Post on 13-Dec-2015
transcript
Towards parametrized GEC current sources for the CESM model
FESD project meeting February 2014
Wiebke Deierling, Andreas Baumgaertner, Tina Kalb
Background
Mach et al. 2011
Investigate parameterizations based on readily available cloud parameters in model such as:- In-Cloud Ice Water Path - Convection Mass Flux - ………
Assumption: Cloud characteristics relate to conduction currents of different type
Step 1: Investigate spatial and temporal distribution of these cloud parameters. How well do they represent observed cloud parameters?
Step 2: Regression between estimated observed currents and cloud parameters to infer currents in model. This can be done on different temporal and spatial scales.
Storm counts from TRMM from Liu et al. 2009
Conversion of thunderstorm (TC) / electrified storm (T30dbZ < -10/-17C) count to current per grid box:
x 1.7A #TC over ocean
x 1.0A #TC over land
x 0.41A #ESC over ocean
x 0.13A #ESC over land
CESMIn-cloud ice water path above 500 hPa
CESMConvection updraftmass flux above 800 hPa
June
Liu et al., 2009 estimated current
MERRAConvection updraftmass flux above 800 hPa
CESMConvection updraftmass flux above 800 hPa
June
Liu et al., 2009 estimated current
Yearly average
CESMConvection updraftmass flux above 800 hPasingle-year mean(low resolution)
Liu et al., 2009 estimated current
Vertical location of charges
Altitude above sea level (km)
Positive charge at -30C
Negativecharge at -10C
km
from CESM temperature distribution
Conclusions and future work
• Convective updraft mass flux from CESM simulations has similar features to derived GEC source current from storm counts
→ possibly useful for parametrizing source current in the model
• Future work: o Derive relationships between storm counts and storm-current from
ER-2 and radaro Compare results from different reanalysis (NCEP/NCAR, ECMWF)o Improve fitting of model variables to “observed” source current