NCEP-NCAR Reanalysis Temperature Change Plots - 1948-2002

The initial 50 years of NCEP/NCAR reanalysis were completed in July, 1998, based on a model that was frozen in August, 1994. NCEP updates these analyses at the end of each month and calculates yr-mo mean analyses for output on a 2.5 degree global grid. The analyses and means are all available from NCAR's Data Support Section.

We wanted some plots of temperature anomalies from these analyses that people could browse. These are given for four latitude bands: Global, 25S-90N, 25S-25N and 25N-90N. We had enough data coverage that analyses for 25S-90N should be very good from 1952/53 - on, and especially from 1956-on. Rawinsondes started at a number of southern islands around 1950, but the first regular roabs in Antarctica started in 1956 and raobs for most of Antarctica and most of South America did not start until mid 1957. However, in South America, there were some earlier pibals. DSS has on-line data coverage plots that can be browsed.

Chavez, et al (2003) note the relationships between the Pacific Decadal Oscillation, global air temperatures and the changes in populations of fish (Science, 10 Jan 2003, p217). They note that there was a cool phase from around 1950-1975, and a warming phase from about 1975 - late 1990s. They wonder if a new cooler phase may be starting. Part of the warming from 1975-2000 was probably due to greenhouse effects, so that also has to be considered.

The data and info was prepared in July, 2003 - Roy Jenne.

The table below links to plots of annual temperature and thickness anomalies for various levels. In all cases, the period used for the long term means was 1970-1999. The anomalies were created for 4 latitude bands : global, 25S-25N,25N-90N and 25S-90N. Plots were created for temperature anomalies at 300,500,700 and 850mb's and also 2 meters (surface temp basically) as well as for 850-300mb thickness temperatures. Elevation grids were not used to denote grid points that may have been below the surface in the lower levels. Plain text tables are available for the temperatures and thickness temperatures anomalies - Joey Comeaux.

credit: Thanks are due to NCEP for making these analyses routinely available. Dennis Joseph (NCAR-retired) prepared these plots in 07/2003, using the GrADS software from COLA. Joey Comeaux in the NCAR Data Support Section put these plots on line.