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:
- latitude
- longitude
- 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 |
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:
For a further description of the upwelling products and methods used in their derivation,
please see the PFEL home page
and the following references:
- Bakun, A. 1973. Coastal upwelling indices, west coast of North America,
1946-71. U.S. Dept. of Commerce, NOAA Tech. Rep., NMFS SSRF-671, 103p.
- Bakun, A. 1975. Daily and weekly upwelling indices, west coast of North
America, 1967-73. U.S. Dept. of Commerce, NOAA Tech. Rep., NMFS SSRF-693,
114p.
- Mason, J.E. and A. Bakun. 1986. Upwelling index update, U.S. west coast,
33N-48N latitude. U.S. Dept. of Commerce, NOAA Tech. Memo.
NOAA-TM-NMFS-SWFC-67, 81p.
- Schwing, F.B. , M. O'Farrell, J. Steger and K. Baltz. 1996. Coastal
Upwelling Indices, West coast of North America, 1946-1995. U.S. Dept. of
Commerce, NOAA Tech. Memo. NOAA-TM-NMFS-SWFC-231, 207p.
