Title: Determining the refractive index structure constant using high-resolution radiosonde data




НазваниеTitle: Determining the refractive index structure constant using high-resolution radiosonde data
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5. CONCLUSIONS


A method to determine the refractive index structure constant, Cn2, from high-resolution radiosonde data has been developed. A full validation of this method was not possible to carry out due to the lack of other datasets, e.g. radar measurements. However, the results obtained present the values and behaviour similar and within the range of those observed by other authors. The statistical behaviour of Cn2 also shows the expected log-normality further confirming the general correctness of the approach. The distributions of turbulent layer thickness are as well within the range of those observed for the outer scale turbulence providing further reassurance on the taken approach. Statistical results were obtained for 4 sites at different latitudes as well as an exponential fit to the median for applications where simplified models for Cn2 suffice. These statistical results show the expected physical impact of the boundary layer, orographic features and local climate.

The authors expect that further work will lead to the full validation of the method and that high-resolution radiosonde data may become of widespread use, due to its availability, to determine turbulence and its parameters.

Acknowledgements


The authors would like to thank the British Atmospheric Data Centre and the UK MetOffice for providing access to its excellent database of high-resolution radiosonde data. They would like to thank Danielle Vanhoenacker as well for providing the raw data as used by Hugues Vasseur in his paper. Special mention has to be made of Pierluigi Silvestrin for his unwaivering support to this activity and of Gottfried Kirchengast and Per Høeg for the constructive criticism in the many discussions with the authors.

REFERENCES



Barat, J., “Some characteristics of clear-air turbulence in the middle stratosphere”, J. Atmos. Sci., vol. 32, pp 2553-2564, 1982.


Barletti, R., Ceppatelli, G., Paterno, L., Righini, A., Speroni, N., “Mean vertical profile of atmospheric turbulence relevant for astronomical seeing”, Journal of the Optical Society of America, vol. 66, no. 12, pp 1380—1383, 1976.


Bufton, J.L., Minott, P.O., Fitzmaurice, M.W., Titterton, P.J., “Measurements of turbulence profiles in the troposphere”, Journal of the Optical Society of America, vol. 62, no. 9, pp 1117—1120, 1972.


Bufton, J.L., “Correlation of microthermal turbulence with meteorological soundings in the troposphere”, Journal of Atmospheric Science, vol. 30, pp 83—87, 1973.


Coulman, C.E., “Vertical profiles of small-scale temperature structure in the atmosphere”, Bound.-Layer Meteor., vol. 4, pp 169—177, 1973.


Dole, J., Wilson, R., Dalaudier, F., Sidi, C., “Energetics of small scale turbulence in the lower stratosphere from high resolution radar measurements”, Ann. Geophys., vol. 19, pp 945—952, 2001.


Eaton, F.D., Nastrom, G.D., “Preliminary estimates of the vertical profiles of inner and outer scales from White Sands Missile Range, New Mexico, VHF radar observation”, Radio Sci., vol. 33, no. 4, pp 895—903, 1998.


European Space Agency, ESA SP-1279 (4) – ACE+ - Atmosphere and Climate Explorer, Reports for Mission Selection, The Six Candidate Earth Explorer Missions, ESA, April 2004


Ghosh, A.K., Siva Kumar, V., Kshore Kumar, K., Jain, A.R., “VHF radar observation of atmospheric winds, associated shears and Cn2 at a tropical location: interdependence and seasonal pattern”, Ann. Geophys., vol. 19, pp 965—973, 2001.


Ishimaru, A., “A new approach to the problem of wave fluctuations in localized smoothly varying turbulence”, IEEE Trans. Antennas Propag., AF-21(1), 1973.


Kolmogorov, A. N., “The Local Structure of Turbulence in Incompressible Viscous Fluid for Very Large Reynolds’ Numbers”, Comptes Rendus (Doklady) de l’Academie des Sciences de l’URSS, vol. 30, pp 301--305, 1941


Monin, A. S. and A. M. Yaglom, Statistical Fluid Mechanics, MIT Press, Cambridge, Massachusetts 1971.


Nastrom, G.D., Gage, K.S., Ecklund, W.L., “Variability of turbulence, 4-20 km, in Colorado and Alaska from MST radar observations”, J. Geophys. Res., vol. 91, pp 6722—6734, 1986.


Ottersten, H., “Atmospheric structure and radar backscattering in clear air”, Radio Sci., vol. 4, no. 12, pp 1179—1193, 1969.


Ottersten, H., “Mean vertical gradient of potential refractive index in turbulent mixing and radar detection of CAT”, Radio Sci., vol. 4, no. 12, pp 1247—1249, 1969.


