Influence of Tibetan Plateau On The North American Summer Monsoon Precipitation

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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The AMV phase-dependence of the connection between February NAO and March surface air temperature over the Tibetan Plateau

10.5194/egusphere-egu21-9879 ◽

2021 ◽

Author(s):

Jingyi Li ◽

Fei Li ◽

Shengping He ◽

Huijun Wang ◽

Yvan J Orsolini

Keyword(s):

Tibetan Plateau ◽

Air Temperature ◽

Rossby Wave ◽

North Atlantic ◽

Wave Train ◽

Surface Air Temperature ◽

The Tibetan Plateau ◽

The North ◽

Rossby Wave Train ◽

The North Atlantic

<p>The Tibetan Plateau (TP), referred to as the &#8220;Asian water tower&#8221;, contains one of the largest land ice masses on Earth. The local glacier shrinkage and frozen-water storage are strongly affected by variations in surface air temperature over the TP (TPSAT), especially in springtime. This study reveals a distinct out-of-phase connection between the February North Atlantic Oscillation (NAO) and March TPSAT, which is non-stationary and regulated by the warm phase of the Atlantic Multidecadal Variability (AMV+). The results show that during the AMV+, the negative phase of the NAO persists from February to March, and is accompanied by a quasi-stationary Rossby wave train trapped along a northward-shifted subtropical westerly jet stream across Eurasia, inducing an anomalous adiabatic descent that warms the TP. However, during the cold phase of the AMV, the negative NAO does not persist into March. The Rossby wave train propagates along the well-separated polar and subtropical westerly jets, and the NAO&#8722;TPSAT connection is broken. Further investigation suggests that the enhanced synoptic eddy and low-frequency flow (SELF) interaction over the North Atlantic in February and March during the AMV+, caused by the enhanced and southward-shifted storm track, help maintain the NAO anomaly pattern via positive eddy feedback. This study provides a new detailed perspective on the decadal variability of the North Atlantic&#8722;TP connections in late winter&#8722;early spring.</p>

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The Atlantic Multidecadal Variability phase-dependence of teleconnection between the North Atlantic Oscillation in February and the Tibetan Plateau in March

Journal of Climate ◽

10.1175/jcli-d-20-0157.1 ◽

2021 ◽

pp. 1-40

Author(s):

Jingyi Li ◽

Fei Li ◽

Shengping He ◽

Huijun Wang ◽

Yvan J Orsolini

Keyword(s):

Tibetan Plateau ◽

Rossby Wave ◽

North Atlantic ◽

Wave Train ◽

The Tibetan Plateau ◽

Atlantic Multidecadal Variability ◽

Multidecadal Variability ◽

The North ◽

Rossby Wave Train ◽

The North Atlantic

AbstractThe Tibetan Plateau (TP), referred to as the “Asian water tower”, contains one of the largest land ice masses on Earth. The local glacier shrinkage and frozen-water storage are strongly affected by variations in surface air temperature over the TP (TPSAT), especially in springtime. This study reveals that the relationship between the February North Atlantic Oscillation (NAO) and March TPSAT is unstable with time and regulated by the phase of the Atlantic Multidecadal Variability (AMV). The significant out-of-phase connection occurs only during the warm phase of AMV (AMV+). The results show that during the AMV+, the negative phase of the NAO persists from February to March, and is accompanied by a quasi-stationary Rossby wave train trapped along a northward-shifted subtropical westerly jet stream across Eurasia, inducing an anomalous adiabatic descent that warms the TP. However, during the cold phase of the AMV, the negative NAO can not persist into March. The Rossby wave train propagates along the well-separated polar and subtropical westerly jets, and the NAO−TPSAT connection is broken. Further investigation suggests that the enhanced synoptic eddy and low frequency flow (SELF) interaction over the North Atlantic in February and March during the AMV+, caused by the enhanced and southward-shifted storm track, help maintain the NAO anomaly pattern via positive eddy feedback. This study provides a new detailed perspective on the decadal variability of the North Atlantic−TP connection in late winter−early spring.

