Calculation of Solar Albedo and Radiation Equilibrium over the Qinghai-Xizang Plateau and Analysisof Their Climatic Features

Using radiation data from the Automatic Weather Stations (AWSs) for thermal balance obser-vations, which were set up at Lhasa, Nagqu, Xigaze and Nyingchi by the Sino-Japanese Asian Monsoon Mechanism Co-operative Project in 1993–1996, and 1985–1989 Earth Radiation Balance Experiment (ERBE) measurements of Langley Research Center/NASA of US, and 1961–1996 monthly mean data from 148 surface stations over the Qinghai-Xizang Plateau (QXP) and its neighborhood, study is performed on empirical calculation methods of surface albedo, surface total radiation, planetary albedo and outgoing longwave radiation with the climatic features of radiation balance at the surface and the atmospheric top examined. Evidences suggest that the empirical formulae for surface albedo, planetary albedo, surface to-tal radiation and outgoing longwave radiation from the atmospheric top are capable of describing their seasonal and interannual variations over the QXP. The surface albedo is marked by noticeable seasonal variation and yearly mean of 0.22 with the maximum of 0.29 in January and minimum of 0.17 in July and August; in winter the albedo has great horizontal difference, bigger in the moun-tains than in the river valleys, and small in summer. The planetary albedo shows a smaller range of its annual variation with the yearly mean of 0.37, the maximum (minimum) occurring in February and March (autumn). In winter its high-value regions are mainly at Gar (Shiquanhe) in the western QXP and from the southwestern Qinghai to the northeastern Tibet and the low-value area at the northern slope of the central Himalayas; in summer, however, the albedo distribution displays clear-ly a progressive decrease from southeast to northwest. As for the surface total radiation, its values and annual varying range are smaller in the east than in the southwest. Its high-value center is at the southern slope of the Himalayas in winter and makes a conspicuous westward migration in spr-ing, remaining there for a long time, and it begins to retreat eastward in autumn. Monthly mean values of the surface net radiation are all positive and larger in summer than in winter. The net ra-diation is significantly intensified under the combined effect of surface total radiation and surface albedo from spring to early summer, resulting in the strongest sector in the mid plateau with its center staying nearly motionless from March to September, and is reduced in autumn dominantly by surface effective radiation. The earth-atmosphere system loses heat outward from October to next February and gains in other months. On an average, the plateau gains heat of 15 W m-2 on an annual basis. Key words The Qinghai-Xizang Plateau - Albedo - Radiation balance - Climatic feature (1)This work was supported under the auspices of the National (G1998040800) and CAS’s Key Project for Basic Research on Tibetan Plateau (KZ951-A1-204; KZ95T-06).

STUDY ON CLIMATIC FEATURES OF SURFACE TURBULENT HEAT EXCHANGE COEFFICIENTS AND SURFACE THERMAL SOURCES OVER THE QINGHAI-XIZANG PLATEAU

Using monthly mean of surface turbulent heat exchange coefficients calculated based on data from four automatic weather stations(AWS)for thermal equilibrium observation in July 1993— September 1996 and of surface conventional measurements,an empirical expression is established for such coefficients.With the expression,the heat exchange coefficients and the components of surface thermal source are computed in terms of 1961—1990 monthly mean conventional data from 148 stations over the Qinghai-Xizang(Tibetan)Plateau(QXP)and its adjoining areas,and the 1961—1990 climatic means are examined. Evidence suggests that the empirical expression is capable of showing the variation of the heat exchange coefficient in a climatic context.The monthly variation of the coefficients averaged over the QXP is in a range of 4×10^(-3)-5×10^(-3).The wintertime values are bigger in the mountains than in the valleys and reversal in summer.Surface effective radiation and sensible heat are the dominant factors of surface total heat.In spring surface sensible heat is enhanced quickly, resulting in two innegligible regions of sensible heat,one in the west QXP and the other in northern Tibet.with their maximums emerging in different months.In spring and summer sensible heat and surface effective radiation are higher in the west than in the east.The effective radiation peaks for the east in October—December and the whole QXP and in June and October for the west.The surface total heat of the plateau maximizes in May.minimizes in December and January,and shows seasonal variation more remarkable in the SW compared to the eastern part.In the SW plateau the total heat is much more intense than the eastern counterpart in all the seasons except winter.Under the effect of the sensible heat,the total heat on the SW plateau starts to considerably intensify in February,which leads to a predominant heating region in the west,with its center experiencing a noticeable westward migration early in summer and twice pronounced weakening in July and after October.However,the weakening courses are owing to different causes.The total heat over the north of QXP is greatly strengthened in March.thus generating another significant thermal region in the plateau.

