Papers in Meteorology and Geophysics

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Measurements of Vertical Wind Profile and Diffusion Parameters with the Doppler Sodar

Tomoaki Yoshikawa

1984 Volume 35 Issue 2 Pages 39-48
Published: 1984
Released on J-STAGE: March 09, 2007

DOIhttps://doi.org/10.2467/mripapers.35.39

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   Three components of the wind vectors and diffusion parameters were obtained automatically in 50 m steps from 150 to 500 m height with an acoustic Doppler radar system (Doppler sodar) in August, at Niihama seashore and in July and August, 1982, at Okayama plain, western Japan. By comparing the data with the pilot balloon and radiosonde data, the following results were obtained:
   a) Horizontal wind vectors with the Doppler sodar agreed fairly well with the pilot balloon data.
   b) Vertical flow with the Doppler sodar matched well with the topographic and thermal conditions. Remarkable vertical flows were produced mainly with thermal plumes or dynamic effect of buildings in the inland flat field, while they were limited in the case of land-sea breeze alternations or synoptic front passage over the seashore.
   c) Diffusion parameters showed also some characteristic patterns. The parameters increased separately in limited wind systems over the inland field in relation to thermal and dynamic conditions, while they increased altogether over the seashore on the occasion of wind turn.
   d) Profile patterns of the diffusion coefficient Kz, estimated from the Doppler sodar data for a fine summer day, agreed roughly with the profiles from the pilot balloon and radiosonde data. However, characteristic differences were found between the Kz values in the specific height in the daytime and those in the nighttime.

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Deep Flow on the Continental Slope off Omaezaki, in the Northern Part of the Cold Water Region Associated with the Kuroshio Meander

Hiroshi Ishizaki, Masahiro Endoh

1984 Volume 35 Issue 2 Pages 49-62
Published: 1984
Released on J-STAGE: March 09, 2007

DOIhttps://doi.org/10.2467/mripapers.35.49

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   A direct measurement of the deep flow was made at 33° 45.6′ N, 137° 35.8′ E on the continental slope off Omaezaki, Central Japan, for 136 days from December 1, 1982 to April 17, 1983. The mooring site is located in the northern part of the cold water region off the Tokai district with a bottom depth of 2200 m and a bottom slope of 4x10^-2. Four current meters were deployed at 30 m (L1), 100 m (L2), 310 m (L3) and 1000 m (L4) above the bottom. Unfortunately, records of speed at L3 were not obtained, except for the first 16 days.
   The mean flow averaged over the whole period is southeastward at L1 (30 m above the bottom) and southward at L2 (100m). A velocity component normal to the large-scale isobaths is larger than a tangential component. This is different from the result obtained in a preceding observation (Ishizaki et al., 1983) made at almost the same position where the current at 100 m above the bottom was generally flowing to the west-southwest along the large-scale isobaths. The difference of the general flow directions is discussed.
   Temporal variations of the flow field are coherent between L1 (30 m) and L2 (100 m), and so are those of the temperature field among the lowest three levels. But the coherency between L4 (1000 m) and lower levels is not so apparent. Examination of vertical variation of the relative magnitude of the variances of the zonal and meridional velocity components indicates that the bottom control of the fluctuations is no longer effective at L4 (1000 m above the bottom). According to spectral calculations, more than half of the total fluctuation kinetic energy is contained in a frequency band (16.3-52 days in period), though the fluctuation energy levels are much different from each other.

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Measurement of CF₂Cl₂ at Memanbetsu over the Period between October 1980 and March 1983

Michio Hirota, Hisafumi Muramatsu, Fumio Fukui, Fujio Muromatsu, Masah ...

1984 Volume 35 Issue 2 Pages 63-69
Published: 1984
Released on J-STAGE: March 09, 2007

DOIhttps://doi.org/10.2467/mripapers.35.63

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   In order to obtain the atmospheric lifetime of CF₂Cl₂ (τ), the measurements of CF₂Cl₂ were performed from October 1980 to March 1983 at Memanbetsu, Hokkaido.
   The trend of monthly mean volume mixing ratios of CF₂Cl₂ when the wind directions were between NW and N was considered to represent the trend of the background mixing ratios. In this case, the mean increase rate from October 1980 to March 1983 was 1₅ ppt/year (ppt=10^-12).
   From the increase rate obtained in this study and the release rate reported by the Chemical Manufacturers Association (1983), τ was calculated to be 24 (5∼∞) years. Such a short lifetime seems to be due to the overestimation of the release rate in 1980 and 1981.

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