Long-term Observational Program Research Articles

A Simple Parameterisation for Flux Footprint Predictions

Flux footprint functions estimate the location and relative importance of passive scalar sources influencing flux measurements at a given receptor height. These footprint estimates strongly vary in size, depending on receptor height, atmospheric stability, and surface roughness. Reliable footprint calculations from, e.g., Lagrangian stochastic models or large-eddy simulations are computationally expensive and cannot readily be computed for long-term observational programs. To facilitate more accessible footprint estimates, a scaling procedure is introduced for flux footprint functions over a range of stratifications from convective to stable, and receptor heights ranging from near the surface to the middle of the boundary layer. It is shown that, when applying this scaling procedure, footprint estimates collapse to an ensemble of similar curves. A simple parameterisation for the scaled footprint estimates is presented. This parameterisation accounts for the influence of the roughness length on the footprint and allows for a quick but precise algebraic footprint estimation.

The Araucaria project – improving stellar distance indicators

AbstractWe present first results of an optical wide field imaging survey of the galaxies NGC 300, NGC 6822, WLM and Phoenix, performed as part of the Araucaria Project, a long-term observational program recently initiated at the Universidad de Concepción. Based on our data, a large number of new Cepheids in these galaxies has been found. Our photometric databases were also used to select blue supergiant candidates in these galaxies, and to search for the photometric variability of these stars, as well as for a number of side projects, such as the search of other types variable stars and OB associations in these galaxies.

Tar ball frequency data and analytical results from a long-term beach monitoring program

Following the spill of fuel oils from the New Carissa in February 1999, approximately 300 km of beaches on the Pacific coast of North America were surveyed. A long-term observation program focused on the documentation of stranded tar balls in the vicinity of the spill site. Systematic beach surveys which were conducted over the period March 1999 to April 2001 and semi-logarithmic scale, time-series plots proved the most useful format for identifying trends. Beach monitoring continued through to August 2001, by which time 212 tar balls had been analyzed by GC/MS for their chemical characteristics. The samples of tar balls collected between February 1999 and August 2001 were qualitatively compared with New Carissa source oils (NCSO) and 101 (48%) were not consistent with NSCO. The presence of tar balls that are not related to an incident can confound attempts to define cleanup or endpoint criteria and to assess possible injury to natural resources.

TARBALL DATA FROM THE OREGON COAST

ABSTRACT Approximately 300 kilometers of the coast of Oregon were surveyed following the spill from the New Carissa and a long-term observation program focused on the documentation of stranded tarballs in the vicinity of the spill site. Field documentation methods applied to shoreline oiling after the spill in February 1999 initially followed standard SCAT reporting procedures. After a brief period of relatively heavy oiling, most of the stranded oil took the form of oil pellets of various sizes (“tarballs”). As the amounts of oil on the shoreline diminished, the standard SCAT method resulted in evaluations of oil quantities that were invariably too high. Field observations were conducted for a year after the incident and the data presented in this discussion cover tarball observations in two segments adjacent to the accident site and at two distant locations over the period March 1999 to June 2000. Data output from the study included maps, tables, and histograms of stranded tarball volumes and concentrations (gm/m2). The semi-logarithmic scale time-series plots of the tarball concentration proved the most useful format for identifying trends, as the data spanned as many as nine orders of magnitude. When plotted on conventional histogram, only the larger values can be identified and smaller trends are masked in the time series. Long-term (> 1 year) data on the monthly median tarball size and the monthly tarball volume are provided for four sites.

CCD Photometry of Cometary Nuclei, I: Observations from 1990–1995

CCD photometry of 18 Jupiter family comets, observed at medium and large heliocentric distances, was carried out between April 1990 and July 1995. This is part of a long-term observational program designed to obtain their nuclear magnitudes. The observations were made with the 1.54-m Danish Telescope at ESO La Silla, the 2.5-m Nordic Optical Telescope (NOT) at Observatorio del Roque de los Muchachos (La Palma), the 2.0-m telescope at Pic du Midi, and the 2.15-m telescope at CASLEO, Argentina. Our estimates of the absolute nuclear magnitudes are discussed in comparison with previous determinations. Estimates (sometimes upper limits) for the effective radius ( R ) of the nuclei are computed considering a typical geometric albedo p v =0.04. The lowest radius found is the one of 37P/Forbes ( R =1.0 km) while the largest corresponds to 65P/Gunn ( R =11.0 km), but in this case the comet was observed very active. Wherever possible, cometary image profiles are compared with stellar profiles, in order to determine the existence of a faint coma. Seven of the comets were active, six of them at heliocentric distances larger than 4 AU. This unexpected activity is also discussed. We find a strong correlation between activity at large heliocentric distances and recent downward jumps in perihelion distance.

