Characteristics and Mechanism of the 10–20-Day Oscillation of Spring Rainfall over Southern China

2013 ◽  
Vol 26 (14) ◽  
pp. 5072-5087 ◽  
Author(s):  
Weijuan Pan ◽  
Jiangyu Mao ◽  
Guoxiong Wu
Keyword(s):  
Tibetan Plateau ◽  
Southern China ◽  
Thermal Structure ◽  
Wave Train ◽  
Lower Troposphere ◽  
Rain Gauge ◽  
Department Of Energy ◽  
The Tibetan Plateau ◽  
Driving Mechanisms ◽  
Intraseasonal Oscillations

Abstract The intraseasonal oscillations (ISOs) of southern China spring rainfall (SCSR) are examined based on daily rain gauge rainfall data and NCEP/Department of Energy Reanalysis 2 (NCEP-2) products for the period 1980–2008. The objective of this study is to reveal the structure and propagation of the dominant ISO of SCSR as well as its driving mechanisms, thereby gaining an understanding of the causes of extreme wet and dry SCSR. The EOF analysis and power spectrum analysis show that the 10–20-day oscillation is a predominant ISO of SCSR in most years. Composite analyses and wave-activity propagation diagnosis demonstrate that the 10–20-day oscillation of SCSR is characterized by an alternate occurrence of a huge anomalous anticyclone (cyclone) encircling the Tibetan Plateau in the lower troposphere, with anomalous low-level northeasterly (southwesterly) winds prevailing over southern China, producing lower-tropospheric divergence (convergence). In the middle and upper troposphere, the oscillation appears as a southeastward propagating coherent wave train made up of a series of anomalous cyclones and anticyclones, which are aligned in a northwest–southeast direction. This whole wave train also drifts eastward, with strong upper-tropospheric convergence (divergence) alternately superimposed over the lower-tropospheric divergence (convergence) within and south of the Yangtze basin, resulting in deficient (excessive) rainfall in southern China. The thermal structure of the 10–20-day ISO of SCSR and its association with the mechanical–thermal forcing of the Tibetan Plateau are also explored.

Impact of Boreal Autumn Antarctic Oscillation on Winter Wet and Cold Weather in East Asia

2021 ◽  
Author(s):  
Zhengxuan Yuan ◽  
Jun Qin ◽  
Shuanglin Li ◽  
Sijing Huang ◽  
Yassin Mbululo ◽  
...  
Keyword(s):  
Southern China ◽  
Wave Train ◽  
Yangtze River Basin ◽  
Air Flow ◽  
Lower Troposphere ◽  
Dominant Mode ◽  
Cold Weather ◽  
Occurrence Rate ◽  
Antarctic Oscillation ◽  
Quasi Biennial Oscillation

<p>The Antarctic Oscillation (AAO) is the dominant mode of the southern extratropical atmospheric mass variability which has potential influences on the Northern Hemisphere (NH). This study reveals a significantly negative correlation between the September-October (SO) AAO index and the occurrence rate of following January-February (JF) wet and cold weather in the Middle and Lower Reaches of Yangtze River Basin (MLRY) in China. The latter is quantified by a Precipitation-Temperature (PT) Index. JF PT is modulated by both northerly air flow in the lower troposphere and southerly air flow in the lower-middle troposphere. The SO AAO stimulates Southern Ocean Dipole (SOD) pattern-like SST anomalies, which induces a North Atlantic Oscillation (NAO)-like atmospheric response in the following JF through ocean-air interaction. As for the northerly flow, the JF NAO-like pattern triggers an eastward propagating wave train, influencing the intensity of East Asian Winter Monsoon (EAWM) and subsequently the northerly cold flow to MLRY. As for southerly flow, the variation of JF SOD regulates the local meridional cell, in turn modulating the Middle East Jet Stream (MEJS) along with the NAO-like pattern, influencing the intensity of precipitation and the wet and warm flow over Southern China and the adjacent regions. In addition to the tropospheric processes, the stratospheric Quasi Biennial Oscillation (QBO) serves as the ‘bridge’ for linking SOD to NH climate, inducing the JF PT response to SOD SST. To summarize, SO AAO affects the JF PT in MLRY by modulating both cold-dry northerly air flow and warm-wet southerly air flow through ocean-atmosphere interactions and stratospheric pathway.</p>

