Large-Scale Aspects of Air-Mass Transformation over the East China Sea during AMTEX'74

Ninomiya, K.

doi:10.2151/jmsj1965.53.5_285

Cited by 35 publications

(25 citation statements)

References 25 publications

(14 reference statements)

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“…(See also Ninomiya, 1975, andNitta, 1976. ) On board the ocean station vessels, Keifu and Ryofu, the air temperature fell from about 17* in the earlier period to about 7* in the latter period, and the wind speed increased from about 5 m s-1 to about 15 m s-1.…”

Section: Datamentioning

confidence: 99%

Heat Balance of the East China Sea during the Air Mass Transformation Experiment

Kondo

1976

Journal of the Meteorological Society of Japan

109

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Transfers of heat and momentum in winter for the East China Sea and adjacent seas were estimated by means of an aerodynamic bulk method under diabatic conditions. It is found that at the Kuroshio region the sensible and latent heat losses (H+IE) are primarily compensated for by the heat convergence caused by the oceanic eddy and/or current transport. The secondary contribution to the heat balance is due to the net flux radiation and the oceanic heat storage. On the basis of heat balance consideration, the thermal diffusivity of the ocean of K= 1.0* 108 cm2 s-1 is obtained for a period of about one month. There is also suggested that in the Yellow Sea there occurs a counterclockwise circulation of water.The average value of H + IE over the AMTEX area for the entire period of AMTEX '74 is by about 10 to 20% smaller than the climatological normal value for the corresponding period. The value of H+IE estimated by the present aerodynamic method agrees in general with those obtained by the atmospheric budget computations by Nitta (1976) and Murty (1976) for both the period of AMTEX '74 and AMTEX '75. During an intense cold-air outbreak the very large amount of latent heat of about 500 to 800 W m-2 is supplied to the atmosphere over the Kuroshio, while only a small amount is supplied to the atmosphere over the shallow seas of the continental shelf. The Bowen ratio (H/IE) is about 0.7 to 0.8 over the Yellow Sea, whereas it is 0.3 to 0.4 over the AMTEX region, and 0.1 to 0.2 over the sub-tropical ocean.

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Section: Datamentioning

confidence: 99%

Heat Balance of the East China Sea during the Air Mass Transformation Experiment

Kondo

1976

Journal of the Meteorological Society of Japan

109

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“…However, a quantitative evaluation based on observations has not yet been conducted, except for the Air Mass Transformation Experiment in 1974 (AMTEX '74) (Ninomiya 1975). AMTEX '74 was conducted in February 1974 over the East China Sea, and the observation area is shown in Fig.…”

Section: Introductionmentioning

confidence: 99%

Cold surge event observed by radiosonde observation from the research vessel “Hakuho-maru” over the Philippine Sea in December 2012

Ogino

Hattori

et al. 2018

Prog Earth Planet Sci

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The thermal energy transfer from the sea surface to the atmosphere associated with a cold surge event was investigated with observations from radiosondes on the research vessel "Hakuho-maru" over the Philippine Sea in December 2012. These observations were analyzed, and the results were compared with those obtained from observations over the East China Sea in the Air Mass Transformation Experiment in 1974 (AMTEX '74). The horizontal advection of cold and dry air associated with the cold surge dominated at heights below 850 hPa. In spite of this strong advection, the local temporal variations in the temperature and moisture were small, because the advection was balanced by the transfer of heat and moisture from the sea surface, which is qualitatively the same behavior as observed during the cold surge event in AMTEX '74. The eddy transport of the total heat energy from the sea surface to the atmosphere was estimated at about 410 W/m 2 , which is about half of the maximum value of 780 W/m 2 observed during AMTEX '74. This result shows the existence of considerable heat transfer from the sea surface to the atmosphere over the Philippine Sea, which is the downstream region of the cold surge, after it passed through the East China Sea.

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“…These surges are generally preceded by the development of extratropical cyclones over the East China Sea region, where air mass modification is quite active with large amounts of moisture and sensible heat supplied by the underlying, warm Kuroshio current. The Air Mass Transformation Experiment (AMTEX) was a short-term, regional observation effort to investigate the role of energy supplied from the sea surface in the generation and development of East China Sea disturbances (Ninomiya, 1975;Nitta, 1976).…”

Section: Introductionmentioning

confidence: 99%

Orographic Influence of the Tibetan Plateau on the Asiatic Winter Monsoon Circulation

Murakami

1981

Journal of the Meteorological Society of Japan

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Empirical orthogonal function analysis was applied to 3.5-5.5 day filtered wind, temperature, and geopotential height data for the 1978-79 winter (1 December 1978 to 28 February 1979 at seven levels (the surface, 850, 700, 500, 300; 200 and 100 mb) over the Tibetan Plateau region (20* to 50*N and 57.5* to 117.5*E). The resulting eigenvector series were then truncated at eigenmode 12 to remove unwanted, small-scale noise which is of questionable accuracy. This was followed by the compositing of each meteorological variable at every level and grid point, with reference to changes in the first eigenvector coefficients for 3.5-5.5 day filtered meridional wind data at 200 mb.Composite charts of 3.5-5.5 day filtered winds and geopotential heights at 200 mb reveal that northeast-southwest oriented trough and ridge systems systematically propagate eastward with nearly the same phase speed (*12 m•s-1) throughout the entire Tibetan Plateau region. However, the amplitudes of these systems decrease as they pass over the Tibetan Plateau. Thus, this area of high mountains appears to exert some measure of control on the activity of 3.5-5.5 day wave perturbations even at the 200 mb level.At 500 mb, wind changes associated with the eastward passage of major trough and ridge systems are much less pronounced over the Tibetan Plateau than those to the north. These weak wind variations over the Plateau are probably a result of the 500 mb level being located within the planetary boundary layer above this highly elevated area. Similarly, midlatitude systems do not appear to extend across the Tibetan Plateau into the subtropical troposphere below 500 mb due to the frictional (or mechanical blocking) effects of these high mountains. This is demonstrated by the rapid weakening of cyclonic (anticyclonic) cells as they propagate northeastward over northern India toward the southern border of the Himalaya Mountains.Interestingly, 700 mb composite charts suggest that small-scale low (high) pressure cells develop near the northeastern periphery of the Tibetan Plateau. These orographically induced, small-scale disturbances then move southward along the eastern border of the Tibetan Plateau, and become most intense over the Red Basin before dissipating near the southeastern corner of the Plateau. Over central China, 700 mb northerlies (cold monsoonal surges) are strongest when an orographically induced anticyclonic cell in the lee of the Tibetan Plateau approaches the Red Basin and a major trough is over northeastern China. However, these northerly surges do not appear to penetrate into the South China Sea region. In contrast, 700 mb northerly surges with periods of 6-9 days may extend as far south as 20*N, and possibly beyond.

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Large-Scale Aspects of Air-Mass Transformation over the East China Sea during AMTEX'74

Cited by 35 publications

References 25 publications

Heat Balance of the East China Sea during the Air Mass Transformation Experiment

Heat Balance of the East China Sea during the Air Mass Transformation Experiment

Cold surge event observed by radiosonde observation from the research vessel “Hakuho-maru” over the Philippine Sea in December 2012

Orographic Influence of the Tibetan Plateau on the Asiatic Winter Monsoon Circulation

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