Estimation of algal biological parameters using water quality modeling and SPOT satellite data

Discovering biological parameters is the essential step to understand and even control an ecosystem. Traditional in situ sampling is time-consuming, expensive, and can only be taken for small areas with limited samples. It also needs a long-term observation program to acquire biological growth records. In this paper, a novel approach is proposed to estimate algal biological parameters, which are important factors of eutrophication control, by using water quality modeling and remote sensing techniques. Algal growth rate and respiration rate were estimated using a one-dimensional water quality model (QUAL2E) and two-dimension spatially distributed water quality data derived from SPOT satellite imagery for the Te-Chi Reservoir in Taiwan. A nonlinear calibration model was developed by minimizing the average difference between observed and simulated values using a least squares method. The calibration model using a mathematical approach provides an alternative method to estimate biological parameters of algae besides in situ sampling and experiment.

Chemical and physical aging of comets

AbstractAging effects for comet nuclei encompass both chemical and physical changes to the nucleus which may be manifested as a change in the level of and type of activity that the nucleus experiences. Recent observations have shown the importance of the amorphous to crystalline water ice phase transition in comet nuclei for controlling activity at large distances, and for altering the porosity and volatile distribution in the interior of comets. Evidence for secular changes in activity levels or differences between dynamical classes of comets which have spent different amounts of time in the inner solar system must be decoupled from expected primordial differences between comets. Long-term observational programs by several groups have demonstrated that the effects of aging are detectable. This paper will discuss the expected primordial comet differences, the expected physical and chemical effects of aging, the techniques for observing differences in activity levels, and will present summaries of results of several observing programs.

The Canaris Type IA Supernovae Archive (I)

This paper presents an atlas containing 59 low-resolution supernova <br>spectra which correspond to 27 type Ia supernovae. These 59 spectra spectra which correspond to 27 type Ia supernovae. These 59 spectra refer to different ages along the postmaximum type Ia evolution, covering from the photospheric to the old (~>300 days) nebular phases. These supernovae were observed as a part of the long-term observational program Supernova Monitoring Project, carried out at the Observatorio del Roque de los Muchachos (La Palma, Spain) from 1990 July to 1994 July. Most of these observations were taken with the Faint Object Spectrograph (FOS) and a few spectra were obtained by means the ISIS spectrograph. Three or more spectra were obtained for ten of these supernovae. Concerning the homogeneity among the type Ia supernova subclass, our sample points to a "first-order" overall homogeneous spectroscopic behavior. However, a finer analysis - comparing spectra at similar evolutionary phase-allows differences to be found in relation to strengths, wavelength positions, and evolution with time of the more significant spectral type Ia supernova features. Furthermore, some objects that exhibit clear signs of spectroscopic peculiarities (SNe 1991F, 1991bg, and 1991bj) are also included in our sample. The parent galaxies of these supernovae present redshifts ranging from z = 0.003 to z = 0.07. Four of these (SNe 1991S, 1991ad, 1992R, and 1992ac) were observed in galaxies with z~>0.05. Only six events in our sample were detected in an early-type (i.e., elliptical or lenticular) galaxy, whereas multiple supernova events were detected in five of the parent galaxies in our supernova sample.

New abundances of southern planetary nebulae

As a continuation of a long-term observational program with the purpose of deriving the chemical abundances of southern planetary nebulae (PN), we present here the line fluxes, colour excesses, electron temperatures and densities, and abundances of He, O, N, S, Ar and Ne for 15 PN. These objects were classied according to the Peimbert classication scheme, taking into account the chemical and kinematical properties as well as distance- independent correlations.

Field Spectroscopy Observations of the Gravitational Lenses H1413+117 and Q2237+030. Preliminary Results

The long-term observational programme for investigation of quasar microlensing spectral effects was devised and now is implemented at the Special Astrophysics Observatory (Russia, N.Arkhys) and at the Astronomical Observatory of Kiev University (Ukraine, Kiev). The main goal of this programme is to study the fine quasar structure. For this purpose the observations of the gravitational lenses H1413+117 and Q2237+030 are carried out with the 6m SAO telescope in the integral field spectroscopy mode. The suitable equipment for such observations - the Multi-Pupil Field Spectrograph - was designed and built in SAO. From February 1993 several observations of each of these objects were performed. Here we present the preliminary results of the Clover Leaf observations on April 23/24, 1993. The quasar images are separated by angles nearly 1 arcsec. At seeing of the order of 1.5 arcsec the separation of the individual quasar image spectra was a problem. For this purpose a special procedure is developed. This procedure is based on the maximum likelihood hypothesis to restore a simple 4-point source picture plus the background. The effect of light scattering for a point source was simulated by means of observations of a reference star. Statistical properties of the radiation flux in question were studied by using the data of photon registration each 40 msec. The individual spectra of quasar images were obtained. The internal relative errors of the spectra separation procedure vary from 7 to 12% depending on wavelength. The spectra of quasar images 1, 2, 4 are not actually distorted. On the contrary, in the spectrum of the third image the profile of the emission line CIV differs considerably from the profile of the same line in the “undisturbed” quasar spectrum. Fig. 1a,b show the spectra of the 1st and the 3rd images.

