Four graphs from the paper
The figure shows the spectral characteristics of the radiation emitted by the Earth’s surface, clouds and atmosphere, known as outgoing longwave radiation (OLR), as well as its trends. (a) Mean OLR in the period 2003 – 2021 from AIRS observations and line-by-line (LBL) radiative transfer calculations using the European Center for Medium-Range Weather Forecasts Reanalysis 5 (ERA5) environmental conditions. (b) Time-series and trend lines for the CO2 channel (710 – 720 cm-1) and the CH4 and N2O channel (1270 – 1280 cm-1) are shown in red and pink, respectively. (c) Trend values for the OLR by wavenumber for AIRS observations and LBL-ERA5 calculations are shown in black and blue, with the uncertainties denoted in grey. (d) Trend values for the OLR for clear-sky only i.e. excluding clouds. Positive values in the trends indicate more emission of radiation, which would cool the Earth, the opposite for negative values. Credit: Raghuraman et al. [2023], Figure 1
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Source: Geophysical Research Letters

Raghuraman et al. [2023] use continuous global infrared satellite experiments to analyze measurements of outgoing longwave radiation (OLR) from 2003 to 2021 emitted by the Earth’s surface, the atmosphere, and clouds. The study focuses on the effect of greenhouse gases on the radiation and compares the measurements with line-by-line radiative simulations of radiation transfers based on the meteorological conditions of the same period.

In these satellite measurements the authors show that increases in concentration of CO2, CH4, and N2O lead to a decrease in OLR, in agreement with the expected response to greenhouse gases, associated with a warming on the Earth’s surface and a cooling in the stratosphere. They also calculate the magnitude of the greenhouse gases forcing and conclude that it is in agreement with the estimates discussed in the latest IPCC report.

Citation: Raghuraman, S. P., Paynter, D., Ramaswamy, V., Menzel, R., & Huang, X. (2023). Greenhouse gas forcing and climate feedback signatures identified in hyperspectral infrared satellite observations. Geophysical Research Letters, 50, e2023GL103947. https://doi.org/10.1029/2023GL103947

—Suzana Camargo, Editor, Geophysical Research Letters

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