super greenhouse effect detection from aqua instruments dan feldman notes for dc trip 10/16/05

Super Greenhouse Effect Detection from Aqua instruments

Dan Feldman

Notes for DC Trip

10/16/05

Clear-sky greenhouse parameter

• g increases linearly with SST for SST<298K

• g increases at a much faster rate for SST>298 K – From Ravel and

Ramanathan (1989) using ERBE data

4

4

s

skyclears

T

OLRTg

g is sensitive to upper tropospheric H2O

• MLS (aboard AURA) sensitive to ice-water content and UT H2O

• g vs. SST similar for AIRS and MLS

• Super greenhouse effect visible from both instruments

• What about convection?

Radiative forcing due to SST>298K

• Do SSTs >298K contribute to increased cloud cover and/or cloud reflectivity to counteract conventional definition of super greenhouse effect?

• Answer may lie with AIRS and CERES data– AIRS: UT H2O, cloud fraction, SST

– CERES: Albedo 0.3 um to 5 um

Analysis period: 08/2004-01/2005

• AIRS UT H2O product agrees well with MLS and radiosondes at ARM TWP site (Nauru)

• SSTs in western Pacific ~300 K• AIRS cloud fraction well-correlated to SST >298

K

• Low UT H2O correlated with low albedo as measured by CERES. The converse statement is not as well supported by the data.

AIRS vs. TWP radiosondes

AIRS SST Product

AIRS UT H2O

AIRS Cloud Fraction

AQUA CERES Albedo