Monitoring midlake water temperature in southern Lake Michigan for climate change studies

Recent studies of potential climatic change on Great Lakes fisheries (e.g. Meisner , 1987; Magnuson , 1990; Regieret al., 1990) and our general ignorance of the natural variability of the basic physical properties of the Great Lakes (McCormick, 1990) have demonstrated the need for a long-term observation program which is representative of the lake-wide environment. In April 1990 a site was established in Lake Michigan to continuously monitor the offshore thermal structure and vertical velocity profile. The site is located near the center of the lake's southern basin in 160 m of water. Temperature is measured at 16 depths (winter) to 28 depths (summer), and the horizontal velocity components are measured at 5 levels which allows us to characterize the offshore environment with high temporal resolution. The goals of this effort are to provide basic physical measurements to better describe the flow of energy through the lake ecosystem and to provide a basis against which future change can be better gauged.

Variations of the Lewis and Gregory Glaciers, Mount Kenya, 1978-86-90

The glaciers of Mount Kenya are the object of a long-term observation program motivated by pro blems of climate-cryosphere interaction and climatic change (Hastenrath 1984), and are in support of international efforts at monitoring glacier fluctua tions (Permanent Service on the Fluctuations of Glaciers, IUGG-FAGS/ICSU 1977, 1985). Regular assessments of changing ice extent and volume are an important part of this endeavor. A map of all glaciers of Mount Kenya has recently appeared (Hastenrath et al. 1989), at scale 1:5,000 and with date of 3 September 1987. For the largest ice body, the Lewis Glacier, in particular, maps have been produced since 1974 at four-year intervals, and have been published in this journal at the original scale of 1:2,500 (Caukwell a. Hastenrath 1977, 1982; Hastenrath a. Caukwell 1979, 1989), so as to ensure a readily accessible historical documentation for glaciological purposes. The present communica tion is the fifth in this series. The Lewis connects with

On the Relation of Net Balance, Ice Flow, and Surface Lowering of Lewis Glacier, Mount Kenya, East Africa, 1982–86

AbstractThe second 4 year phase of a long-term observation program on Lewis Glacier, Mount Kenya, was completed in March 1986. As for the 1978–82 interval, net-balance results at a stake network and repeated mapping of the ice-surface topography allowed assessment of the mass economy by both “glaciological” and “geodetic” methods.The general findings from the 1978–82 observations are confirmed: the vertical flow component is directed downward in the upper glacier, and upward in the lower glacier; surface lowering and negative net balance increase down-glacier; ice flow mitigates surface lowering by the negative net balance in the lower glacier, but enhances it in the upper glacier. However, the major difference between the 1982–86 and 1978–82 periods is the progressive slow-down of ice flow. This entails a reduction of mass redistribution, in consequence of which the surface lowering becomes increasingly dependent on the in-situ net balance. It is expected that this circumstance will simplify any inference on future glacier behavior.

On the Relation of Net Balance, Ice Flow, and Surface Lowering of Lewis Glacier, Mount Kenya, East Africa, 1982–86

AbstractThe second 4 year phase of a long-term observation program on Lewis Glacier, Mount Kenya, was completed in March 1986. As for the 1978–82 interval, net-balance results at a stake network and repeated mapping of the ice-surface topography allowed assessment of the mass economy by both “glaciological” and “geodetic” methods.The general findings from the 1978–82 observations are confirmed: the vertical flow component is directed downward in the upper glacier, and upward in the lower glacier; surface lowering and negative net balance increase down-glacier; ice flow mitigates surface lowering by the negative net balance in the lower glacier, but enhances it in the upper glacier. However, the major difference between the 1982–86 and 1978–82 periods is the progressive slow-down of ice flow. This entails a reduction of mass redistribution, in consequence of which the surface lowering becomes increasingly dependent on thein-situnet balance. It is expected that this circumstance will simplify any inference on future glacier behavior.

Snow parameter determination by multichannel microwave radiometry

A long-term observational program on the microwave scatter and emission behavior of snow began in 1977 at a high-altitude Alpine test site. The brightness temperatures at 4.9, 10.5, 21, 36, and 94 GHz measured at different incidence and polarization angles during the first season are analyzed with the aid of correlation, factorial, and cluster algorithms. The structure mathematically found within the data is compared with classical parameters of the snow cover. Snow state changed from a high winter state to a late spring state during our measurements. At least three different snow qualities and two grades of moisture for the uppermost 10 cm of the snow layer can clearly be distinguished with a high degree of accuracy. The information content of our measurements does not substantially degrade by reducing our data to data as delivered by the NIMBUS-5 and as expected of the NIMBUS-G satellites. Recommendations for optimum frequencies for the remote sensing of snow are given.