Articles | Volume 17, issue 11
Technical note
14 Jun 2017
Technical note |  | 14 Jun 2017

Technical note: Fu–Liou–Gu and Corti–Peter model performance evaluation for radiative retrievals from cirrus clouds

Simone Lolli, James R. Campbell, Jasper R. Lewis, Yu Gu, and Ellsworth J. Welton

Abstract. We compare, for the first time, the performance of a simplified atmospheric radiative transfer algorithm package, the Corti–Peter (CP) model, versus the more complex Fu–Liou–Gu (FLG) model, for resolving top-of-the-atmosphere radiative forcing characteristics from single-layer cirrus clouds obtained from the NASA Micro-Pulse Lidar Network database in 2010 and 2011 at Singapore and in Greenbelt, Maryland, USA, in 2012. Specifically, CP simplifies calculation of both clear-sky longwave and shortwave radiation through regression analysis applied to radiative calculations, which contributes significantly to differences between the two. The results of the intercomparison show that differences in annual net top-of-the-atmosphere (TOA) cloud radiative forcing can reach 65 %. This is particularly true when land surface temperatures are warmer than 288 K, where the CP regression analysis becomes less accurate. CP proves useful for first-order estimates of TOA cirrus cloud forcing, but may not be suitable for quantitative accuracy, including the absolute sign of cirrus cloud daytime TOA forcing that can readily oscillate around zero globally.

Short summary
We compare net TOA radiative forcing between the simplified Corti–Peter (CP) and relatively complex Fu–Liou–Gu models for cirrus clouds observed by NASA MPLNET at Singapore in 2010–11 and Greenbelt, Maryland, in 2012. We find daytime forcing discrepancies up to 65 % between the two, which is greater than previous studies. In some cases, the sign of net TOA daytime forcing also differs. We attribute model differences to numerical simplifications in CP via regression that are not valid globally.
Final-revised paper