Olson Ecosystem Complex: Grilled Veggies
The GHCN station inventory includes two vegetative descriptions. The first is a two character marker stveg which is described as “general vegetation near the station based on Operational Navigation Charts; MA marsh; FO forested; IC ice; DE desert; CL clear or open;”. The second is grveg which is described as “gridded vegetation for the 0.5×0.5 degree grid point closest
to the station from a gridded vegetation data base.” The gridded vegetation
appears to have been is derived directly from the Olson World Ecosystem Complexes data.*
The Olson World Ecosystem Complexes data is available from the Carbon Dioxide Information Analysis Center at the Oak Ridge National Laboratories. The dataset has a long history with portions of it originating from a Jerry Olson project from 1970.
The Olson Ecosystem NDP data is available in two formats: a table formatted as an ARC/INFO interchange file (*.e00) and a long format where each row represents one lat/long cell (ndp017_g.dat). This later data file included the ecosystem label in the lat/lon row data. Since my toolkit does not yet include a utility for reading or converting the ARC/INFO interchange data, I wrote a custom Java data reader class for the long file. The data resolution is 30′.
The following is the Olson Ecosystem map that is included in the NDP017 dataset.
Match between GHCN and Whiteboard station gridded vegetation types:
94.5% match rate
A new GHCN-type station inventory built using the Olson data set is available here: v2.olson.inv
A “stacked” comparison file is available here (the GHCN data is on the top line, my reproduction on the second): v2.compare.inv
|Olson Vegetation||GHCN Count||Whiteboard Count|
|BOGS, BOG WOODS||19||19|
|E. SOUTH. TAIGA||12||12|
|TROPICAL DRY FOR||107||104|
|WARM FIELD WOODS||305||302|
What’s there to say? While still working on mastering the DMSP/RC data, it was nice to find a dataset that instantly lined up with data in the GHCN v2.temperature.inv even if I had to write my own data reader to handle the columnar format of ndp017_g.dat. 95% match.
One small oddity is that the max length of the ecosystem labels were one character shorter than those in the GHCN inventory. I modified the affected labels as part of the data reader.
It seems unlikely that anybody is using the metadata components in the GHCN inventory that are unrelated to urbanity, population, and satellite brightness. I expect that v3 won’t include these at all.
Other Land Cover products are available, although the recent ones tend to be oriented more towards carbon cycles than the literal description of vegetation types. These include >Murai and Honda, NDVI and MODIS products.
Jerry S. Olson, Julia A. Watts, and Linda J. Allison, 1985, rev 2001Major World Ecosystem Complexes Ranked by Carbon in Live Vegetation: A Database, NDP-017 DOI: 10.3334/CDIAC/lue.ndp017
Holly K. Gibbs, 2006Olson’s Major World Ecosystem Complexes Ranked by Carbon in Live Vegetation: An Updated Database Using the GLC2000 Land Cover Product , NDP-017b DOI: 10.3334/CDIAC/lue.ndp017.2006
(A different Olson but a quick look into similar land cover data and its use)
RJ Olson, KR Johnson, DL Zheng, JMO Scurlock, 2001,Global and regional ecosystem modeling: Databases of model drivers and validation measurements, ORNL/TM-2001/196,
* Update: 2010 04 25
Peterson and Vose 1997 clearly state that Olson is used for the gridded vegetation filed (grveg)
Vegetation. If the station is rural, the vegetation for that location is documented. The classifications used on the ONC are forested, clear or open, marsh, ice, and desert. Not all ONC had complete vegetation data, so these metadata are not available for all stations. An additional source of vegetation data is included in GHCN metadata: the vegetation listed at the nearest grid point to each station in a 0.5° ´ 0.5° gridded vegetation dataset (Olson et al. 1983). This vegetation database creates a global vegetation map of 44 different land ecosystem complexes comprising seven broad groups. These metadata do not indicate the exact vegetation type at the station location, but they do provide useful information. In particular, an ecosystem classification can be used to some degree as a surrogate for climate regions since vegetation classes depend, to a large extent, on climate.