January 20, 2004

 

 I.    Introductions

II.    Overview of Class & Website

III.   Brief Intro to the Reanalysis

NCEP =  National Center for Environmental Prediction (formerly known as the National Meteorological Center or NMC) Visit:  http://www.ncep.noaa.gov/ to find out what this center does.

NCAR = National Center for Atmospheric Research    Visit:  http://www.ncar.ucar.edu/ncar/ to find out what this center does.

CDC = Climate Diagnostics Center  Visit:  http://www.cdc.noaa.gov/ to find out what this center does

CPC = Climate Prediction Center  Visit: http://www.cpc.ncep.noaa.gov/index.html to find out what this center does.

The Reanalysis Project

• purpose of the Project was to reanalyze historical atmospheric data using state-of-the-art models. 
   

•  The Project started in 1989 at NCEP with the goal of building a "Climate Data Assimilation System" (CDAS).
   

• Data assimilation can be defined as a process that "makes similar" or alters by assimilation; a process of receiving new data in conformity with what is already available.
   

• The motivation for the Project was to remove the apparent "climate changes" that resulted from the many adjustments in the numerical weather prediction operational systems which were made over time in an effort to improve forecasts. 
   

• The Project has produced a research quality dataset suitable for many uses, including weather and short-term climate research, and it is an ongoing activity, i.e, there is currently a Reanalysis 2 & a North American Regional Scale reanalysis in the works. 
   

• The unique characteristics of the project are the length of the period covered (now 1948- present for most variables) and the assembly of a very comprehensive observational database. 
   

  • The observations include: balloon soundings (global rawindsonde data), surface marine data (from buoys), aircraft data, surface synoptic data (e.g., surface gauge measurements, etc.) and satellite measurements. 
     

  • These are all real observations, not output from a numerical model.
     

• Reliability of the Reanalysis
   

  • The daily atmospheric and surface fields are, "for some variables, close to a best estimate of the evolving state of the atmosphere." 
     

  • The dynamics of the analysis computations allow it to "transport information from data-rich to data-poor regions, so that even in relatively data-void areas the reanalysis can estimate the evolution of the atmosphere over both synoptic and climatological timescales.
     

  • A researcher using the reanalysis should be aware, however, that the different outputs are not uniformly reliable."  (p 453).

IV.  ASSIGNMENTS

• Explanation of Assignments

• Assigned sections of Climate & Weather Links webpage
   

V.    WRAP-UP & QUESTIONS