2. DATA DESCRIPTIONS [DATAXDESCRIP, 3] This section contains brief descriptions of the sources for data found in the Handbook. Each description is preceded by a definition of the data file variables and their ranges and units, as well as a list of the file names (capital letters). 2.1 ATTENUATION COEFFICIENTS 2.1.1 Absorption (km**-1) and Scattering (cm**-1) vs. Altitude (0 to 85 km) ATTENHT, AERXCLR, AERXHAZ, MIDLATSUM, MIDLATWIN, SUBARCSUM, SUBARCWIN, TROPIC (all accessed by program ATTENCOEF) The tables contain values of attenuation coefficients as a function of altitude for five atmospheric and two aerosol models from McClatchey et al. (1972). The altitude range is 0 to 85 km and the radiation wavelength is 0.6943 micrometers. Numerical values for the coefficients were computed and then logarithmically interpolated for each atmospheric layer. The aerosol attenuation coefficients are identical for all geographical and seasonal models. If the total attenuation (G) is required, the four coefficients can be summed: G = molecular absorption + molecular scattering + aerosol absorption + aerosol scattering. The tables are accessed by program ATTENCOEF. 2.1.2 Attenuation (m**-1) and Scattering (m**-1) vs. Wavelength (3.75E-7 to 8E-7 meters) for Water H2OXATTENSCAT Jerlov (1968) collected the observed attenuation coefficients of Clarke and James (1939) and the theoretical scattering coefficients of LeGrand (1939) for pure water in the range 3.75E-7 to 8E-7 meters. In their experiments Clarke and James found no palpable differences between the attenuances of distilled water and ocean water, and therefore the values for distilled water can be used when attenuation coefficients for salt water are needed. 2.2 STANDARD ATMOSPHERES Pressure (mb), Temperature (K), and Number Densities (mols cm**-3) vs. Altitude (0 to 100 km) of H2O, CO2, O3, N2O, CO, CH4, O2, and N2 MLS, MLW, SAS, SAW, TROPICAL, USXSTAN These tables are taken from the Air Force Geophysics Lab computer code for FSCDATM, Gallery ey al. (1981). Data were originally derived from McClatchey et al. (1972). They originate from "Handbook of Geophysics and Space Environments" (Valley, 1965). The six profiles consist of the pressure, temperature, and number densities of H2O, CO2, O3, N2O, CO, CH4, O2, and N2 vs. altitude for the following atmospheric types: Tropical (15 deg. N.), Midlatitude Summer (45 deg. N., July), Midlatitude Winter (45 deg. N., January), Subarctic Summer (60 deg. N., July), Subarctic Winter (60 deg. N., January), and the 1962 U.S. Standard Atmosphere. A draft version of a section of the report on FSCDATM states: "The water vapor density for the 1962 Standard corresponds to relative humidities of approximately 50% for altitudes up to 10 km, whereas the relative humidity values for the other models tend to decrease with altitude from approximately 80% at sea level to approximately 30% at 10 km. Above 12 km the water vapor number densities of all models but the 1962 Standard are identical and represent volume mixing ratios which reach a minimum of about 6.5 ppmv at 17 km, increase to 30 ppmv at 30 km, then decrease to 10 ppmv at 50 ppmv. For all models, the gases CO2, N2O, CO, CH4, O2, and N2 are considered uniformly mixed with volume mixing ratios of 330, 0.28, 0.075, 1.6, 1.095E05, and 7.905E05 ppmv respectively." In correspondance with us, W.O. Gallery of AFGL commented that the data on which these profiles are based are old. The report continues: "The stratospheric water vapor concentrations for the six profiles are now known to be too large by a factor of 5 at 30 km. The models may still be considered representative of their respective conditions up to about 50 km for temperature, up to 30 km for ozone densities, and up to the tropopause ( approximately 15 km in the Tropics to 8 km in the Arctic) for water vapor." Two useful recent reports are WMO (1982) and M. Smith (1982). The U.S. Standard Atmosphere for 1976 updates the 1962 Standard for temperature above 50 km and provides revised estimates for the surface concentrations of what was previously termed the "uniformly mixed gases". New values for the volume mixing ratios of CO2, N2O, CO, and CH4 are 322, 0.27, 0.19, and 1.60 ppmv respectively. The 1976 Standard gives equations for the computation of the number density of individual species. When updated tables are released by AFGL, we plan to incorporate them into the Handbook. 2.3 CLOUD DROP SIZE DISTRIBUTIONS NOTE: All cloud files contain the number density of drops or ice particles per unit interval (m**-3 m**-1). The number density (m**-3) in the interval is given by multiplying the number density per unit interval (m**-3 m**-1) by the absolute difference between the beginning and ending radius. 2.3.1 Number Density of Drops (m**-3 m**-1) vs. Radius (meters) CLOUD1 to CLOUD8 Carrier et al. (1967) presented theoretical scattering parameters for eight different water cloud models at 4.88E-7, 6.94E-7, 1.06E-6, 4E-6, and 1.06E-5 meter radiations. These wavelengths, excluding 4E-6, correspond to the monochromatic wavelengths of operationally significant lasers. The authors presented representative cloud drop size distributions and concentrations for major water cloud types, assuming spherical water droplets only, and calculated the optical extinction coefficients for each model using the exact Mie theory. Consequently the calculated optical properties are accurate only for the cloud models used. We calculated data values in the CLOUD1 - 8 tables from both tabular and graphed data in Carrier et al. (1965, 1967). Carrier gives these figures for the concentrations of the drop size distributions: Type File Name Concentration (number/cm**3) ---- --------- -------------- Stratus I CLOUD1 464 (458) Stratocumulus CLOUD2 350 (370) Fairweather Cumulus CLOUD3 300 (157)* Stratus II CLOUD4 260 (260) Cumulonimbus CLOUD5 72 (63) Cumulus Congestus CLOUD6 207 (198) Nimbostratus CLOUD7 330 (326) Altostratus CLOUD8 450 (461) *The numbers in parentheses represent the results of calculations we performed on histograms derived from Carrier's figures. The concentration for Fairweather Cumulus, CLOUD3, is different enough that we suggest taking our value as correct for the data as presented. 