Annual Cycles of Convective Parameters


(Updated 18 March 2005)

Comments to Harold Brooks (harold.brooks at noaa.gov)

I'm putting together loops of the annual cycle of convectively-relevant climatogical parameters from the NCEP/NCAR reanalysis.

Color loops

Region\Parameter Lowest 100 hPa Mean Mixing Ratio
 700-500 hPa Lapse Rate
 CAPE
 0-6 km Vector Wind Difference
 LCL Height
 0-1 km Vector Wind Difference
 Mixing Ratio/ 700-500
 hPa Lapse Rate
 CAPE (contoured)/
Deep Shear (filled)
 LCL Height (contoured)/
Shallow Shear (filled)
Eastern US
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Europe
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Grayscale loops


Region\Parameter Lowest 100 hPa Mean Mixing Ratio
 700-500 hPa Lapse Rate
 CAPE
 0-6 km Vector Wind Difference
 LCL Height
 0-1 km Vector Wind Difference
 Mixing Ratio/ 700-500
 hPa Lapse Rate
 CAPE (contoured)/
Deep Shear (filled)
 LCL Height (contoured)/
Shallow Shear (filled)
Eastern US
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Europe
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Soundings have been created from the NCAR/NCEP reanalysis every 6 hours (00, 06, 12, and 18 UTC) for 7 years (1973, 1987, 1995-1999) and analyzed with John Hart's NSHARP program.  Analysis of those fields is done using GEMPAK.  For the mixing ratio and lapse rates, the sounding with the highest mixing ratio on each day is selected.  The mean for each day of the year (7 input values) is found, and then a 31-day running mean of those values are used to create the loop.  One frame per week is shown and the date is at the bottom of the figure.  

For CAPE and the 0-6 km Vector Wind Difference ("Deep Shear"), the parameters are calculated using the values from the time of day when CAPE is greatest, only when CAPE is positive.  Shades change every 100 J/kg for CAPE and 2.5 m/s for the deep shear.  Every other shading is labelled on the separate CAPE and deep shear plots.

The CAPE/Deep Shear combination plot has CAPE contoured every 100 J/kg and shading every 2.5 m/s for the deep shear.  Labels are every 10 m/s for the deep shear.

The LCL/Shallow Shear combination plot has LCL height contoured every 500 m and shading every 1 m/s for the shallow shear.  Labels are every 4 m/s for the shallow shear.  Shallow shear is the 0-1 km Vector Wind Difference.