Results of a lichenological and bryological exploration of Cerro Guaiquinima (Guayana Highland, Venezuela)

1992 ◽  
Vol 6 (1) ◽  
pp. 1-31 ◽  
Author(s):  
H. J. Sipman
Keyword(s):  
Vegetation Structure ◽  
North Slope ◽  
The North ◽  
Table Mountain ◽  
Guayana Highland

214 Lichen and 38 bryophyte species are reported from Cerro Guaiquinima, a sandstone table mountain in southeastern Venezuela, thus far almost unexplored for these groups and apparently undisturbed by man. Slightly over half of these species have also been reported from the north slope of Mount Roraima and surroundings, a nearby area with similar edaphic and climatological conditions. Altitudinal differences in the flora are probably largely dependent on differences in vegetation structure: the closed froests at the foot harbour more Cladoniaceae and Trypetheliaceae are found. On the highest site bryophytes are more frequent. First descriptioins are given for nine lechens and one moss: Buellia bellardii Sipman, Hypotrachyna adaffinis Sipman, Myriotrema flavolucens Sipman, Myriotrama squamuloides Sipman, Ocellularia croceoisidiata Sipman, Ocellularia glaucoglyphica Sipman, Thelotrema caarneoradians Sipman, Thelotrema guaiquinimae Sipman, Sphagnum sipmanii Crum and Ocellularia sinuosa Sipman (in appendix, from Colombia). Myriotrema guianense is reduced to synonymy of Myriotrema columellatum (A. Zahlbr.) Sipman, comb. nov.

Geologic framework of the "North Slope" petroleum province

1969 ◽  
Author(s):  
George Gryc ◽  
Irvin L. Tailleur ◽  
William Peters Brosge
Keyword(s):  
North Slope ◽  
The North

Dispersive noise removal in t-x space: Application to Arctic data

Geophysics ◽  
1988 ◽  
Vol 53 (3) ◽  
pp. 346-358 ◽  
Author(s):  
Greg Beresford‐Smith ◽  
Rolf N. Rango
Keyword(s):  
Signal To Noise Ratio ◽  
Noise Analysis ◽  
Noise Removal ◽  
North Slope ◽  
Frequency Bandwidth ◽  
The North ◽  
North Slope Of Alaska ◽  
Seismic Records ◽  
Time Offset ◽  
Undersampled Data

Strongly dispersive noise from surface waves can be attenuated on seismic records by Flexfil, a new prestack process which uses wavelet spreading rather than velocity as the criterion for noise discrimination. The process comprises three steps: trace‐by‐trace compression to collapse the noise to a narrow fan in time‐offset (t-x) space; muting of the noise in this narrow fan; and inverse compression to recompress the reflection signals. The process will work on spatially undersampled data. The compression is accomplished by a frequency‐domain, linear operator which is independent of trace offset. This operator is the basis of a robust method of dispersion estimation. A flexural ice wave occurs on data recorded on floating ice in the near offshore of the North Slope of Alaska. It is both highly dispersed and of broad frequency bandwidth. Application of Flexfil to these data can increase the signal‐to‐noise ratio up to 20 dB. A noise analysis obtained from a microspread record is ideal to use for dispersion estimation. Production seismic records can also be used for dispersion estimation, with less accurate results. The method applied to field data examples from Alaska demonstrates significant improvement in data quality, especially in the shallow section.

Cloud Properties over the North Slope of Alaska: Identifying the Prevailing Meteorological Regimes

2012 ◽  
Vol 25 (23) ◽  
pp. 8238-8258 ◽  
Author(s):  
Johannes Mülmenstädt ◽  
Dan Lubin ◽  
Lynn M. Russell ◽  
Andrew M. Vogelmann
Keyword(s):  
Time Series ◽  
Climate Model ◽  
North Slope ◽  
Test Cases ◽  
Synoptic Scale ◽  
Long Time Series ◽  
The North ◽  
Cloud Properties ◽  
North Slope Of Alaska ◽  
Long Time

Abstract Long time series of Arctic atmospheric measurements are assembled into meteorological categories that can serve as test cases for climate model evaluation. The meteorological categories are established by applying an objective k-means clustering algorithm to 11 years of standard surface-meteorological observations collected from 1 January 2000 to 31 December 2010 at the North Slope of Alaska (NSA) site of the U.S. Department of Energy Atmospheric Radiation Measurement Program (ARM). Four meteorological categories emerge. These meteorological categories constitute the first classification by meteorological regime of a long time series of Arctic meteorological conditions. The synoptic-scale patterns associated with each category, which include well-known synoptic features such as the Aleutian low and Beaufort Sea high, are used to explain the conditions at the NSA site. Cloud properties, which are not used as inputs to the k-means clustering, are found to differ significantly between the regimes and are also well explained by the synoptic-scale influences in each regime. Since the data available at the ARM NSA site include a wealth of cloud observations, this classification is well suited for model–observation comparison studies. Each category comprises an ensemble of test cases covering a representative range in variables describing atmospheric structure, moisture content, and cloud properties. This classification is offered as a complement to standard case-study evaluation of climate model parameterizations, in which models are compared against limited realizations of the Earth–atmosphere system (e.g., from detailed aircraft measurements).

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