 0.8500 0.8500 0.8500 0.8480 0.8460 715 Weak Absorption 721.933138 0.8480 0.8500 0.8540 0.8600 0.8660 728.460569 0.8700 0.8720 0.8750 0.8770 0.8790 734.988000 0.8830 0.8850 0.8850 0.8910 0.8910 741.515432 0.8930 0.8930 0.8950 0.8950 0.8950 748.042863 0.8990 0.9010 0.9050 0.9070 0.9110 754.570295 0.9110 0.9130 0.9130 0.9130 0.9130 761.097726 0.9150 0.9180 0.9180 0.9180 0.9180 767.625157 0.9180 0.9200 0.9200 0.9200 0.9200 774.152589 0.9180 0.9150 0.9150 0.9150 0.9130 780.680020 0.9070 0.9050 0.9030 0.9030 0.9010 787.207451 0.8990 0.8970 0.8950 0.8950 0.8910 793.734883 0.8890 0.8870 0.8870 0.8870 0.8890 793 Weak Absorption 800.262314 0.8890 0.8910 0.8910 0.8910 0.8910 806.789746 0.8910 0.8910 0.8930 0.8950 0.9010 813.317177 0.9050 0.9110 0.9110 0.9130 0.9150 819.844608 0.9180 0.9200 0.9220 0.9240 0.9240 826.372040 0.9240 0.9260 0.9260 0.9280 0.9280 832.899471 0.9280 0.9280 0.9280 0.9280 0.9280 839.426902 0.9280 0.9260 0.9260 0.9260 0.9260 845.954334 0.9260 0.9240 0.9240 0.9240 0.9240 846 Weak Absorption 852.481765 0.9240 0.9240 0.9260 0.9260 0.9260 859.009197 0.9260 0.9260 0.9260 0.9260 0.9260 865.536628 0.9260 0.9260 0.9260 0.9260 0.9260 872.064059 0.9260 0.9260 0.9260 0.9260 0.9260 878.591491 0.9260 0.9260 0.9260 0.9260 0.9260 885.118922 0.9260 0.9260 0.9260 0.9260 0.9260 891.646354 0.9260 0.9240 0.9240 0.9220 0.9220 892 Weak Absorption 898.173785 0.9220 0.9220 0.9240 0.9240 0.9220 904.701216 0.9200 0.9200 0.9200 0.9200 0.9200 911.228648 0.9200 0.9180 0.9180 0.9180 0.9180 917.756079 0.9180 0.9150 0.9150 0.9150 0.9150 924.283510 0.9150 0.9130 0.9130 0.9130 0.9130 930.810942 0.9110 0.9110 0.9110 0.9110 0.9090 937.338373 0.9090 0.9090 0.9070 0.9070 0.9070 943.865805 0.9070 0.9070 0.9070 0.9070 0.9070 950.393236 0.9070 0.9070 0.9070 0.9070 0.9070 956.920667 0.9050 0.9070 0.9070 0.9070 0.9050 963.448099 0.9050 0.9050 0.9050 0.9030 0.9030 969.975530 0.9010 0.9010 0.8990 0.8970 0.8950 976.502961 0.8950 0.8930 0.8910 0.8870 0.8830 983.030393 0.8790 0.8750 0.8700 0.8640 0.8580 989.557824 0.8540 0.8360 0.8310 0.8170 0.7990 990 Low Frequency Edge 996.085256 0.7820 0.7661 0.7580 0.7291 0.7131 ABSORPTION 1002.612687 0.6940 0.6700 0.6330 0.6020 0.5880 ABSORPTION 1009.140118 0.5611 0.5361 0.4912 0.4562 0.4361 ABSORPTION 1015.667550 0.3990 0.3910 0.3810 0.3660 0.3480 ABSORPTION 1022.194981 0.3171 0.2931 0.2821 0.2721 0.2621 ABSORPTION 1028.722413 0.2600 0.2600 0.2600 0.2600 0.2620 1029 Local MAXIMUM ABSORPTION 1035.249844 0.2660 0.2720 0.2720 0.2740 0.2740 ABSORPTION 1041.777275 0.2739 0.2314 0.7170 0.5771 0.4362 1042 Local Minimum absorption 1048.304707 0.3911 0.3461 0.2683 0.2133 0.1633 ABSORPTION 1054.832138 0.1470 0.1390 0.1350 0.1370 0.1450 1054 MAXIMUM ABSORPTION 1061.359569 0.1550 0.1650 0.2596 0.4660 0.5018 ABSORPTION 1067.887001 0.5882 0.7251 0.7970 0.8340 0.8500 1068 High Frequency Edge 1074.414432 0.8520 0.8540 0.8540 0.8600 0.8680 1080.941864 0.8700 0.8720 