Simulation of Earth’s Outward Radiative Flux and Its Radiance in Moon-Based View

Haolu Shang,Guoqiang Chen,Huadong Guo,Lei Liang,Jie Wu,Yixing Ding,Guang Liu,Hao Jiang,Xiaoyu Liu

doi:10.3390/rs13132535

Abstract

To study the Earth’s energy balance and to extend exoplanet research, the Earth’s outward radiative flux and its radiance in the Moon-based view were simulated according to the Earth–Sun–Moon geometry model, with the help of ERA5. A framework was developed to identify the angular distribution model (ADM) of Earth’s surface and its scene types, according to the surface and atmospheric data from ERA5. Our simulation shows that the specific viewing geometry controls the periodical variations in the Moon-based view radiative flux and its radiance, which reflect the orbital period of the Moon. The seasonal variations in shortwave and longwave radiative flux follow the energy balance in general, which is probably influenced by the Earth albedo. The derived global ADM would help to identify the anisotropic factor of observations at DSCOVR. Our simulations prove that Moon-based observation is a valuable source for Earth observation and that the orbital information of exoplanets could be derived from the radiance observation.

Highlights

We developed a framework to simulate the radiance of whole Earth in the Moon-based view and to simulate global anisotropic factor of the whole Earth, with the help of climate reanalysis data, CERES/Tropical Rainfall Measuring Mission (TRMM) angular distribution model (ADM), and a geometric model of an ESM observation system
Fast Fourier transform (FFT) was used here to illustrate the spectral information of time series of the simulated radiative flux and radiance
The global top of atmosphere (TOA) outward radiative flux and its radiance of the whole Earth observed in the Moon-based view was simulated in this study, with the help of ERA5 reanalysis

Summary

Introduction

Solar radiation is the radiative force of the Earth climate system (ECS). The Earth energy balance (EEB) determines our planetary climate by partitioning solar radiation among land, ocean, and atmosphere [1,2]. For studying and predicting ECS, it is crucial to understand how to partition solar radiative flux among different components of ECS, e.g., Earth radiation budget (ERB). One of the methods of studying ERB is to measure the Earth radiance using radiometers onboard satellites at various orbits, which is normally used to derive the top of atmosphere (TOA) outward radiative flux [3]. If we could take the whole Earth as a “point light”, the observation system of global TOA outward radiative flux could help us to build up new perspectives for studying exoplanets, for example, the rotation of an exoplanet and its possible climate [4,5]

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