Assignment:

In this activity, you will explore large-scale atmospheric circulation and climate zones using an internet-based data viewer and datasets, including observations of wind, temperature, precipitation, and vegetation. 

1. How do the climatological fields (and the resulting distribution of vegetation) compare with the idealized view of atmospheric circulation and climate zones that we constructed during lecture?

2. What features of this idealized circulation and climate zones are reproduced in this actual data?

3. What features are different? (Be sure to examine both still frames from individual months and animations of seasonal cycle – see "selecting a month" in the instructions below). Attribute the differences to some of the effects we discussed during lecture.

Be prepared to discuss your results with the class.

Dataset links:

a) Zonal (east-west) wind component at 1000 mbar (close to mean sea level, other pressure levels are also available - if you wish to also look at the north-south, or meridional, component of the wind, you can find it here).

b) Temperature at 1000 mbar (close to mean sea level, other pressure levels are also available)

c) Precipitation over land (based on monthly averages for 1961-1990)

d) Normalized Difference Vegetation Index (NDVI) July 1981 - Dec 2003 (bimonthly) - Note that values of 0.1 and below correspond to barren areas, moderate values (0.2-0.3) correspond to shrub and grassland and high values (0.6-0.8) correspond to temperate and tropical forests.

Getting started with the data viewer:

Views: A variety of ways of mapping the dataset are available (e.g., contour plots, color images, continents shown as outlines, continents hidden) - to start, click on the color image view with continents shown as outlines.  This brings you to a map view of the data, where the data is displayed using a color scale.  The uppermost of the three buttons at the left of the image redraws the plot. 

Selecting a pressure level:  Type in a pressure level in the uppermost box or use the buttons to toggle to adjacent pressure levels (note that 1000 = 1000 mbars, or pressure near mean sea level).

Selecting a month: You can step through months using the buttons or by typing the month name in the box (note that typing "Jan-Dec" in the box will load an animation containing all of the months).

Selecting a geographic region: The latitude and longitude bounds of the plot can be changed by typing in different bounds in the boxes that are initially marked "90N"(northern boundary), "90S"(southern boundary), "1.25W" (on the left is the western boundary) and "1.25W" (on the right is the eastern boundary).  Note that longitude can be specified as either degrees E or degrees W.

Modify the color scale range by entering different values in the boxes underneath either end of the color bar.

Dataset details:

The wind and temperature data linked below were produced by the NOAA NCAR-NCEP Reanalysis, a project that has collected atmospheric and oceanic observations from past decades, applied quality-control tests, and gridded the resulting fields to fill gaps in the data.  Each monthly field in the resulting data set represents an average from 1971-2000.

The precipitation data linked below was produced by M.New, M.Hulme and P.Jones at the Climate Research Unit at the University of East Anglia, UK by analyzing and gridding meteorological station observations collected between 1961 and 1990.

The NDVI dataset linked below was produced by Tucker et al. at the University of Maryland.

These fields are part of an extensive library of climatological data that is maintained by the Lamont-Doherty Earth Observatory of Columbia University (which also maintains the accompanying web-based data viewer).