0.8720 0.8750 0.8770 1087.469295 0.8790 0.8810 0.8810 0.8830 0.8830 1093.996726 0.8830 0.8830 0.8830 0.8830 0.8830 1100.524158 0.8830 0.8850 0.8850 0.8850 0.8850 1107.051589 0.8850 0.8830 0.8830 0.8830 0.8830 1113.579020 0.8830 0.8830 0.8830 0.8810 0.8810 1114 Weak Absorption 1120.106452 0.8810 0.8810 0.8830 0.8830 0.8830 1126.633883 0.8830 0.8830 0.8850 0.8890 0.8890 1133.161315 0.8910 0.8910 0.8930 0.8930 0.8930 1139.688746 0.8910 0.8910 0.8870 0.8870 0.8850 1140 Weak Absorption 1146.216177 0.8870 0.8910 0.8910 0.8930 0.8930 1152.743609 0.8930 0.8930 0.8930 0.8930 0.8950 1159.271040 0.8950 0.8950 0.8930 0.8910 0.8890 1159 Weak Absorption 1165.798471 0.8870 0.8890 0.8950 0.9089 0.9110 1172.325903 0.9110 0.9130 0.9150 0.9200 0.9200 1178.853334 0.9130 0.9090 0.9090 0.9110 0.9150 1179 Weak Absorption 1185.380766 0.9180 0.9220 0.9260 0.9300 0.9300 1191.908197 0.9300 0.9320 0.9320 0.9320 0.9320 1198.435628 0.9320 0.9320 0.9280 0.9200 0.8910 1204.963060 0.8750 0.8720 0.8700 0.8700 0.8700 1211.490491 0.8680 0.8680 0.8660 0.8620 0.8620 1218.017923 0.8580 0.8580 0.8620 0.8620 0.8640 1218 Weak Absorption 1224.545354 0.8640 0.8660 0.8700 0.8640 0.8640 1231.072785 0.8640 0.8640 0.8640 0.8660 0.8680 1237.600217 0.8700 0.8750 0.8770 0.8770 0.8770 1244.127648 0.8790 0.8790 0.8810 0.8810 0.8810 1250.655079 0.8810 0.8770 0.8750 0.8750 0.8720 1257.182511 0.8700 0.8700 0.8700 0.8700 0.8680 1263.709942 0.8680 0.8600 0.8600 0.8660 0.8660 1264 Weak Absorption 1270.237374 0.8660 0.8660 0.8660 0.8640 0.8640 1276.764805 0.8640 0.8620 0.8620 0.8640 0.8640 1283.292236 0.8680 0.8700 0.8700 0.8720 0.8720 1289.819668 0.8720 0.8700 0.8680 0.8680 0.8640 1296.347099 0.8600 0.8560 0.8520 0.8520 0.8520 1302.874530 0.8500 0.8500 0.8500 0.8480 0.8480 1303 Weak Absorption 1309.401962 0.8480 0.8480 0.8500 0.8500 0.8520 1315.929393 0.8520 0.8540 0.8560 0.8560 0.8560 1322.456825 0.8560 0.8560 0.8560 0.8560 0.8540 1328.984256 0.8540 0.8540 0.8520 0.8520 0.8520 1335.511687 0.8520 0.8500 0.8500 0.8480 0.8480 1342.039119 0.8480 0.8480 0.8460 0.8420 0.8380 1348.566550 0.8360 0.8360 0.8340 0.8310 0.8310 1355.093982 0.8290 0.8250 0.8230 0.8170 0.8130 1361.621413 0.8110 0.8110 0.8110 0.8110 0.8110 1368.148844 0.8090 0.8030 0.8010 0.7990 0.7970 1374.676276 0.7970 0.7970 0.7970 0.7970 0.7990 1375 Absorption 1381.203707 0.7990 0.7990 0.8010 0.8010 0.8050 1387.731138 0.8070 0.8090 0.8170 0.8170 0.8190 1394.258570 0.8190 0.8190 0.8210 0.8250 0.8270 1400.786001 0.8290 0.8310 0.8310 0.8340 0.8340 1407.313433 0.8360 0.8380 0.8400 0.8420 0.8420 1413.840864 0.8420 0.8420 0.8420 0.8311 0.8340 1414 Weak Absorption 1420.368295 0.8360 0.8420 0.8420 0.8440 0.8480 1426.895727 0.8480 0.8500 0.8500 0.8500 0.8500 1433.423158 0.8500 0.8500 0.8480 0.8380 0.8500 1434 Weak Absorption 1439.950589 0.8500 0.8500 0.8520 0.8520 0.8520 1446.478021 0.8520 0.8520 0.8500 0.8500 0.8500 1453.005452 0.8480 0.8440 0.8380 0.8360 