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Understanding the Interdecadal Variability of East Asian Summer Monsoon Precipitation: Joint Influence of Three Oceanic Signals

Journal of Climate ◽

10.1175/jcli-d-17-0657.1 ◽

2018 ◽

Vol 31 (14) ◽

pp. 5485-5506 ◽

Cited By ~ 21

Author(s):

Zhiqi Zhang ◽

Xuguang Sun ◽

Xiu-Qun Yang

Keyword(s):

Summer Monsoon ◽

North Atlantic ◽

Asian Summer Monsoon ◽

Wave Train ◽

Eastern China ◽

Monsoon Precipitation ◽

The North ◽

Joint Influence ◽

Asian Summer ◽

Precipitation Anomalies

Abstract East Asian summer monsoon precipitation (EASMP) features complicated interdecadal variability with multiple time periods and spatial patterns. Using century-long datasets of HadISST, CRU precipitation, and the ECMWF twentieth-century reanalysis (ERA-20C), this study examines the joint influence of three oceanic interdecadal signals [i.e., Pacific decadal oscillation (PDO), Atlantic multidecadal oscillation (AMO), and Indian Ocean Basin mode (IOBM)] on the EASMP, which, however, is found not to be simply a linear combination of their individual effects. When PDO and AMO are out of phase, the same-sign SST anomalies occur in the North Pacific and North Atlantic, and a zonally orientated teleconnection wave train appears across the Eurasian mid-to-high latitudes, propagating from the North Atlantic to northern East Asia along the Asian westerly jet waveguide. Correspondingly, the interdecadal precipitation anomalies are characterized by a meridional tripole mode over eastern China. When PDO and AMO are in phase, with opposite sign SST anomalies in the North Pacific and North Atlantic, the sandwich pattern of anomalous stationary Rossby wavenumber tends to reduce the effect of the waveguide in the eastern Mediterranean region, and the teleconnection wave train from the North Atlantic travels only to western central Asia along a great circle route, causing Indian summer monsoon precipitation (ISMP) anomalies. The ISMP anomalies, in turn, interact with the teleconnection wave train induced by the PDO and AMO, leading to a meridional dipole mode of interdecadal precipitation anomalies over eastern China. Through the impact on the ISMP, the IOBM exerts significantly linear modulation on the combined impacts of PDO and AMO, especially over northern East Asia.

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A Unified Nonlinear Multiscale Interaction Model of Pacific–North American Teleconnection Patterns

Journal of the Atmospheric Sciences ◽

10.1175/jas-d-19-0312.1 ◽

2020 ◽

Vol 77 (4) ◽

pp. 1387-1414

Author(s):

Dehai Luo ◽

Yao Ge ◽

Wenqi Zhang ◽

Aiguo Dai

Keyword(s):

North Atlantic ◽

North American ◽

Wave Train ◽

Interaction Model ◽

Energy Dispersion ◽

Pacific North American ◽

The North ◽

The North Atlantic ◽

The Difference ◽

Multiscale Interaction

Abstract In this paper, reanalysis data are first analyzed to reveal that the individual negative (positive)-phase Pacific–North American pattern (PNA) or PNA− (PNA+) has a lifetime of 10–20 days, is characterized by strong (weak) westerly jet stream meanders, and exhibits clear wave train structures, whereas the PNA− with rapid retrogression tends to have longer lifetime and larger amplitude than the PNA+ with slow retrogression. In contrast, the wave train structure of the North Atlantic Oscillation (NAO) is less distinct, and the positive (negative)-phase NAO shows eastward (westward) movement around a higher latitude than the PNA. Moreover, it is found that the PNA wave train occurs under a larger background meridional potential vorticity gradient (PVy) over the North Pacific than that over the North Atlantic for the NAO. A unified nonlinear multiscale interaction (UNMI) model is then developed to explain why the PNA as a nonlinear wave packet has such characteristics and its large difference from the NAO. The model results reveal that the larger background PVy for the PNA (due to its location at lower latitudes) leads to its larger energy dispersion and weaker nonlinearity than the NAO, thus explaining why the PNA (NAO) is largely a linear (nonlinear) process with a strong (weak) wave train structure, though it is regarded as a nonlinear initial-value problem. The smaller PVy for the PNA− than for the PNA+ leads to lower energy dispersion and stronger nonlinearity for PNA−, which allows it to maintain larger amplitude and have a longer lifetime than the PNA+. Thus, the difference in the background PVy is responsible for the asymmetry between the two phases of PNA and the difference between the PNA and NAO.

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Why Is There an Early Spring Cooling Shift Downstream of the Tibetan Plateau?

