CO$_{\textrm{2}}$ Dependence in Global Estimation of All‐Sky Downwelling Longwave: Parameterization and Model Comparison. Kawaguchi, K., Shakespeare, C. J., & Roderick, M. L. Geophysical Research Letters, 51(18):e2024GL110384, September, 2024.
CO$_{\textrm{2}}$ Dependence in Global Estimation of All‐Sky Downwelling Longwave: Parameterization and Model Comparison [link]Paper  doi  abstract   bibtex   
Abstract The downwelling longwave radiation at the surface (DLR) is a key component of the Earth's surface energy budget. We present a novel set of equations that explicitly account for both clouds and the effect to calculate the all‐sky DLR. This paper first extends the clear‐sky DLR model of Shakespeare and Roderick (2021, https://doi.org/10.1002/qj.4176 ) to include temperature inversions and clouds. We parameterize relevant cloud properties through theoretical and empirical considerations to formulate an all‐sky model. Our model is more accurate than existing methods (reduces Root Mean Squared Error by 2.1–8.7 and 1.2–10.1 compared to ERA5 reanalysis and in‐situ data respectively), and provides a strong physical basis for the estimation of the downwelling longwave from near‐surface information. We highlight the important role of dependence by showing our model largely captures the change in atmospheric emissivity purely due to (i.e., the instantaneous radiative forcing) in CMIP6 models. , Plain Language Summary The downwelling longwave radiation (DLR) at the surface is a key component of the energy balance at the Earth's surface. Understanding how the DLR will change under future climate conditions is vital. For the first time, we explicitly write a set of equations to calculate the DLR that sufficiently account for the impact of and clouds simultaneously. Our model is more accurate than existing methods, and provides a much stronger physical basis for the estimation of the downwelling longwave from near‐surface information. In this paper, we extend an existing method for estimating the DLR under clear‐sky conditions (i.e., no clouds) to operate under all sky conditions. This method can be used to inform models where the DLR is needed, but only basic observations are available. , Key Points Downwelling longwave radiation (DLR) is a poorly estimated element of the surface energy budget by existing analytical models Explicitly accounting for temperature inversions and cloud emissivities improves the accuracy of DLR estimation Considering the radiative forcing from increasing is necessary to produce unbiased future estimates of DLR
@article{kawaguchi_co2_2024,
	title = {{CO}$_{\textrm{2}}$ {Dependence} in {Global} {Estimation} of {All}‐{Sky} {Downwelling} {Longwave}: {Parameterization} and {Model} {Comparison}},
	volume = {51},
	issn = {0094-8276, 1944-8007},
	shorttitle = {{CO}$_{\textrm{2}}$ {Dependence} in {Global} {Estimation} of {All}‐{Sky} {Downwelling} {Longwave}},
	url = {https://agupubs.onlinelibrary.wiley.com/doi/10.1029/2024GL110384},
	doi = {10.1029/2024GL110384},
	abstract = {Abstract
            
              The downwelling longwave radiation at the surface (DLR) is a key component of the Earth's surface energy budget. We present a novel set of equations that explicitly account for both clouds and the  effect to calculate the all‐sky DLR. This paper first extends the clear‐sky DLR model of Shakespeare and Roderick (2021,
              https://doi.org/10.1002/qj.4176
              ) to include temperature inversions and clouds. We parameterize relevant cloud properties through theoretical and empirical considerations to formulate an all‐sky model. Our model is more accurate than existing methods (reduces Root Mean Squared Error by 2.1–8.7  and 1.2–10.1  compared to ERA5 reanalysis and in‐situ data respectively), and provides a strong physical basis for the estimation of the downwelling longwave from near‐surface information. We highlight the important role of  dependence by showing our model largely captures the change in atmospheric emissivity purely due to  (i.e., the instantaneous radiative forcing) in CMIP6 models.
            
          , 
            Plain Language Summary
            The downwelling longwave radiation (DLR) at the surface is a key component of the energy balance at the Earth's surface. Understanding how the DLR will change under future climate conditions is vital. For the first time, we explicitly write a set of equations to calculate the DLR that sufficiently account for the impact of  and clouds simultaneously. Our model is more accurate than existing methods, and provides a much stronger physical basis for the estimation of the downwelling longwave from near‐surface information. In this paper, we extend an existing method for estimating the DLR under clear‐sky conditions (i.e., no clouds) to operate under all sky conditions. This method can be used to inform models where the DLR is needed, but only basic observations are available.
          , 
            Key Points
            
              
                
                  Downwelling longwave radiation (DLR) is a poorly estimated element of the surface energy budget by existing analytical models
                
                
                  Explicitly accounting for temperature inversions and cloud emissivities improves the accuracy of DLR estimation
                
                
                  Considering the radiative forcing from increasing  is necessary to produce unbiased future estimates of DLR},
	language = {en},
	number = {18},
	urldate = {2024-11-26},
	journal = {Geophysical Research Letters},
	author = {Kawaguchi, Koh and Shakespeare, Callum J. and Roderick, Michael L.},
	month = sep,
	year = {2024},
	pages = {e2024GL110384},
}

Downloads: 0