Five year (2004–2009) observations of upper tropospheric water vapor and cloud ice from MLS and comparisons with GEOS‐5 analyses

Abstract

upper tropospheric (UT) water vapor (H 2 O) and ice water content (IWC) from the Aura Microwave Limb Sounder (MLS) and comparisons with outputs from the NASA Goddard Earth Observing System Version 5 (GEOS-5) data assimilation system. Both MLS and GEOS-5 show that high values of H 2 O and IWC at 215 to 147 hPa are associated with areas of deep convection. They exhibit good (within ∼15%) agreement in IWC at these altitudes, but GEOS-5 H 2 O is ∼50% (215 hPa) to ∼30% (147 hPa) larger than MLS values, possibly due to higher temperatures in the data assimilation system at these altitudes. A seasonally migrating band of tropical deep convection is clearly evident in both the MLS and GEOS-5 UT H 2 O and IWC, but GEOS-5 produces a weaker intertropical convergence zone than MLS. MLS and GEOS-5 both show spatial anticorrelation between IWC and H 2 O at 100 hPa, where low H 2 O is associated with low temperatures in regions of tropical convection. At 100 hPa, GEOS-5 produces 50% less IWC and 15% less H 2 O in the tropics, and ∼20% more H 2 O in the extratropics, than does MLS. Behavior of the 100 hPa H 2 O is consistent with it being controlled by temperature. The seasonal cycle in the vertical transport of tropical mean H 2 O from ∼147 hPa to ∼10 hPa appears much stronger in MLS than in GEOS-5. The UT IWC and H 2 O interannual variations, from both MLS and GEOS-5, show clear imprints of the El Niño-Southern Oscillation.

Influence of convection and aerosol pollution on ice cloud particle effective radius

“…Liu (2007) showed in detail that MLS detected ice clouds are geographically and seasonally correlated with deep convection as inferred from the TRMM brightness temperature <210 K. He used MLS IWC at 100 hPa and 147 hPa in particular. Our analysis (Jiang et al, 2007(Jiang et al, , 2010Su et al, 2006) showed 215 hPa IWC correlates with convective intensity. Figure 1 shows the relationship between the MLS IWC measurements at 215 hPa and the GEOS-5 OLR for the tropical region (30 • S to 30 • N).…”

“…The GEOS-5 analyses are "snapshots" of the atmospheric state produced four times daily (at 00:00 Z, 06:00 Z, 12:00 Z, and 18:00 Z) using optimal combinations of model forecasts and many observations (Rienecker et al, 2008) via the Gridpoint Statistical Interpolation (GSI) technique of Wu et al (2002). For this study, the GEOS-5 OLR data, which have a 0.5 • × 0.67 • latitude-longitude resolution, are sampled onto the MLS footprints (Jiang et al, 2010) to match the observations. The level of convective detrainment is approximately ∼200 hPa (e.g.…”

Impacts of 2006 Indonesian fires and dynamics on tropical upper tropospheric carbon monoxide and ozone

“…MLS cloud IWC was derived from the 240 GHz cloudinduced radiances at high tangent heights and is scientifically useful at 215-83 hPa (Wu et al, 2008). We include the IWC data in our analysis because it is a proxy for deep convection in the UT (Fu et al, 2006;Jiang et al, 2010Jiang et al, , 2011: larger IWC indicates stronger deep convection. In addition to MLS cloud IWC data, we also examine NOAA outgoing longwave radiation (OLR) interpolated from satellite observations (Liebmann and Smith, 1996).…”

Hydration or dehydration: competing effects of upper tropospheric cloud radiation on the TTL water vapor

“…The control simulation (referred to as CTRL) runs at 50 km horizontal resolution, covering 15 • S to 45 • N and 180 • W to 180 • E. The meridional asymmetry is to avoid a deleterious feedback from a systematic high bias in the Southern Hemispheric (south to 15 • S) TTL water vapor, which appears to be related to poor representation of the stratospheric circulation in this version of WRF (Jiang et al, 2010). A periodic boundary condition is used in the east-west direction.…”