FAT or FiTT: Are Anvil Clouds or the Tropopause Temperature Invariant?

Journal Article · 10 February 2019 · Geophysical Research Letters

DOI: https://doi.org/10.1029/2018gl080096 · OSTI ID:1513799

Seeley, Jacob T.  ^[1]; Jeevanjee, Nadir ^[2]; Romps, David M.  ^[3]

---

1. Univ. of California, Berkeley, CA (United States)
2. Princeton Univ., NJ (United States)
3. Univ. of California, Berkeley, CA (United States); Lawrence Berkeley National Lab. (LBNL), Berkeley, CA (United States)

The Fixed Anvil Temperature (FAT) hypothesis proposes that upper tropospheric cloud fraction peaks at a special isotherm that is independent of surface temperature. It has been argued that a FAT should result from simple ingredients: Clausius-Clapeyron, longwave emission from water vapor, and tropospheric energy and mass balance. Here the first cloud-resolving simulations of radiative-convective equilibrium designed to contain only these basic ingredients are presented. This setup does not produce a FAT: the anvil temperature varies by about 40% of the surface temperature range. However, the tropopause temperature varies by only 4% of the surface temperature range, which supports the existence of a Fixed Tropopause Temperature (FiTT). Lastly, in full-complexity radiative-convective equilibrium simulations, the spread in anvil temperature is smaller by about a factor of 2, but the tropopause temperature remains more invariant than the anvil temperature by an order of magnitude. In other words, our simulations have a FiTT, not a FAT.

• Research Organization: Lawrence Berkeley National Laboratory (LBNL), Berkeley, CA (United States)
• Sponsoring Organization: National Science Foundation (NSF); USDOE Office of Science (SC), Biological and Environmental Research (BER) (SC-23)
• Grant/Contract Number: AC02-05CH11231
• OSTI ID: 1513799
• Journal Information: Geophysical Research Letters, Journal Name: Geophysical Research Letters Journal Issue: 3 Vol. 46; ISSN 0094-8276
• Publisher: American Geophysical UnionCopyright Statement
• Country of Publication: United States
• Language: English