Improving Convective Sensitivity to Tropospheric Relative Humidity
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Transcript of Improving Convective Sensitivity to Tropospheric Relative Humidity
Improving Convective Sensitivity to Tropospheric Relative Humidity
Richard Neale (NCAR)and
Brian Mapes (RSMAS, University of
Miami)
AMWG Meeting, Mar 20, 2006
0 Moisture sensitivity +
FreeTroposphere
Alti
tude
PBL
0.2 X 100% +0.8 X RHclr =1.0 X 10%=> RHclr = -12.5%
dzE
EP
LNB
LFC v
vvgUCAPE
.constP v
Undilute
Pseudoadiabatic Ascent-No cloud water-No freezing-No entrainment (but implied)
DilutedzE
EP
LNB
LFC v
vgDCAPE
Entraining Plume-Cloud water (1 g/kg)-Freezing below 273K-Entrainment chosen
))(),0(( klevf Ev
PP
DiluteUndilute
Dilute
Undilute
Undilute - GPCPDilute minus GPCP
JJA FV 2x2.5 1979-1988
Dilute minus ERS
Undilute minus ERS
DiluteUndilute
Dilute
Undilute
CAPTCCCP-ARM ParametrizationTestbed
Dilute
Undilute
Variance of 5-day ave rainfall
Dilute
Undilute
ENSOWarmminusCold
DJF Prect.
Amplitude of Diurnal Cycle (mm/day) (JJA 1984)
CAM3 (T85)3B42 TRMMTMI/PR
Local Time of Daily Rainfall Max
CAM3 (T85)3B42 TRMMTMI/PR
0300 Local Rainfall
OverallJJA significant improvements (DJF some improvements Africa/Australia rainfall)-Reduction in S. Indian Ocean ITCZ-Enhanced Asian-Monsoon rainfall-Reduced twin ITCZ bias-Improved tropospheric humidity, MSE structure-Decrease in large Pacific high PSL error-Reduction in amplitude of diurnal cycle of rainfall/increased night-time rainfall-More realistic balance of convective/stratiform rainfall-CAPT tests, < half the error through day 5 forecast-ENSO wider Pacific equatorial signal (tentative)-Enhanced subseasonal variability (too much?)
Some deterioration-Indian monsoon precipitation excess-South Atlantic circulation pattern-No change or slightly earlier diurnal cycle rainfall maximum