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The super-cycle of the global land-monsoon system

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National Science Review 2024年第5期11卷 107-109页

作者： Yongyun Hu Laboratory for Climate and Ocean-Atmosphere studies Department of Atmospheric and Oceanic Sciences School of Physics Peking University

The modern monsoon system consists of six regional monsoons [1]. These regional monsoons demonstrate coherently annual variations of precipitation and atmospheric circulation patterns, although they have different characteristics. Therefore, these regional monsoons are unified in the context of the global monsoon [1,2], which reflects the dominant mode of coherent annual variations of precipitation and atmospheric circulations in the tropics and subtropics.

关键词： global system land-monsoon super-cycle

The Predictability of a Squall Line in South China on 23 April 2007

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Advances in Atmospheric Sciences 2013年第2期30卷 485-502页

作者：吴多常孟智勇严大春 Laboratory for Climate and Ocean-Atmosphere studies Department of Atmospheric and Oceanic Sciences School of PhysicsPeking University

This study investigated the predictability of a squall line associated with a quasi-stationary front on 23 April 2007 in South China through deterministic and probabilistic forecasts. Our results show that the squallline simulation was very sensitive to model error from horizontal resolution and uncertainties in physical parameterization schemes. At least a 10-km grid size was necessary to decently capture this squall line. The simulated squall line with a grid size of 4.5 km was most sensitive to long-wave radiation parameterization schemes relative to other physical schemes such as microphysics and planetary boundary layer. For a grid size from 20 to 5 km, a cumulus parameterization scheme degraded the squall-line simulation （relative to turning it off）, with a more severe degradation to grid size -10 km than 〉10 km. The sensitivity of the squall-line simulation to initial error was investigated through ensemble forecast. The performance of the ensemble simulation of the squall line was very sensitive to the initial error. Approximately 15% of the ensemble members decently captured the evolution of the squall line, 25% failed, and 60% dislocated the squall line. Using different combinations of physical parameterization schemes for different members can improve the probabilistic forecast. The lead time of this case was only a few hours. Error growth was clearly associated with moist convection development. A linear improvement in the performance of the squall line simulation was observed when the initial error was decreased gradually, with the largest contribution from initial moisture field.

关键词： squall line predictability South China ensemble moisture

TIDAL FEATURES IN THE CHINA SEAS AND THEIR ADJACENT SEA AREAS AS DERIVED FROM TOPEX/POSEIDON ALTIMETER DATA

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Chinese Journal of Oceanology and Limnology 2001年第4期19卷 293-305页

作者：胡建宇 Hiroshi KAWAMURA 洪华生 Fumiaki KOBASⅢ 谢强 Marine Environmental Laboratory of the Ministry of Education College of Oceanography and Environmental ScienceXiamen University centerforatmospheric and oceanic studies Faculty of Science Tohoku University Sendai South China Sea Institute of Oceanology Chinese Academy of Sciences

Some important tidal features of 8 major tidal constituents ( M 2, S 2, K 1, O 1, P 1, Sa, N 2 and K 2 ) in the China Seas and their adjacent sea areas were obtained using six years’ TOPEX/POSEIDON altimeter data. The results showed that the obtained co tidal and co range charts for these major tidal constituents agreed well with those of previous researches using observational data from coastal tidal gauge stations and numerical models.

关键词： TOPEX/POSEIDON altimeter data tidal features the China Seas tidal features

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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Impact of assimilating Taiwan＇s coastal radar radial velocity on forecasting Typhoon Morakot (2009) in southeastern China using a WRF-based EnKF

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Science China Earth Sciences 2017年第2期60卷 315-327页

作者： YUE Jian MENG ZhiYong Laboratory for Climate and Ocean-Atmosphere studies Department of Atmospheric and Oceanic Sciences School of Physics Peking University Beij'ing 100871 China

This study explores for the first time the impact of assimilating radial velocity(Vr)observations from a single or multiple Taiwan's coastal radars on tropical cyclone(TC)forecasting after landfall in the Chinese mainland by using a Weather Research and Forecasting model(WRF)-based ensemble Kalman filter(EnKF)data assimilation *** Morakot(2009),which caused widespread damage in the southeastern coastal regions of the mainland after devastating Taiwan,was chosen as a case *** results showed that assimilating Taiwan's radar Vr data improved environmental field and steering flow and produced a more realistic TC position and structure in the final EnKF cycling ***,the subsequent TC track and rainfall forecasts in southeastern China were *** addition,better observations of the TC inner core by Taiwan's radar was a primary factor in improving TC rainfall forecast in the Chinese mainland.

