Central-eastern Tibetan Plateau Research Articles

April–September minimum temperature reconstruction based on Sabina tibetica ring-width chronology in the central eastern Tibetan Plateau, China

Minimum temperatures have remarkable impacts on tree growth at high-elevation sites on the Tibetan Plateau, but the shortage of long-term and high-resolution paleoclimate records inhibits understanding of recent minimum temperature anomalies. In this study, a warm season (April–September) reconstruction is presented for the past 467 years (1550–2016) based on Sabina tibetica ring-width chronology on the Lianbaoyeze Mountain of the central eastern Tibetan Plateau. Eight warm periods and eight cold periods were identified. Long-term minimum temperature variations revealed a high degree of coherence with nearby reconstructions. Spatial correlations between our reconstruction and global sea surface temperatures suggest that warm season minimum temperature anomalies in the central eastern Tibetan Plateau were strongly influenced by large-scale ocean atmospheric circulations, such as the El Niño-Southern Oscillation and the Atlantic Multidecadal Oscillation.

Complementarity of lacustrine pollen and sedimentary DNA in representing vegetation on the central-eastern Tibetan Plateau

Complementarity of lacustrine pollen and sedimentary DNA in representing vegetation on the central-eastern Tibetan Plateau

Quasi-Biweekly Oscillation of Surface Sensible Heating over the Central-Eastern Tibetan Plateau and Its Relationship with Spring Rainfall in China

Abstract This study examines the characteristics and phase evolution of the quasi-biweekly oscillation of surface sensible heating (SH) over the central-eastern Tibetan Plateau (CETP) during spring. The mechanism connecting CETP SH to spring rainfall in China on the quasi-biweekly time scale is further investigated. Results show that the dominant mode of quasi-biweekly CETP SH presents a monopole pattern, in which the peak leads the maximum of the quasi-biweekly rainfall in the middle and lower reaches of the Yangtze River (MLYR) and South China by approximately 5 and 7 days, respectively. As an upper-level Rossby wave train propagates eastward, an anomalous center of convergence moves to the CETP, which leads to a strong downdraft and reduced cloud cover. The resultant elevated shortwave radiation input and drier soil conditions are favorable for the CETP SH quasi-biweekly oscillation to enter a positive phase. When reaching its peak, the CETP SH efficiently heats the lower atmosphere, resulting in a local updraft. Due to the “SH-driven air pump” effect, abundant water vapor is transported from the oceans to China. A lower-layer southerly anomaly on the east side of the TP develops into an anomalous cyclonic circulation via the effect of topographic friction, which leads to the expansion of the positive potential vorticity anomaly and the maximum of the quasi-biweekly rainfall in the MLYR. Further southeastward propagation of the wave train leads to a shift in the rainfall anomaly center to South China. These findings suggest that the CETP monopole SH warming could be a good indicator for predicting intraseasonal variations in spring rainfall over China.

Distinct Impacts of Two Types of Developing El Niño–Southern Oscillations on Tibetan Plateau Summer Precipitation

El Niño–Southern Oscillation (ENSO) has remarkable impacts on Tibetan Plateau (TP) summer precipitation. However, recently identified ENSO spatial diversity brings complexity to these impacts. This study investigates the distinct impacts of the Eastern Pacific (EP) and Central Pacific (CP) ENSOs on TP summer precipitation based on numerous precipitation data and satellite-observed and reanalyzed circulation data. The results show that the EP El Niño and the CP La Niña have opposite effects on summer precipitation in the southwestern TP, with significant decreases and increases, respectively, indicating a trans-type inversion. In contrast, the CP El Niño causes significant decreases in summer precipitation in the central-eastern TP. No significant anomaly occurs during the EP La Niña. Moisture budget and circulation analyses suggest that these distinct precipitation characteristics can be attributed to different atmospheric teleconnections, which provide varying vertical motion and moisture conditions. The EP El Niño triggers an atmospheric response similar to the Indian Summer Monsoon–East Asian Summer Monsoon teleconnection, and the CP La Niña generates a teleconnection in the opposite phase. In contrast, the CP El Niño mainly causes a teleconnection resembling the East Asian–Pacific pattern. This study may deepen our understanding of ENSO impacts on TP summer precipitation and have implications for regional climate predictions.

