Estimating the Refractive Index Structure Parameter (Cn2) over the Ocean Using Bulk Methods

Infrared scintillation measurements were obtained along a 7-km path over San Diego Bay concurrently with meteorological measurements obtained from a buoy at the midpoint of the path. Bulk estimates of the refractive index structure parameter C2 were computed from the buoy data and compared with scintillation-derived C2 n n values. The bulk C2 estimates agreed well with the scintillation measurements in unstable conditions. In stable n conditions the bulk C2 estimates became increasingly higher than the scintillation values as the air–sea temperature n difference increased. This disagreement may be due to enhanced wave-induced mixing of the lower atmosphere that decreases the vertical temperature and humidity gradients in stable conditions from the assumed Monin– Obukhov similarity (MOS) theory forms, resulting in bulk C2 values that are too high. The bulk C2 estimates n n decrease rapidly when the absolute air–sea temperature difference approaches small positive values. These predicted decreases in C2 were not observed in either the path-averaged scintillation measurements or in single- n point turbulence measurements, indicating that bulk models for estimating scalar structure parameters based on mean air–sea scalar differences are not valid when the mean air–sea difference approaches zero. The authors believe that the most promising means toward improving the bulk C2 model is to obtain a better understanding n of the MOS functions over the ocean for a wide stability range, and particularly of the role of ocean waves in modifying near-surface vertical gradients and turbulence characteristics

Low-altitude infrared propagation in a coastal zone: refraction and scattering

Applied Optics, Volume 41, No. 18, pp. 3706-3724 (20 June 2002)Midwave and long-wave infrared propagation were measured in the marine atmosphere close to the surface of the ocean. Data were collected near San Diego Bay for two weeks in November 1996 over a 15-km horizontal path. The data are interpreted in terms of effects expected from molecules, aerosol particles, and refraction. Aerosol particles are a dominant influence in this coastal zone. They induce a diurnal variation in transmission as their character changes with regular changes in wind direction. A refractive propagation factor calculation is introduced, and it is systematically applied to the model and to the data analysis. It is shown that this refractive propagation factor is a necessary component of a complete near-sea-surface infrared transmission model

Broad-Line Reverberation in the \u3ci\u3eKepler\u3c/i\u3e-Field Seyfert Galaxy Zw 220-015

The Seyfert 1 galaxy Zw 229-015 is among the brightest active galaxies being monitored by the Kepler mission. In order to determine the black hole mass in Zw 229-015 from Hβ reverberation mapping, we have carried out nightly observations with the Kast Spectrograph at the Lick 3 m telescope during the dark runs from 2010 June through December, obtaining 54 spectroscopic observations in total. We have also obtained nightly V-band imaging with the Katzman Automatic Imaging Telescope at Lick Observatory and with the 0.9 m telescope at the Brigham Young University West Mountain Observatory over the same period. We detect strong variability in the source, which exhibited more than a factor of two change in broad Hβ flux. From cross-correlation measurements, we find that the Hβ light curve has a rest-frame lag of 3.86+0.69 –0.90 days with respect to the V-band continuum variations. We also measure reverberation lags for Hα and Hγ and find an upper limit to the Hδ lag. Combining the Hβ lag measurement with a broad Hβ width of σline = 1590 ± 47 km s–1 measured from the rms variability spectrum, we obtain a virial estimate of M BH = 1.00+0.19 –0.24 × 107 M ☉ for the black hole in Zw 229-015. As a Kepler target, Zw 229-015 will eventually have one of the highest-quality optical light curves ever measured for any active galaxy, and the black hole mass determined from reverberation mapping will serve as a benchmark for testing relationships between black hole mass and continuum variability characteristics in active galactic nuclei

Broad-Line Reverberation In The Kepler-Field Seyfert Galaxy Zw 229-015

The Seyfert 1 galaxy Zw 229-015 is among the brightest active galaxies being monitored by the Kepler mission. In order to determine the black hole mass in Zw 229-015 from H beta reverberation mapping, we have carried out nightly observations with the Kast Spectrograph at the Lick 3 m telescope during the dark runs from 2010 June through December, obtaining 54 spectroscopic observations in total. We have also obtained nightly V-band imaging with the Katzman Automatic Imaging Telescope at Lick Observatory and with the 0.9 m telescope at the Brigham Young University West Mountain Observatory over the same period. We detect strong variability in the source, which exhibited more than a factor of two change in broad H beta flux. From cross-correlation measurements, we find that the H beta light curve has a rest-frame lag of 3.86(-0.90)(+0.69) days with respect to the V-band continuum variations. We also measure reverberation lags for H alpha and H gamma and find an upper limit to the H delta lag. Combining the H beta lag measurement with a broad H beta width of sigma(line) = 1590 +/- 47 km s(-1) measured from the rms variability spectrum, we obtain a virial estimate of M-BH = 1.00(-0.24)(+0.19) x 10(7) M-circle dot for the black hole in Zw 229-015. As a Kepler target, Zw 229-015 will eventually have one of the highest-quality optical light curves ever measured for any active galaxy, and the black hole mass determined from reverberation mapping will serve as a benchmark for testing relationships between black hole mass and continuum variability characteristics in active galactic nuclei.NSF AST-0548198, AST-0908886, AST-0618209, NSF-0642621TABASGO FoundationGary and Cynthia BengierRichard and Rhoda Goldman FundSun Microsystems, Inc.Hewlett-Packard CompanyAuto-Scope CorporationLick ObservatoryUniversity of CaliforniaSylvia & Jim Katzman FoundationPackard FellowshipMinistry of Education, Science and Technology 2010-0021558NASAMarc J. Staley for a Graduate FellowshipAstronom