Studying global precipitation responses in a simplified one-column model
Abstract
The robustness of model precipitation responses to increased levels of atmospheric carbon dioxide suggests that many aspects of the fundamental physical response of the Earth system can be reproduced with simple models. We show that simulations with the one-dimensional Climate Modeling Toolkit (CliMT), which has full representation of radiative transfer, convection, and surface-atmosphere interactions but no cloud feedbacks, capture many important features of temperature-dependent evolution of atmospheric and surface energy budgets seen in fully-coupled GCMs. Such simple one-dimensional models can provide useful insight into global precipitation responses because nearly 70% of global evaporative fluxes occur in low-latitude regions (40S-40N) which are reasonably well represented by radiative-convective equilibrium. The computational efficiency of simple models allows testing nonlinear responses to a wide range of perturbations in both transient and equilibrium conditions, as well as isolating individual processes by manually fixing physical properties such as surface temperature or radiative properties of water vapor. Resulting insights include that immediately after abrupt addition of CO2, initial precipitation suppression and reduction of latent heat flux balances ocean heat uptake, and that in equilibrium conditions, increased latent heat flux is driven predominantly by the longwave effect of additional atmospheric water vapor. Simple one-dimensional radiative-convective models can provide a valuable tool for precipitation studies by allowing flexible testing of a wide range of forcings and model settings.
- Publication:
-
AGU Fall Meeting Abstracts
- Pub Date:
- December 2019
- Bibcode:
- 2019AGUFMGC43J1388S
- Keywords:
-
- 1616 Climate variability;
- GLOBAL CHANGE;
- 1655 Water cycles;
- GLOBAL CHANGE;
- 1836 Hydrological cycles and budgets;
- HYDROLOGY;
- 4215 Climate and interannual variability;
- OCEANOGRAPHY: GENERAL