Monsoons, ITCZs and the Concept of the Global Monsoon

Abstract

Theoretical understanding of the dynamics of Hadley cells, monsoons and ITCZs 9 is developing rapidly 10 • Some aspects of observed monsoons and their variability can now be understood 11 through theory 12 • Parallel theories should be reconciled and extended to account for zonal asymme-13 tries and transients 14

On the Correspondence Between Atmosphere‐Only and Coupled Simulations for Radiative Feedbacks and Forcing From CO2

“…However, even for the net cloud feedback, some regions exhibit less consistency, like India, western Pacific Ocean, North Atlantic Ocean, and high‐latitude oceans. The different warming pattern in Indian and Pacific Ocean between amip4K and coupled experiments might lead to different cloud feedbacks over India because monsoon simulation is very sensitive to the air‐sea coupling and land‐sea temperature contrast (Endo et al., 2018; Geen et al., 2020; Singh et al., 2019; Wang, 2005). A “warming hole” is commonly simulated by coupled models in the North Atlantic (Chemke et al., 2020; Drijfhout et al., 2012; Josey et al., 2018), which could cause a locally different cloud feedback compared to that occurring when SSTs are warmed uniformly.…”

Deciphering the Migration of the Intertropical Convergence Zone During the Last Deglaciation

“…Paleo‐evidences suggest pronounced changes in global hydroclimate and global monsoon system during the last deglaciation (Clark et al., 2012; Geen et al., 2020; McGee et al., 2014; Schneider et al., 2014). During Heinrich Stadial 1 (HS1; ∼14.7–19 ka BP; BP: before present) and Younger Dryas (YD, ∼12.9–11.7 ka BP), precipitation decreases in Central America (Escobar et al., 2012), west African Sahel (McGee et al., 2013; Otto‐Bliesner et al., 2014), Arabian Sea (Deplazes et al., 2013) and East and South Asia (Y. J. Wang et al., 2001; Yancheva et al., 2007) but increases in subtropical Brazil (Cruz et al., 2005; X. Wang et al., 2007), northern Australia (Ayliffe et al., 2013; Denniston et al., 2013), and the southern African tropics and subtropics (Konecky et al., 2011; Stager et al., 2011; also c.f.…”

Forecasting South China Sea Monsoon Onset Using Insight From Theory

“…This could relate to a lack of memory in the system for upper‐level wind anomalies or could indicate issues with applying ideas from highly idealized models to Earth. The theoretical foundation for understanding the climatological monsoon still shows some key gaps, in particular the role of zonal asymmetries and transient weather systems in the seasonality of the Hadley cells (Geen et al., 2020). The results presented here suggest that bridging these gaps may provide further opportunities for improved seasonal forecasts.…”

“…To select potential mechanistic pathways, I apply results from idealized modeling studies that compare the seasonal behavior of the Hadley cell in aquaplanets with Earth's monsoons (Geen et al., 2020; Hill, 2019). One important expectation from this theoretical work is that, if the tropical atmosphere is near convective quasi‐equilibrium (CQE) and the influence of extra‐tropical eddies on the Hadley cell is weak, then the 0‐streamfunction line separating the Hadley cells is colocated with the maximum in subcloud moist static energy (MSE).…”