On the relationship between C<sub>n</sub><sup>2</sup> and humidity

Carlos O. Font; Mark P. J. L. Chang; Erick A. Roura; Eun Oh; Charmaine Gilbreath

doi:10.1117/12.672205

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12 July 2006 On the relationship between C_n² and humidity

Carlos O. Font, Mark P. J. L. Chang, Erick A. Roura, Eun Oh, Charmaine Gilbreath

Author Affiliations +

Proceedings Volume 6268, Advances in Stellar Interferometry; 62683D (2006) https://doi.org/10.1117/12.672205
Event: SPIE Astronomical Telescopes + Instrumentation, 2006, Orlando, Florida , United States

Abstract

We have recently shown the refractive index structure constant C²_n in the visible and near infrared to be a strong function of humidity in the absence of solar insolation effects, in stark contrast to the commonly held assumption that the humidity contribution can be ignored in that waveband. We expand our analysis of the effects of humidity on C²_n as measured across a 100-m long horizontal beam path to include temperature. Also we present a new technique for extracting information on changes in the parameter space of C²_n and local weather variables, which we term Hilbert Phase Analysis (HPA). This methodology, based on extracting the phase of the analytic signal via Hilbert transforms, reveals a wealth of detail that conventional analysis techniques cannot determine. The HPA provides additional confirmation that C²_n is strongly influenced by local humidity in the visible region. We have also found that HPA provides a clear demonstration that humidity competes with temperature in affecting the value of C²_n.

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Carlos O. Font, Mark P. J. L. Chang, Erick A. Roura, Eun Oh, and Charmaine Gilbreath "On the relationship between C_n² and humidity", Proc. SPIE 6268, Advances in Stellar Interferometry, 62683D (12 July 2006); https://doi.org/10.1117/12.672205

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