2.3.2 Number Density of Ice Particles (m**-3 m**-1) vs. Radius (1.5E-6 to 7.5E-5 meters) CLOUD9 Schickel (1975) took samplings from 56 1980 publications on droplet distributions of water clouds. CLOUD9 is a sampling for ice fog. 2.3.3 Number Density of Ice Particles (m**-3 m**-1) vs. Radius (1E-6 to 5E-5 meters (CLOUD10) and 5E-5 to 5E-4 meters (CLOUD11)) CLOUD10 and CLOUD11 Heymsfield (1975) studied the growth of the ice phase in cirrus uncinus and cirrostratus clouds through aircraft measurements of cloud particle spectra at different altitudes. The temperature range was -14 to -46 degrees. CLOUD10 and CLOUD11 are taken from data for particle spectra taken near the top of a cirrostratus deck. The cirrostratus clouds sampled had their nucleation regions near the top of the clouds; crystals sedimented and grew from this source region near the top to near the base, and then evaporated to the base. The crystal concentrations were about 0.2 cm**-3, with 0.01 **-3 longer than 100 micrometers. The mean length of crystals larger than 100 micrometers ranged between 0.2 and 0.5 mm. The ice water content ranged between 0.01 and 0.16 g m**-3. 2.3.4 Number Density of Ice Particles (m**-3 m**-1) vs. Radius (3E-6 to 1.33E-5 meters) CLOUD12 Heymsfield and Jahnsen (1974) sampled thin, nearly invisible tropopause cirrus layers by aircraft over the continental United States and Pacific Ocean. In the data set used, samplings took place in a thin cirrus layer between 55,000 and 52,000 ft topped at the tropopause, near the Marshall Islands in the Pacific in December of 1973. There were no clouds below this level. There was a double tropopause, one at 55,000 ft and a weak one between 53,000 and 54,000 ft. The ice water content increased from the cloud top at the tropopause to 300 feet below the tropopause, decreased to 54,000 ft, increased in the second tropopause to 53,500 ft, and evaporated below. The "source" region of the ice crystals was at the cloud top where there were high concentrations of small crystals; there was a secondary source region at 53,800 ft. An SRI lidar also indicated two cloud layers, one topped at 55,000 ft, the other at 53,800 ft. 2.3.5 Number Density of Ice Particles (m**-3 m**-1) vs. Radius (3.97E-7 to 3.97E-5 meters) CLOUD13 CLOUD13 contains ice size distributions for cirrus clouds at 13.3 km as reported by Kraus and Barnes (1976b). The freezing level was between 4.6 and 4.9 km, and tropopause was at approximately 15.5 km. 2.3.6 Number Density of Ice Particles (m**-3 m**-1) vs. Radius (3.97E-7 to 2E-4 meters) CLOUD14 CLOUD14 contains the ice size distributions for cirrus clouds at 12.5 km. They represent Kraus and Barnes's (1976a) best estimate of the worst case situation along their missile trajectory. The freezing level was near 4.9 km, and the tropopause was at 15.8 km. 2.3.7 Number Density of Ice Particles (m**-3 m**-1) vs. Radius (3.97E-7 to 1.58E-4 meters) CLOUD15 Barnes (1977) reported ice size distributions for cirrus clouds at approximately 15 km. 2.3.8 Number Density of Ice Particles (m**-3 m**-1) vs. Radius (8.05E-6 to 5.64E-4 meters) CLOUD16 CLOUD16 was taken from Glass and Varley's (1978) report of data collected during a morning flight through a layer of thin cirrus in December 1977 by AFGL cloud physics research aircraft over northern Arizona and New Mexico. The aircraft flew at an altitude of approximately 7 km MSL and the ambient temperature was -25 degrees C. The 500-mb synoptic chart on this day indicated a weakening ridge pattern over this region. 2.3.9 Number Density of Ice Particles (m**-3 m**-1) vs. Radius (1E-6 to 8.6E-4 meters) CLOUD17 Varley and Brooks (1978) reported data from a February 1978 cirrus sampling flight in Albuquerque, New Mexico, aimed at acquiring information on the typical type and concentration of ice particles in cirrus clouds. 2.3.10 Number Density of Ice Particles (m**-3 m**-1) vs. Radius (1E-6 to 3.1E-5 meters) CLOUD18 CLOUD18 is a cirrus cloud distribution synthesized from several sources by Dr. Vernon Derr of NOAA/ERL to be a small particle distribution (<31 micrometers) for test purposes. 2.4 SOLAR SPECTRAL IRRADIANCE 2.4.1 Solar Spectral Irradiance (watts m**-2 m**-1) vs. Wavelength (1.27E-7 to 1E-4 meters) FLUX1 Thekaekara (1972) presented results of experiments made by NASA Goddard Space Flight Center on the solar constant and solar spectrum from a research aircraft at 11.6 km. In the wavelength range 3E-7 to 1.5E-5 meters these values were based mainly on measurements made from the research aircraft. The instruments used were a Perkin-Elmer model 112 spectrometer with a lithium-based fluoride window, a Leiss double quartz prism monochrometer, a filter radiometer, a polarization type inter- ferometer and, for the infrared range beyond 4 micrometers, a Michelson type interferometer. In the wavelength range 3E-7 to 2.6E-6 meters an independent set of data is available from the Eppley-JPL measurements, made with a filter radiometer during several series of flights. The wavelength range covered is 1.2E-7 to 1E-4 meters. Thekaekara writes, "...the spectral irradiance is determined in narrow wavelength ranges and the integral energy is computed to give the solar constant. The solar constant...is the energy due to the sun incident on unit area exposed normally to the sun's rays at the average sun-earth distance in the absence of the earth's atmosphere. The solar spectral irradiance is the distribution of this energy as a function of wavelength." The data in FLUX1 are reprinted from Thekaekara (1972) with permission from PHOTONICS SPECTRA, copyright holder. 