Journal of Climate ◽

10.1175/jcli3568.1 ◽

2005 ◽

Vol 18 (22) ◽

pp. 4660-4668 ◽

Cited By ~ 80

Author(s):

Jian Li ◽

Rucong Yu ◽

Tianjun Zhou ◽

Bin Wang

Keyword(s):

Tibetan Plateau ◽

North Africa ◽

North Atlantic ◽

Radiative Forcing ◽

Temperature Shift ◽

Early Spring ◽

Climate Feedback ◽

The Tibetan Plateau ◽

The North ◽

The North Atlantic

Abstract The temperature shift over the eastern flank of the Tibetan Plateau is examined using the last 50 yr of Chinese surface station observations. It was found that a strong cooling shift occurs in early spring (March and April) and late summer (July, August, and September) in contrast to the warming shift in other seasons. The cause of the March–April (MA) cooling is investigated in this study. The MA cooling shift on the lee side of the Tibetan Plateau is found to be not a local phenomenon, but rather it is associated with an eastward extension of a cooling signal originating from North Africa that is related to the North Atlantic Oscillation (NAO) in the previous winter. The midtropospheric westerlies over the North Atlantic and North Africa tend to intensify during positive NAO phases. The enhanced westerlies, after passing over the Tibetan Plateau, result in strengthened ascending motion against the lee side of the plateau, which favors the formation of midlevel stratiform clouds. The increased amount of stratus clouds induces a negative net cloud–radiative forcing, which thereby cools the surface air and triggers a positive cloud–temperature feedback. In this way, the cooling signal from the upstream could “jump” over the Tibetan Plateau and leave a footprint on its lee side. The continental stratiform cloud–climate feedback plays a significant role in the amplification of the cooling shift downstream of the Tibetan Plateau.

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Penultimate deglaciation Asian monsoon response to North Atlantic circulation collapse

Nature Geoscience ◽

10.1038/s41561-021-00851-9 ◽

2021 ◽

Author(s):

Jasper A. Wassenburg ◽

Hubert B. Vonhof ◽

Hai Cheng ◽

Alfredo Martínez-García ◽

Pia-Rebecca Ebner ◽

...

Keyword(s):

Summer Monsoon ◽

North Atlantic ◽

Asian Monsoon ◽

Monsoon Season ◽

Isotope Effects ◽

Meridional Overturning Circulation ◽

The North ◽

Kinetic Isotope ◽

Monsoon System ◽

Meridional Overturning

AbstractDuring glacial terminations, massive iceberg discharges and meltwater pulses in the North Atlantic triggered a shutdown of the Atlantic Meridional Overturning Circulation (AMOC). Speleothem calcium carbonate oxygen isotope records (δ18OCc) indicate that the collapse of the AMOC caused dramatic changes in the distribution and variability of the East Asian and Indian monsoon rainfall. However, the mechanisms linking changes in the intensity of the AMOC and Asian monsoon δ18OCc are not fully understood. Part of the challenge arises from the fact that speleothem δ18OCc depends on not only the δ18O of precipitation but also temperature and kinetic isotope effects. Here we quantitatively deconvolve these parameters affecting δ18OCc by applying three geochemical techniques in speleothems covering the penultimate glacial termination. Our data suggest that the weakening of the AMOC during meltwater pulse 2A caused substantial cooling in East Asia and a shortening of the summer monsoon season, whereas the collapse of the AMOC during meltwater pulse 2B (133,000 years ago) also caused a dramatic decrease in the intensity of the Indian summer monsoon. These results reveal that the different modes of the AMOC produced distinct impacts on the monsoon system.

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Portraying the Impact of the Tibetan Plateau on Global Climate

Journal of Climate ◽

10.1175/jcli-d-18-0734.1 ◽

2020 ◽

Vol 33 (9) ◽

pp. 3565-3583 ◽

Cited By ~ 2

Author(s):

Haijun Yang ◽

Xingchen Shen ◽

Jie Yao ◽

Qin Wen

Keyword(s):

Tibetan Plateau ◽

North Atlantic ◽

Thermohaline Circulation ◽

Global Climate ◽

Tropical Pacific ◽

The Tibetan Plateau ◽

The North ◽

The North Atlantic ◽

The Impact ◽

The Tropical Pacific

AbstractAs the most extensive highland in the world, the Tibetan Plateau (TP) plays an important role in shaping the global climate. Quantifying the effect of the TP on global climate is the first step for a full understanding of the TP’s standing on planet Earth. Through coupled model sensitivity experiments, we draw a panorama of the TP’s global impact in this paper. Our model results show that the absence of the TP would result in a 4°C colder and 10% drier climate in the Northern Hemisphere (NH). The TP has a striking remote effect on the North Atlantic. Removing the TP would enhance the westerlies in the mid- to high latitudes of the NH and weaken the easterlies over the tropical Pacific. More moisture would be relocated from the tropical Pacific to the North Atlantic, shutting down the Atlantic thermohaline circulation, which would eventually result in more than 15°C colder and 20% drier climate over the North Atlantic. Our model results suggest that the presence of the TP may have contributed greatly to the hospitable modern climate in the NH, by promoting the establishment of the thermohaline circulation in the Atlantic, and therefore enhancing the northward ocean heat transport and atmosphere moisture transport across the equator.

