Modeling the Reflectance of the Lunar Regolith by a New Method Combining Monte Carlo Ray Tracing and Hapke’s Model with Application to Chang’E-1 IIM Data

In this paper, we model the reflectance of the lunar regolith by a new method combining Monte Carlo ray tracing and Hapke’s model. The existing modeling methods exploit either a radiative transfer model or a geometric optical model. However, the measured data from an Interference Imaging spectrometer (IIM) on an orbiter were affected not only by the composition of minerals but also by the environmental factors. These factors cannot be well addressed by a single model alone. Our method implemented Monte Carlo ray tracing for simulating the large-scale effects such as the reflection of topography of the lunar soil and Hapke’s model for calculating the reflection intensity of the internal scattering effects of particles of the lunar soil. Therefore, both the large-scale and microscale effects are considered in our method, providing a more accurate modeling of the reflectance of the lunar regolith. Simulation results using the Lunar Soil Characterization Consortium (LSCC) data and Chang’E-1 elevation map show that our method is effective and useful. We have also applied our method to Chang’E-1 IIM data for removing the influence of lunar topography to the reflectance of the lunar soil and to generate more realistic visualizations of the lunar surface.

Download Full-text

Two Simulated Spectral Databases of Lunar Regolith: Method, Validation, and Application

Remote Sensing ◽

10.3390/rs14020277 ◽

2022 ◽

Vol 14 (2) ◽

pp. 277

Author(s):

Ping Zhou ◽

Zhe Zhao ◽

Guangyuan Wei ◽

Hong-Yuan Huo

Keyword(s):

Particle Size ◽

Lunar Regolith ◽

Simulation Method ◽

Lunar Soil ◽

Optimization Method ◽

Least Square ◽

Radiative Transfer Model ◽

Transfer Model ◽

Spectral Simulation ◽

Mean Square Errors

Our simulated lunar regolith spectra database, based on the Hapke AMSA radiative transfer model (RTM), is a large supplement to the limited number of lunar spectra data. By analyzing the multiple solutions and applicable scopes of the Hapke model by means of Newton interpolation and the least square optimization method, an improved method was found for the simulation of spectra, but it remained challenging to use to invert mineral abundance. Then, we simulated the spectra, mineral abundance, particle size and maturity of 57 mare and highland samples of the Lunar Soil Characterization Consortium (LSCC) in size groups of 10 µm, 10–20 µm and 20–45 µm. The simulated and measured spectra fit well with each other, with correlation coefficients greater than 0.99 and root mean square errors at a magnitude of 10-3. The parameters of mineral abundance, particle size and maturity are highly consistent with the measured values. Having confirmed the reliability of our simulation method, we analyzed the mechanism, reliability and applicability of the “spectral characteristic angle parameter” proposed by Lucey using the simulated spectral data of lunar regolith. Lucey’s method is only suitable for macro analysis of the entire moon, and the error is large when it is used for areas with high abundance of forsterite or ilmenite. In the spectral simulation of lunar regolith, olivine was subdivided into forsterite and fayalite, and the two end-members were mixed to approximately estimate the effect of the chemical composition of olivine on the spectra, which has been confirmed to be feasible.

Download Full-text

Semianalytic Monte Carlo radiative transfer model for oceanographic lidar systems

Applied Optics ◽

10.1364/ao.20.003653 ◽

1981 ◽

Vol 20 (20) ◽

pp. 3653 ◽

Cited By ~ 60

Author(s):

L. R. Poole ◽

D. D. Venable ◽

J. W. Campbell

Keyword(s):

Monte Carlo ◽

Radiative Transfer ◽

Radiative Transfer Model ◽

Transfer Model

Download Full-text

Large-scale validation of SCIAMACHY reflectance in the ultraviolet

Atmospheric Chemistry and Physics Discussions ◽

10.5194/acpd-5-1771-2005 ◽

2005 ◽

Vol 5 (2) ◽

pp. 1771-1796 ◽

Cited By ~ 1

Author(s):

G. van Soest ◽

L. G. Tilstra ◽

P. Stammes

Keyword(s):

Radiative Transfer ◽

Validation Study ◽

Large Scale ◽

Scale Validation ◽

Radiative Transfer Model ◽

Transfer Model ◽

Time Level ◽

Standard Calibration ◽

Level 1 ◽

Reflectance Data

Abstract. In this paper we present an extensive validation of calibrated SCIAMACHY nadir reflectance in the UV (240–400 nm) by comparison with spectra calculated with a fast radiative transfer model. We use operationally delivered near-real-time level 1 data, processed with 5 standard calibration tools. A total of 9 months of data has been analysed. This is the first reflectance validation study incorporating such a large amount of data. It is shown that this method is a valuable tool for spotting spatial and temporal anomalies. We conclude that SCIAMACHY reflectance data in this wavelength range are stable over the investigated period. In addition, we show an example of an 10 anomaly in the data due to an error in the processing chain that could be detected by our comparison. This validation method could be extremely useful too for validation of other satellite spectrometers, such as OMI and GOME-2.