2.4.2 Solar Spectral Irradiance (watts m**-2 m**-1) vs. Wavelength (2.5E-10 to 1.95E-2 meters) FLUX2 From Smith and Gottlieb (1974), the tables in FLUX2 represent solar irradiance data as derived from various sources by the authors, in the wavelength range 2.5E-10 to 1.95E-2 meters. Smith and Gottlieb used the formula H = pi [(r**2)/(R**2)]F = 6.80 X (10**-5)F to derive the solar irradiance (the solar flux at 1 AU) from the total solar flux, where H is the solar irradiance, F is the total solar flux, r is the radius of the sun, and R is 1 AU. "AU" is defined as "Astronomical Unit", the mean distance from the earth to the sun, where 1 AU = 1.49E11 meters. ("pi" stands for the mathematical constant). The data in FLUX2 are reproduced from Smith and Gottlieb (1974) with permission from D. Reidel Publishing, copyright holder. 2.5 SKY SPECTRAL RADIANCE NOTE: Sky spectral radiance is the power falling on area A per unit optical aperture (steradians), per unit wavelength range. Sky Spectral Radiance (watts m**-2 m**-1) vs. Wavelength (3.1E-7 to 7.2E-7 meters) SKYBAC10, SKYBACSL SKYBACSL and SKYBAC10 are files of the spectral radiance of the sky at sea level and at 10,000 feet. Walter Clark (1969) designed, built, and calibrated a spectrophotometer that was used at sea level and carried in an aircraft to collect the data. The data are for the wavelength region 3.1E-7 to 7.2E-7 meters. Clark reports that error computations of sky luminance using the root mean square method resulted in 6.5% to 11.5% error depending upon the signal amplitudes, and thus the spectral radiance absolute accuracy probably varies between 13% and 16%. 2.6 RAYLEIGH COEFFICIENTS, AIR Mass Scattering Coefficient (m**2 kg**-2), Volume Scattering Coefficient (m**-1), and Scattering Cross Section (m**2) vs. Wavelength (2E-7 to 2E-5 meters) for Air MASSXSCAT, VOLXSCAT, RAYXSCATCROSS Penndorf (1957) calculated the real refractive indices of standard air based on Edlen's formula for the wavelength range 2E-7 to 2E-5 meters (2.7.2). Computations of the Rayleigh scattering cross sections and mass and volume scattering coefficients were tabulated in the same range. Standard air is defined as dry air containing 0.03% CO2 by volume at normal pressure 760 mm Hg (=1013.25 mb) and having an air temperature of 15 degrees C. When calculating the refractive indices Penndorf made allowances for the influence of temperature and pressure. Penndorf used a standard textbook formula in figuring the Rayleigh scattering coefficient, and advised that its accuracy is correct to about +/- 10%; his computations for the coefficient can be considered correct to four figures. Refer to the original article for complete discussions of all formulas used. 2.7 REFRACTIVE INDICES NOTE: In instances where one experiment resulted in data for more than one substance, only one data description is given. It contains parenthesized numerical references to the location of the data for other substances. The aerosol refractive indices are alphabetized according to substance, and then listed according to the file name prefixes "RF", "RFI", or "RFC", in that order. The particular substance, wavelength range (meters), and refractive index type (real, imaginary, or complex, all dimensionless) are as indicated preceding the file names. 2.7.1 Aerosols 2.7.1.1 ADP (Ammonium Dihydrogen Phosphate) Real Refractive Index vs. Wavelength (2E-7 to 2E-6 meters) RFXADPO, RFXADPE Zernike (1964) measured the real refractive indices of ammonium dihydrogen phosphate (ADP) and potassium dihydrogen phosphate (KDP, 2.7.1.14) in air at wavelengths between 2E-7 and 2E-6 meters, at temperatures ranging from 24.6 to 24.9 degrees C. The accuracy of the indices is +/- 3E-5 or better. Zernike measured the indices using the method of known incidence used by F. Rydberg (1828) and Tilton et al. (1949). The ADP and KDP prisms had angles of approximately 61.5 and 60 degrees respectively. Zernike also included the real refractive indices of fused silica (2.7.1.21) for ten wavelengths between 3.65E-7 and 5.78E-7 meters. 2.7.1.2 Aerosol, Synthetic Complex Refractive Index vs. Wavelength (4E-7 to 1.5E-5 meters) RFCXSYNAER Ivlev and Popova (1973) studied the optical constants of sulfates, silicates, nitrates, metal oxides, and minerals containing the cation [NH4] in the wavelength range 4E-7 to 1.5E-5 meters. Missing data on the complex indices were calculated by the Kramers- Kronig method from the transmission and reflectance spectra. The authors collected and analyzed data on the optical constants and other optical characteristics of minerals that are present in the materials of atmospheric aerosols, and the variations of these characteristics on transition from one mineral of a given class to another, within the given wavelength region. On the basis of available observational data on the chemical composition of aerosol particles in the surface layer of the atmosphere, a model was constructed for the matter of the atmospheric-aerosol dispersed phase, and effective values of the complex index were calculated assuming the absence of free water. It was assumed that all the chemical compounds are uniformly distributed in the material of aerosol particles of different sizes. The refractive index values can be recommended for calculations of the optical characteristics of dry atmospheric aerosols. 