Model Currents

Model Currents#

Surface currents modeled by CIOFS and NWGOA are shown for each NOAA Cook Inlet ADCP survey location for 4 years meant to represent a range of possible conditions. The annual mean temperature represents the yearly averaged surface temperature along the southern open boundary of the CIOFS model. It is calculated by taking the open boundary forcing of CIOFS (derived from HYCOM GOFS 3.1 Global Reanalysis), extracting the surface level, and averaging this 2D slice over the year and boundary nodes to derive a single value summarizing the annual surface temperature along the southern open boundary. The inflow is calculated as a sum across the rivers for the year, relative across the years.

Looking at the spread of years, which only include the years that NWGOA was also run, we chose the warm year as 2003 and cool year as 1999 since they have relatively equal river forcing. We were not able to disentangle the river forcing from the temperature forcing so we chose two years at opposite ends of the spread: 2005 (warm and more river inflow) and 2008 (cool and less river inflow). These are the years shown below. The locations align with NOAA’s ADCP survey locations since that is where time series of velocity data is available.

Surface currents for CIOFS are fairly consistent across the years and tend to be more focused and aligned in time (especially in higher, bi-directional flow areas) as compared with NWGOA surface currents which tend to have more spread (see for example Fig. 7). The spread of the NWGOA surface currents can be attributed to the presence of freshwater as compared with the CIOFS model output which is much saltier and lacks this presence most of the time. Additionally, we see some additional surface speed across stations in the fresher year (2005, Fig. 7) as compared with the saltier year (2008, Fig. 8).