Pan-spectral observing system simulation experiments of shortwave reflectance and longwave radiance for climate model evaluation
Abstract. Top-of-atmosphere spectrally-resolved shortwave reflectances and longwave radiances describe the evolution of the Earth's surface and atmosphere response to feedbacks in and human-induced forcings on the climate system. In order to evaluate proposed long-duration spectral measurements, we have projected 21st century changes described by the Community Climate System Model (CCSM3.0) conducted for the Intergovernmental Panel on Climate Change (IPCC) A2 Emissions Scenario onto shortwave reflectance spectra from 0.3 to 2.5 μm and longwave radiance spectra from 5 to 50 μm at 8 nm and 1 cm−1 resolution, respectively. The radiative transfer calculations have been rigorously validated against published standards and produce complementary signals describing the climate system forcings and feedbacks. Additional demonstration experiments were performed with the MIROC5 and HadGEM2-ES models for the Representative Concentration Pathway 8.5 (RCP8.5) scenario. The calculations contain readily distinguishable signatures of low clouds, snow/ice, aerosols, temperature gradients, and water vapour distributions. The goal of this effort is to understand both how climate change alters the spectrum of the Earth and determine whether spectral measurements enhance our detection and attribution of climate change. This effort also presents a path forward for hyperspectral measurement-model intercomparison by enabling a diverse set of comparisons between model results from coupled model intercomparisons and existing and proposed satellite instrument measurement systems.