2.7.1.3 Ammonium Sulphate 2.7.1.3.1 Complex Refractive Index vs. Wavelength (9.3E-6 to 9.5E-6 meters) RFCXAMSP1 to RFCXAMSP3 Jennings (1981) applied an "attenuated total reflectance" goniometric system to the measurement of complex refractive indices of aerosol constituents at CO2 laser wavelengths. He demonstrated the reliability of the system through a comparison of his experimental and previously reported values. Jennings chose water (2.7.4.4) and ammonium sulphate solutions for these checks. Water was triply distilled, and any ammonia or carbon dioxide was removed. The final sample was stored under argon. Ammonium sulphate solutions were prepared from finely ground ammonium sulphate powder, and their molality was determined gravimetrically. Our data files are for the three molalities 1.6, 2.4, and 3.2, (as indicated by the first line of the individual files). Polystyrene latex particles (2.7.1.17) with mean diameter 9.1E-8 meters were used in suspensions ranging from 5% to 20% by weight. These percentages correspond to the percentage values in the first line of each data file. From these suspension values, Jennings used the Maxwell Garnet mixture rule and an extrapolation scheme to derive the refractive index (file RFCXPLTX1). 2.7.1.3.2 Complex Refractive Index vs. Wavelength (4.05E-7 to 4E-5 meters) RFCXAMSP4 Toon et al. (1976) reviewed techniques for finding optical constants and assessed their accuracy. From these sources they compiled the optical constants of sodium chloride (2.7.1.19) and aluminum oxide (2.7.1.20.5) in the wavelength ranges 2E-7 to 1E-4 and 2E-7 to 3E-4 meters respectively. The constants of ammonium sulphate were derived partly from values quoted and partly from their own measurements, for the wavelength range 4.05E-7 to 4E-5 meters. 2.7.1.4 Barium Fluoride Real Refractive Index vs. Wavelength (4.05E-7 to 7.7E-7 meters) RFXBARF1 to RFXBARF3 Malitson (1964) presented data from a 1944 National Bureau of Standards experiment on the real refractive indices of barium fluoride for nine visible wavelengths in the range 4.05E-7 to 7.68E-7 meters at 15, 35, and 55 degrees C. The uncertainty of these index measurements was estimated at 3E-6. Malitson included data from a 1958 experiment in which he determined values for the real refractive index of a commercially grown barium fluoride prism with refracting angle near 61 degrees. Measurements were made at temperatures near 25 degrees C for 46 calibrated wavelengths of various emission sources and absorption bands from 2.66E-7 meters in the ultraviolet to 1.03E-5 meters in the infrared. Malitson claims that an average absolute residual of 1.9E-5 indicates that values for the index may be interpolated to five decimal places. 2.7.1.5 Cadmium Sulfide 2.7.1.5.1 Real Refractive Index vs. Wavelength (5.12E-7 to 1.4E-6 meters) RFXCDS1O, RFXCDS1E Bieniewski and Czyzak (1963) reported their experimental data for the real refractive index, ordinary and extraordinary rays, of zinc (2.7.1.24.1) and cadmium sulfide in the wavelength range 3.6E-7 to 1.4E-6 meters (ZnS) and 5.12E-7 to 1.4E-6 meters (CdS). 2.7.1.5.2 Real Refractive Index vs. Wavelength (5.5E-7 to 1.4E-6 meters) RFXCDS2O, RFXCDS2E Czyzak et al. (1957) determined the real refractive index of single synthetic zinc sulfide (2.7.1.24.2 ordinary ray) and cadmium sulfide crystals (ordinary and extraordinary rays) in the wavelength range 4.4E-7 to 1.4E-6 meters (ZnS) and 5.5E-7 to 1.4E-6 meters (CdS). The prisms used were cut to angles between 10 and 15 degrees. 2.7.1.6 Calcite Complex Refractive Index vs. Wavelength (2E-7 to 6E-6 meters) RFCXCALCE, RFCXCALCO Ivlev and Popova (1974) examined the optical constants of various chemical compounds constituting the atmospheric aerosol including calcite, graphite (2.7.1.12), gypsum (2.7.1.13), mascagnite (2.7.1.15). quartz (2.7.1.18.5). sapphire (2.7.1.20.4), and sodium nitrate (2.7.1.23). In the original data tables, Ivlev and Popova left large gaps between data entries (which correspond to "-1" in the Handbook tables), with no directions for proper interpretation. With the exception of three entries for the real index of graphite at 1.1E-6, 1.2E-6, and 1.9E-6 meters, for which the authors entered "?", there are at least two ways in which to interpret the gaps: 1) values were out of range; 2) values did not change from the last entry before the gap, until the next cited index. Additionally, the authors seemingly distinguished between the value of "10**-X", where X is any integer, and "1 * 10**-X" with the same value for X; we chose not to draw a distinction between the two representations. The data in RFCXCALCE and any other associated data files are reproduced from Ivlev and Popova (1972) with permission from Plenum Publishing Corporation, copyright holder. 2.7.1.7 Calcium Fluoride Real Refractive Index vs. Wavelength (4.05E-7 to 7.68E-7 meters) RFXCAF1 to RFXCAF3 Malitson (1963) reproduced real refractive index data from experiments done at the National Bureau of Standards in 1944. The indices were determined for two samples of synthetic fluorite prisms for nine visible wavelengths (4.05E-7 to 7.68E-7 meters) at temperatures of 15, 35, and 55 degrees C. Malitson states that the real refractive index values of both prisms were averaged. The values were taken from previously published reports by Stockberger and Early (1944) and Stockberger (1949). Malitson states that the uncertainty of these index measurements is estimated at 2E-6. 2.7.1.8 Dust 2.7.1.8.1 Imaginary Refractive Index vs. Wavelength (3E-7 to 1.7E-6 meters) RFIXDUST1 to RFIXDUST10 Lindberg et al. (1976) determined the imaginary part of the complex refractive index for dust samples from the Panama Canal Zone, Germany, France, Denmark, the Netherlands, Great Britain, Israel, and various locations in the United States in the wavelength range 3E-7 to 1.7E-6 meters. The samples were collected by air filtration using ultra-thin cellulose membranes. Their values for the imaginary index are dependent on the assumption that the specific gravity of the particulate matter is 2.2. The authors claim their values for the index are an underestimate by some amount less than a factor of 2. Transmission spectroscopy examination of each sample led to the following profiles of sample composition: samples from Europe were often dominated by ammonium sulphate and some strong spectrally broad absorber such as free carbon which led to a relatively high imaginary index in the visible spectrum. Samples from less populated desert areas in the U.S. and Israel showed the presence of silicate clay minerals, quartz, calcite, and gypsum, and proportionately less ammonium sulfate and carbon. Samples from industrial or high population density areas had a significantly higher imaginary index than those from more remote desert locations. This presumably was because urban samples contained more free carbon from various man-made combustion sources, whereas desert areas had a stronger soil component which tended to reduce the overall imaginary index. 