The identification of possible future climate change under global warming is essential for China, which has the largest population and a vulnerable ecological environment. As such, high-resolution ...climate simulations are important for understanding the regional-scale impact of climate change and variation such as heat extremes and drought. In a previous paper (Yu et al. in Climate Dynamics 45: 2013–2031, 2015), a high-resolution simulation using the Weather Research and Forecasting (WRF) model (forced by the Model for Interdisciplinary Research On Climate (MIROC5) 6-h outputs in the context of phase 5 of the Coupled Model Intercomparison Project (CMIP5)) was validated with observation. In this study, the near-term (2016–2035), mid-term (2046–2065) and long-term (2080–2099) future climate projections are explored by focusing on temperature, precipitation and surface wind speed. Under the Representative Concentration Pathways 6.0 (RCP6.0) scenario, the national mean annual temperatures are expected to increase by 0.9 (0.93), 1.71 (1.78), and 3.3 (3.29) °C in the early, middle and late twenty-first century in the MIROC5 (WRF) simulation, respectively, with different spatial and seasonal features in the WRF simulation. Specifically, temperature is projected to increase more slowly in winter but faster in summer, which might lead to more frequent summer extreme hot events in the WRF results. Precipitation is expected to generally increase in the future, with the national averaged precipitation increasing by 4.13 (6.54), 5.65 (6.99) and 13 (12.85)% in the three periods in the twenty-first century. The amplitudes of precipitation change in the late twenty-first century are twice those of the previous two periods, thus indicating more extreme rainfall events at the end of this century, especially in summer time. The surface wind speed in the future is projected to decrease over China in both the MIROC5 and WRF simulations for the annual mean case, but in summer, these values are expected to increase in the eastern region of China. The results are generally consistent with the previous high-resolution projection simulations over China but offer projections of surface wind speed that were rarely investigated in earlier studies.
Previous climate modeling studies suggest that the surface uplift of the Himalaya–Tibetan plateau (TP) is a crucial parameter for the onset and intensification of the East Asian monsoon during the ...Cenozoic. Most of these studies have only considered the Himalaya–TP in its present location between ∼26°N and ∼40°N despite numerous recent geophysical studies that reconstruct the Himalaya–TP 10° or more of latitude to the south during the early Paleogene. We have designed a series of climate simulations to explore the sensitivity of East Asian climate to the latitude of the Himalaya–TP. Our simulations suggest that the East Asian climate strongly depends on the latitude of the Himalaya–TP. Surface uplift of a proto-Himalaya–TP in the subtropics intensifies aridity throughout inland Asia north of ∼40°N and enhances precipitation over East Asia. In contrast, the rise of a proto-Himalaya–TP in the tropics only slightly intensifies aridity in inland Asia north of ∼40°N, and slightly increases precipitation in East Asia. Importantly, this climate sensitivity to the latitudinal position of the Himalaya–TP is non-linear, particularly for precipitation across East Asia. The simulated precipitation patterns across East Asia are significantly different between our scenarios in which a proto-plateau is situated between ∼11°N and ∼25°N and between ∼20°N and ∼33°N, but they are similar when the plateau translates northward from between ∼20°N and ∼33°N to its modern position. Our simulations, when interpreted in the context of climate proxy data from Central Asia, support geophysically-based paleogeographic reconstructions in which the southern margin of a modern-elevation proto-Himalaya–TP was located at ∼20°N or further north in the Eocene.
•East Asian climate strongly depends on the latitude of the Himalaya–TP.•The climate sensitivity to the latitudinal position of the Himalaya–TP is non-linear.•Our ∼40 Ma experiments do not simulate a modern-like East Asian monsoon.•Our ∼40 Ma results with a subtropical plateau are more consistent with proxy data.
The climatic effect of Tibetan Plateau (TP) uplift is a hot topic in paleoclimate research. In this paper, the results of a set of numerical simulations are reported to analyze the impact of regional ...TP uplift on the Asian monsoon climate. The focus is on the impact of the regional uplift in the west and east parts on South Asian summer monsoon, as well as the impact of regional uplift on East Asian winter monsoon. The results show that the uplifts of the Himalaya and the central-southern TP have little effect on summer precipitation increasing over South Asia. Whereas, the further uplifts of the TP in the west and east parts, including the uplifts of both the eastern and western TP, have important effects on the strengthening of the South Asian summer monsoon. The uplift of the eastern TP leads to low-level cyclonic circulation anomalies appearing in the Bay of Bengal, accompanied by anomalous upward movement, and in turn precipitation markedly increases in the Bay of Bengal. Whereas, the uplift of the western TP produces low-level cyclonic circulation anomalies around the uplifted region and intensifies the moisture transport from the tropical ocean, and thus precipitation further increases in South Asia, especially in the northern Arabian Sea. The strengthened summer monsoon in South Asia is coupled with the intensification in diabatic heating and moisture convergence. For the East Asian winter monsoon, the intensification of winter monsoon winds is related more to the regional uplifts than the uplift of the whole TP. The uplifts of the central-southern TP, the northern TP and other northern topography have greater effects on the strengthening of the winter monsoon winds.