Glaciological and climatological drivers of heterogeneous glacier mass loss in the Tanggula Shan (Central-Eastern Tibetan Plateau), since the 1960s

AbstractDespite their extreme elevation, glaciers on the Tibetan Plateau are losing mass in response to atmospheric warming, the pattern of which purportedly reflects regional contrasts in climate. Here we examine the evolution of glaciers along ~500 km of the Tanggula Shan, Central-Eastern Tibetan Plateau. Using remotely sensed datasets, we quantified changes in glacier mass, area and surface velocity, and compared these results to time series of meteorological observations, in order to disentangle drivers of glacier mass loss since the 1960s. Glacier mass loss has increased (from −0.21 ± 0.12 m w.e. a−1 in 1960s–2000s, to −0.52 ± 0.18 m w.e. a−1 in 2000s–2015/18) in association with pervasive positive temperature anomalies (up to 1.85°C), which are pronounced at the end of the now lengthened ablation season. However, glacier mass budget perturbations do not mirror the magnitude of temperature anomalies in sub-regions, thus additional factors have heightened glacier recession. We show how proglacial lake expansion and glacier surging have compounded glacier recession over decadal/multi-decadal time periods, and exert similar influence on glacier mass budgets as temperature changes. Our results demonstrate the importance of ice loss mechanisms not often incorporated into broad-scale glacier projections, which need to be better considered to refine future glacier runoff estimates.

Decadal difference in influential factors for interannual variations of winter Tibetan Plateau snow

Using the monthly data of the number of days covered by snow (SCD) at meteorological stations, the NCEP-NCAR atmospheric reanalysis, and the Hadley Centre Sea Ice and Sea Surface Temperature dataset during 1973–2019, we investigate the influential factors for interannual variations of winter SCD in the central-eastern Tibetan Plateau (hereafter called the TP) and their decadal difference. The results show that the winter TP SCD exhibits a decadal shift from a positive phase to a negative phase around the late 1990s. Concurrent with this decadal shift, the dominant influential factor for the interannual variability of the winter TP SCD has an alternation from the tropical ocean to the Arctic signal. Before the late 1990s, the winter TP SCD is closely related with the synergistic effects from the tropical central-eastern Pacific (TCEP) and the tropical eastern Indian Ocean (TEIO) along the tropical ocean-TP path, while it is closely related with the AO along the Arctic-TP path since the late 1990s. Different from the significantly weakened interannual fluctuation of the TEIO and TCEP SSTs, the interannual fluctuation of the AO show a remarkably strengthening trend in the recent 20 years. The strengthened Arctic signal could exert a strong influence on the TP SCD through a wave train that goes along the path from the Greenland and adjacent areas to the TP via the extratropical Atlantic Ocean and the middle-high latitudes of Eurasia. The opposite trends in the interannual fluctuation intensities of the tropical SST and AO may lead to a larger contribution of the Arctic signal to the interannual variability of the winter TP snow in the recent 20 years.

What Are the Dominant Synoptic Patterns Leading to the Summer Regional Hourly Extreme Precipitation Events Over Central‐Eastern Tibetan Plateau and Sichuan Basin?

AbstractRevealing the synoptic patterns related to hourly extreme precipitation (EP) is very important to deepen our recognition and understanding of EP formation. The predominant synoptic patterns associated with the summer regional hourly EP events (RHEPE) over the central‐eastern Tibetan Plateau (CETP) and Sichuan Basin (SCB) have been systematically identified. Results show the summer RHEPE over CETP and SCB are dominated by the background large‐scale circulations featured by the configuration of eastward‐extended South Asia high (SAH) and westward‐extended Western North Pacific Subtropical High (WNPSH) and their northward advance, except for that an obvious low‐level vortex imbedded in the background large‐scale circulations is mainly responsible for the summer RHEPE over SCB. The frequency and intensity of the total summer RHEPE over CETP and SCB all show an obvious increasing trend during 2000–2020, which is largely contributed by the synoptic pattern characterized by the configuration of eastward extended SAH and westward extended WNPSH.

Relationship between summer extreme precipitation anomaly in Central Asia and surface sensible heat variation on the Central-Eastern Tibetan Plateau