2.7.1.8.2 Complex Refractive Index vs. Wavelength (3E-7 to 1.7E-6 meters) RFCXDUST1 to RFCXDUST3 These tables (Lindberg, 1977) contain imaginary index data from experiments at White Sands Missile Range in New Mexico in the wavelength range 3E-7 to 1.7E-6 meters. Dust from three geographic locations was measured by diffuse reflectance methods. The dry material as collected on cellulose ester membrane filters was dissolved in acetone and centrifuged to recover the particulate matter. The tables contain infrared laser line imaginary index measurements Lindberg obtained using a spectrophone technique. technique. Lindberg suggests 1.55 as a reasonable estimate for the real refractive index in the 3E-6 to 5E-6 meter region. However the silicate absorption band near the 10E-6 meter region makes both parts of the index strongly wave dependent. (As an example of this, Lindberg suggests an examination of the index values in Peterson & Weinman - see 2.7.1.18.4: "Quartz": RFCXQUA1+). 2.7.1.9 Fly Ash 2.7.1.9.1 No data files. In September 1970 (Grams et al., 1972) the National Center for Atmospheric Research (NCAR) obtained data on the vertical distribution of particulate material over Boulder, Colorado. Particles from a layer of matter at approximately 13 km differed from normal tropospheric particles. NCAR assumed the particles were fly ash created by forest fires in California during the previous week. Assuming the real part of the refractive index to be 1.55, the imaginary part was estimated at 0.044 +/- 0.001. An analysis of errors due to the expected statistical variability of the number of particles counted and the combined instrumental and measurement errors led to an estimate of approximately 40% error. By considering that the error results in a factor of 1.4 uncertainty, the error in the measurement of the imaginary index is 0.011. 2.7.1.9.2 No data files. P.B. Russell et al. (1974) measured the angular variation and size distribution of the intensity of light scattered from a collimated beam by airborne soil particles 1.5 meters above the ground. From their measurements they derived an estimate of the complex index of refraction of the soil particles. For the real refractive index, the value 1.525 was taken as representative. By applying Mie scatter theory to each of the observed distributions of particle size, the expected angular variation of the intensity of the scattered light was calculated for a fixed value of the real index and a wide range of values of the imaginary index. For each set of simultaneous measurements the representative value for the imaginary index was taken to be that value which provided the best fit to the experimental data. The upper limit of the value of the imaginary index for the airborne soil particles studied was determined to be 0.005 with an overall uncertainty factor of 2.3. 2.7.1.9.3 No data files. Wyatt (1980) examined several hundred single fly ash particles. More than 40 particles were suspended in a controlled high humidity environment to permit detailed light scattering measurement. Computerized analyses of the light scattering data from six typical ash particles showed considerable refractive index variation from particle to particle. Refractive indices, both real and complex, were observed spanning the range 1.48 to 1.57 (real) and 0 to 0.1 (imaginary). The accuracy of the values was +/- 0.01 for the real parts and +/- 0.002 for the imaginary. 2.7.1.10 Germanium 2.7.1.10.1 Real Refractive Index vs. Wavelength (2.55E-6 to 1.24E-5 meters) RFXGERM1 to RFXGERM4 Icenogle et al. (1976) examined the real refractive indices of silicon (2.7.1.22.1, 2.55E-6 to 1.03E-5 wavelength meters) and germanium (2.55E-6 to 1.24E-5 wavelength meters). They stated their errors to be about +/- 6E-4 for germanium and +/-3E-4 for silicon. The indices for germanium were taken at temperatures of 297, 275, 204, and 94 kelvins. The indices for silicon were taken at 296, 275, 202, and 104 kelvins. 2.7.1.10.2 Real Refractive Index vs. Wavelength (2.06E-6 to 1.65E-5 meters) RFXGERM5 Salzburg and Villa (1957) determined data for the infrared real refractive index for single crystal germanium, silicon(2.7.1.22.2), and modified selenium glass(2.7.11.2), at about 27 degrees C. The respective wavelength ranges are 2.06E-6 to 1.6E-5, 1.36E-6 to 1.1E-5, and 1.01E-6 to 1.1E-5, all in meters. They estimate their accuracy of the index measurements to be +/-2 in the fourth decimal place. 2.7.1.11 Glass 2.7.1.11.1 Real Refractive Index vs. Wavelength (3.65E-7 to 2.6E-6 meters) RFXGLASS1 to RFXGLASS17 Kingslake and Conrady (1937) measured the real refractive indices of 17 different types of 60-degree prism Bausch & Lomb and Parra- Mantois optical glass, in the wavelength range 3.65E-7 to 2.6E-6 meters. They cite their indices as correct to five or six in the fifth decimal place. NOTE: The Kingslake article contained only the data for glasses 1 through 11. The remainder of the Kingslake-Conrady data was reprinted by Herzberger (1942), where we obtained it. Note that Dr. Herzberger found some minor errors in the far red and near infrared region of the spectrum. These errors resulted from Kingslake's use of some early and slightly inaccurate data on the temperature coefficient of the refractive index of rock salt in calibrating the wavelength scale of his refractometer. 