NCEP / NCAR Global Reanalysis Data

NCEP/NCAR Global Reanalysis Data Nodes:
Left = Nodes Covering Western Europe. Right = Nodes Covering France.

Data from the NCEP/NCAR reanalysis project is currently available to users of WindPRO as part of the on-line services from the EMD server. A connection to the internet is thus required. Users may download updated data from the present moment (typically the preceding month) back until 1948.

The sub-set of the NCEP/NCAR Global Reanalysis Data that we hold at EMD is updated on a monthly to bi-monthly update cycle.

Data Description

The NCEP/NCAR model dataset is immense, containing a very wide range of descriptive atmospheric model data. The actual measured climate data sources used in the global reanalysis model are:

• Upperair rawinsonde observations of temperature, horizontal wind, and specific humidity (i.e. weather balloons)
• Operational Television Infrared Observation Satellite (TIROS) Operational Vertical Sounder (TOVS) vertical temperature soundings from NOAA polar orbiters over ocean, with microwave retrievals excluded between 20°N and 20°S due to rain contamination
• TOVS temperature soundings over land only above 100 hPa
• Cloud-tracked winds from geostationary satellites
• Aircraft observations of wind and temperature
• Land surface reports of surface pressure
• Oceanic reports of surface pressure, temperature, horizontal wind, and specific humidity

These data are used as input into a frozen global assimilation system and processed by a spectral model in order to provide the model output of the variables in the grid.

NCEP/NCAR Global Reanalysis Dataset at EMD

Currently, two types of NCEP/NCAR modeled wind data are available from the EMD server. Both types of data are distributed through the NCAR_Basic dataset from the EMD server. The raw data are processed by EMD as the original data holds the vector components for the wind speeds only (U and V – winds). We convert the raw data into a format appropriate for use with wind turbine applications, i.e. wind speed and direction instead.

Table: Surface Data

Name	Description
Abbreviation	srf
External URL	http://www.cdc.noaa.gov/cdc/data.ncep.reanalysis.surface.html
Data valid at time	Instantaneous values at the reference time
Referred to as	“Wind" at level "sig995" under main title "Surface"
Level	99.5% of surface pressure (approximately 42m a.g.l. for standard atmosphere conditions)
Grid	2.5 degree latitude x 2.5 degree longitude global grid (144x73)
Coverage	Global
Columns in data-file	srf.dir.2 = Wind Direction at sigma level 0.995, i.e. 42 m a.g.l srf.wsp.2 = Wind Speed at sigma level 0.995, i.e. 42 m a.g.l gl.tmp.2 = Temperature at sigma level 0.995, i.e. at 42 m a.g.l