Future changes in precipitation and water availability over the Tibetan Plateau projected by CMIP6 models constrained by climate sensitivity

Precipitation projections over the Tibetan Plateau(TP)show diversity among existing studies,partly due to model uncertainty.How to develop a reliable projection remains inconclusive.Here,based on the IPCC AR6–assessed likely range of equilibrium climate sensitivity(ECS)and the climatological precipitation performance,the authors constrain the CMIP6(phase 6 of the Coupled Model Intercomparison Project)model projection of summer precipitation and water availability over the TP.The best estimates of precipitation changes are 0.24,0.25,and 0.45 mm d^(−1)(5.9%,6.1%,and 11.2%)under the Shared Socioeconomic Pathway(SSP)scenarios of SSP1–2.6,SSP2–4.5,and SSP5–8.5 from 2050–2099 relative to 1965–2014,respectively.The corresponding constrained projections of water availability measured by precipitation minus evaporation(P–E)are 0.10,0.09,and 0.22 mm d^(−1)(5.7%,4.9%,and 13.2%),respectively.The increase of precipitation and P–E projected by the high-ECS models,whose ECS values are higher than the upper limit of the likely range,are about 1.7 times larger than those estimated by constrained projections.Spatially,there is a larger increase in precipitation and P–E over the eastern TP,while the western part shows a relatively weak difference in precipitation and a drier trend in P–E.The wetter TP projected by the high-ECS models resulted from both an approximately 1.2–1.4 times stronger hydrological sensitivity and additional warming of 0.6℃–1.2℃ under all three scenarios during 2050–2099.This study emphasizes that selecting climate models with climate sensitivity within the likely range is crucial to reducing the uncertainty in the projection of TP precipitation and water availability changes.

The Tibetan Plateau bridge:Influence of remote teleconnections from extratropical and tropical forcings on climate anomalies

本文回顾了青藏高原桥梁作用方面的最新研究进展,涉及北大西洋气候异常对春,夏亚洲季风和厄尔尼诺-南方涛动(ENSO)事件的遥相关影响,热带海洋异常和中国东部极端气候异常之间的联系以及华南春雨的季节内变化等.介绍了年际时间尺度上,冬-春季北大西洋海表温度强迫如何影响南亚季风的季节性转变以及随后ENSO事件的触发.5月份青藏高原上空显著的负感热斜压结构,为北大西洋影响亚洲季风和ENSO提供了桥梁效应,夏季北大西洋涛动与华东夏季降水变化显著相关,高原潜热在这一关系中起着桥梁作用.另一方面,这种高原桥梁效应也存在于从热带海洋异常到东亚夏季极端降水事件的连接中,以及从中纬度波列到华南春雨准双周振荡的联系中.