•Uplifts of eastern and western TP markedly intensify the South Asian monsoon climate.•The strengthened South Asian summer monsoon is related to intensified diabatic heating.•The strengthened East Asian winter winds are related to specific regional uplifts.•The uplifts of central-southern and northern TP strengthen more the winter winds.
The question of European hydroclimate anomaly associated with El Niño-Southern Oscillation (ENSO) is revisited by composite analyses on data from Dai et al.'s Palmer Drought Severity Index, the Old ...World Drought Atlas (OWDA), and a 10-member CESM coupled-model Last Millennium Ensemble (CESM-LME) simulations. This study benefits from exceptionally long or large samples in OWDA and CESM-LME. The averagely strong El Niño (1-2 standard deviations, or about one event per decade) is correlated to wet condition in western and southern Europe, and dry condition in Northern Europe; this result agrees with previous studies and thus provides a further support to this scenario. We also find in OWDA that extremely strong El Niño (>2 standard deviation, or about one event every 70-100 years) is related to a dry condition in western Europe. This suggests that the extreme El Niño impact in western Europe is opposite, or at least not linear, to that for the averagely strong El Niño. The impact of extreme El Niño does not appear to be reproduced by the LME, and will require further analyses on other climate reconstructions and models data.
Extreme heat events (EHEs) often hit North China, resulting in significant losses. The devastating EHE in the 1743 summer, marked as the highest temperature in the past 300 years, led to ∼11,000 ...fatalities. These historical EHEs prompt us to explore potential mechanisms beyond anthropogenic influences. We employ the Norwegian Earth System Model here to simulate the past millennium climate and then dynamically downscale the July 1743 event using the Weather Research and Forecasting Model. The successful simulation of warming in North China, although it has been a fortunate outcome, is supported by tree‐ring records, providing a compelling case study for the event. Through composite and case analyses, we discover a connection between EHEs and active Northeast China Vortexes (NCVs) which induce warm advection, consequently heating the lower atmosphere. Reanalysis further confirms the connection in the modern era. Our study suggests modeling past EHEs, while challenging, is indeed feasible.
Plain Language Summary
Nowadays, heat waves have a significant impact on our society and result in substantial economic losses. Climate projections indicate that extreme heat events (EHEs) will become more frequent. However, heat waves have also often occurred in the past 300 years during periods with much lower anthropogenic forcing. One notable example is the severe heat event in the summer of 1743, which killed more than 10 thousand people in North China. The mechanism behind such events remains uncertain, making it exciting and valuable to investigate such heat waves in the past. In this study, we use a global model, a nested regional model, and tree‐ring records to explore the mechanisms driving EHEs. The statistical robustness of the connection between EHEs in North China and Northeast China Vortexes is supported by modern observations. Notably, from 1950 to 2021, 63.6% of EHEs in North China coincide with active Northeast China Vortexes.
Key Points
Our simulation, supported by tree‐ring, shows that warm advection linked to Northeast China Vortex likely drove the 1743 extreme heat event (EHE)
Reanalysis data from 1950 to 2021 indicate that 63.6% of EHEs in North China coincide with active Northeast China Vortexes
Our study implies that modeling past extreme climate events is feasible to gain insights into their causes and dynamics
An extreme rainfall event that occurred in Beijing city during 19–21 July 2016 was investigated. The analysis indicated that the main pattern at 500 hPa was a “two-ridges-one-trough” pattern; ...meanwhile, the cyclonic circulation at 850 hPa controlled the Beijing area and the southerly wind brought wet air to Beijing, causing abundant water vapor during this event. Hindcast experiments were carried out using the NCAR’s Weather Research and Forecasting model with the NCEP’s Global Forecast System datasets as the initial and boundary conditions. We found that the model ensemble could reproduce the spatial distribution of the rainfall, and different model physical parameterization scheme combinations led to differing simulation skill. Furthermore, the analysis indicated that the model performed differently in different periods of the rainfall event. The water vapor supply, divergence, rain mixing ratio, and cloud mixing ratio were the main factors that influenced the model’s performance.
