JISAO data

Surface air temperature and precipitation variability characterized by the trends and regressions onto AO, PNA, ENSO, PDO, and G indices.

This WWW page presents maps of monthly surface air temperature and precipitation anomalies regressed onto the trend and normalized anomalies of the AO (definition and time series), PNA (definition and time series), PDO (definition, time series), ENSO, and G. The calculations are performed separately for November through April and May through October months. The maps should be interpreted as typical anomalies of a field associated with fluctuations of the given index.

The details of the data sets, indices, and how to quickly obtain the analyses are described at the bottom of this page.

Part I. Trends:
1. November through April
a) Global Temperature and precipitation:
PDF | image | JPEG
b) "North America"

  • Land Temperature: PDF | image | JPEG
  • Air temperature over the oceans: PDF | image | JPEG
  • Precipitation: PDF | image
  • sea-level pressure: PDF | image
    c) "Europe"
  • Land Temperature: PDF | image
  • Air temperature over the oceans: PDF | image
  • Precipitation: PDF | image
    d) SLP trend netCDF file

    2. May through October
    a) Global Temperature and precipitation: PDF | image
    b) "North America":

  • Land temperature: PDF | image
  • Air temperature over the oceans: PDF | image
  • Precipitation: PDF | image
    c) "Europe":
  • Land temperature: PDF | image
  • Air temperature over the oceans: PDF | image
  • Precipitation: PDF | image
    
    
    Part II. AO:
    The sign of the map anomalies is consistent with the "high index" polarity of the AO.
    November through April
    a) Global figures
  • land air temperature and precipitation PDF | image
  • air temperature over the oceans PDF | image
    b) "North America" figures
  • land and marine temperature: PDF | image (GIF) | PNG
  • land temperature: PDF | image
  • precipitation: PDF | image
  • air temperature over the oceans: PDF | image
  • sea-level pressure: PDF | image
    c) "Atlantic" land and marine temperature: GIF | big GIF | PDF | PNG | PS
    d) "Europe" figures
  • land temperature: PDF | image
  • precipitation: PDF | image
  • air temperature over the oceans: PDF | image
    e) Netcdf files of the analyses so that you can make your own plots. The fourth map of the following netCDF files are the regression coefficients of the named field onto normalized values of the AO.
  • land and marine temperature (map 1 of this file.) | the data set
  • land air temperature
  • land precipitation
  • air temperature over the oceans
  • The sixth map in this netCDF file contains the SLP regressions.
    f) "North America" summer (May through October) figures
  • land and marine temperature: PDF | image (GIF) | PNG | netCdf file (map 2 is the regressions)
    
    
    Part III. PNA: The traditional definition of the Pacific North American (PNA) index (
    Wallace and Gutzler 1981; hereafter WG) is not used for this analysis. Instead, I am using a PNA index defined as the second principal component (PC) of Northern Hemisphere extratropical monthly (all calendar months) sea-level pressure anomalies. The first PC is the AO. PC2 and the WG PNA indices are correlated at 0.73 (0.84) for all calendar months (December,January,February) for 1948-99. By construction PC2 has a slightly broader spatial scale than the WG PNA. The polarity of the following analyses corresponds to a large block and low zonal winds.
    November through April
    a) Global figures
  • land air temperature and precipitation PDF | image | JPEG
  • air temperature over the oceans PDF | image | JPEG
    b) "North America" figures
  • land temperature: PDF | image | JPEG
  • precipitation: PDF | image | JPEG
  • air temperature over the oceans: PDF | image | JPEG
    c) Netcdf files of the analyses so that you can make your own plots. The second map of the following netCDF files are the regression coefficients of the named field onto normalized values of the PNA index.
  • land air temperature
  • land precipitation
  • air temperature over the oceans
    
    
    Part IV. ENSO: The sign of the map anomalies is consistent with the warm phase of ENSO.

    For ENSO I have also calculated regression maps for ocean and land precipitation using a merged satellite - rain gauge data set produced by the Global Precipitation Climatology Project (GPCP). These maps are at this link, and are calculated for all calendar month combined, and for November through April and May through October seasons. The precipitation anomalies in the tropics are much larger than those at high latitudes, and these plots are drawn to highlight the tropical features. NetCDF files of the maps are provided so that you can draw your own pictures.

    November through April
    a) Global figures

  • land temperature and precipitation PDF | image
  • air temperature over the oceans PDF | image
    b) "North America" figures
  • land temperature: PDF | image
  • precipitation: PDF | image
  • air temperature over the oceans PDF | image
    c) Netcdf files so that you can make your own analyses. The second map of each of the following netCDF files contains the regression coefficients of the named field onto normalized values of the CTI.
  • land air temperature
  • land precipitation
  • air temperature over the oceans
    
    
    Part V. PDO:
    The sign of the map anomalies is consistent with the "warm phase" of the PDO.
    November through April
    a) Global figures
  • land air temperature and precipitation PDF | image
  • air temperature over the oceans PDF | image
    b) "North America" figures
  • land temperature: PDF | image
  • precipitation: PDF | image
  • air temperature over the oceans: PDF | image
    c) Netcdf files of the analyses so that you can make your own figures. The sixth map of each of the following netCDF files contains the regression coefficients of the named field onto normalized values of the PDO.
  • land air temperature
  • land precipitation
  • air temperature over the oceans
    
    
    
    Part VI. G: The sign of the map anomailes is consistent with the "warm phase" of G (warm tropical Pacific).
    November through April
    a) "North America" figures
  • land temperature: PDF | image
  • sea surface temperature: PDF | image
  • precipitation: PDF | image
  • normalized precipitation: PDF | image
    b) Netcdf files of the analyses so that you can make your own figures. The following netCDF files containing the regression coefficients from this analysis.
  • land air temperature (regressions are the second map)
  • land precipitation (regressions are the second map)
  • normalized land precipitation (regressions are the third map)
  • sea surface temperature (regressions are the second map)
    
    

    
    
    Calculation details

    The land data sets are from the
    Univerisity of Delaware (UD), the ocean data is COADS (1-degree latitude-longitude resolution) air or sea-surface temperature, and the atmospheric circulation fields are from the NCEP NCAR reanalysis. The native resolution of the UD data is 0.5-degrees latitude-longitude, and it has been averaged into 1-degree latitude-longitude resolution so that the resulting PDF files are of a manageable size. No other smoothing is performed. The 0.5- and 1.0-degree resolution UD data can be downloaded.

    There are many analyses and everything is in color. PDF files have been onto an ftp directory ( ftp://ftp.atmos.washington.edu/pub/jisao/mitchell/analyses0500/). [ If using command lines, set the prompt option to off (type "prompt"), and use "mget *".]

    The figure titles and filename conventions employed:

  • "summer" for May through October analyses. If it doesn't say "summer" then the analysis is for November through April.
  • "trends" for trends
  • "ao" for AO, "cti" for ENSO, "pdo" for PDO
  • Precipitation is always in cm/month, so precipitation trends are in units of cm/month/decade (Unfortunately I omitted the "/month" in the titles of some of the precipitation plots.).

    The land temperature and precipitation data are for 1950-96, the COADS data for 1960-96, and the NCEP reanalysis for 1950-96.

    
    

    May 2002
    Todd Mitchell (mitchell@atmos.washington.edu)
    JISAO data publications