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Quantitative estimation of global mean precipitation throughout the Phanerozoic era

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Science China Earth Sciences 2024年第5期67卷 1616-1624页

作者： Xiujuan BAO yongyun hu Laboratory for Climate and Ocean-Atmospheric Studies Department of Atmospheric and Oceanic SciencesSchool of PhysicsPeking UniversityBeijing 100871China

Quantitatively estimating the global mean precipitation(GMP)throughout Earth's history is crucial for enhancing our understanding of long-term climate evolution and the hydrological ***,currently there is no established methodology for estimating global mean ***,we present the first study that estimates GMP in the Phanerozoic *** relationship between GMP and global mean surface temperature(GMST)is investigated by analyzing data from 23 models in the Coupled Model Intercomparison Project phase 6(CMIP6).The result reveals consistent and significant impact of temperature on precipitation,with a sensitivity range of 2–3%K^(-1).Additionally,we propose a method for accessing latitudinal variations in precipitation caused by land area distributions and paleo-Koppen climatic *** climatic belts are determined based on geological indicators such as coals,evaporites,and glacial *** GMP is thus quantitatively estimated by combining variations in GMST,land area distributions,and paleo-koppen climatic belts,spanning from 540 Ma to the present *** quantitative GMP curve demonstrates fluctuations in GMP about 500 mm yr^(-1),with values ranging from 948 to1442 mm yr-1over the Phanerozoic *** curve aligns closely with findings derived from numerical *** presented paleoprecipitation variations facilitate a more comprehensive understanding of the interconnected geological and paleoclimatic developments.

关键词： Paleoprecipitation Paleoclimate K?ppen climatic belts Global mean precipitation Hydrological cycle

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Extremely cold and persistent stratospheric Arctic vortex in the winter of 2010-2011

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Chinese Science Bulletin 2013年第25期58卷 3155-3160页

作者： hu yongyun XIA Yan Laboratory for Climate and Ocean-Atmosphere Studies Department of Atmospheric and Oceanic Sciences School of Physics Peking University

Record ozone loss was observed in the stratospheric Arctic in the spring of 2011. In the present work, we show observational evidence that the record loss of Arctic ozone is due to the extremely cold and persistent stratospheric polar vortex in the winter of 2010-2011. The polar vortex was as usual in early winter, but was intensified twice in middle January and middle February, respectively, and remained anomalously strong and stable until early April, 2011. Record low polar temperatures and record high subpolar zonal winds occurred in February and March. Stratospheric wave activity was anomalously weak because waves were refracted equatorward by the anomalously strong polar night jet. With such an extremely cold and isolated environment, Arctic stratospheric ozone was largely depleted in March and early April, 2011. Corresponding to Arctic ozone depletion, the stratospheric Northern-Hemisphere Annular Mode (NAM) displayed anomalously strong high-polarity, and the positive stratospheric NAM propagated downward and led to anomalously strong positive NAM in the troposphere and near the surface.

关键词：北极地区平流层活动异常冬天旋涡臭氧损耗赤道异常臭氧耗损

Widening and weakening of the Hadley circulation under global warming

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Science Bulletin 2018年第10期63卷 640-644页

作者： yongyun hu Han huang Chen Zhou Laboratory for Climate and Ocean-Atmosphere Studies Department of Atmospheric and Oceanic SciencesSchool of PhysicsPeking University School of Atmospheric Sciences Nanjing University

The Hadley circulation is one of the most important atmospheric *** of the Hadley circulation has drawn extensive studies in the past *** key concern is that widening of the Hadley circulation would cause poleward shift of the subtropical dry *** metrics have been applied to measure the widening of the *** are responsible for the observed widening trends of the Hadley circulation? How anthropogenic and natural forcings caused the widening? How the widening results in regional climatic effects? These are the major questions in studing the widening of the Hadley *** both observations and simulations all show widening of the Hadley circulation in the past few decades,there are no general agreements of changes in the strength of the Hadley *** some reanalysis datasets show strengthening of the Hadley circulation,it was shown that the strengthening trend could be artificial,and simulations show weakening of the Hadley circulation for global greenhouse *** the present paper,we shall briefly review the major progresses of studies in trends in width and strength of the Hadley *** address answers to these questions,clarify inconsistent results,and propose ideas for future studies.

