Identification of Cirrus over Wausau during the 1986 FIRE IFO from ground-based radiometer data

The potential of using irradiation data to indicate episodes of cirrus cloudiness during the daylight hours is explored. Thresholds separating cirrus from other clouds and clear skies are determined using four days of irradiation data, hourly weather observations, sky photographs, sky video, and occasional lidar observations. Data were gathered during the First International Satellite Cloud Climatology Program (ISCCP) Regional Experiment (FIRE) Intensive Field Observations (IFO) cirrus project. Thresholds are tested using data from the remaining 17 days of the IFO. Cirrus episodes are defined as intervals when the sky cover is primarily cirrus. Measurements of incoming shortwave and near infrared full hemispheric and diffuse irradiation, and atmospheric infrared irradiation were made at Wausau, Wisconsin Municipal Airport. Data were collected between October 13 and November 2, 1986 and are one minute averages of ten second samples. Data from October 23 and from October 27 to 29 were used for threshold determination. Using weather observations, lidar output, photographs and video, sky conditions were grouped into three categories: noncirrus cloudy, cirrus, and clear. Irradiation data from all periods falling under each of the sky categories were then examined and thresholds denoting a change from one sky category to another were determined. Variables with only a small amount of overlap between sky categories were selected as key indicators

Impact of cirrus on the surface radiative environment at the FIRE ETLA Palisades, NY site

FIRE Extended Time Limited Area (ETLA) observations provide year round information critical to gaining a better understanding of cloud/climate interactions. The Lamont/Rutgers team has participated in the ETLS program through the collection and analysis of shortwave and longwave downwelling irradiances at Palisades, NY. These data are providing useful information on surface radiative fluxes with respect to sky condition, solar zenith angle and season. Their utility extends to the calibration and validation of cloud/radiative models and satellite cloud and radiative retrievals. The impact cirrus clouds have on the surface radiative environment is examined using Palisades ETLA information on atmospheric transmissivities and downwelling longwave fluxes for winter and summer cirrus and clear sky episodes in 1987

Ariel - Volume 4 Number 1

Editors David A. Jacoby Eugenia Miller Tom Williams Associate Editors Paul Bialas Terry Burt Michael Leo Gail Tenikat Editor Emeritus and Business Manager Richard J. Bonnano Movie Editor Robert Breckenridg

FIRE extended time/limited area observations at Palisades, New York

Downwelling shortwave and longwave irradiation are being continuously monitored at Palisades, New York as part of the First International Satellite Cloud Climatology Project (ISCCP) Regional Experiment (FIRE) Extended Time/Limited Area Initiative. In addition, fisheye (180 degree) sky photographs are taken at the times of NOAA 9 and LANDSAT satellite overpasses on select days, particularly when cirrus clouds are present. Measurements of incoming shortwave (0.28 to 2.80 microns) hemispheric and diffuse, hemispheric near infrared (0.7 to 2.80 microns), and downwelling hemispheric infrared (4.0 to 50.0 microns) irradiation have been made from a rooftop location on the grounds of the Lamont-Doherty Geological Observatory since December 1986. The three Eppley Precision Spectral Pyranometers and the Eppley Pyrgeometer used to measure these variables were calibrated with Colorado State University instruments at Madison, Wisconsin as part of the FIRE Intensive Laboratory. Pyrgeometer output contains an adjustment for body temperature but not for dome temperature. Data are transmitted to a Campbell CR-21 Digital Recorder, where one minute averages of ten second samples are stored and subsequently dumped to a cassette recorder. Using a Campbell C-20 Cassette Interface, these data are transferred to an Apple Macintosh computer for analysis and for archiving on floppy disks. In addition to the raw irradiances collected, variables derived from these data are generated and stored. These include: the ratio of near infrared irradiation to visible irradiation and the fraction of the full shortwave irradiation which is diffuse; and will soon include: shortwave transmissivity and optical depth in the shortwave. Sky photographs are taken with an Olympus OM2-N 35 mm camera and are timed to be coincident with overpassing NOAA and LANDSAT satellites. Palisades is within the field of view of the NOAA 9 daily in the middle to late afternoon. The satellite viewing angle is within 45 degrees of nadir over Palisades on approximately half of the passes