关键词： Radial velocity EnKF TC track forecast Rainfall forecast Chinese mainland

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

Soil Moisture Effects on Sand Saltation and Dust Emission Observed over the Horqin Sandy Land Area in China

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Journal of Meteorological Research 2014年第3期28卷 444-452页

作者：李晓岚张宏升 Laboratory for Climate and Ocean-Atmosphere studies Department of Atmospheric and Oceanic SciencesSchool of Physics Peking University

In this study, the eff ects of soil moisture on sand saltation and dust emission over the Horqin Sandy Land area are investigated, based on observations of three dust events in 2010. The minimum friction velocity initiating the motion of surface particles, namely, the threshold friction velocity, is estimated to be 0.34, 0.40, and 0.50 m s？1 under the very dry, dry, and wet soil conditions, respectively. In comparison with the observations during the dust events under the very dry and dry soil conditions, the dust emission fl ux during the wet event is smaller, but the saltation activities of sand particles （d≧50 μm） are stronger. The size distributions of airborne dust particles （0.1≦d≦20 μm） show that concentrations of the fi ner dust particles （0.1≦d≦0.3 μm） have a secondary peak under dry soil conditions, while they are absent under wet soil conditions. This suggests that the surface soil particle size distribution can be changed by soil moisture. Under wet soil conditions, the particles appear to have a larger size, and hence more potential saltating particles are available. This explains the occurrence of stronger saltation processes observed under wet soil conditions.

关键词： soil moisture sand saltation dust emission Horqin Sandy Land area

Review of the Field Measurements and Parameterization for Dust Emission During Sand-Dust Events

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Journal of Meteorological Research 2014年第5期28卷 903-922页

作者：张宏升李晓岚 Laboratory for Climate and Ocean-Atmosphere studies Department of Atmospheric and Oceanic SciencesSchool of PhysicsPeking University

Dust emission generated by wind erosion is a basic process before the transport and deposition of dust particles. Parameterization of dust emission flux is important for accurate simulation and prediction of dust events. Field observation and numerical simulation are two approaches to understand the complex process of dust emission. Great progress has been made on the characteristics and mechanism of dust emission during dust storm events. This review introduces the major factors influencing dust emission and summarizes the calculation methods of several key parameters of dust emission, including the threshold friction velocity u.t, threshold wind speed Ut, streamwise saltation flux Q, and （vertical） dust emission flux F, from perspectives of both observation and parameterization. The paper also discusses the improvement, application, and validation of different dust emission schemes in dust models. Existing problems and future research directions are elaborated as well.

关键词： dust emission by wind erosion dust storm experimental observation parameterization

The Characteristics of Turbulence Structure and Transfer over the Middle Area of the Tibetan Plateau

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Atmospheric and oceanic Science Letters 2013年第2期6卷 67-73页

作者： LI Fu-Yu LI Xiao-Lan ZHANG Hong-Sheng Department of Atmospheric and oceanic Sciences & Laboratory for Climate and Ocean-Atmosphere studies Peking University

In this paper, turbulent data obtained from the Damxung site during the Secondary Tibetan Plateau Science Experiment (TIPEX) in 1998 are used to study the characteristics of the turbulent spectra, turbulence transport, and the dissipation rates of turbulent kinetic energy, temperature variance, and humidity variance in the middle area of the Tibetan Plateau. The turbulent spectra of wind velocity, potential temperature, and humidity satisfy the-2/3 power law in the high frequency range. Horizontal transportation of heat and water vapor is negligible compared with vertical transportation under strong unstable conditions, and as the stability parameter z/L increases (where z is the observational height, and L is the Monin Obukhov length), horizontal transportation becomes dominant under near-neutral, neutral, and stable conditions. The non-dimensional temperature and humidity variances are 20% less than the temperature and humidity gradient variances. These deficits appear to increase as the absolute stability parameter increases. Moreover, the effects of turbulence transportation and pressure variance exist throughout the entire stability region.

关键词： turbulence structure turbulence transfer dissipation rate observational method Tibetan Plateau