In the context of global warming, the frequency and intensity of extreme weather and climate events have increased, especially in Central Asia (CA). In this study, we investigate the characteristics of summer extreme precipitation (SEP) in CA and its relationship with the surface sensible heat (SSH) variation over the central–eastern Tibetan Plateau (CETP). The results suggest that the distribution of SEP in CA is extremely uneven, and the SEP thresholds range from 2 to 32 mm/day, and 80% of them are concentrated in 4–10 mm/day. Both the total amount of SEP and the number of SEP days show significant increasing trends, with the climatic tendencies of 4.4 mm/decade and 0.4 day/decade, respectively. The SSH anomalies over the CETP can affect the SEP and summer drought in CA by regulating the strength of South Asia High (SAH) and the subtropical jet over CA. The strong SSH anomalies over the CETP in late spring (April–May) can be transmitted from the lower to the upper layers through the continuous heating to the atmosphere and lead to the anomalously strong subtropical high over northern Africa and the Arabian Peninsula, the anomalously weak subtropical westerly jet over CA and the anomalously strong SAH in summer. At the same time, the Ural ridge strengthens, the CA trough weakens, and the northern CA is controlled by an anomaly of warm high-pressure ridge. Therefore, the anomaly of water vapor convergence in northern CA weakens. The SEP there will be abnormally less, and the summer drought intensifies. When the SSH over CETP is anomalously weak in late spring, the key circulations are just the opposite. Furthermore, the anomalous water vapor from the Arctic, North Atlantic and western Pacific converges in northern CA and northern Xinjiang, China, which is conducive to the generation of widespread extreme precipitation and the alleviation of summer drought in these regions.

An Interdecadal Change in the Influence of ENSO on the Spring Tibetan Plateau Snow-Cover Variability in the Early 2000s

AbstractEl Niño–Southern Oscillation (ENSO) and the Tibetan Plateau snow cover are important factors in interannual climate variability. The relationship between ENSO and the Tibetan Plateau snow variation is still undetermined. While some studies suggested that ENSO is a key factor of changes in snow cover over the Tibetan Plateau, other studies noted independence between the two. The present study revealed a prominent interdecadal change in the relationship between ENSO and the spring Tibetan Plateau snow-cover variation in the early 2000s. There is a significant positive correlation between ENSO and the spring Tibetan Plateau snow-cover variation in the period 1988–2003, but an obvious negative relationship is detected in the period 2004–19. The interdecadal change in the ENSO–snow relationship is related to the distinct pathway of ENSO influence on the spring Tibetan Plateau snow-cover variation during the two periods. In the period 1988–2003, ENSO induces anomalous convection over the tropical western North Pacific that in turn causes atmospheric circulation and moisture anomalies over the Tibetan Plateau. The resultant winter snow anomalies over the central-eastern Tibetan Plateau persist to the following spring. In the period 2004–19, ENSO induces North Atlantic sea surface temperature (SST) anomalies in winter that are maintained to the following spring. The North Atlantic SST anomalies then stimulate the atmospheric circulation anomalies extending to the Tibetan Plateau that induce snow-cover anomalies there in spring. The different processes of ENSO influence lead to opposite anomalies of spring snow cover over the Tibetan Plateau in the two periods.

Influence of organic matter on soil hydrothermal processes in the Tibetan Plateau: Observation and parameterization

AbstractIn the central-eastern Tibetan Plateau (TP) there is abundant organic matter in topsoils, which plays a crucial role in determining soil hydraulic properties that need to be properly described in land surface models. Limited soil parameterizations consider the impacts of soil organic matter (SOM), but they still show poor performance in the TP. A dedicated field campaign is therefore conducted by taking undisturbed soil samples in the central TP to obtain in-situ soil hydraulic parameters and to advance SOM parameterizations. The observed findings are twofold. 1) The SOM pore-size distribution parameter, derived from measured soil water retention curves, has been demonstrated to be much underestimated in previous studies. 2) SOM saturated hydraulic conductivity is overestimated. Accordingly, a new soil hydraulic parameterization is established by modifying a commonly used one based on observations, which is then evaluated by incorporating it into Noah-MP. Compared with the original ones, the new parameterization significantly improves surface soil liquid water simulations at stations with high surface SOM content, especially in the warm season. A further application with the revised Noah-MP indicates that SOM can enhance sensible heat flux but decrease evaporation and subsurface soil temperature in the warm season, and tends to have a much weak effect in the cold season. This study provides insights into the role of SOM in modulating soil state and surface energy budget. Note that, however, there are many other factors at play and the new parameterization is not necessarily applicable beyond the TP.

