Wind Speed vs. Wind Direction and Upwelling Indices
Notes:
Slide 14. WIND SPEED VS. WIND DIRECTION AND UPWELLING INDICES
-Wind data from Destruction Is.
-Strongest winds Shift from NW to SE from Aug to Oct
-Upwelling consistent with winds
-Possibly the nutrient source for plankton (data being analyzed)
MESSAGE: WINDS SHIFT, UPWELLING SUBSIDES, BLOOM IN SURFACE WATERS GOES AWAY
Physical climatic and oceanographic factors may be involved. Here we show plots of Wind Speed vs. Wind Direction for August through October and a plot of upwelling indices for the coast of Washington. The wind data are hourly observations made at a weather station on Destruction Island, which is near the Kalaloch site. The data were obtained from the NDBC. In each month, low speed winds were variable. In August, the strongest winds come from the NW. In September, we also see the NW winds and a beginning of a shift to SE winds. By October, most of the strongest winds were from the SE. During the period of the bloom (August to October) there was a shift of winds from the NW to the SE.
The upwelling index might useful. Along the coast, north winds are upwelling favorable while south winds are downwelling favorable. In this plot, anything above the line is upwelling and anything below the line is considered downwelling. During our bloom period we had upwelling (which is generally favorable for phytoplankton blooms because the upwelling bring nutrient rich waters to the surface) then around October 10th we experienced very noticeable strong downwelling. At this time the Pseudo-nitzschia population crashed. The winds shifted, upwelling stopped, and reversed, however, the bloom did not return. Possibly, the seed cells may have been moved out of our study area.