This paper reviews the methods which may be used to estimate the state of the atmosphere, i.e., the distribution of temperature and composition, from measurements of emitted thermal radiation such as are made by remote sounding instruments on satellites. The principles of estimation theory are applied to a linear version of the problem, and it is shown that many of the apparently different methods to be found in the literature are particular cases of the same general method. As an aid to understanding, the optimum linear solution is described in terms of the geometry of n dimensions, with n = 3 for illustration. In generalizing the approach to the nonlinear problem there are two stages: (1) finding any member of the infinite family of possible solutions, which may be done by any convenient iterative method, and (2) finding the optimum solution by satisfying appropriate constraints.

Retrieval of atmospheric temperature and composition from remote measurements of thermal radiation

The purpose of this paper is to put forward a new estimate, in the context of previous assessments, of the annual global mean energy budget. A description is provided of the source of each component to this budget. The top-of-atmosphere shortwave and longwave flux of energy is constrained by satellite observations. Partitioning of the radiative energy throughout the atmosphere is achieved through the use of detailed radiation models for both the longwave and shortwave spectral regions. Spectral features of shortwave and longwave fluxes at both the top and surface of the earth's system are presented. The longwave radiative forcing of the climate system for both clear (125 W m-2) and cloudy (155 W m-2) conditions are discussed. The authors find that for the clear sky case the contribution due to water vapor to the total longwave radiative forcing is 75 W m-2, while for carbon dioxide it is 32 W m-2. Clouds alter these values, and the effects of clouds on both the longwave and shortwave budget are a...

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Earth's annual global mean energy budget

Leaf structure and function are shown to result in distinctive variations in the absorption and reflection of solar radiation from plant canopies. The leaf properties that determine the radiation-interception characteristics of plant canopies are directly linked to photosynthesis, stomatal resistance and evapotranspiration and can be inferred from measurements of reflected solar energy. The effects of off-nadir viewing and atmospheric constituents, coupled with the need to measure changing surface conditions, emphasize the need for multitemporal measurements of reflected radiation if primary production is to be estimated.

https://www.tandfonline.com/doi/pdf/10.1080/01431168608948944

Satellite remote sensing of primary production

This paper introduces the new Polarization and Directionality of the Earth's Reflectances (POLDER) instrument. The spaceborne POLDER sensor, which is selected to fly aboard the Japanese ADEOS satellite scheduled for launch in early 1996, has nearly completed phase C of its development at the Centre National d'Etudes Spatiales, the French space agency. To prepare for the 1996 space mission, airborne prototypes are being tested and evaluated in the framework of various measurement campaigns. The POLDER sensor is designed to collect global observations of polarized and directional solar radiation reflected by the Earth-atmosphere system for climate and global change studies. Aboard the ADEOS platform, the POLDER mission will provide near-daily coverage of the Earth at 6/spl times/7 km/sup 2/ resolution. The POLDER system will offer unprecedented opportunities to observe biophysical parameters over the oceans and land surfaces. The sensor's unique features, when compared to current and planned spaceborne instruments, include its ability to: 1) measure polarized reflectance in the visible and near-infrared spectral regions; 2) observe Earth target reflectance from 12 directions during a single satellite pass; and 3) operate in two dynamic modes in order to achieve both high signal to noise ratio and wide dynamic range. Six of POLDER's eight channels are optimized for observing atmospheric aerosols, clouds, ocean color, and land surfaces. The other two are centered on the H/sub 2/O and O/sub 2/ absorption bands for retrieving atmospheric water vapor amount and cloud top altitude, respectively. POLDER data will be subject to the high calibration standards defined by the POLDER mission team, with absolute calibration accuracies of 2% for the shorter wavelength channels (/spl lambda//spl les/565 nm) and 3% for the longer wavelengths. A 1% accuracy is the goal for the intercalibration between the spectral channels. The POLDER instrument aboard ADEOS will contribute significantly to climate-related research on aerosol cycling, cloud-radiation interactions, the Earth radiation budget, ocean primary productivity, and continental biosphere dynamics. POLDER mission's scientific objectives will be to: 1) map atmospheric aerosols, including their sources and transport, and study their influence on the Earth radiation budget; 2) assess cloud properties, namely their height, phase and type; 3) estimate total integrated water vapor amount; 4) improve Earth radiation budget estimates; 5) estimate chlorophyll-like pigment content in the ocean surface layer and its role in the carbon cycle; and 6) characterize land surface properties and vegetation cover. >