2.7.1.11.2 Real Refractive Index vs. Wavelength (1.01E-6 to 1.1E-5 meters) RFXGLASS18, RFXGLASS19 See 2.7.1.10.2: "Germanium": RFXGERM5. 2.7.1.11.3 Real Refractive Index vs. Wavelength (5.77E-7 to 1.19E-5 meters) RFXGLASS20 Rodney et al. (1958) determined the real refractive indices of an arsenic trisulfide prism with refracting angle of 25 degrees in the wavelength range 5.77E-7 to 1.19E-5 meters. The sample was measured at temperatures near 19, 25, and 31 degrees C. The averaged thermal coefficients of the refractive index were used to reduce all data to 25 degrees C. 2.7.1.11.4 Complex Refractive Index vs. Wavelength (4.8E-7 to 6.9E-7 meters) RFCXGLASS1 The data represent the refractive indices for Corning Glass code 0080/0081 glass in the wavelength range 4.8E-7 to 6.9E-7, as taken from correspondence with Herbert Hoover of Corning Glass Works in Corning, New York. Hoover suggests the best guess for the real refractive index at 6.943E-7 meters is 1.505 +/- 0.003. The large uncertainty allows for the fact that normal variations in manufacturing are occasionally this large. In case the index must be known closer than 0.001, consideration must be given the state of annealing, because rapidly cooled glass has a lower index than well-annealed glass. Hoover estimates an absorption coefficient for code 0080 glass (having about 0.04% total iron) of 0.14 cm**-1 in determining refractive indices. He proposes this as a safe upper bound. It should be noted that a substantially clear glass with dissolved iron as a colorant has a smaller spectral absorption coefficient near the middle of the wavelength range (5.5E-7 to 6E-7). Hoover advises if for your use you cannot assume a constant absorption coefficient over the 4.8E-7 to 6.943E-7 meter range, you can make a second approximation by assuming equal values at each end and a value one-half as large at 5.75E-7, and interpolating on a smooth curve through the three points for other values. Since we used the figures derived from an absorption coefficient of 0.14 cm**-1 for 6.943E-7, all of the other estimates represent upper bounds. 2.7.1.12 Graphite Complex Refractive Index vs. Wavelength (2.5E-7 to 6E-6 meters) RFCXGRAPH See 2.7.1.6: "Calcite". 2.7.1.13 Gypsum Complex Refractive Index vs. Wavelength (2E-7 to 6E-6 meters) RFCXGYPS See 2.7.1.6: "Calcite". 2.7.1.14 KDP (Potassium Dihydrogen Phosphate) Real Refractive Index vs. Wavelength (2E-7 to 2E-6 meters) RFXKDPO, RFXKDPE See 2.7.1.1: "ADP". 2.7.1.15 Mascagnite Complex Refractive Index vs. Wavelength (2E-7 to 2E-6 meters) RFCXMASCAG See 2.7.1.6: "Calcite". 2.7.1.16 Molybdenite Complex Refractive Index vs. Wavelength (3.3E-4 to 5E-4 meters) RFCXMOLYB Meyer (1926) gave the averaged results of experiments which determined the complex refractive index of molybdenite for nine wavelengths in the range 3.3E-4 to 5E-4 meters. Observations were made at various angles of incidence for the same wavelength, (65, 70, and 76 degrees) and averaged. Meyer reported that individual observations varied about 5% from the average. 2.7.1.17 Polystyrene Latex Complex Refractive Index vs. Wavelength (9.3E-6 to 1.06E-5 meters) RFCXPLTX1 to RFCXPLTX5 See 2.7.1.3.1: "Ammonium Sulphate": RFCXAMSP1. 2.7.1.18 Quartz 2.7.1.18.1 Real Refractive Index vs. Wavelength (4.96E-5 to 4.95E-4 meters) RFXQUA1O, RFXQUA1E Russell and Bell (1967) obtained the real refractive index of crystal quartz in the wavelength range 4.96E-5 to 4.95E-4 meters, with the asymmetric Fourier-Transform method. The extrapolated, zero- frequency real refractive indices are 2.1062 (ordinary), and 2.1538 (extraordinary) with an experimental uncertainty of +/- 0.001. The total, estimated probable error in the measured values contained in the data table is +/- 0.001, except at frequencies less than 25 cm**-1 and greater than 175 cm**-1, where, the authors claim, the error can be somewhat greater. 2.7.1.18.2 Real Refractive Index vs. Wavelength (1.6E-4 to 3.49E-3 meters) RFXQUA2 Laikin (1961) measured the real refractive index of a 30-degree synthetic quartz prism for the ordinary ray, in the wavelength range 1.6E-4 to 3.49E-3 meters, at 47 degrees F. The indices were corrected to air. Laikin reported the accuracy of the indices good to 6E-5. 2.7.1.18.3 Real Refractive Index vs. Wavelength (1.44E-7 to 2.31E-7 meters) RFXQUA3O, RFXQUA3E Chandrasekharan and Damany (1968) reported the measurements of the ordinary and extraordinary real refractive indices of synthetic quartz in the vacuum ultraviolet in the wavelength range 1.44E-7 to 2.31E-7 meters as deduced from the determination of the orders of interference fringes in a thin parallel plate. The ordinary and extraordinary channeled spectra were obtained by interference in transmission and recorded at room temperature. The authors estimate the absolute error in the indices to be less than 0.001. 2.7.1.18.4 Complex Refractive Index vs. Wavelength (7.68E-7 to 3.6E-5 meters) RFCXQUA1O, RFCXQUA1E Peterson and Weinman (1969) tabulated the complex indices of quartz in the wavelength range 7.7E-7 to 3.6E-5 meters. An ensemble of spherical dust particles was utilized in conjunction with Mie theory to determine the extinction coefficient and other optical properties. The data in Peterson and Weinman were originally collected by Spitzer and Kleinman (1961) at a temperature of 24 degrees C. Wavelengths shorter than 5E-6 meters were compiled by D.E. Gray (1963). 2.7.1.18.5 Complex Refractive Index vs. Wavelength (5E-7 to 6E-6 meters) RFCXQUA2O, RFCXQUA2E See 2.7.1.6: "Calcite". 2.7.1.18.6 Complex Refractive Index vs. Wavelength (1E-7 to 1.65E-7 meters) RFCXQUA3, RFCXQUA4 Lamy (1977) gave the near-normal incidence reflectance measurements (complex) of crystal and fused quartz (ordinary ray) in the 1E-7 to 1.65E-7 meter wavelength interval. 