Confluence Theory of the High Tropospheric Jet Stream

Namias, Jerome; Clapp, Philip F.

doi:10.1175/1520-0469(1949)006<0330:ctotht>2.0.co;2

Cited by 143 publications

(53 citation statements)

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“…4b). The feature is similar to the confluence theory of jet streams presented by Namias and Clapp (1949), but it occurs in the lower troposphere rather than in the upper troposphere.…”

Section: Observed Feature and Results Of The Control Experimentssupporting

confidence: 80%

The Effect of Qinghai-Tibet Plateau Forcing on the Meso-Scale Rain-bearing Circulation Systems over Eastern China during Presummer Rainy Season

Chen

Dell'osso

1986

Journal of the Meteorological Society of Japan

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The low level jet and the associated low level south-west vortex are the main mesoscale systems which bring heavy rains over East Asia. In order to examine the influence of Qinghai-Tibet Plateau (QTP) on these circulation systems, a control and two experiments were performed with the ECMWF grid point limited area model for a typical heavy rainfall case during the presummer rainy (Mei-yu) season.The control experiment, in which the orography represents the mean value over a grid box, reproduces the variation of the low level jet, the formation of the south-west vortex and the heavy rainfall area. When the height of QTP is halved, the south-west monsoon south of the Plateau interacts with the middle latitude westerlies.A baroclinic disturbance then develops instead of the meso-scale systems, and the heavy rainfall zone is shifted to the east. Increasing the QTP height causes the meso-scale systems to be enhanced and restricted to the vicinity of the Plateau, and the rainfall zone is shifted to the west.The results show that the forcing effect of the QTP on the three low level branches of the flow (the northerlies from middle latitude, the south-west monsoon from the Bay of Bengal and the easterlies from the West Pacific) develops and maintains the meso-scale rain-bearing systems.

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“…4b). The feature is similar to the confluence theory of jet streams presented by Namias and Clapp (1949), but it occurs in the lower troposphere rather than in the upper troposphere.…”

Section: Observed Feature and Results Of The Control Experimentssupporting

confidence: 80%

The Effect of Qinghai-Tibet Plateau Forcing on the Meso-Scale Rain-bearing Circulation Systems over Eastern China during Presummer Rainy Season

Chen

Dell'osso

1986

Journal of the Meteorological Society of Japan

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“…The fact that southerlies in *x are stronger over the continent than over the ocean to the east is consistent with the idea that the north-south thermal gradient increases mainly over the continent causing a stronger cross-contour flow (Namias and Clapp, 1949;Blackmon et al 1977;and Lau, 1978).…”

Section: Mean State and Cross-sectionssupporting

confidence: 85%

“…8. The strong southerly *x in the entrance region of the jet stream is accompanied by a divergence-convergence pair in the divergence pattern between 20*N and 45*N. This is similar to the divergence pattern suggested by Namias and Clapp (1949). The cross-section of the seasonal mean vertical motion field along 114.375*E between 1.875*N and 58.125*N is shown in Fig.…”

Section: Mean State and Cross-sectionssupporting

confidence: 80%

The 10-20 Day Tropical-Midlatitude Interactions during the Winter Monsoon Season

Pan

Fa-xiu

1985

Journal of the Meteorological Society of Japan

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The lower-frequency variations in the winter monsoon system have been examined using a l0-day low-pass filter. Results indicate that the lower tropospheric north-south thermal gradient over eastern Asia, the Siberian high pressure system, and the eastern Asia subtropical jet stream varied coherently with a time scale of 10-20 days. Composite study reveals that the 200-mb streamfunction variations on the 10-20 day time scale are longsynoptic-scale disturbances propagating slowly eastward. The cyclonic disturbances weaken as they move eastward south of the Tibetan Plateau and begin to strengthen when the lower tropospheric thermal troughs from Siberia move southward. The irrotational circulations on the 10-20 day time scale are closely related to the streamfunction variation with a quarter-wave phase shift. The tropical-midlatitude interactions in the winter monsoon system are seen to be the interactions between these long-synoptic-scale waves and the local monsoon circulations based on the phase relationships among various elements studied. The divergent circulations of the propagating waves trigger the cold air outbreak over eastern Asia when the wave trough is situated south of the Tibetan Plateau. The propagating waves are seen to intensify over the ocean suggesting a transfer of energy from the monsoon system to the waves.

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“…The TP was situated between these two maxima, in association with the entrance and exit of the westerly jets. Rossby (1947) and Namias and Clapp (1949) pointed out the existence of a direct cross-jet vertical circulation in the jet entrance, with warmer air ascending south of the jet and colder air descending to its north, converting available potential energy (APE) into kinetic energy. In the exit region, the reverse cross-jet vertical circulation facilitated the increase of APE and cyclogenesis in the lower troposphere (University of Chicago, 1947).…”

Section: Tibetan Plateau Snow and Large-scale Atmospheric Circulationmentioning

confidence: 99%

Interannual Variability of Snow Depth over the Tibetan Plateau and Its Associated Atmospheric Circulation Anomalies

Mao

2010

Atmospheric and Oceanic Science Letters

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The interannual variability of wintertime snow depth over the Tibetan Plateau (TP) and related atmospheric circulation anomalies were investigated based on observed snow depth measurements and NCEP/NCAR reanalysis data. Empirical orthogonal function (EOF) analysis was applied to identify the spatio-temporal variability of wintertime TP snow depth. Snow depth anomalies were dominated by a monopole pattern over the TP and a dipole structure with opposite anomalies over the southeastern and northwestern TP. The atmospheric circulation conditions responsible for the interannual variability of TP snow depth were examined via regression analyses against the principal component of the most dominant EOF mode. In the upper troposphere, negative zonal wind anomalies over the TP with extensively positive anomalies to the south indicated that the southwestward shift of the westerly jet may favor the development of surface cyclones over the TP. An anomalous cyclone centered over the southeastern TP was associated with the anomalous westerly jet, which is conducive to heavier snowfall and results in positive snow depth anomalies. An anomalous cyclone was observed at 500 hPa over the TP, with an anomalous anticyclone immediately to the north, suggesting that the TP is frequently affected by surface cyclones. Regression analyses revealed that significant negative thickness anomalies exist around the TP from March to May, with a meridional dipole anomaly in March. The persistent negative anomalies due to more winter TP snow are not conducive to earlier reversal of the meridional temperature gradient, leading to a possible delay in the onset of the Asian summer monsoon. Keywords: Tibetan Plateau, snow depth, interannual variability, atmospheric circulation anomalies Citation: Mao, J.-Y., 2010: Interannual variability of snow depth over the Tibetan Plateau and its associated atmospheric circulation anomalies, Atmos. Oceanic Sci. Lett., 3,[213][214][215][216][217][218]

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Confluence Theory of the High Tropospheric Jet Stream

Cited by 143 publications

References 0 publications

The Effect of Qinghai-Tibet Plateau Forcing on the Meso-Scale Rain-bearing Circulation Systems over Eastern China during Presummer Rainy Season

The Effect of Qinghai-Tibet Plateau Forcing on the Meso-Scale Rain-bearing Circulation Systems over Eastern China during Presummer Rainy Season

The 10-20 Day Tropical-Midlatitude Interactions during the Winter Monsoon Season

Interannual Variability of Snow Depth over the Tibetan Plateau and Its Associated Atmospheric Circulation Anomalies

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