The Characteristics of Climate Change over the Tibetan Plateau in the Last 40 Years and the Detection of Climatic Jumps

Through analyzing the yearly average data obtained from 123 regular meteorological observatories located in the Tibetan Plateau (T-P), this article studies the characteristics of climate change in T-P in the last 40 years. Prom the distribution of the linear trend, it can be concluded that the southeastern part of T-P becomes warmer and wetter, with an obvious increase of rainfall. The same characteristics are found in the southwestern part of T-P, but the shift is smaller. In the middle of T-P, temperature and humidity obviously increase with the center of the increase in Bangoin-Amdo. The south of the Tarim Basin also exhibits the same tendency. The reason for this area being humid is that it gets less sunshine and milder wind. The northeastern part of T-P turns warmer and drier. Qaidam Basin and its western and southern areas are the center of this shift, in which the living environment is deteriorating. Analyzing the characteristics of the regional average time series, it can be found that in the mid-1970s, a significant sudden change occurred to annual rainfall, yearly average snow-accumulation days and surface pressure in the eastern part of T-P. In the mid-1980s, another evident climatic jump happened to yearly average temperature, total cloud amount, surface pressure, relative humidity, and sunshine duration in the same area. That is, in the mid 1980s, the plateau experienced a climatic jump that is featured by the increase of temperature, snow-accumulation days, relative humidity, surface pressure, and by the decrease of sunshine duration and total cloud amount. The sudden climatic change of temperature in T-P is later than that of the global-mean temperature. Prom this paper it can be seen that in the middle of the 1980s, a climatic jump from warm-dry to warm-wet occurred in T-P.

Climatic trends over the Tibetan Plateau during 1971-2000

Trends of annual and monthly temperature, precipitation, potential evapotranspiration and aridity index were analyzed to understand climate change during the period 1971-2000 over the Tibetan Plateau which is one of the most special regions sensitive to global climate change. FAO56-Penmen-Monteith model was modified to calculate potential evapotranspiration which integrated many climatic elements including maximum and minimum temperatures, solar radiation, relative humidity and wind speed. Results indicate generally warming trends of the annual averaged and monthly temperatures, increasing trends of precipitation except in April and September, decreasing trends of annual and monthly potential evapotranspiration, and increasing aridity index except in September. It is not the isolated climatic elements that are important to moisture conditions, but their integrated and simultaneous effect. Moreover, potential evapotranspiration often changes the effect of precipitation on moisture conditions. The climate trends suggest an important warm and humid tendency averaged over the southern plateau in annual period and in August. Moisture conditions would probably get drier at large area in the headwater region of the three rivers in annual average and months from April to November, and the northeast of the plateau from July to September. Complicated climatic trends over the Tibetan Plateau reveal that climatic factors have nonlinear relationships, and resulte in much uncertainty together with the scarcity of observation data. The results would enhance our understanding of the potential impact of climate change on environment in the Tibetan Plateau. Further research of the sensitivity and attribution of climate change to moisture conditions on the plateau is necessary.

The Impact of Climatic and Environmental Factors on n-Alkanes Indices in Southwestern Tibetan Plateau

n-Alkanes are widely used in paleoenvironmental reconstructions.However,our understanding of changes in the distribution of n-alkanes with climatic and environmental factors remains unclear in arid/semi-arid regions.We sampled 26 surface sediments from three climatic zones across the southwestern Tibetan Plateau to evaluate the sensitivity of chain length distributions of n-alkanes to climatic and environmental parameters.Our observations demonstrate that average chain length(ACL),proportion of aquatic macrophyte(Paq),carbon preference index(CPI)and ratio of the contents of nC_(27)and nC_(31)(nC_(27)/nC_(31))are all sensitive to hydroclimatic conditions.In contrast to commonly-adopted assumptions,the correlations between these indices and hydrological parameters are not always good,which indicates that the interpretation of n-alkane indices is special on the southwestern Tibetan Plateau.These might be related to the vegetation characteristics and seasonality of biological activity,and need to be considered in paleoclimatic reconstruction.The impact of seasonal precipitation on n-alkanes indices was also evaluated.