2.7.1.19 Salt Complex Refractive Index vs. Wavelength (2E-7 to 1E-4 meters) RFCXSALT See 2.7.1.3.2: "Ammonium Sulphate": RFCXAMSP4. 2.7.1.20 Sapphire 2.7.1.20.1 Real Refractive Index vs. Wavelength (2.54E-7 to 6.91E-7 meters) RFXSAPPH1O, RFXSAPPH1E Jeppeson (1958) measured the ordinary and extraordinary real refractive indices for synthetic sapphire at 24 degrees C in the wavelength range 2.54E-7 to 6.91E-7 meters. He reports that between 4E-7 and 6.9E-7 meters the measurements are good to about four parts in the fifth decimal place. This error increases towards the violet. 2.7.1.20.2 Real Refractive Index vs. Wavelength (2.65E-7 to 5.58E-6 meters) RFXSAPPH2 Malitson (1962) measured the real refractive index of a synthetic sapphire prism, with reflecting angle near 40 degrees, at 46 wavelengths from 2.65E-7 to 5.58E-6 meters at controlled room temperatures near 24 degrees C. 2.7.1.20.3 Real Refractive Index vs. Wavelength (RFXSAPPH3: 2.65E-7 to 4.25E-6, RFXSAPPH4 - 6: 4.05E-7 to 7.07E-7 meters) RFXSAPPH3 to RFXSAPPH6 Malitson et al. (1958) collected data on the real refractive indices of a synthetic sapphire prism, for the ordinary ray. The indices in the ultraviolet and infrared (2.65E-7 to 4.26E-6 meters) were measured at controlled room temperatures near 19 and 24 degrees C. In the visible region (4.05E-7 to 7.07E-7 meters) measurements were made at three temperatures near 17, 24, and 31 degrees C. 2.7.1.20.4 Complex Refractive Index vs. Wavelength (2E-7 to 6E-6 meters) RFCXSAPPH1 See 2.7.1.6: "Calcite". 2.7.1.20.5 Complex Refractive Index vs. Wavelength (RFCXSAPPH2O: 2E-7 to 3.3E-4, RFCXSAPPH2E: 9E-6 to 3.3E-4 meters) RFCXSAPPH2O, RFCXSAPPH2E See 2.7.1.3.2: "Ammonium Sulphate": RFCXAMSP4. 2.7.1.21 Silica Real Refractive Index vs. Wavelength (3.65E-7 to 1.53E-6 meters) RFXSILICA See 2.7.1.1: "ADP". 2.7.1.22 Silicon 2.7.1.22.1 Real Refractive Index vs. Wavelength (2.55E-6 to 1.03E-5 meters) RFXSILIC1 to RFXSILIC4 See 2.7.1.10.1: "Germanium": RFXGERM1. 2.7.1.22.2 Real Refractive Index vs. Wavelength (1.36E-6 to 1.1E-5 meters) RFXSILIC5 See 2.7.1.10.2: "Germanium": RFXGERM5. 2.7.1.23 Sodium Nitrate Real Refactive Index vs. Wavelength (4E-7 to 7E-7 meters) RFXSODNITO, RFXSODNITE See 2.7.1.6: "Calcite". 2.7.1.24 Zinc Sulfide 2.7.1.24.1 Real Refractive Index vs. Wavelength (3.6E-7 to 1.4E-6 meters) RFXZNS1O, RFXZNS1E See 2.7.1.5.1: "Cadmium Sulfide": RFXCDS1+. 2.7.1.24.2 Real Refractive Index vs. Wavelength (4.4E-7 to 1.4E-6 meters) RFXZNS2 See 2.7.1.5.2: "Cadmium Sulfide": RFXCDS2+. 2.7.2 Air Real Refractive Index vs. Wavelength (2E-7 to 2E-5 meters) RFXAIR+ (N30,N15,0,15,30) See 2.6: Rayleigh Coefficients, Air. 2.7.3 Ice 2.7.3.1 Complex Refractive Index vs. Wavelength (9.5E-7 to 1.52E-4 meters) RFCXICE1 Irvine and Pollack (1968) critically reviewed existing literature on the absorption coefficient and reflectivity of water (2.7.4.5) and ice in the infrared, and chose best values for the complex index of refraction for wavelengths in the range 9.5E-7 to 1.5E-4 meters. 2.7.3.2 Complex Refractive Index vs. Wavelength (2E-6 to 3.3E-5 meters) RFCXICE2 Schaaf and Williams (1973) measured the normal-incidence spectral absolute reflectance of ice at -7 degrees C in the wavelength range 2E-6 to 3.3E-5 meters (2.8.1). They employed a Kramers-Kronig phase-shift analysis of the measured spectral reflectance to provide values of the real and imaginary parts of the refractive index. 2.7.3.3 Complex Refractive Index vs. Wavelength (1.25E-6 to 3.3E-4 meters) RFCXICE3 Bertie et al. (1969) measured the absorbance of several samples of Ice Ih at 100 K in the wavelength range 1.25E-6 to 3E-4 meters, and scaled it to that of a particular film of unknown thickness. They obtained the complex index, permittivity, and the normal incidence reflectivity from the absorptivity and from Kramers-Kronig relations. 2.7.3.4 Complex Refractive Index vs. Wavelength for ice, microwave range. See 3.2.7.3: "Data File Formats" for wavelength ranges. RFICEM+ (N50,N30,N10,0) (accessed by program MICRO) Note that additional microwave ice refractive index data were acquired after the completion of program MICRO, and thus are not available to the user through the program. See 2.7.3.6.) Program MICRO handles microwave refractive indices for water and ice as a function of wavelength at different temperatures, using data taken from the following sources: Ryde and Ryde (1945) found values for the complex refractive index of ice in the millimeter and microwave region using a combination of the Debye formula and constants taken from Saxton (1945) and Dunsmuir and Lamb (1945). Lane and Saxton (1952) measured the refractive index of water at 6.2 micrometers, 1.24 cm, and 3.21 cm over the temperature range -10 to 50 degrees C. They used the Debye formula, as well as a method based on the fact that the rate of attenuation of radio frequency energy along a wave guide filled with the liquid is dependent upon both the absorption coefficient and the refractive index when the guide is operated near to cut off conditions. The authors believe their measurements to be accurate to about +/- 1%. Collie et al. (1948) measured the dielectric constant and loss angle of water and heavy water at widely separated wavelengths in the region of anomalous dispersion. In addition to the Debye formula, they used a method involving the observation of the attenuation in transmission through wave guides of differing cross-sectional dimensions containing the liquid. The data taken from Collie et al. (1948) are reproduced with permission from the Institute of Physics, copyright holder. Deirmendjian (1963) calculated the complex index for water and ice at two temperatures by means of the Debye formula. 