Simulated Cycles of East Asian Temperature and Precipitation Over the Past 425 ka

Abstract

Records from a wide range of geological archives covering the last few glacial‐interglacial cycles show large inconsistencies in the East Asian summer monsoon variability, which severely hampers our understanding of the evolution and potential mechanisms of the regional East Asian climate on orbital timescales. Here, we examine the simulated temperature and precipitation in East Asia based on a series of equilibrium simulations conducted for the past 425 ka, and we investigate the sensitivity of temperature and precipitation to potential forcings. Our simulations show that, in East Asia, the seasonal mean temperature is dominated by a ∼20‐kyr cycle, and the annual mean temperature (AMT) is dominated by a ∼100‐kyr cycle, which is consistent with previous modeling efforts and geological reconstructions. Additional sensitivity experiments indicate that the greenhouse gas concentration, in combination with the ice volume, is the dominant force for the variations of AMT in East Asia on orbital timescales. For the precipitation in East Asia, our equilibrium simulations and additional sensitivity experiments, together with comprehensive model‐data intercomparison analysis, suggest that the cycles of simulated annual mean precipitation over East Asia are highly model‐dependent, although the dominant ∼20‐kyr cycle in summer precipitation appears to be a robust feature. Overall, the results highlight the large model uncertainty with regard to the relative roles of forcings in hydroclimate variations in East Asia on orbital time scales. There is, therefore, an urgent need to implement more realistic precipitation schemes in models in order to decrease the model spread in simulated precipitation.

Winter Insolation Modulates Boreal Tropical Monsoonal Temperatures in the Late Pleistocene

“…And the variations in annual temperature and precipitation in the study area are forced by distinct patterns of seasonal insolation (e.g., Bosmans et al, 2015). Therefore, the tropical monsoon climate is quite different from the adjacent Mediterranean climate (Figure 1b) and monsoon climate in East Asia (Dai et al, 2021(Dai et al, , 2022.…”

“…With the low-resolution version of the Norwegian Earth System Model (NorESM-L), these equilibrium experiments consider variations in orbital parameters, ice sheets, and greenhouse gas levels spanning the past 425 ka (Yan et al, 2021;Zhang et al, 2020). They covered 77 time slices throughout the past 425 ka and well simulate the climate changes in the monsoon region during past glacial-interglacial cycles (Dai et al, 2021(Dai et al, , 2022.…”

Loess deposits in the low latitudes of East Asia reveal the ~20-kyr precipitation cycle

“…The temperature and precipitation in East Asia over the past 425 kyr were simulated recently 54 . The simulated MAT in East Asia is mainly dominated by the 100-kyr cycle.…”