Pacific Fisheries Environmental Laboratory

National Marine Fisheries Service
Southwest Fisheries Science Center
                          

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PFEL Live Access Server

PFEL Global 1-degree Upwelling Index

This page allows the user to calculate a time series of upwelling index (off-shore component of Ekman Transport) for any location along a coastline, given the orientation of the coastline.

The upwelling index on this page differs in several ways from the standard calculation used by PFEL because of differences in the way the air/ocean indices were calculated. Please see the discussion on the Air/Ocean Indices page (monthly, current month 6-hourly) for calculation details. A few comparisons with the historical PFEL product are shown below.

The user must enter the following quantities:

  1. latitude
  2. longitude
  3. coast angle
The "coast angle" is the angle the landward side of the coastline makes with a vector pointing north as illustrated in the following images (where the angle alpha is what should be entered for "coast angle" in the LAS form):
land on NE land on NW land to east
land on NEland on NWland to east

Please note that the "coast angle" required here should not be confused with the rotation angle (offshore vector direction) listed in the PFEL output for flow indices at the 15 standard locations.

As discussed on the Air/Ocean Indices page (monthly, current month 6-hourly) the upwelling index found here differs from the standard monthly PFEL 15-location North American product. The magnitude of the difference varies by location and time. The following graphs show comparisons at two locations. In the upper panel of these plots, the black line is the product obtained on this page, the red line is the PFEL historical monthly upwelling index calculated from the monthly mean pressure field, and the green line is the monthly average of the PFEL historical 6-hourly upwelling index. The differences in calculation method between the green and the black lines are: mesh size (1-degree for the new calculation, 3-degrees for the historical calculation) and parametrization of drag coefficient (function of wind speed for the new calculation and taken as a constant for the historical calculation). The bottom panel in each plot is the difference between the new calculation and historical monthly calcuation (black and red lines).

Click on the plot to view a full size image:

48N 125W
upwelling index 48N
Upwelling Index Comparison

36N 122W
upwelling index 36N
Upwelling Index Comparison

For a further description of the upwelling products and methods used in their derivation, please see the PFEL home page and the following references: