• What is PHC?

  Our Climatology provides temperature and salinity data at 1X1 degree intervals for all the earth's oceans, down to a depth of 5500m (at incremental depths identical to Levitus' WOA). This global climatology is the combination of Levitus' 1998 world climatology (WOA) and of the EWG Arctic only climatology (AOA). While the Levitus data includes the Arctic ocean, the EWG data provides a better description of this region. These data sets were merged using an optimal interpolation routine such that our PHC retains the high quality world description provided by Levitus while improving the Arctic with the EWG fields.

• Product Summary

  	Product I: Seasonal Fields	Product II: Monthly Fields	Product III: Annual Fields
  Quantities	Temperature & Salinity	Temperature & Salinity	Temperature & Salinity
  Available Depths (same as Levitus)	33 total:	24 total:	33 total:
  Time Period	Winter (March, April, May) Summer (June, July, August)	January to December	Annual Average
  Spatial Distribution	Global 1X1 degree intervals	Global 1X1 degree intervals	Global 1X1 degree intervals

  Addition information about how the data files are structured appears on the data dowload page.
  

  Download Data

• How is PHC 2.0 different than PHC 1.0? (Return to: PHC 1.0 SITE)

  1. PHC 2.0 used Levitus' 1998 WOA data whereas PHC 1.0 used Levitus '94 data.

  2. The Arctic vs. Non-Arctic regions were redefined for PHC 2.0.

     The orginal PHC 1.0 defined everything north of latitude 65.5 to be "Arctic", while our new PHC 2.0 excludes the Nordic Seas from this definition. This new Arctic domain is shown in figure 3 of the paper. The reason for this change was to give more weight to the WOA fields in the Nordic Seas, where they provide a more realistic representation than the EWG fields.

  3. The parameters used in the Optimal Interpolation were refined for PHC 2.0.

     c - correlation length
     md - radius of influence
     n - number of points used in the calculation
     error - Read the caption in figure 3 of the paper for an interpretation of this quantity

     PHC 2.0 Parameters:	WOA	AOA
     THE ARCTIC REGION c = 500km n=20 md=1000km	error = .5	error = .0001
     OUTSIDE THE ARCTIC c = 100km n = 20 md = 1000km	error = .0001	error = .5
     THE BOUNDARY REGION c = 4000km n = 100 md = 1000km	North of 83.5: error = .5 South of 83.5: error = .0001	North of 83.5: error = .0001 South of 83.5: error = .5

     PHC 1.0 Parameters:
     c = 1000km, md = 1000km, n = 20 everywhere
     EWG error = .00005
     Levitus error = .01 for points north of latitude 65.5, and = .0001 for points south of latitude 65.5.

  4. The function used to create the EWG monthly fields from the given seasonal fields was modified.

     PHC 1.0 created monthly AOA fields by fitting the seasonal data to a sine wave function. In an attempt to create more realistic monthly fields, PHC 2.0 uses a cycloid function to accomplish this task. This is described in the paper: Creating Monthly AOA fields

We thank you for your interest in our database, which may be cited as:

Steele, M., R. Morley, and W. Ermold, PHC: A global
ocean hydrography with a high quality Arctic Ocean,
J. Climate, 14, 2079-2087, 2001.