MODERN CLIMATIC SIGNALS DEDUCED FROM STABLE ISOTOPE IN SHELLS IN XINGCUO LAKE SEDIMENTS,EAST TIBETAN PLATEAU,CHINA

Xingcuo lake,a closed one,is situated in eastern Tibetan Plateau.There are abundant snail shells Gy-raulus sibirica in its sediments.Here we display the determining results ofδ 13 C,δ 18 O in shell Gyraulus sibirica continuous-ly preserved in Xincuo Lake sediment s in the recent 50years.And by coupling the indexes ofδ 13 C,δ 18 O and instrumen-tal meteorological data in its basin to build relative function relation s among them,we probe quantitatively climatic sig-nals recorded in those indexes.The r esults show that there are remarkabl e relations betweenδ 13 C proxy and precipitation,δ 18 Oproxy and air temperature,of which correlative coefficient was 0.89an d 0.71,respectively.Besides,we also demon-strated that average variation betw eenδ 13 C proxy and precipitation(dδ 13 C /dP)was 0.027‰/mm and 1.64‰/℃forδ 18 O and air temperature(dδ 18 O /dT).

PROXY RECORD OF A FIRN-CORE FROM AN ALPINE GLACIER AND ITS IMPLICATION TO RECENT GLACIO-CLIMATIC VARIATIONS ON MT. YULONG, SOUTHEASTERN PART OF TIBETAN PLATEAU

Mt. Yulong, located in the eastern part of Tibetan Plateau, is the southmost present glaciation area both in China and Europe\|Asia continent,where distributes 19 typical sub\|tropics temperate glaciers. In the summer of 1999, a firn core, 10 10m long to the glacier ice, was successfully recovered in the accumulation area at the largest glacier (No.1 Baishui) on Mt. Yulong. Annual and seasonal variations of different climatic signals above the depth of 7 8m are apparent and five\|year snow accumulation can be clearly identified by the seasonal changes of isotopic and ionic composition, some higher values of electrical conductivity and pH values. These annual boundaries can be also verified by the positions of dirty refrozen ice layers at summer surface of each year. The mean annual net accumulation between the balance years of 94/95 and 97/98 are calculated to about 900mm water equivalent. The amplitude of isotopic changes becomes smaller with the increasing depth of the core and isotopic homogenization occurred below the depth of 7 8m. Concentrations of Ca 2+ and Mg 2+ are much higher than those of Na + and K +, reflecting that the air masses for precipitation came far from their marine sources and passed over a longer continental route. Cl - and Na + show well corresponding variation patterns in the firn profile,indicating their same genesis. Concentrations of SO 2- 4 and NO - 3 are low, reflecting very slight pollution caused by human activities in this area. According to the sum of net income recovered from the firn core and the estimated ablation amount, the average annual precipitation above the equilibrium line is estimated in the scope of 2250mm and 3200mm but it needed to be verified by long\|term observation of mass balance. As indicated by the trend of local climatic changes in last 50years, climatic signals in the firn core and recent observation at the terminal of glacier No.1 Baishui, the glaciers in Mt. Yulong start to advance in 1998 after continuous retreat from early 1980’s to late 1990’s.

A comparison of climatic change between Svalbard in Arctic and the Qinghai-Tibetan Plateau

Discussion is focused on the characteristics of climatic change in Svalbard for the last 80 a, there the climate tend to be slightly warming. But the decreasing of temperature is an abnormal phenomenon in the background of global temperature increasing since the mid 1970s in Svalbard. By analysis of temperature and precipitation at key stations in the last 40 a, it is concluded that in climatic change Svalbard may be compared with the Qinghai Tibetan Plateau, though there are differences that are caused by other factors.

Response of Lake Environment to Climatic Changes on The Tibetan Plateau,Western China

The large-scale summer monsoon circulations of south Asia makes a strong impact on precipitation in the area of southwestern China including Qinghai-Tibetan Plateau and Yun-Gui Plateau.however,the monsoon is both spatially and temporally complex and smaller-scale circulations are forced by a variety of local or regional orographic effects,local or regional land-atmosphere or

Projected changes in extreme snowfall events over the Tibetan Plateau based on a set of RCM simulations

