NMML Harbor Porpoise Aerial Survey, Alaska Peninsula, Replicate 1, 1992Entry ID: seamap135
Abstract: On 6 July to 9 August 1992, as part of a larger study, Alaska harbor
porpoise (Phocoena phocoena) abundance was investigated during an aerial survey
off the south side of the Alaska Peninsula. Employing a Twin Otter as the
survey platform, the first of two identical saw-tooth tracklines was flown at
an altitude of 152.2 m (500ft) and at an airspeed of 100 kn. Line-transect
... methodology was used, and only those observations made during optimal
conditions were analyzed. Density of harbor porpoises was calculated using line
transect estimates based on perpendicular distances of sightings to the cruise
track of the airplane. On average, porpoise group size and density off the
south side of the Alaska Peninsula was 1.1 (SE = .10) and 2.03 groups/100 km^2
Purpose: Although harbor porpoises, Phocoena phocoena, are known to occur
throughout Alaska waters (Fiscus et al. 1976; Leatherwood and Reeves 1978;
Lawry et al. 1982; Leatherwood et al. 1983), few estimates of abundance exist.
In 1991, the National Marine Mammal Laboratory initiated a 3-yr study on Alaska
harbor porpoises. The objectives of this program were to: 1) Obtain minimum
... population estimates in coastal waters using line transect methodology with a
coefficient of variation for density estimates of less than 30% for each survey
area. 2) Establish a baseline for detecting changes in abundance through time,
for analysis of trends.
SUPPLEMENTAL INFORMATION: Note: This dataset and associated effort data was
updated on Sept 8, 2005. Those who downloaded them before that date should
renew them. During the present study, it was not fiscally possible to survey
all areas of the state in any one year. Accordingly, we selected sections of
the state to survey in consecutive years to maximize the likelihood of
including all of the animals for a particular area surveyed while minimizing
the likelihood of significant movement between areas among survey years.
CURRENTNESS REFERENCE: ground condition
SPATIAL REFERENCE INFORMATION -
Horizontal Datum Name: D_WGS_1984
Ellipsoid Name: WGS_1984
Semi-major Axis: 6378137.000000
Denominator of Flattening Ratio: 298.257224
Data Set Citation
Dataset Originator/Creator: Keith Dixon
Dataset Title: Will the Wet Get Wetter and the Dry Drier?
Dataset Publisher: NOAA/GFDLOnline Resource: http://www.gfdl.noaa.gov/will-the-wet-get-wetter-and-the-dry-drier
Start Date: 1901-01-01Stop Date: 2100-12-31
ISO Topic Category
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IPCC ... (Intergovernmental Panel on Climate Change) (2007): Climate Change 2007: The Physical Science Basis, Summary for Policymakers. (published online 2 Feb 2007 at http://www.ipcc.ch/)
Knutson, et al., (2006): Assessment of Twentieth Century Regional Surface Temperature Trends using the GFDL CM2 Coupled Models, Journal of Climate, Vol. 19, No. 9, pages 1624-1651.
Held, et al., (2005): Simulation of Sahel drought in the 20th and 21st centuries. Proceedings of the National Academy of Sciences, Vol. 102, No. 50, page 17891-17896.
Held and Soden, (2006): Robust responses of the hydrological cycle to global warming, Journal of Climate, Vo. 19, No. 21, pages 5686-5699
Lau, et al. (2006): Attribution of Atmospheric Variations in the 1997-2003 Period to SST Anomalies in the Pacific and Indian Ocean Basins, of Climate, Vol. 19, No. 15, pages 3607-3628.
Lu, et al. (2007): Expansion of the Hadley Cell under global warming, Geophys. Res. Lett,. Vol. 34, L06805, doi:10.1029/2006GL028443.
Creation and Review Dates
DIF Creation Date: 2010-09-27
Last DIF Revision Date: 2010-09-27