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Land–atmosphere–ocean coupling associated with the Tibetan Plateau and its climate impacts

National Science Review ◽

10.1093/nsr/nwaa011 ◽

2020 ◽

Vol 7 (3) ◽

pp. 534-552 ◽

Cited By ~ 9

Author(s):

Yimin Liu ◽

Mengmeng Lu ◽

Haijun Yang ◽

Anmin Duan ◽

Bian He ◽

...

Keyword(s):

Tibetan Plateau ◽

Summer Monsoon ◽

Thermal State ◽

Asian Summer Monsoon ◽

Climate Impacts ◽

Meridional Overturning Circulation ◽

South Asian High ◽

The Tibetan Plateau ◽

Ocean Coupling ◽

Asian Summer

Abstract This paper reviews recent advances regarding land–atmosphere–ocean coupling associated with the Tibetan Plateau (TP) and its climatic impacts. Thermal forcing over the TP interacts strongly with that over the Iranian Plateau, forming a coupled heating system that elevates the tropopause, generates a monsoonal meridional circulation over South Asia and creates conditions of large-scale ascent favorable for Asian summer monsoon development. TP heating leads to intensification and westward extension (northward movement) of the South Asian High (Atlantic Intertropical Convergence Zone), and exerts strong impacts on upstream climate variations from North Atlantic to West Asia. It also affects oceanic circulation and buoyancy fields via atmospheric stationary wave trains and air–sea interaction processes, contributing to formation of the Atlantic Meridional Overturning Circulation. The TP thermal state and atmospheric–oceanic conditions are highly interactive and Asian summer monsoon variability is controlled synergistically by internal TP variability and external forcing factors.

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Spring Dust Mass Flux over the Tibetan Plateau during 2007–19 and Connections with North Atlantic SST Variability

Journal of Climate ◽

10.1175/jcli-d-19-0481.1 ◽

2020 ◽

Vol 33 (22) ◽

pp. 9691-9703

Author(s):

Chao Xu ◽

Yaoming Ma ◽

Jiehua Ma ◽

Chao You ◽

Huijun Wang

Keyword(s):

Tibetan Plateau ◽

North Atlantic ◽

Tarim Basin ◽

Mass Flux ◽

The Tibetan Plateau ◽

Indian Peninsula ◽

The North ◽

Dust Mass ◽

The North Atlantic ◽

Spring Dust

AbstractDust is the major aerosol type over the Tibetan Plateau (TP), and the TP plays an important role in forming the spring dust belt across the Northern Hemisphere in the upper troposphere. Estimated spring dust mass flux (DMF) showed a significant declining trend over the TP during 2007–19. The total spring DMF across the TP (TDMFTP) was mainly affected by DMFs over the Tarim Basin, while the spring DMF across the TP in the midtroposphere was also connected with DMFs over the northwest Indian Peninsula and central Asia. Interannual variability of spring TDMFTP was strongly correlated with the North Atlantic winter sea surface temperature (SST) tripole. A cold preceding winter induced by the North Atlantic winter SST tripole over midlatitude Eurasia promotes dust activities in the subsequent spring. The North Atlantic winter SST tripole anomalies persist into the subsequent spring and induce a corresponding atmosphere response. Enhanced atmospheric baroclinicity develops over northwest China and the northern Indian Peninsula during spring, which is attributed to surface thermal forcing induced by the positive winter SST tripole phase. A strong positive North Atlantic winter SST tripole anomaly strengthens the upper-level westerly jets, enhancing airflow toward the TP midtroposphere; together, these circulation patterns cause anomalous cyclonic conditions in the lower troposphere, especially over the Tarim Basin, via the eastward propagation of a Rossby wave train. These atmospheric circulation conditions are likely to increase the frequency of dust occurrence and promote the transport of dust onto the TP.

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