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

June composite day: loop through 0-23 UT

CESM updraft mass flux above 800hPa, deviation from mean

Carnegie curve: Percent deviation from mean (June)

Liu et al. 2009current

CESM%

UT UT

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