Extreme snowfall events over the Tibetan Plateau(TP)cause considerable damage to local society and natural ecosystems.In this study,the authors investigate the projected changes in such events over the TP and its surrounding areas based on an ensemble of a set of 21st century climate change projections using a regional climate model,RegCM4.The model is driven by five CMIP5 global climate models at a grid spacing of 25 km,under the RCP4.5 and RCP8.5 pathways.Four modified ETCCDI extreme indices-namely,SNOWTOT,S1mm,S10mm,and Sx5day-are employed to characterize the extreme snowfall events.RegCM4 generally reproduces the spatial distribution of the indices over the region,although with a tendency of overestimation.For the projected changes,a general decrease in SNOWTOT is found over most of the TP,with greater magnitude and better cross-simulation agreement over the eastern part.All the simulations project an overall decrease in S1mm,ranging from a 25%decrease in the west and to a 50%decrease in the east of the TP.Both S10mm and Sx5day are projected to decrease over the eastern part and increase over the central and western parts of the TP.Notably,S10mm shows a marked increase(more than double)with high cross-simulation agreement over the central TP.Significant increases in all four indices are found over the Tarim and Qaidam basins,and northwestern China north of the TP.The projected changes show topographic dependence over the TP in the latitudinal direction,and tend to decrease/increase in low-/high-altitude areas.

Weather and Climate Effects of the Tibetan Plateau

Progress in observation experiments and studies concerning the effects of the Tibetan Plateau （TP） on weather and climate during the last 5 years are reviewed. The mesoscale topography over the TP plays an important role in generating and enhancing mesoscale disturbances. These disturbances increase the surface sensible heat （SH） flux over the TP and propagate eastward to enhance convection and precipitation in the valley of Yangtze River. Some new evidence from both observations and numerical simulations shows that the southwesterly flow, which lies on the southeastern flank of the TP, is highly correlated with the SH of the southeastern TP in seasonal and interannual variability. The mechanical and thermal forcing of the TP is an important climatic cause of the spring persistent rains over southeastern China. Moreover, the thermodynamic processes over the TP can influence the atmospheric circulation and climate over North America and Europe by stimulating the large-scale teleconnections such as the Asian-Pacific oscillation and can affect the atmospheric circulation over the southern Indian Ocean. Estimating the trend in the atmospheric heat source over the TP shows that, in contrast to the strong surface and troposphere warming, the SH over the TP has undergone a significant decreasing trend since the mid-1980s. Despite the fact that in situ latent heating presents a weak increasing trend, the springtime atmospheric heat source over the TP is losing its strength. This gives rise to reduced precipitation along the southern and eastern slopes of the TP and to increased rainfall over northeastern India and the Bay of Bengal.

Sensitivity of East Asian Climate to the Progressive Uplift and Expansion of the Tibetan Plateau Under the Mid-Pliocene Boundary Conditions

A global atmospheric general circulation model has been used to perform eleven idealized numerical experiments, i.e., TP10, TP10, .., TP100, corresponding to different percentages of the Tibetan Plateau altitude. The aim is to explore the sensitivity of East Asian climate to the uplift and expansion of the Tibetan Plateau under the reconstructed boundary conditions for the mid-Pliocene about 3 Ma ago. When the plateau is progressively uplifted, global annual surface temperature is gradually declined and statistically significant cooling signals emerge only in the Northern Hemisphere, especially over and around the Tibetan Plateau, with larger magnitudes over land than over the oceans. On the contrary, annual surface temperature rises notably over Central Asia and most parts of Africa, as well as over northeasternmost Eurasia in the experiments TP60 to TP100. Meanwhile, the plateau uplift also leads to annual precipitation augmentation over the Tibetan Plateau but a reduction in northern Asia, the Indian Peninsula, much of Central Asia, parts of western Asia and the southern portions of northeastern Europe. Additionally, it is found that an East Asian summer monsoon system similar to that of the present initially exists in the TP60 and is gradually intensified with the continued plateau uplift. At 850 hPa the plateau uplift induces an anomalous cyclonic circulation around the Tibetan Plateau in summertime and two anomalous westerly currents respectively located to the south and north of the Tibetan Plateau in wintertime. In the mid-troposphere, similarto-modern spatial pattern of summertime western North Pacific subtropical high is only exhibited in the experiments TP60 to TP100, and the East Asian trough is steadily deepened in response to the progressive uplift and expansion of the Tibetan Plateau.