The POLDER mission: instrument characteristics and scientific objectives

Helium and heavy-element diffusion are both included in precise calculations of solar models. In addition, improvements in the input data for solar interior models are described for nuclear reaction rates, the solar luminosity, the solar age, heavy-element abundances, radiative opacities, helium and metal diffusion rates, and neutrino interaction cross sections. The effects on the neutrino fluxes of each change in the input physics are evaluated separately by constructing a series of solar models with one additional improvement added at each stage. The effective 1 σ uncertainties in the individual input quantities are estimated and used to evaluate the uncertainties in the calculated neutrino fluxes and the calculated event rates for solar neutrino experiments. The calculated neutrino event rates, including all of the improvements, are 9.3-1.4+1.2 SNU for the 37Cl experiment and 137-7+8 SNU for the 71Ga experiments. The calculated flux of 7Be neutrinos is 5.1 (1.00-0.07+0.06)×10^9 cm^-2 s^-1 and the flux of 8B neutrinos is 6.6(1.00-0.17+0.14)×10^6 cm^-2 s^-1. The primordial helium abundance found for this model is Y=0.278. The present-day surface abundance of the model is Ys=0.247, in agreement with the helioseismological measurement of Ys=0.242±0.003 determined by Hernandez and Christensen-Dalsgaard (1994). The computed depth of the convective zone is R=0.712R⊙, in agreement with the observed value determined from p-mode oscillation data of R=0.713±0.003R⊙ found by Christensen-Dalsgaard et al. (1991). Although the present results increase the predicted event rate in the four operating solar neutrino experiments by almost 1 σ (theoretical uncertainty), they only slightly increase the difficulty of explaining the existing experiments with standard physics (i.e., by assuming that nothing happens to the neutrinos after they are created in the center of the sun). For an extreme model in which all diffusion (helium and heavy-element diffusion) is neglected, the event rates are 7.0-1.0+0.9 SNU for the 37Cl experiment and 126-6+6 SNU for the 71Ga experiments, while the 7Be and 8B neutrino fluxes are, respectively, 4.5(1.00-0.07+0.06)×10^9 cm^-2 s^-1 and 4.9(1.00-0.17+0.14)×10^6 cm^-2 s^-1. For the no-diffusion model, the computed value of the depth of the convective zone is R=0.726R⊙, which disagrees with the observed helioseismological value. The calculated surface abundance of helium, Ys=0.268, is also in disagreement with the p-mode measurement. The authors conclude that helioseismology provides strong evidence for element diffusion and therefore for the somewhat larger solar neutrino event rates calculated in this paper.

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Solar models with helium and heavy-element diffusion

The development of ERB observational systems is traced from its beginnings in the late 1950's through to the current ERB on the Nimbus 7 satellite. The instruments comprising the current 22-channel ERB experiment are described in some detail. Noteworthy are the inclusion in one solar channel, of a self-calibrating cavity to measure the solar constant and the use of biaxial scanning telescopes to determine the angular reflection and emission model required for processing the narrow-angle radiometric data. A fairly detailed description of the prelaunch and in-flight calibrations is given along with an analysis of the radiometric performance of the instruments. The data processing system is traced with the aid of a schematic flow diagram showing the steps required to produce the many tape and microfilm products archived. Future plans for improving the quality and accuracy of the data products are discussed. Finally, the upcoming Earth Radiation Budget Experiment (ERBE) is briefly mentioned. It will be capable of simultaneously measuring the radiation budget from three satellites, each having a different equator crossing time and angle.

The Earth Radiation Budget (ERB) experiment - An overview

The calculation of limb radiance as a function of tangent height is shown to require information about the vertical distribution of temperature and the pressure at one level. Conversely, given the limb radiance curve and the pressure corresponding to one tangent point, it is possible to determine the temperature profile as a function of height relative to the given level, using an iterative technique. Results of inverting synthesized realistic data are presented. The data include the effects of water vapor and ozone contamination of the carbon dioxide signal, instrument field of view, and random and systematic noise for real atmospheres having small-scale vertical structure.

On the inversion of limb radiance measurements. I.

The calculation of limb radiance as a function of tangent height is shown to require the vertical distribution of temperature and the pressure at one level. Conversely, given the limb radiance curve and the pressure corresponding to one tangent point, it is possible to determine the temperature profile as a function of height relative to the given level, using an iterative technique. If the given pressure is incorrect, there will be systematic errors in the inferred temperatures. This feature may he used to determine the correct pressure by requiring that temperatures inferred from measurements in two spectral regions of differing opacities agree. Results of inverting synthesized realistic data are presented. The data include the effects of water vapor and ozone contamination of the carbon dioxide signal, instrument field of view, and random and systematic noise for real atmospheres having small-scale vertical structure. Results indicate that the temperature may be obtained from the tropopause to...

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On the inversion of limb radiance measurements. I: Temperature and thickness

Preliminary results from solar radiation measurements from the earth radiation budget experiment on the Nimbus 7 satellite yield a mean value of 1376.0 watts per square meter for the "solar constant" from 16 November 1978 to 15 May 1979. The observed variability (root-mean-square deviation) is +/- 0.73 watt per square meter (+/- 0.05 percent) for the period.

Initial solar irradiance determinations from nimbus 7 cavity radiometer measurements.

The history of satellite missions and their measurements of the earth radiation budget from the beginning of the space age until the present time are reviewed. The survey emphasizes the early struggle to develop instrument systems to monitor reflected shortwave and emitted long-wave exitances from the earth, and the problems associated with the interpretation of these observations from space. In some instances, valuable data sets were developed from satellite measurements whose instruments were not specifically designed for earth radiation budget observations.

Frederick B. House

Papers

The Earth Radiation Budget (ERB) experiment - An overview

On the inversion of limb radiance measurements. I.

On the inversion of limb radiance measurements. I: Temperature and thickness

Initial solar irradiance determinations from nimbus 7 cavity radiometer measurements.

History of satellite missions and measurements of the Earth Radiation Budget (1957–1984)