0.8270 1453 Absorption 1459.532884 0.8340 0.8420 0.8440 0.8460 0.8460 1466.060315 0.8460 0.8460 0.8500 0.8500 0.8401 1472.587746 0.8340 0.8310 0.8340 0.8360 0.8440 1473 Absorption 1479.115178 0.8480 0.8480 0.8480 0.8500 0.8500 1485.642609 0.8500 0.8500 0.8420 0.8400 0.8360 1492.170040 0.8400 0.8420 0.8480 0.8500 0.8500 1498.697472 0.8460 0.8440 0.8440 0.8440 0.8440 1505.224903 0.8380 0.8250 0.8150 0.8150 0.8250 1505 Absorption 1511.752335 0.8270 0.8290 0.8340 0.8340 0.8310 1518.279766 0.8250 0.8190 0.8150 0.8170 0.8190 1518 Absorption 1524.807197 0.8210 0.8210 0.8210 0.8250 0.8270 1531.334629 0.8310 0.8310 0.8310 0.8310 0.8270 1537.862060 0.8190 0.8150 0.8110 0.8030 0.8030 1538 Absorption 1544.389492 0.8090 0.8130 0.8170 0.8230 0.8310 1550.916923 0.8360 0.8340 0.8310 0.8290 0.8290 1551 Weak Absorption 1557.444354 0.8110 0.7761 0.7760 0.8308 0.8340 1563.971786 0.8360 0.8360 0.8360 0.8290 0.8250 1564 Weak Absorption 1570.499217 0.8270 0.8360 0.8360 0.8360 0.8360 1577.026648 0.8250 0.8340 0.8360 0.8400 0.8420 1583.554080 0.8420 0.8420 0.8440 0.8440 0.8460 1590.081511 0.8460 0.8460 0.8440 0.8440 0.8440 1596.608943 0.8440 0.8440 0.8480 0.8480 0.8440 1603.136374 0.8440 0.8440 0.8440 0.8440 0.8440 1609.663805 0.8440 0.8420 0.8420 0.8420 0.8400 1616.191237 0.8290 0.8270 0.8290 0.8340 0.8340 1622.718668 0.8340 0.8340 0.8340 0.8340 0.8340 1629.246099 0.8310 0.8310 0.8340 0.8340 0.8340 1635.773531 0.8250 0.8150 0.8150 0.8270 0.8270 1642.300962 0.8270 0.8270 0.8250 0.8230 0.8210 1648.828394 0.8190 0.8170 0.8030 0.7861 0.7860 1649 Absorption 1655.355825 0.7951 0.8170 0.8230 0.8250 0.8290 1661.883256 0.8270 0.8250 0.8250 0.8250 0.8250 1668.410688 0.8170 0.8130 0.8110 0.8090 0.8090 1674.938119 0.8090 0.8110 0.8110 0.8130 0.8150 1681.465551 0.8130 0.8110 0.7970 0.7950 0.7950 1681 Absorption 1687.992982 0.8090 0.8110 0.8110 0.8090 0.8070 1694.520413 0.8050 0.8030 0.7970 0.7680 0.7640 1695 Absorption 1701.047845 0.7660 0.7969 0.7990 0.8010 0.7970 1707.575276 0.8010 0.8070 0.8090 0.8110 0.8110 1714.102707 0.8030 0.7950 0.7880 0.7721 0.7720 1714 Absorption 1720.630139 0.7820 0.7820 0.7840 0.7840 0.7840 1727.157570 0.7840 0.7840 0.7820 0.7780 0.7740 1733.685002 0.7580 0.7520 0.7450 0.7430 0.7430 1734 Absorption 1740.212433 0.7430 0.7430 0.7430 0.7450 0.7470 1746.739864 0.7500 0.7500 0.7520 0.7580 0.7600 1753.267296 0.7640 0.7700 0.7720 0.7760 0.7780 1759.794727 0.7820 0.7840 0.7840 0.7900 0.7930 1766.322158 0.7950 0.7970 0.7990 0.7990 0.7930 1772.849590 0.7900 0.7930 0.7950 0.7970 0.8030 1779.377021 0.8050 0.8090 0.8090 0.8090 0.8090 1785.904453 0.8090 0.8090 0.8090 0.8070 0.8070 1792.431884 0.8050 0.8050 0.8050 0.8070 0.8070 1792 Absorption 1798.959315 0.8070 0.8090 0.8090 0.8110 0.8110 1805.486747 0.8110 0.8130 0.8130 0.8130 0.8130 1812.014178 0.8150 0.8150 0.8170 0.8170 0.8190 1818.541610 0.8190 0.8210 0.8210 0.8210 0.8210 1825.069041 0.8190 0.8190 0.8170 0.8130 0.8130 