关键词： Hadley circulation Greenhouse gases Ozone depletion ENSO Global warming

Attribution of Biases of Interhemispheric Temperature Contrast in CMIP6 Models

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Advances in Atmospheric Sciences 2024年第2期41卷 325-340页

作者： Shiyan ZHANG yongyun hu Jiankai ZHANG Yan XIA Laboratory for Climate and Ocean-Atmosphere Studies Department of Atmospheric and Oceanic SciencesSchool of PhysicsPeking UniversityBeijing 100871China College of Atmospheric Sciences Lanzhou UniversityLanzhou 730000China School of Systems Science Beijing Normal UniversityBeijing 100875China

One of the basic characteristics of Earth's modern climate is that the Northern Hemisphere(NH) is climatologically warmer than the Southern Hemisphere(SH). Here, model performances of this basic state are examined using simulation results from 26 CMIP6 models. Results show that the CMIP6 models underestimate the contrast in interhemispheric surface temperatures on average(0.8 K for CMIP6 mean versus 1.4 K for reanalysis data mean), and that there is a large intermodel spread, ranging from -0.7 K to 2.3 K. A box model energy budget analysis shows that the contrast in interhemispheric shortwave absorption at the top of the atmosphere, the contrast in interhemispheric greenhouse trapping, and the crossequatorial northward ocean heat transport, are all underestimated in the multimodel mean. By examining the intermodel spread, we find intermodel biases can be tracked back to biases in midlatitude shortwave cloud forcing in AGCMs. Models with a weaker interhemispheric temperature contrast underestimate the shortwave cloud reflection in the SH but overestimate the shortwave cloud reflection in the NH, which are respectively due to underestimation of the cloud fraction over the SH extratropical ocean and overestimation of the cloud liquid water content over the NH extratropical *** that underestimate the interhemispheric temperature contrast exhibit larger double ITCZ biases, characterized by excessive precipitation in the SH tropics. Although this intermodel spread does not account for the multimodel ensemble mean biases, it highlights that improving cloud simulation in AGCMs is essential for simulating the climate realistically in coupled models.

关键词： interhemispheric temperature contrast energy balance shortwave cloud forcing ITCZ CMIP6 AGCM

Lower Stratospheric Water Vapor Variations Diagnosed from Satellite Observations,Reanalysis Data,and a Chemistry-Climate Model

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Journal of Meteorological Research 2021年第4期35卷 701-715页

作者： Yan XIA Yi huANG yongyun hu Jun YANG College of Global Change and Earth System Science Beijing Normal UniversityBeijing 100875China Key Laboratory of Middle Atmosphere and Global Environment Observation Institute of Atmospheric PhysicsChinese Academy of SciencesBeijing 100029China Department of Atmospheric and Oceanic Sciences McGill UniversityMontrealQuebec H3A 0B9、Canada Laboratory for Climate and Ocean-Atmosphere Studies Department of Atmospheric and Oceanic SciencesSchool of PhysicsPeking UniversityBeijing 100871China

Stratospheric water vapor variations,which may play an important role in surface climate,have drawn extensive ***,the variation in stratospheric water vapor is investigated by using data from observations of the Microwave Limb Sounder(MLS)on the Aura satellite,from the ECMWF Interim Reanalysis(ERAI),and simulations by the Whole Atmosphere Community Climate Model(WACCM).We find that the differences of annual mean stratospheric water vapor among these datasets may be partly caused by the differences in vertical *** budget analysis,we find that the upward transport of water vapor at 100 h Pa is mainly located over the Pacific warm pool region and South America in the equatorial tropics in boreal winter and over the southeast of the South Asian high and south of North America in boreal *** is found that temperature averaged over regions with upward transport is a better indicator of interannual variability of tropical mean stratospheric water vapor than the tropical mean *** seems that the distributions of the seasonal cycle amplitude of lower stratospheric water vapor in the tropics can also be impacted by the vertical *** radiative effects of the interannual changes in water vapor in the lowermost stratosphere are underestimated by approximately 29%in both ERAI and WACCM compared to MLS,although the interannual variations of water vapor in the lowermost stratosphere are dramatically overestimated in ERAI and *** results here indicate that the radiative effect of long-term changes in water vapor in the lowermost stratosphere may be underestimated in both ERAI and WACCM simulations.

关键词： stratospheric water vapor horizontal and vertical transport chemistry-climate model radiative effects interannual variations

Record Arctic Ozone Loss in Spring 2020 is Likely Caused by North Pacific Warm Sea Surface Temperature Anomalies

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Advances in Atmospheric Sciences 2021年第10期38卷 1723-1736页

作者： Yan XIA yongyun hu Jiankai ZHANG Fei XIE Wenshou TIAN College of Global Change and Earth System Science Beijing Normal UniversityBeijing 100875China Key Laboratory of Middle Atmosphere and Global Environment Observation Institute of Atmospheric PhysicsChinese Academy of SciencesBeijing 100029China Laboratory for Climate and Ocean-Atmosphere Studies Department of Atmospheric and Oceanic SciencesSchool of PhysicsPeking UniversityBeijing 100871China College of Atmospheric Sciences Lanzhou UniversityLanzhou 730000China

Record ozone loss was observed in the Arctic stratosphere in spring *** study aims to determine what caused the extreme Arctic ozone *** and simulation results are examined in order to show that the extreme Arctic ozone loss was likely caused by record-high sea surface temperatures(SSTs)in the North *** is found that the record Arctic ozone loss was associated with the extremely cold and persistent stratospheric polar vortex over February-April,and the extremely cold vortex was a result of anomalously weak planetary wave *** analysis reveals that the weak wave activity can be traced to anomalously warm SSTs in the North *** observations and simulations show that warm SST anomalies in the North Pacific could have caused the weakening of wavenumber-1 wave activity,colder Arctic vortex,and lower Arctic *** results suggest that for the present-day level of ozone-depleting substances,severe Arctic ozone loss could form again,as long as certain dynamic conditions are satisfied.

