DOI: 10.24431/rw1kaid
title: Modeled associations between Alaskan seabird communities and Velocity of Climate Change, 1975-2021

description: This model was developed as a subset model of a larger modeling effort to examine the long-term spatial shifts of 9 foundational seabird groups in the Alaskan marine ecosystem, and how their shifts relate to shifts in Velocity of Climate Change statistics.

Input data for at-sea seabird observations used in modeling were extracted from the publically available North Pacific Pelagic Seabird Database V.4, hosted by the United States Geological Survey.

The VoCC model shapefile.zip represents a study region that accompanies the seabird density predictions used in a Decadal VAST model on 9 seabird groups, encompassing May-September and 1975-2021 at a spatial resolution of approximately 100 x 100-km grid cells.

The VoCC_VAST_model_density_estimates.csv data represents modeled seabird density predictions for nine taxa, encompassing data observations collected between May and September from 1975 to 2021 at a spatial resolution of approximately 100 x 100-km grid cells. It was produced using a gamma-distribution joint dynamic species distribution model using the VAST modeling approach. Density estimates are available in 5 decadal intervals (i.e. 1975-1979; 1980-1989; 1990-1999; 2000-2021; 2010-2021).

The HadISST_gbVoCC_velTraj_1975-1989.zip, HadISST_gbVoCC_velTraj_1980-1999.zip, HadISST_gbVoCC_velTraj_1990-2009.zip data, HadISST_gbVoCC_velTraj_2000-2021.zip, HadISST_gbVoCC_Magnitudes_1975-2021.zip, and HadISST_gbVoCC_Magnitudes_byPeriod.zip data accompanies the seabird density data and was focused on the breeding period for seabirds in Alaska, May through October, at approximately 100 x 100-km grid cells to match the spatial resolution of the seabird data. It was calculated using the Hadley Centre Sea Ice and Sea Surface Temperature (HadISST) dataset which contains monthly SST data back to 1870 at 1° x 1° (~111 x 111-km) spatial resolution. This data represents the velocity trajectories ("velTraj") and the magnitudes of the gradient-based velocity of climate change (VoCC) calculated using the VoCC R package, and the voccTraj and gVoCC functions to calculate the climate velocity trajectories and magnitudes. Since the goal of the project was to correlate VoCC with shifts in the distribution of seabird groups, the VoCC was calculated in overlapping 20-year time scales to match with the between-decade shifts in seabird distributions. VoCC was calculated in overlapping approximate 20-year periods: 1975–1989, 1980–1999, 1990–2009, and 2000–2021 for analysis against the seabird data. VoCC was also calculated for the whole period spanning 1975-2021. The VoCC was calculated for the Alaska region 45-70°N and 120-180°W.

The OISST_gbVoCC_Magnitudes_byPeriod.zip data also accompanies the seabird density data, and has the same temporal extent, spatial extent, 20-year time scales, and spatial resolution as the above accompanying velocity trajectory and magnitute data to match that of the seabird data. It was calculated using the NOAA OI SST V2 High Resolution Dataset as it contains daily data from 1982 to the present at a 0.25° x 0.25° (~27 x 27-km) spatial resolution. This data represents the magnitude of the gradient-based velocity of climate change (VoCC) calculated using the VoCC R package and gVoCC functions.