The physical parameterizations have important influence on model performance in precipitation simulation and prediction; however, previous investigations are seldom conducted at very high resolution ...over Hebei Province, which is often influenced by extreme events such as droughts and floods. In this paper, the influence of parameterization schemes and analysis nudging on precipitation simulation is investigated using the WRF (weather research and forecasting) model with many sensitivity experiments at the cumulus “gray-zone” resolution (5 km). The model performance of different sensitivity simulations is determined by a comparison with the local high-quality observational data. The results indicate that the WRF model generally reproduces the distribution of precipitation well, and the model tends to underestimate precipitation compared with the station observations. The sensitivity simulation with the Tiedtke cumulus parameterization scheme combined with the Thompson microphysics scheme shows the best model performance, with the highest temporal correlation coefficient (0.45) and lowest root mean square error (0.34 mm/day). At the same time, analysis nudging, which incorporates observational information into simulation, can improve the model performance in precipitation simulation. Further analysis indicates that the negative bias in precipitation may be associated with the negative bias in relative humidity, which in turn is associated with the positive bias in temperature and wind speed. This study highlights the role of parameterization schemes and analysis nudging in precipitation simulation and provides a valuable reference for further investigations on precipitation forecasting applications.
Using the high-resolution regional climate model–Weather Research and Forecasting model(WRF)–nested within the National Center for Atmospheric Research Community Atmosphere Model(CAM4), a set of ...sensitivity experiments were conducted to investigate the Asian climate response to the regional uplift of the Tibetan Plateau (TP). The results indicated that the presence of Asian orography, including the TP, strengthened both the Indian and East Asian summer monsoon (ISM and EASM), respectively. The uplift of the central-southern TP and western TP caused an asynchronous response of monsoon precipitation over India and East Asia, while the presence of the Himalayan mountains, Gobi Altai mountains, and Mongolian Plateau increased both ISM and EASM precipitation. The enhanced summer monsoon precipitation over southeastern China due to the TP uplift was caused by strong water vapor transportation, vapor convergence and ascending movement. The Indian and East Asian winter monsoons (IWM and EAWM), however, showed asynchronous change in response to the TP uplift; the EAWM was strengthened, but the opposite holds for the IWM. This study provides further understanding of the response of Asian monsoons to the regional uplift of the TP and emphasizes the importance of high-resolution regional climate model simulation nested within global climate model.
•The uplift of Asian orography strengthened both the Indian and East Asian summer monsoons.•The Indian and East Asian winter monsoons showed asynchronous change in response to the TP uplift.•Model resolution, physical parametrization and lateral boundary conditions have large influence on the simulation results.•It is important to study the climate response of regional Tibetan Plateau uplift using high-resolution RCM nested with GCM.
In Northeast China (NEC), snowfalls usually occur during winter and early spring, from mid-October to late March, and strong snowfalls rarely occur in middle spring. During 12–13 April 2010, an ...exceptionally strong snowfall occurred in NEC, with 26.8 mm of accumulated water-equivalent snow over Harbin, the capital of the most eastern province in NEC. In this study, the major features of the snowfall and associated large-scale circulation and the predictability of the snowfall are analyzed using both observations and models. The Siberia High intensified and shifted southeastward from 10 days before the snowfall, resulting in intensifying the low-pressure system over NEC and strengthening the East Asian Trough during 12–13 April. Therefore, large convergence of water vapor and strong rising motion appeared over eastern NEC, resulting in heavy snowfall. Hindcast experiments were carried out using the NCAR Weather Research and Forecasting (WRF) model in a two-way nesting approach, forced by NCEP Global Forecast System data sets. Many observed features including the large-scale and regional circulation anomalies and snowfall amount can be reproduced reasonably well, suggesting the feasibility of the WRF model in forecasting extreme weather events over NEC. A quantitative analysis also shows that the nested NEC domain simulation is even better than mother domain simulation in simulating the snowfall amount and spatial distribution, and that both simulations are more skillful than the NCEP Global Forecast System output. The forecast result from the nested forecast system is very promising for an operational purpose.
There are water resource shortages and frequent drought disasters in the arid region of northwestern China (ARNC). The purpose of this study is to understand the spatiotemporal variations of the ...droughts in this region and to further estimate future changes. Multiple drought indexes such as the standardized precipitation index (SPI), the standardized precipitation evapotranspiration index (SPEI), and the self-calibrated Palmer drought severity index (SC-PDSI) are used to investigate the temporal and spatial characteristics of the ARNC drought from 1950 to 2012. Our results indicate the following: (1) The drought indexes exhibit significant increasing trends, and the highest drought frequency occurred in the 1960s, followed by a decreasing trend during the next few decades. All four seasons exhibit a wet trend, with a higher drought frequency in summer than in the other seasons. (2) The changes of the drought indexes in the ARNC also exhibit distinct spatial variations, with a wet trend in the subregions of North Xinjiang (NXJ), the Tianshan Mountains (TS), South Xinjiang (SXJ), and the Qilian Mountains (QL), but with a dry trend in the subregions of the Hexi Corridor (HX) and the western part of Inner Mongolia (WIM). (3) There was a major climate variability in the ARNC that occurred in the 1980s, and there were dry and wet climate oscillation periods of 8a, 17a, and >20a.
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