The Influence of Mechanical and Thermal Forcing by the Tibetan Plateau on Asian Climate

2007 ◽  
Vol 8 (4) ◽  
pp. 770-789 ◽  
Author(s):  
Guoxiong Wu ◽  
Yimin Liu ◽  
Qiong Zhang ◽  
Anmin Duan ◽  
Tongmei Wang ◽  
...  
Keyword(s):  
Tibetan Plateau ◽  
East Asia ◽  
South China ◽  
Local Heating ◽  
Lower Troposphere ◽  
Early Spring ◽  
The Tibetan Plateau ◽  
Continental Scale ◽  
The North ◽  
Meridional Winds

Abstract This paper attempts to provide some new understanding of the mechanical as well as thermal effects of the Tibetan Plateau (TP) on the circulation and climate in Asia through diagnosis and numerical experiments. The air column over the TP descends in winter and ascends in summer and regulates the surface Asian monsoon flow. Sensible heating on the sloping lateral surfaces appears from the authors’ experiments to be the major driving source. The retarding and deflecting effects of the TP in winter generate an asymmetric dipole zonal-deviation circulation, with a large anticyclone gyre to the north and a cyclonic gyre to the south. Such a dipole deviation circulation enhances the cold outbreaks from the north over East Asia, results in a dry climate in south Asia and a moist climate over the Indochina peninsula and south China, and forms the persistent rainfall in early spring (PRES) in south China. In summer the TP heating generates a cyclonic spiral zonal-deviation circulation in the lower troposphere, which converges toward and rises over the TP. It is shown that because the TP is located east of the Eurasian continent, in summertime the meridional winds and vertical motions forced by the Eurasian continental-scale heating and the TP local heating are in phase over the eastern and central parts of the continent. The monsoon in East Asia and the dry climate in middle Asia are therefore intensified.

scholarly journals Assessment of the GPM and TRMM Precipitation Products Using the Rain Gauge Network over the Tibetan Plateau

2018 ◽  
Vol 32 (2) ◽  
pp. 324-336 ◽  
Author(s):  
Sijia Zhang ◽  
Donghai Wang ◽  
Zhengkun Qin ◽  
Yaoyao Zheng ◽  
Jianping Guo
Keyword(s):  
Tibetan Plateau ◽  
Rain Gauge ◽  
The Tibetan Plateau ◽  
Trmm Precipitation ◽  
Rain Gauge Network

scholarly journals MAX-DOAS measurements of NO<sub>2</sub>, SO<sub>2</sub>, HCHO, and BrO at the Mt. Waliguan WMO GAW global baseline station in the Tibetan Plateau

2020 ◽  
Vol 20 (11) ◽  
pp. 6973-6990 ◽  
Author(s):  
Jianzhong Ma ◽  
Steffen Dörner ◽  
Sebastian Donner ◽  
Junli Jin ◽  
Siyang Cheng ◽  
...  
Keyword(s):  
Tibetan Plateau ◽  
Trace Gases ◽  
Elevation Angle ◽  
Lower Troposphere ◽  
Statistical Error ◽  
Tropospheric Chemistry ◽  
Ozone Production ◽  
Optical Absorption Spectroscopy ◽  
The Tibetan Plateau ◽  
Mixing Ratios

Abstract. Mt. Waliguan Observatory (WLG) is a World Meteorological Organization (WMO) Global Atmosphere Watch (GAW) global baseline station in China. WLG is located at the northeastern part of the Tibetan Plateau (36∘17′ N, 100∘54′ E, 3816 m a.s.l.) and is representative of the pristine atmosphere over the Eurasian continent. We made long-term ground-based multi-axis differential optical absorption spectroscopy (MAX-DOAS) measurements at WLG during the period 2012–2015. In this study, we retrieve the differential slant column densities (dSCDs) and estimate the tropospheric background mixing ratios of different trace gases, including NO2, SO2, HCHO, and BrO, using the measured spectra at WLG. Averaging of 10 original spectra is found to be an “optimum option” for reducing both the statistical error of the spectral retrieval and systematic errors in the analysis. The dSCDs of NO2, SO2, HCHO, and BrO under clear-sky and low-aerosol-load conditions are extracted from measured spectra at different elevation angles at WLG. By performing radiative transfer simulations with the model TRACY-2, we establish approximate relationships between the trace gas dSCDs at 1∘ elevation angle and the corresponding average tropospheric background volume mixing ratios. Mixing ratios of these trace gases in the lower troposphere over WLG are estimated to be in a range of about 7 ppt (January) to 100 ppt (May) for NO2, below 0.5 ppb for SO2, between 0.4 and 0.9 ppb for HCHO, and lower than 0.3 ppt for BrO. The chemical box model simulations constrained by the NO2 concentration from our MAX-DOAS measurements show that there is a little net ozone loss (−0.8 ppb d−1) for the free-tropospheric conditions and a little net ozone production (0.3 ppb d−1) for the boundary layer conditions over WLG during summertime. Our study provides valuable information and data sets for further investigating tropospheric chemistry in the background atmosphere and its links to anthropogenic activities.