Characteristics and Synoptic Patterns of Regional Extreme Rainfall over the Central and Eastern Tibetan Plateau in Boreal Summer

In this research, the observation datasets from 106 gauge stations over the central and eastern areas of the Tibetan Plateau (TP) and the ERA (ECMWF Re-Analysis)-Interim reanalysis datasets in the summers of 1981–2016 are used to study the characteristics and synoptic patterns of extreme precipitation events over the TP. By using a modern statistical method, the abnormal circulation characteristics at high, middle, and low latitudes in the Northern Hemisphere during extreme precipitation events over the central-eastern Tibetan Plateau are discussed, and the physical mechanisms related to the extreme precipitation events are investigated. The results show that the largest amount of extreme precipitation is found in the southern and eastern areas of the TP, where the frequency of daily extreme rainfall events (exceeding 25 mm) and the frequency of all extreme precipitation events both show obvious quasi-biweekly oscillation. When the daily extreme precipitation event threshold over the TP is met and more than 5 stations show daily extreme precipitation at the same time, with at least three of them being adjacent to each other, this is determined as a regional extreme precipitation event. As such, 33 regional daily extreme precipitation events occur during the summer periods of 1981–2016. According to the influence system, the 33 regional extreme precipitation events can be divided into three types, namely the plateau trough type, the plateau shear line type, and the plateau vortex type. For the plateau trough type, the South Asian high is anomalously strong at 100 hPa. For the other two types, the South Asian high is slightly weaker than usual. For the plateau shear line type, the development of the dynamic disturbance is the strongest, reaching 200 hPa. In the plateau trough type and plateau vortex type, the water vapor is transported by the westerly belt and the southwesterly flow from the Bay of Bengal.

On the Interdecadal Change in the Interannual Variation in Autumn Snow Cover Over the Central Eastern Tibetan Plateau in the Mid‐1990s

AbstractThe interdecadal changes in the mechanisms accounting for the interannual variation in autumn snow cover over the central eastern Tibetan Plateau (TP) are investigated in this study. An autumn snow index is constructed by area averaging the snow cover over the central eastern TP. The snow index changed from a predominantly negative phase to a positive phase in 1995. Then, the data were divided into two subperiods, 1979–1994 (P1) and 1995–2017 (P2), and the differences in the mechanisms accounting for the variation in autumn snow cover were compared between P1 and P2. An analysis of the local process shows that the autumn snow cover variations over the central eastern TP are caused by snowfall from both autumn and late summer. The autumn snow cover variation over the central eastern TP imposed more significant atmospheric cooling effects during P1 than P2. During P2, except for the local process, the interannual variation in autumn snow cover in the central eastern TP is also affected by atmospheric circulation anomalies originating from the upstream North Atlantic Ocean. During P2, snow‐related North Atlantic sea surface temperature (SST) anomalies (SSTA) can induce a wave train‐like atmospheric pattern that propagates eastward across the Eurasian continent and reaches the TP. Further analysis shows that this wave train‐like atmospheric pattern over the midlatitude Eurasian continent mainly obtains energy from climatological mean flow through baroclinic energy conversion. In contrast, during P1, the North Atlantic SSTA‐related atmospheric circulation pattern tends to propagate northeastward and cannot contribute to the variation in autumn snow cover over the central eastern TP.

Late quaternary slip rate of the east segment of the Yushu fault in the central-eastern Tibetan Plateau

The Yushu fault is a mainly left-lateral strike slip fault with some normal component within the Ganzi-Yushu fault system in central-eastern Tibetan Plateau. In 2010, the catastrophic Yushu Ms 7.1 earthquake occurred along this fault, causing approximately 3000 casualties and widespread damages; however, the late Quaternary slip rate of this fault was not tightly constrained due to poor research. Based on the interpretation of satellite images, field measurement of the offset of terrace risers, optically stimulated luminescence (OSL) and radiocarbon (14C) dating of terrace ages, the late Quaternary slip rate of the east segment of the Yushu fault is estimated to be 6.8–8.2 mm/yr. In consideration of the partitioning effect of the Batang fault south of Yushu, the late Quaternary slip rate of the entire Yushu segment is approximately 9–12 mm/yr. Given the characteristic offset of about 6–8 m, the recurrence interval of large earthquakes along the Yushu fault is estimated to be approximately 750–1150 yr. This research provides basic parameters for the long-term seismic hazards assessment of the Yushu area and implies the limited southeastward extrusion rate (~10 mm/yr) of Qiangtang block relative to the Bayan Har block.