Rao, D.N., Kishore, P., Rao, T.N., Rao, S.V.B., Reddy, K.K., Yarraiah, M., Hareesh, M., “Studies on refractivity structure constant, eddy dissipation rate, and momentum flux at a tropical latitude”, Radio Sci., vol. 32, no. 2, pp 1375—1389, 1997.


Rao, D.N., Rao, T.N., Venkataratnam, M., Thulasiraman, S., Rao, S.V.B., Srinivasulu, P., Rao, P.B., “Diurnal and seasonal variability of turbulence parameters observed with Indian mesosphere-stratosphere-troposphere radar”, Radio Sci., vol. 36, no. 6, pp 1439—1457, 2001.


Richardson, L. F., Weather Prediction by Numerical Process, Cambridge University Press, Cambridge, 1922


Stull, R. B., Meteorology for Scientists and Engineers, Brooks/Cole, Pacific Grove, 2000.


Tatarskii, V. I., Wave Propagation in a Turbulent Medium, McGraw -Hill, New York, 1961.


Tatarskii, V. I., The Effects of the Turbulent Atmosphere on Wave Propagation, Israel Program for Scientific Translations Ltd., Jerusalem, 1971.


Thompson, M.C., Marler, F.E., Allen, K.C., “Measurement of the microwave structure constant profile”, IEEE Trans. Antennas Propag., vol. AP-28, no. 2, pp 278—280, 1980.


VanZandt, T.E., Green, J.L., Gage, K.S., Clark W.L., “Vertical profiles of refractivity turbulence structure constant: Comparison of observations by the Sunset Radar with a new theoretical model”, Radio Sci., vol. 13, no. 5, pp 819—829, 1978.


Vasseur, H., "Prediction of Tropospheric Scintillation on Satellite Links from Radiosonde Data", IEEE Trans. Antennas Propag., vol. 47, 2, pp. 293--301, 1999.


Wallace, J. M. and P. V. Hobbs, Atmospheric Science: An Introductory Survey, pp 437-439, Academic Press, San Diego, 1977.


Warnock, J. M. and T. E. VanZandt, "A statistical model to estimate the refractivity turbulence structure constant Cn2 in the free atmosphere", NOOA Tech. Memo ERL, AL-10, Aeronom. Lab., Boulder, CO, 1985


Wheelon, A. D., Electromagnetic Scintillation, I. Geometrical Optics, Cambridge University Press, Cambridge, 2001.


Woo, R., Ishimaru, A., “Effects of turbulence in a planetary atmosphere on radio occultation”, IEEE Trans. Antennas Propag., AF-22(4), 1974.

Table 1: Technical specifications of the Vaisala RS80 radiosonde.

Table 2: Radiosonde stations


Figure 1: Block diagram of methodology


Figure 2: Cn2 for a single radiosonde launch (Camborne 1st January 2002 at 0600 UTC). Data points at 10-21 represent stable layers while scattered data points show Cn2 for turbulent layers


Figure 3: Histogram of Cn2 at a height of 6000 meters. Data covers 4 years (1994-1996, 2002) of 4 daily radiosonde launches in Camborne.


Figure 4: Mean of log Cn2 and 10, 50 and 90 percentiles as a function of height derived from the cumulative distribution of Cn2 for Camborne (data comprising 4 years of 4 daily launches).


Figure 5: The probability of turbulence as a function of height for Camborne (data for 4 years of 4 daily launches).


Figure 6: Percentiles derived from the probability distribution of Cn2 conditioned to having turbulence at Camborne (data for 4 years of 4 daily launches).


Figure 7: Percentiles as a function of height for the thickness of the turbulent layer. The percentiles refer only to turbulent samples.


Figure 8: Mean of log Cn2 and 10, 50 and 90 percentiles as a function of height derived from the cumulative distribution of Cn2 for Lerwick.


Figure 9: Mean of log Cn2 and 10, 50 and 90 percentiles as a function of height derived from the cumulative distribution of Cn2 for Gibraltar.


Figure 10: Mean of log Cn2 and 10, 50 and 90 percentiles as a function of height derived from the cumulative distribution of Cn2 for St. Helena.





Measuring Range

Accuracy

Resolution

Pressure (hPa)

1060 to 3

± 0.5

0.1

Temperature (oC)

+60 to -90

± 0.2

0.1

Humidity (%RH)

0 to 100

± 2

1







Latitude (o)

Longitude (o)

AMSL

(m)

Launches

UTC

Years of data

Lerwick

60.13 N

1.18 W

82

00, 06, 12, 18

99-02

Camborne

50.22 N

5.32 W

88

00, 06, 12, 18

94-96, 02

Gibraltar

36.14 N

5.35 W

10

00, 12

00-02

St. Helena

15.23 S

5.18 W

400

12

00, 02
























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