1825 Absorption 1831.596472 0.8130 0.8150 0.8170 0.8190 0.8210 1838.123904 0.8210 0.8250 0.8250 0.8230 0.8130 1844.651335 0.8130 0.8150 0.8150 0.8190 0.8210 1845 Absorption 1851.178766 0.8230 0.8270 0.8270 0.8270 0.8290 1857.706198 0.8290 0.8290 0.8290 0.8290 0.8290 1864.233629 0.8290 0.8270 0.8270 0.8250 0.8250 1870.761061 0.8250 0.8270 0.8270 0.8270 0.8290 1871 Absorption 1877.288492 0.8290 0.8310 0.8310 0.8310 0.8310 1883.815923 0.8310 0.8310 0.8310 0.8340 0.8340 1890.343355 0.8310 0.8310 0.8310 0.8310 0.8310 1890 Absorption 1896.870786 0.8310 0.8310 0.8340 0.8340 0.8340 1903.398217 0.8340 0.8340 0.8340 0.8310 0.8310 1909.925649 0.8310 0.8310 0.8310 0.8290 0.8290 1916.453080 0.8270 0.8250 0.8250 0.8250 0.8270 1922.980512 0.8270 0.8270 0.8270 0.8250 0.8250 1923 Weak Absorption 1929.507943 0.8290 0.8290 0.8290 0.8290 0.8290 1936.035374 0.8290 0.8290 0.8290 0.8270 0.8270 1942.562806 0.8270 0.8270 0.8270 0.8270 0.8270 1949.090237 0.8270 0.8250 0.8250 0.8250 0.8250 1955.617668 0.8250 0.8250 0.8250 0.8230 0.8230 1956 Weak Absorption 1962.145100 0.8250 0.8250 0.8250 0.8250 0.8290 1968.672531 0.8290 0.8250 0.8250 0.8250 0.8270 1975.199963 0.8290 0.8290 0.8290 0.8270 0.8250 1981.727394 0.8250 0.8250 0.8250 0.8250 0.8270 1982 Weak Absorption 1988.254825 0.8270 0.8270 0.8250 0.8230 0.8230 1994.782257 0.8230 0.8250 0.8290 0.8290 0.8290 2001.309688 0.8290 0.8290 0.8280 0.8270 0.8220 Note the absorption band in the range 963 cm^-1 to 1080 cm^-1.There is a very narrow passband at 1041 cm^-1.
METHANE AND NITROUS OXIDE:
Methane (CH4) has an absorption band in the range 1200 cm^-1 to 1400 cm^-1 (8.3 um to 7.14 um). Nitrous oxide (N2O) has a narrow absorption line at 600 cm^-1 (16.6 um) and an absorption band in the range 1200 cm^-1 to 1350 cm^-1 (8.3 um to 7.4 um).
The nitrous oxide absorption is coincident with the carbon dioxide and methane absorption bands, so when both carbon dioxide and methane are both present nitrous oxide has little effect on greenhouse warming.
Methane and nitrous oxide both have the potential to make a significant contribution to greenhouse warming. However, this contribution is partially suppressed by water vapor absorption. However, an issue of major concer is the relatively rapid recent increase in the atmospheric concentration of methane, thought to be due to a combination of permafrost melting and sloppy practices in the fossil fuel industry.
ABSORPTION CALCULATIONS:
Accurately calculating the change in Ftw(W) caused by an increase in carbon dioxide concentration is not simple because of the complex temperature distribution in the upper atmosphere and temperature changes across the area being viewed. Fortunately, for local warming calculations we only need to concern ourselves with the change in absorption band area, not its exact profile.
This web page last updated January 17, 2020.
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