Summer Atmospheric Heat Sources over the Western–Central Tibetan Plateau: An Integrated Analysis of Multiple Reanalysis and Satellite Datasets

Multiple bias-corrected top-quality reanalysis datasets, gauge-based observations, and selected satellite products are synthetically employed to revisit the climatology and variability of the summer atmospheric heat sources over the Tibetan Plateau (TP). Verification-based selection and ensemble-mean methods are utilized to combine various datasets. Different from previous works, this study pays special attention to estimating the total heat source (TH) and its components over the data-void western plateau (70°–85°E), including the surface sensible heat (SH), latent heat released by precipitation (LH), and net radiation flux (RD). Consistent with previous studies, the climatology of summer SH (LH) typically increases (decreases) from southeast to northwest. Generally, LH dominates TH over most of the TP. A notable new finding is a minimum TH area over the high-altitude region of the northwestern TP, where the Karakoram mountain range is located. We find that during the period of 1984–2006, TH shows insignificant trends over the eastern and central TP, whereas it exhibits an evident increasing trend over the western TP that is attributed to the rising tendency of LH before 1996 and to that of RD after 1996. The year-to-year variation of TH over the central–eastern TP is highly correlated with that of LH, but that is not the case over the western TP. It is also worth noting that the variations of TH in each summer month are not significantly correlated with each other, and hence study of the interannual variation of the TP heat sources should consider the remarkable subseasonal variations.

Multi-terrane structure controls the contrasting lithospheric evolution beneath the western and central\u2013eastern Tibetan plateau

The Tibetan plateau is manifested by contrasting along-strike lithospheric structures, but its formation mechanism and the relationship with the heterogeneous multi-terrane configuration is a challenging problem. Here we conduct systematic numerical modeling to explore the roles of width, density, and rheological properties of the multiple terranes in the lithospheric evolution of the Tibetan plateau, which reveals two distinct collision modes. In Mode-I, the lithospheric mantles of both the strong and weak terranes in the Tibetan plate are completely detached, followed by the underthrusting of Indian lithosphere beneath the whole plateau. Alternatively, Mode-II is characterized by full detachment of the weak terranes, but (partial) residue of the strong terranes during collision. These two contrasting modes, broadly consistent with the lithospheric structures of western and central–eastern Tibetan plateau, respectively, are strongly dependent on the along-strike variation of the width of the strong Lhasa–Qiangtang terranes.

Pedogenesis, permafrost, substrate and topography: Plot and landscape scale interrelations of weathering processes on the central-eastern Tibetan Plateau

Weathering indices (WI) and pedogenic oxides ratios (POR) were used to describe patterns of weathering intensities and pedogenesis along climatic gradients, mainly affected by varying influences of the Asian and Indian Monsoon. These climate settings induce particular soil moisture (SM) conditions, in turn closely related to permafrost state, substrate, and topography. Nine sites including a total of 30 soil profiles were examined along an eastern and a western transect across the central-eastern Qinghai–Tibet Plateau. Additionally, differences between four soil groups were analysed. According to our knowledge, the presented study is the first attempt of a comprehensive application of different WI and POR to substrates of currently permafrost-affected soils. It provides an evaluation of various tools in terms of chemically describing and differentiating the related processes to distinct environmental settings in low-weathering regions. We found that weathering trends along the climatic gradients could be clearly outlined by WI, whereas POR rather account for small scale variations, describing significant differences of pedogenesis between continuous and discontinuous permafrost conditions. Pyrophosphate soluble iron (Fep) proved to be useful for differentiating permafrost and ground water influenced soils, showing a strong correlation to total organic carbon (r=0.89). The chemical index of alteration (CIA) is the most suitable WI, whereas Ca-free CPA is more easily biased by salinity variations of topsoils at sites with negative water balance, thus pretending lower weathering intensities. Regression analyses for WI and POR with main independent variables underline the specific characteristics: climatic parameters best explain WI, while SM is dominant for POR. The ratio (Fed-Feo)/Fet proved as the most appropriate POR with 64% explained variation by a multiple linear regression model, implying significantly lower iron release with higher SM and pH values. Variation of Fep can be explained by 63% with soil acidity being most important, followed by SM. Importantly, the presented research provides tools for investigating past and future stability or respective degradation processes of permafrost ecosystems on the Tibetan Plateau and may be applicable to other permafrost-affected environments.

Amplitudes, rates, periodicities and causes of temperature variations in the past 2485 years and future trends over the central-eastern Tibetan Plateau

Amplitudes, rates, periodicities, causes and future trends of temperature variations based on tree rings for the past 2485 years on the central-eastern Tibetan Plateau were analyzed. The results showed that extreme climatic events on the Plateau, such as the Medieval Warm Period, Little Ice Age and 20th Century Warming appeared synchronously with those in other places worldwide. The largest amplitude and rate of temperature change occurred during the Eastern Jin Event (343–425 AD), and not in the late 20th century. There were significant cycles of 1324 a, 800 a, 199 a, 110 a and 2–3 a in the 2485-year temperature series. The 1324 a, 800 a, 199 a and 110 a cycles are associated with solar activity, which greatly affects the Earth surface temperature. The long-term trends (>1000 a) of temperature were controlled by the millennium-scale cycle, and amplitudes were dominated by multi-century cycles. Moreover, cold intervals corresponded to sunspot minimums. The prediction indicated that the temperature will decrease in the future until to 2068 AD and then increase again.

