Assessing the impact of sea surface temperature on global atmospheric river activity in an aquaplanet model
Abstract
Transient filaments of enhanced moisture transport called atmospheric rivers (ARs) drive a substantial portion of Earth's global energy transport and regional water resources. Studies performed in comprehensive (Earth-like) climate models under climate change scenarios can be useful for predictive purposes, but their inherent complexity can make it difficult to isolate the physical drivers behind the AR response. Here we use idealized experiments to isolate sea surface temperature (SST) impacts on the large-scale circulation and the changes in ARs which follow.
This study examines ARs generated by the Community Atmosphere Model version 5 (CAM5) in an aquaplanet configuration with a prescribed zonally uniform and equatorially symmetric SST distribution. A suite of four SST scenarios are used: northern- and southern-hemisphere only distributions in combination with present-day and end-of-century RCP8.5-like conditions. Previous studies have examined the large-scale circulation in aquaplanet simulations under varying prescribed SSTs, but they have not yet examined in depth how these changes translate to AR activity. An objective algorithm conditioned on vertically integrated vapor transport is used to identify AR conditions. Comparisons across runs will include assessments of the circulation response to SST changes, including the descending branch of the Hadley cell, and jet stream positions. Energy transport in terms of atmospheric sensible and latent heat fluxes will be examined, as will the fractional AR contribution to these heat fluxes across runs. AR-specific statistics will include changes in AR occurrence frequency, meridional distribution, vapor transport, and precipitation across SST scenarios. Aquaplanet results will further be compared against an ensemble of CAM5 Atmospheric Model Intercomparison Project (AMIP) runs under present-day and RCP8.5 conditions, providing a more Earth-like set of simulations with which to contextualize this idealized study.- Publication:
-
AGU Fall Meeting Abstracts
- Pub Date:
- December 2018
- Bibcode:
- 2018AGUFM.A53M2695M
- Keywords:
-
- 3305 Climate change and variability;
- ATMOSPHERIC PROCESSESDE: 3319 General circulation;
- ATMOSPHERIC PROCESSESDE: 3337 Global climate models;
- ATMOSPHERIC PROCESSESDE: 3373 Tropical dynamics;
- ATMOSPHERIC PROCESSES