An optimization method for nacelle design

A multi-objective optimiZation method is demonstrated using an evolutionary genetic algorithm. The applicability of this method to preliminary nacelle design is demonstrated by coupling it with a response surface model of a wide range of nacelle designs. These designs were modelled using computational fluid dynamics and a Kriging interpolation was carried out on the results. The NSGA-II algorithm was tested and verified on established multi-dimensional problems. Optimisation on the nacelle model provided 3-dimensional Pareto surfaces of optimal designs at both cruise and off-design conditions. In setting up this methodology several adaptations to the basic NSGA-II algorithm were tested including constraint handling, weighted objective functions and initial sample size. The influence of these operators is demonstrated in terms of the hyper volume of the determined Pareto set

Earthshine as an Illumination Source at the Moon

Earthshine is the dominant source of natural illumination on the surface of the Moon during lunar night, and at locations within permanently shadowed regions that never receive direct sunlight. As such, earthshine may enable the exploration of areas of the Moon that are hidden from solar illumination. The heat flux from earthshine may also influence the transport and cold trapping of volatiles present in the very coldest areas. In this study, Earth's spectral radiance at the Moon is examined using a suite of Earth spectral models created using the Virtual Planetary Laboratory (VPL) three dimensional modeling capability. At the Moon, the broadband, hemispherical irradiance from Earth near 0 phase is approximately 0.15 watts per square meter, with comparable contributions from solar reflectance and thermal emission. Over the simulation timeframe, spanning two lunations, Earth's thermal irradiance changes less than a few mW per square meter as a result of cloud variability and the south-to-north motion of sub-observer position. In solar band, Earth's diurnally averaged light curve at phase angles < 60 degrees is well fit using a Henyey Greenstein integral phase function. At wavelengths > 0.7 microns, near the well known vegetation "red edge", Earth's reflected solar radiance shows significant diurnal modulation as a result of the longitudinal asymmetry in projected landmass, as well as from the distribution of clouds. A simple formulation with adjustable coefficients is presented for estimating Earth's hemispherical irradiance at the Moon as a function of wavelength, phase angle and sub-observer coordinates. It is demonstrated that earthshine is sufficiently bright to serve as a natural illumination source for optical measurements from the lunar surface.Comment: 27 pages, 15 figures, 1 tabl

Phosphorylation of Sli15 by Ipl1 is important for proper CPC localization and chromosome stability in <em>Saccharomyces cerevisiae</em>

The chromosomal passenger complex (CPC) is a key regulator of eukaryotic cell division, consisting of the protein kinase Aurora B/Ipl1 in association with its activator (INCENP/Sli15) and two additional proteins (Survivin/Bir1 and Borealin/Nbl1). Here we have identified multiple sites of CPC autophosphorylation on yeast Sli15 that are located within its central microtubule-binding domain and examined the functional significance of their phosphorylation by Ipl1 through mutation of these sites, either to non-phosphorylatable alanine (sli15-20A) or to acidic residues to mimic constitutive phosphorylation (sli15-20D). Both mutant sli15 alleles confer chromosome instability, but this is mediated neither by changes in the capacity of Sli15 to activate Ipl1 kinase nor by decreased efficiency of chromosome biorientation, a key process in cell division that requires CPC function. Instead, we find that mimicking constitutive phosphorylation of Sli15 on the Ipl1 phosphorylation sites causes delocalization of the CPC in metaphase, whereas blocking phosphorylation of Sli15 on the Ipl1 sites drives excessive localization of Sli15 to the mitotic spindle in pre-anaphase cells. Consistent with these results, direct interaction of Sli15 with microtubules in vitro is greatly reduced either following phosphorylation by Ipl1 or when constitutive phosphorylation at the Ipl1-dependent phosphorylation sites is mimicked by aspartate or glutamate substitutions. Furthermore, we find that mimicking Ipl1 phosphorylation of Sli15 interferes with the 'tension checkpoint'--the CPC-dependent mechanism through which cells activate the spindle assembly checkpoint to delay anaphase in the absence of tension on kinetochore-microtubule attachments. Ipl1-dependent phosphorylation of Sli15 therefore inhibits its association with microtubules both in vivo and in vitro and may negatively regulate the tension checkpoint mechanism