Mesozoic cooling across the Yidun Arc, central-eastern Tibetan Plateau: A reconnaissance 40Ar/ 39Ar study

40Ar/ 39Ar dating of hydrous minerals from igneous and metamorphic rocks was undertaken with the aim of characterizing the thermal history of the Yidun Arc, eastern Tibetan Plateau. Regional metamorphism of Palaeozoic rocks of the western Yidun Arc occurred during the Early Triassic collision with the Qiangtang Block along the Jinsha Jiang Suture. Hornblende, muscovite, and biotite 40Ar/ 39Ar ages from syn-tectonic igneous rocks within this collision zone suggest that the region had cooled to below 300 °C by the Late Triassic. Muscovite samples from mica–schists within this collision zone yield variably discordant age spectra with generally Triassic 40Ar/ 39Ar ages, consistent with cooling of the region to below muscovite closure temperatures by the close of the Triassic. Hornblende and biotite 40Ar/ 39Ar ages from granite and granodiorite plutons in the eastern Yidun Arc suggest post-emplacement cooling of these plutons occurred rapidly, consistent with these granites being high-level intrusions. In sum, these results suggest that by the beginning of the Jurassic the Yidun Arc as a whole had cooled to below 300 °C. Two Cretaceous granites in the central Yidun Arc also experienced rapid cooling, suggesting they too were emplaced at shallow crustal depths. Post-Triassic deformation of the region must have occurred at or below the brittle–ductile transition within the crustal levels now exposed.

Thermochronology of the Yidun Arc, central eastern Tibetan Plateau: constraints from 40Ar/ 39Ar K-feldspar and apatite fission track data

Four K-feldspar samples from the Yidun Arc, eastern Tibetan Plateau, were analysed by the 40Ar/ 39Ar method with the aim of recovering information on their thermal history using multiple diffusion domain (MDD) theory. Arrhenius plots for each of the samples reveal low retentivity early in the heating experiments, a property that is attributed to their recrystallised nature. This low argon retentivity appears to violate the MDD assumption that volume diffusion is the only mechanism for argon transport within the crystals, thus the thermal histories derived from these analyses are considered suspect. Nevertheless, the age spectra themselves suggest that the majority of samples had cooled below ∼200 °C prior to the Eocene collision of India with Asia. Thermal history modelling from apatite fission track analyses from the same and nearby samples shows slow cooling through the apatite fission track partial annealing zone during the Cenozoic in samples from the high elevation, low relief areas of the Yidun Arc, while samples from the major Jinsha River valley show rapid cooling through the partial annealing zone beginning in the Miocene. These results suggest that significant Cenozoic denudation has been localised and that most parts of the Yidun Arc have experienced very little denudation during the Cenozoic.

Thermal field over Tibetan Plateau and Indian summer monsoon rainfall

AbstractThe interannual variability of the temperature anomalies over the Tibetan Plateau (25–45 °N, 75–105 °E) is examined in relation to the Indian summer monsoon rainfall (ISMR: June to September total rainfall). For this purpose, the temperature anomaly data of the central‐eastern Tibetan Plateau is divided into three regions using principal component analysis and the ISMR data for the period 1957–89 have been used. It is found that the January temperature anomaly of Region 2 has a significant negative relationship (r = −0.67) with the ISMR of the subsequent season. This region is located over the northeastern part of the Tibetan Plateau, mostly in Qinghai province, including the Bayan Harr Mountain range and the Qaidam Basin. This relationship is consistent and robust during the period of analysis and can be used to predict the strength of the Indian summer monsoon in the subsequent season. It was found that the January temperature anomaly in this region was associated with a persistent winter circulation pattern over the Eurasian continent during January through to March. Finally, the variation patterns of the temperature anomalies in all three regions over the central‐eastern Tibetan Plateau during extreme years of the ISMR are examined. It is concluded that the January temperature anomaly over the northeastern Tibetan Plateau can be useful in forecasting the drought and flood conditions over India, especially in predicting the monsoon rainfall over the areas lying along the monsoon trough. Copyright © 2003 Royal Meteorological Society