Personal tools
 
You are here: GES DISC Home Ocean Color Additional Features Science Focus LOCUS The Giovanni-NEO Instructional Cookbook: Peru Upwelling Zone

The Giovanni-NEO Instructional Cookbook: Peru Upwelling Zone

Peru Upwelling Zone:One of the mightiest of the coastal upwelling zones, made famous by anchovies and a little child Chlorophyll concentration image of the Peru Upwelling Zone

Data Sets for this Chapter

  • SeaWiFS Monthly chlorophyll
  • MODIS sea surface temperature

Visualizations for this Chapter

  • Area Plot (Giovanni)
  • Anomaly Area Plot (Giovanni)
  • Histogram (NEO)

Location Map and Coordinates

Peru Upwelling Location Map Peru Upwelling geographic coordinates

Step-by-Step

Refer to the pages for Giovanni functions and NEO functions if you are unfamiliar with the functions described below.

Area Plot (Giovanni)

  1. Select the area.
  2. Parameter: Chlorophyll a
  3. Plot type: Lat-Lon Map, Area Averaged
  4. Time Period: Begin Year - 2002; Begin Month - December; End Year - 2003; End Month - March. This selects the December 2002 to March 2003 four-month time-period.
  5. Generate plot.

Peru Upwelling, December 2002 to March 2003, chlorophyll concentration

Anomaly Area Plot (Giovanni)

In the Data Type field, the default option is "Parameter". For SeaWiFS monthly data, anomalies (differences from the climatological average) can be generated.

  1. Use the same values as before (at left). Change Data Type to "Anomaly".
  2. Generate plot. Negative anomalies (lower than average) are blue and purple. Positive anomalies are yellow, orange, and red.

Peru Upwelling, December 2002 to March 2003, chlorophyll concentration anomaly

Histogram (NEO)

  1. Select MODIS SST for January 1 - February 1, 2003 (first) and for January 1 - February 1, 2004 (second). Launch the analysis.
  2. Select the same area as for Giovanni (above), using the map or the geographical coordinates.
  3. Choose the "Outline Area" option. It will take some practice to outline the desired area. Outline an area very close to the coast of Peru, as shown in the figure at left (below).
  4. Click on "Histogram". The histogram should look similar to the figure on the right (below). If it looks markedly different, then the area outline probably extends too far offshore. The SST monthly data must be selected in order so that 2003 data is red and 2004 data is green.

Peru Upwelling area outline Peru upwelling coastal SST histogram

Extended Investigations

The Peru Upwelling Zone is famous because it is home to a very productive anchovy fishery -- except in years when the upwelling system falters. The story goes (it can be researched for more detail) that when it began to rain on the Peruvian coast just before Christmas, the fishermen expected that there would be a few poor months of fishing. Because this seemed to occur just before Christmas, they called the weather El Niño, for the "little child" born at Christmas. The coastal rains formed due to warmer surface waters on the coast.

Before the time of oceanographic data and remote sensing, the occurrences of El Niño could be determined by the harvest of anchovies. Now, the reduction in chlorophyll concentration and the shift in sea surface temperatures that indicates El Niño can be observed in remote-sensing data.

  • Determine when other El Niño (and La Niña) events occurred during the period covered by the remote-sensiing data in Giovanni and NEO, and examine the effects on chlorophyll concentration and SST.
  • Examine precipitation data for the Peruvian coast to determine why coastal rain is such an unusual event.
  • Determine the names of the currents and the direction that they flow to better understand the dynamics of coastal upwelling.
Document Actions
NASA Logo - nasa.gov
  • Last updated: Sep 09, 2009 02:29 PM ET