Download Full-text

On the Computation of Apparent Direct Solar Radiation

Journal of the Atmospheric Sciences ◽

10.1175/jas-d-19-0030.1 ◽

2019 ◽

Vol 76 (9) ◽

pp. 2761-2780 ◽

Cited By ~ 4

Author(s):

Petri Räisänen ◽

Anders V. Lindfors

Keyword(s):

Monte Carlo ◽

Solar Radiation ◽

Optical Depth ◽

Scattered Radiation ◽

Fine Tuning ◽

Direct Solar Radiation ◽

Radiative Transfer Model ◽

Transfer Model ◽

Scaling Factors ◽

Ice Clouds

Abstract Near-forward-scattered radiation coming from the vicinity of the sun’s direction impacts the interpretation of measurements of direct solar radiation by pyrheliometers and sun photometers, and it is also relevant for concentrating solar technology applications. Here, a Monte Carlo radiative transfer model is employed to study the apparent direct solar transmittance t(α), that is, the transmittance measured by an instrument that receives the radiation within a half-field-of-view (half-FOV) angle α from the center of the solar disk, for various ice cloud, water cloud, and aerosol cases. The contribution of scattered radiation to t(α) increases with increasing particle size, and it also depends strongly on ice crystal morphology. The Monte Carlo calculations are compared with a simple approach, in which t(α) is estimated through Beer’s law, using a scaled optical depth that excludes the part of the phase function corresponding to scattering angles smaller than α. Overall, this optical depth scaling approach works very well, although with some degradation of the performance for ice clouds for very small half-FOV angles (α < 0.5°–1°), and in optically thick cases. The errors can be reduced by fine-tuning the optical depth scaling factors based on the Monte Carlo results. Parameterizations are provided for computing the optical depth scaling factors for water clouds, ice clouds, aerosols, and for completeness, Rayleigh scattering to allow for a simple calculation of t(α). It is also shown that the optical depth scaling used in delta-two-stream approximations is inappropriate for simulating the direct solar radiation received by pyrheliometers.

Download Full-text

High resolution and Monte Carlo additions to the SASKTRAN radiative transfer model

Atmospheric Measurement Techniques Discussions ◽

10.5194/amtd-8-3357-2015 ◽

2015 ◽

Vol 8 (3) ◽

pp. 3357-3397 ◽

Cited By ~ 1

Author(s):

D. J. Zawada ◽

S. R. Dueck ◽

L. A. Rieger ◽

A. E. Bourassa ◽

N. D. Lloyd ◽

...

Keyword(s):

Monte Carlo ◽

High Resolution ◽

Radiative Transfer ◽

Spatial Resolution ◽

High Spatial Resolution ◽

Reference Model ◽

Monte Carlo Model ◽

Radiative Transfer Model ◽

Transfer Model ◽

Systematic Bias

Abstract. The OSIRIS instrument on board the Odin spacecraft has been measuring limb scattered radiance since 2001. The vertical radiance profiles measured as the instrument nods are inverted, with the aid of the SASKTRAN radiative transfer model, to obtain vertical profiles of trace atmospheric constituents. Here we describe two newly developed modes of the SASKTRAN radiative transfer model: a high spatial resolution mode, and a Monte Carlo mode. The high spatial resolution mode is a successive orders model capable of modelling the multiply scattered radiance when the atmosphere is not spherically symmetric; the Monte Carlo mode is intended for use as a highly accurate reference model. It is shown that the two models agree in a wide variety of solar conditions to within 0.2%. As an example case for both models, Odin-OSIRIS scans were simulated with the Monte Carlo model and retrieved using the high resolution model. A systematic bias of up to 4% in retrieved ozone number density between scans where the instrument is scanning up or scanning down was identified. It was found that calculating the multiply scattered diffuse field at five discrete solar zenith angles is sufficient to eliminate the bias for typical Odin-OSIRIS geometries.

Download Full-text