Drying Tendency over the Southern Tibetan Plateau in Recent Past Decades

2020 ◽  
Author(s):  
Ziqian Wang ◽  
Song Yang ◽  
Anmin Duan
Keyword(s):  
Tibetan Plateau ◽  
Asian Summer Monsoon ◽  
Wave Train ◽  
Dynamic Change ◽  
Internal Variability ◽  
The Tibetan Plateau ◽  
Southern Slope ◽  
South Asian Summer Monsoon ◽  
Budget Analysis ◽  
Upper Level

&lt;p&gt;The Tibetan Plateau (TP) exerts a significant impact on the weather and climate over many places of the world through both mechanical and thermal-dynamical effects. In summer, the major rainfall of the TP occurs over the southern slope, and the associated atmospheric latent heating dominates the total diabatic heating of TP. Then the variation of summer rainfall can directly regulate the TP&amp;#8217;s thermal effects. On the other hand, the rainfall center over the southern slope is corresponding with the northern branch of South Asian summer monsoon, which is important to the agricultural productivity and economic stability along the Ganges River with dense population. This study shows that there existed a drying tendency over the southern TP (STP) in the rainy season of recent decades. A moisture budget analysis indicates that the dynamic change in vertical moisture advection is the dominant contributor to the drying trend, which is associated with the weakened upward motion over the STP. The changes in dynamic process over STP are induced by the northward shift of the subtropical westerly jet, whose northward shift reduces the upper-level anticyclone over STP and weakens the upper-level divergence, leading to a trend of vertical sinking motion. Furthermore, the northward shift of the jet is mainly attributed to the internal variability of the atmosphere, characterized by an upper-level circum-global wave train. The influence of atmospheric internal variability is demonstrated by the CESM Large Ensemble Project data.&lt;/p&gt;

scholarly journals High-resolution ensemble projections and uncertainty assessment of regional climate change over China in CORDEX East Asia

2018 ◽  
Vol 22 (5) ◽  
pp. 3087-3103 ◽  
Author(s):  
Huanghe Gu ◽  
Zhongbo Yu ◽  
Chuanguo Yang ◽  
Qin Ju ◽  
Tao Yang ◽  
...  
Keyword(s):  
Climate Change ◽  
Tibetan Plateau ◽  
Model Uncertainty ◽  
Climate Models ◽  
Southern China ◽  
Regional Climate ◽  
Regional Climate Change ◽  
Internal Variability ◽  
Northeastern China ◽  
The Tibetan Plateau

Abstract. An ensemble simulation of five regional climate models (RCMs) from the coordinated regional downscaling experiment in East Asia is evaluated and used to project future regional climate change in China. The influences of model uncertainty and internal variability on projections are also identified. The RCMs simulate the historical (1980–2005) climate and future (2006–2049) climate projections under the Representative Concentration Pathway (RCP) RCP4.5 scenario. The simulations for five subregions in China, including northeastern China, northern China, southern China, northwestern China, and the Tibetan Plateau, are highlighted in this study. Results show that (1) RCMs can capture the climatology, annual cycle, and interannual variability of temperature and precipitation and that a multi-model ensemble (MME) outperforms that of an individual RCM. The added values for RCMs are confirmed by comparing the performance of RCMs and global climate models (GCMs) in reproducing annual and seasonal mean precipitation and temperature during the historical period. (2) For future (2030–2049) climate, the MME indicates consistent warming trends at around 1 ∘C in the entire domain and projects pronounced warming in northern and western China. The annual precipitation is likely to increase in most of the simulation region, except for the Tibetan Plateau. (3) Generally, the future projected change in annual and seasonal mean temperature by RCMs is nearly consistent with the results from the driving GCM. However, changes in annual and seasonal mean precipitation exhibit significant inter-RCM differences and possess a larger magnitude and variability than the driving GCM. Even opposite signals for projected changes in average precipitation between the MME and the driving GCM are shown over southern China, northeastern China, and the Tibetan Plateau. (4) The uncertainty in projected mean temperature mainly arises from the internal variability over northern and southern China and the model uncertainty over the other three subregions. For the projected mean precipitation, the dominant uncertainty source is the internal variability over most regions, except for the Tibetan Plateau, where the model uncertainty reaches up to 60 %. Moreover, the model uncertainty increases with prediction lead time across all subregions.

