Quantifying East Asian Summer Monsoon Dynamics in the ECP4.5 Scenario With Reference to the Mid-Piacenzian Warm Period

Yong Sun (1, 2) , Gilles Ramstein (2, 3) , Laurent Li (4) , Camille Contoux (2) , Ning Tan , Tianjun Zhou (5)

1 IAP - Institute of Atmospheric Physics [Beijing]
2 LSCE - Laboratoire des Sciences du Climat et de l'Environnement [Gif-sur-Yvette]
3 CLIM - Modélisation du climat
4 LMD - Laboratoire de Météorologie Dynamique (UMR 8539)
5 Joint Center for Global Change Studies

The mid-Piacenzian (~3.3-3.0 Ma), which was characterized by high pCO 2 (~400 ppm) and global surface air temperatures that were 1.84-3.60°C above pre-Industrial levels, provides clues to the likely changes in atmospheric dynamics in a future climate affected by anthropogenic warming, although its suitability as an analogue of the future climate has yet to be assessed. This study investigates the extent to which the dynamics of the East Asian summer monsoon during the mid-Piacenzian can aid our understanding of East Asian summer monsoon behavior in the Extended Concentration Pathway version 4.5 scenario, using water vapor and moist static energy equations. The temperature-dependent large-scale moisture transport explains the similar pattern of precipitation increase in the two climates, whereas regional patterns of vertical motion differ significantly. Two of the main terms of the moist static energy equation control the changes in regional dynamics relative to the pre-Industrial period. These terms relate to zonal advection of stationary eddy dry enthalpy by the mean zonal wind and meridional stationary eddy velocity over East Asia. Topographic differences between the two cases have a negligible effect on regional precipitation. Plain Language Summary The mid-Piacenzian (~3.3-3.0 Ma, mid-Pliocene warm period) is the most recent warm period in Earth's history, characterized by high pCO 2 levels (~400 ppm) and global warming (increase of 1.84-3.60°C above pre-Industrial levels). Thus, it is of interest to compare this period with atmospheric dynamics responses to anthropogenic warming in a future climate, especially in terms of the monsoon. This study investigates the extent to which the dynamics of the East Asian summer monsoon during the mid-Piacenzian aid our understanding of the future behavior of the monsoon according to the Extended Concentration Pathway version 4.5 scenario. The analyses are based on water vapor and moist static energy equations. It is shown that increases in large-scale moisture transport under thermal control in the two warm climates enhance East Asian summer monsoon precipitation. Regional differences in East Asian summer monsoon precipitation arise from different contributions of dynamic processes, primarily zonal warm advection by zonal wind and meridional stationary eddy velocity. Topographic differences between the two cases have a negligible effect on regional precipitation.

Domaines: Climatologie

Yong Sun, Gilles Ramstein, Laurent Li, Camille Contoux, Ning Tan, et al.. Quantifying East Asian Summer Monsoon Dynamics in the ECP4.5 Scenario With Reference to the Mid-Piacenzian Warm Period. Geophysical Research Letters, 2018, 45 (22), pp.12,523-12,533. ⟨10.1029/2018GL080061⟩. ⟨hal-02412922⟩