Interannual Variability of the Normalized Difference Vegetation Index on the Tibetan Plateau and Its Relationship with Climate Change

The Qinghai-Xizang Plateau, or Tibetan Plateau, is a sensitive region for climate change, where the manifestation of global warming is particularly noticeable. The wide climate variability in this region significantly affects the local land ecosystem and could consequently lead to notable vegetation changes. In this paper, the interannual variations of the plateau vegetation are investigated using a 21-year normalized difference vegetation index （NDVI） dataset to quantify the consequences of climate warming for the regional ecosystem and its interactions. The results show that vegetation coverage is best in the eastern and southern plateau regions and deteriorates toward the west and north. On the whole, vegetation activity demonstrates a gradual enhancement in an oscillatory manner during 1982-2002. The temporal variation also exhibits striking regional differences： an increasing trend is most apparent in the west, south, north and southeast, whereas a decreasing trend is present along the southern plateau boundary and in the central-east region. Covariance analysis between the NDVI and surface temperature/precipitation suggests that vegetation change is closely related to climate change. However, the controlling physical processes vary geographically. In the west and east, vegetation variability is found to be driven predominantly by temperature, with the impact of precipitation being of secondary importance. In the central plateau, however, temperature and precipitation factors are equally important in modulating the interannual vegetation variability.

Review of the studies on climate change since the last inter-glacial period on the Tibetan Plateau

As the ＂Third Pole＂ of the world, the Tibetan Plateau has important effects on climate of its surrounding areas and even the whole world. Many results have been achieved on climate change since the last inter-glacial period in recent decades from ice core, tree-ring and lake sediment records over the Tibetan Plateau. In this paper, we review these achievements, especially those in the special periods. During the last inter-glacial period, temperature went down rapidly and went up slowly. The temperature record of the last glacial period is consistent with Greenland ice core records, also having own features over the Tibetan Plateau. Younger Dryas event agrees with the records from Europe and Greenland. Generally speaking, it is warm in the Holocene, and temperature has been rising gradually in the last 2000 years and gone up rapidly in recent decades. Climate changes on different time scales on the Tibetan Plateau occurred earlier and the change amplitude is larger than those in other parts of China.

Paleoclimate Changes during the Early Oligocene in the Hoh Xil Region, Northern Tibetan Plateau

Sedimentological, cyclic-stratigraphic, paleomagnetic, and clay-mineralogical studies on the early Oligocene Yaxicuo Group in the Hoh Xil Basin, the largest Cenozoic sedimentary basin in the hinterland of the Tibetan Plateau, provide abundant information of paleoclimate changes. A 350-m thick section in the middle-lower Yaxicuo Group was analyzed to reveal the climatic history that occurred in the Hoh Xil region during the early Oligocene interval 31.30-30.35 Ma, dated with the paleomagnetic chronostratigraphy. The results indicate that arid and cold climate dominated the Hoh Xil region during the early Oligocene in general, being related to the global cooling and drying events that occurred in the earliest Oligocene. Within this period, relatively warm and wet climate accompanied by strong tectonic activity occurred in the 31.05-30.75 Ma interval; while arid and cold climate and relatively inactive tectonics occurred in the 31.30-31.05 and 30.75-30.35 Ma intervals. Furthermore, spectral analyses of high-temporal resolution paleoclimatic records show orbital periods including eccentricity, obliquity, and precession. It is concluded that paleoclimate changes during the early Oligocene in the Hoh Xil region were forced by both tectonic activity and orbital periods.