Roles of Anomalous Tibetan Plateau Warming on the Severe 2008 Winter Storm in Central-Southern China

2010 ◽  
Vol 138 (6) ◽  
pp. 2375-2384 ◽  
Author(s):  
Qing Bao ◽  
Jing Yang ◽  
Yimin Liu ◽  
Guoxiong Wu ◽  
Bin Wang
Keyword(s):  
Tibetan Plateau ◽  
General Circulation ◽  
Extreme Event ◽  
Southern China ◽  
Inversion Layer ◽  
Circulation Model ◽  
Central China ◽  
The Tibetan Plateau ◽  
Freezing Rain ◽  
Mean Sea Surface

Abstract Anomalous warming occurred over the Tibetan Plateau (TP) before and during the disastrous freezing rain and heavy snow hitting central and southern China in January 2008. The relationship between the TP warming and this extreme event is investigated with an atmospheric general circulation model. Two perpetual runs were performed. One is forced by the climatological mean sea surface temperatures in January as a control run; and the other has the same model setting as the control run except with an anomalous warming over the TP that mimics the observed temperature anomaly. The numerical results demonstrate that the TP warming induces favorable circulation conditions for the occurrence of this extreme event, which include the deepened lower-level South Asian trough, the enhanced lower-level southwesterly moisture transport in central-southern China, the lower-level cyclonic shear in the southerly flow over southeastern China, and the intensified Middle East jet stream in the middle and upper troposphere. Moreover, the anomalous TP warming results in a remarkable cold anomaly near the surface and a warm anomaly aloft over central China, forming a stable stratified inversion layer that favors the formation of the persistent freezing rain. The possible physical linkages between the TP warming and the relevant resultant circulation anomalies are proposed. The potential reason of the anomalous TP warming during the 2007–08 winter is also discussed.

scholarly journals Influence of Tibetan Plateau On The North American Summer Monsoon Precipitation

2021 ◽  
Author(s):  
Qin Wen ◽  
Zixuan Han ◽  
Hajun Yang ◽  
Jianbo Cheng ◽  
Zhengyu Liu ◽  
...  
Keyword(s):  
Tibetan Plateau ◽  
Summer Monsoon ◽  
North Atlantic ◽  
North American ◽  
Wave Train ◽  
Meridional Overturning Circulation ◽  
Hadley Cell ◽  
Dynamical Process ◽  
The Tibetan Plateau ◽  
The North

Abstract It has been well known that the uplift of the Tibetan Plateau (TP) can significantly enhance the Asian monsoon. Here, by comparing the sensitivity experiments with vs without the TP, we find that TP uplift can also increase the precipitation of North American Summer Monsoon (NASM), with atmosphere teleconnection accounting for 6% and oceanic dynamical process accounting for another 6%. Physically, TP uplift generates a stationary Rossby wave train traveling from Asian continent to the North Atlantic region, resulting in an anomalous high-pressure over tropical-subtropical North Atlantic. The anomalous subtropical high enhances the low level southerly winds, forcing an anomalous upward motion over North American monsoon (NAM) region and then an increased summer precipitation there. In addition, TP uplift enhances the Atlantic meridional overturning circulation, which reduces the meridional temperature gradient and leads to a northward shift of Hadley Cell over eastern Pacific-Atlantic section. The latter shifts the convection center northward to 10°N and further increases the NASM precipitation. The enhanced NASM precipitation can also be understood by the northward shift of Intertropical Convergence Zone. Our study implies that the changes of NAM climate can be affected by not only local process but also remote forcing, including the Asian highland.

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