2.7.3.5 Complex Refractive Index vs. Wavelength (4.43E-8 to 1.67E-4 meters) RFCXICE4 Warren (1984) compiled the optical constants of Ice Ih for temperatures within 60 degrees of the melting point. The imaginary part of the complex index of refraction is obtained from measurements of spectral absorption coefficients; the real part is computed to be consistent with the imaginary part by use of known dispersion relations. Warren states that the compilation of the imaginary part requires subjective imterpolation in the near ultraviolet and microwave, a temperature correction in the far-infrared, and a choice between two conflicting sources in the near-infrared. Warren advises that for intermediate wavelengths not given in the table one should interpolate the real index linearly in the log of the wavelength and the log of the imaginary index linearly in the log of the wavelength. 2.7.3.6 Complex Refractive Index vs. Wavelength (1.67E-4 to 8.6 meters) RFCXICE+ (5,6,7,8) Warren (1984) found the complex refractive indices of Ice Ih for four temperatures: -1, -5, -20, and -60 degrees C, in the wavelength range 1.67E-4 to 8.6 meters. For intermediate wavelengths Warren advises interpolating the real index linearly in the log of the wavelength, the log of the imaginary index linearly in the log of the wavelength, the real index linearly in the temperature, and the log of the imaginary index linearly in the temperature. See also 2.7.3.5. 2.7.4 Liquid Water 2.7.4.1 Complex Refractive Index vs. Wavelength (5.46E-7 to 2.53E-5 meters) RFCXH2O1 Data in this table were compiled from various experiments by Zuev et al. (1974) in the 5E-7 to 2.53E-5 meter wavelength interval for pure water at 18 to 20 degrees C. In the original data tables, Zuev left gaps between numerous data entries; in preparing RFCXH2O1, a cubic interpolation routine was used to approximate these missing data values. In the event that finer accuracy is needed, the real refractive indices at the following wavenumbers (cm**-1) should be modified using the measured real indices of the wavenumbers that bound these ranges with a more precise interpolation method: 18100-17550, 17200-16700, 16450-16350,16200-16000,15800-15700,15500-15100,14900,14600,14300 14100,13850-13550,13300-13150,12900-12650,12400-12150,11950,11700, 11450,11200,10900,10650,10350,10100,9800,9500,9190,8900,8600,8320, 8060,7800,7540,7275,7100,6660,6470,6200,5880,5635,5602,5376,5277, 5165,5040,4938,4830,4746,4646,4546,4446,4346,4296,4196,4146. For example, if greater accuracy is needed in a wavenumber range including 18100-17550, take the frequencies preceding 18100 and following 17550, 18300 and 17400, and use them and any other neighboring measured values not included in the above list of ranges in the interpolation method of your choice. The real refractive indices at wavelengths in the above ranges were calculated using cubic interpolation. The data in RFCXH2O1 are reproduced from Zuev et al. with permission of Keter Publishing House Ltd., copyright holder. 2.7.4.2 Complex Refractive Index vs. Wavelength (2E-7 to 2E-4 meters) RFCXH2O2 Hale and Querry (1973) determined extinction coefficients for water at 25 degrees C through a broad spectral region by manually smoothing a point-by-point graph of extinction coefficients vs. wavelength, that was plotted for data obtained from a review of the scientific literature on the optical constants of water. Where data in the vacuum UV and soft X-ray regions were not available, they postulated absorption bands representing extinction coefficients. A subtractive Kramers- Kronig analysis of the combined postulated and smoothed portions of the extinction coefficient spectrum provided the index of refraction for the spectral wavelength region 2E-7 to 2E-4 meters. 2.7.4.3 Complex Refractive Index vs. Wavelength (2E-6 to 1E-3 meters) RFCXH2O3 Downing and Williams (1975) compiled values for the optical constants of liquid H2O from current studies. Their values were based primarily on a study by Robertson et al. (1971) which measured Lambert absorption coefficients, and a Rusk et al. (1971) experiment measuring spectral reflectance at near normal incidence. They used the work of Palmer and Williams (1974) in the near infrared and the work of National Physical Labs in the extreme infrared (100 to 20 cm**-1). They determined real and imaginary indices in other regions using Fresnel's equation and Kramers-Kronig analysis. All the data were obtained for liquid H2O at 27 degrees C in the wavelength range 2E-6 to 1E-3 meters. 2.7.4.4 Complex Refractive Index vs. Wavelength (9.6E-6 to 1.05E-5 meters) RFCXH2O4 See 2.7.1.3.1: "Aerosols": Ammonium Sulphate: RFCXAMSP1. 2.7.4.5 Complex Refractive Index vs. Wavelength (2E-7 to 2E-4 meters) RFCXH2O5 See 2.7.3.1: "Ice": RFCXICE1. 2.7.4.6 Complex Refractive Index vs. Wavelength (2E-6 to 2E-5 meters) RFCXH2O6 to RFCXH2O11 By using distilled water as the standard reflection, Querry et al. (1977) measured the relative specular reflectance spectra in the 2E-6 to 2E-5 meter wavelength region of the infrared for surface water samples collected from San Francisco Bay, the Pacific and Atlantic Oceans, the Great Salt Lake (Utah), the Dead Sea (Israel), and an effluent phosphate mine in central Florida (2.8.2). They compiled spectral values for the complex refractive index for each water sample by applying a Kramers-Kronig analysis to the relative reflectance spectra. For a chemical analysis of the monatomic and polyatomic ions of the natural waters, refer to the original article. 2.7.4.7 Complex Refractive Index vs. Wavelength for water in the microwave range. See 3.2.7.4: "Data File Formats" for wavelength ranges. RFH2OM+ (N8,0,10,18,20,30,40,50,60,75) (accessed by program MICRO) See 2.7.3.4:"Ice": RFICEM+ (microwave ice files). 2.8 RELATIVE REFLECTANCE: ICE, WATER 2.8.1 Relative Reflectance (dimensionless) vs. Wavelength (2E-6 to 3.3E-5 meters) for Ice RRXICE1 See 2.7.3.2: "Ice": RFCXICE2. 2.8.2 Relative Reflectance (dimensionless) vs. Wavelength (2E-6 to 2E-5 meters) for Water RRXH2O1 - 6 See 2.7.4.6: "Liquid Water": RFCXH2O6.