Temporal and Spatial Variations in the Climate Controls of Vegetation Dynamics on the Tibetan Plateau during 1982–2011

The ecosystem of the Tibetan Plateau is highly susceptible to climate change. Currently, there is little discussion on the temporal changes in the link between climatic factors and vegetation dynamics in this region under the changing climate.By employing Normalized Difference Vegetation Index data, the Climatic Research Unit temperature and precipitation data,and the in-situ meteorological observations, we report the temporal and spatial variations in the relationships between the vegetation dynamics and climatic factors on the Plateau over the past three decades. The results show that from the early 1980s to the mid-1990s, vegetation dynamics in the central and southeastern part of the Plateau appears to show a closer relationship with precipitation prior to the growing season than that of temperature. From the mid-1990s, the temperature rise seems to be the key climatic factor correlating vegetation growth in this region. The effects of increasing temperature on vegetation are spatially variable across the Plateau: it has negative impacts on vegetation activity in the southwestern and northeastern part of the Plateau, and positive impacts in the central and southeastern Plateau. In the context of global warming, the changing climate condition(increasing precipitation and significant rising temperature) might be the potential contributor to the shift in the climatic controls on vegetation dynamics in the central and southeastern Plateau.

Influence of the Tibetan Plateau on the Summer Climate Patterns over Asia in the IAP/LASG SAMIL Model

A series of numerical experiments are carried out by using the Spectral Atmospheric Model of State Key Laboratory of Numerical Modeling Atmospheric Sciences and Geophysical Fluid Dynamics/Institute of Atmospheric Physics （SAMIL） to investigate how the Tibetan Plateau （TP） mechanical and thermal forcing affect the circulation and climate patterns over subtropical Asia. It is shown that, compared to mechanical forcing, the thermal forcing of TP plays a dominant role in determining the large-scale circulation in summer. Both the sensible heating and the latent heating over TP tend to generate a surface cyclonic circulation and a gigantic anticyclonic circulation in the mid- and upper layers, whereas the direct effect of the latter is much more significant. Following a requirement of the time-mean quasi-geostrophic vorticity equation for large-scale air motion in the subtropics, convergent flow and vigorous ascending motion must appear to the east of TP. Hence the summer monsoon in East China is reinforced efficiently by TP. In contrast, the atmosphere to the west of TP is characterized by divergent flow and downward motion, which induces the arid climate in Mid-Asia.

Evaluation of CORDEX regional climate models in simulating temperature and precipitation over the Tibetan Plateau

Using a regional climate model（RCM） is generally regarded as a promising approach in researching the climate of the Tibetan Plateau, due to the advantages provided by the high resolutions of these models. Whilst previous studies have focused mostly on individual RCM simulations, here, multiple RCMs from the Coordinated Regional Climate Downscaling Experiment are evaluated in simulating surface air temperature and precipitation changes over the Tibetan Plateau using station and gridded observations. The results show the following：（1） All RCMs consistently show similar spatial patterns, but a mean cold（wet） bias in the temperature（precipitation） climatology compared to station observations. The RCMs fail to reproduce the observed spatial patterns of temperature and precipitation trends, and on average produce greater trends in temperature and smaller trends in precipitation than observed results. The multi-model ensemble overall produces superior trends in both simulated temperature and precipitation relative to individual models. Meanwhile, Reg CM4 presents the most reasonable simulated trends among the five RCMs.（2） Considerable dissimilarities are shown in the simulated quantitative results from the different RCMs, which indicates a large model dependency in the simulation of climate over the Tibetan Plateau. This implies that caution may be needed when an individual RCM is used to estimate the amplitude of climate change over the Tibetan Plateau.（3） The temperature（precipitation） in 2016–35, relative to 1986–2005, is projected by the multi-model ensemble to increase by 1.38 ± 0.09 °C（0.8% ± 4.0%） and 1.77 ± 0.28 °C（7.3% ± 2.5%） under the RCP4.5 and RCP8.5 scenario, respectively. The results of this study advance our understanding of the applicability of RCMs in studies of climate change over the Tibetan Plateau from a multiple-RCM perspective.