Lightning and upper-tropospheric water vapor (UTWV)

• A complex question:• Diagnostic for climate change (more lightning/storms = more

UTWV)• As a feedback process – increase absorption of longwave

radiation by water vapor warming increased deep convection?

• Theory• Water vapor should increase with increasing temperature • UTWV increases even more so, due to transport: Deep

convection deposits large amounts of water vapor in the upper troposphere – largely through sublimation of anvil ice

• So should UTWV vary with lightning activity on regional to global scales?

• UTWV thought to act as a positive feedback to warming – additional positive feedback by increasing frequency/intensity of deep convection? Price (2000)

Price and Asfur (2006)

• Challenges:• Difficulty of measuring water vapor on a global scale• How to measure global lightning activity (easily)? – Price

(2000), Price and Asfur (2006) propose use of Schumann resonances – easily measurable ELF radiation at any location around the globe; very well correlated with UTWV

• Schumann resonance variability as an indicator of UTWV variability – simple means to measure global lightning activity; no complex global detection necessary

• If Schumann resonance magnetic field amplitudes (what’s shown in plots) increase over time, can we infer a similar change in UTWV – preliminary studies suggest we can – need better water vapor measurements!

Price (2000), Price and Asfur (2006)

NASA Water Vapor Project (NVAP)NCEP-NCAR Reanalyses