关键词： Arctic ozone loss stratospheric polar vortex sea surface temperature planetary-scale wave climate change

Assessment of Snow Depth over Arctic Sea Ice in CMIP6 Models Using Satellite Data

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Advances in Atmospheric Sciences 2021年第2期38卷 168-186页

作者： Shengzhe CHEN Jiping LIU Yifan DING Yuanyuan ZHANG Xiao CHENG yongyun hu Department of Atmospheric and Environmental Sciences University at AlbanyState University of New YorkAlbanyNY 12222USA College of Global Change and Earth System Science and State Key Laboratory of Remote Sensing ScienceBeijing Normal UniversityBeijing 100875China School of Geospatial Engineering and Science Sun Yat-sen UniversityZhuhai 519000China Southern Marine Science and Engineering Guangdong Laboratory(Zhuhai) Zhuhai 519000China Department of Atmospheric and Oceanic Sciences School of PhysicsPeking UniversityBeijing 100871China University Corporation for Polar Research Beijing 100875China

Snow depth over sea ice is an essential variable for understanding the Arctic energy *** this study,we evaluate snow depth over Arctic sea ice during 1993-2014 simulated by 31 models from phase 6 of the Coupled Model Intercomparison Project(CMIP6)against recent satellite *** CMIP6 models capture some aspects of the observed snow depth climatology and *** observed variability lies in the middle of the models’*** the models show negative trends of snow depth during ***,substantial spatiotemporal discrepancies are *** to the observation,most models have late seasonal maximum snow depth(by two months),remarkably thinner snow for the seasonal minimum,an incorrect transition from the growth to decay period,and a greatly underestimated interannual variability and thinning trend of snow depth over areas with frequent occurrence of multi-year sea *** models are unable to reproduce the observed snow depth gradient from the Canadian Arctic to the outer areas and the largest thinning rate in the central *** projections suggest that snow depth in the Arctic will continue to decrease from 2015 to *** the SSP5-8.5 scenario,the Arctic will be almost snow-free during the summer and fall and the accumulation of snow starts from *** investigation into the possible causes of the issues for the simulated snow depth by some models based on the same family of models suggests that resolution,the inclusion of a hightop atmospheric model,and biogeochemistry processes are important factors for snow depth simulation.

关键词： snow depth Arctic sea ice CMIP6 satellite projection

Stratospheric Ozone-induced Cloud Radiative Effects on Antarctic Sea Ice

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Advances in Atmospheric Sciences 2020年第5期37卷 505-514页

作者： Yan XIA yongyun hu Jiping LIU Yi huANG Fei XIE Jintai LIN Laboratory for Climate and Atmosphere–Ocean Studies Department of Atmospheric and Oceanic SciencesSchool of PhysicsPeking UniversityBeijing 100871China Department of Atmospheric and Environmental Sciences University at AlbanyState University of New YorkAlbanyNY 12222US Department of Atmospheric and Oceanic Sciences McGill UniversityMontrealCanada College of Global Change and Earth System Science Beijing Normal UniversityBeijing 100875China

Recent studies demonstrate that the Antarctic Ozone Hole has important influences on Antarctic sea *** most of these works have focused on effects associated with atmospheric and oceanic dynamic processes caused by stratospheric ozone changes,here we show that stratospheric ozone-induced cloud radiative effects also play important roles in causing changes in Antarctic sea *** simulations demonstrate that the recovery of the Antarctic Ozone Hole causes decreases in clouds over Southern Hemisphere(SH)high latitudes and increases in clouds over the SH *** decrease in clouds leads to a reduction in downward infrared radiation,especially in austral *** results in cooling of the Southern Ocean surface and increasing Antarctic sea *** cooling also involves ice-albedo *** sea ice reflects solar radiation and causes further cooling and more increases in Antarctic sea ice.

关键词： stratospheric ozone recovery Antarctic sea ice cloud radiative effects ice-albedo feedback climate change

The Walker Circulation shaped by tectonics

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National Science Review 2021年第5期8卷 22-22页

作者： yongyun hu Department of Atmospheric and Oceanic Sciences School of PhysicsPeking University

The Walker Circulation is a thermally driven tropical atmospheric circulation in the longitudinal direction. At present, the ascending branch of the Walker Circulation is over the warm pool in the tropical western Pacific and the descending branch is over the tropical eastern Pacific where sea-surface temperatures(SSTs) are cooler. How could the Walker Circulation be a few tens of million years ago (Ma)? How did it evolve over tectonic time scales?

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