Relative Humidity in the Troposphere with AIRS

AbstractNew global satellite data from the Atmospheric Infrared Sounder (AIRS) are applied to study the tropospheric relative humidity (RH) distribution and its influence on outgoing longwave radiation (OLR) for January and July in 2003, 2007, and 2011. RH has the largest maxima over 90% in the equatorial tropopause layer in January. Maxima in July do not arise above 60%. Seasonal variations of about 20% in zonally averaged RH are observed in the equatorial region of the low troposphere, in the equatorial tropopause layer, and in the polar regions. The seasonal variability in the recent decade has increased by about 5% relative to that in 1973–88, indicating a positive trend. The observed RH profiles indicate a moist bias in the tropical and subtropical regions typically produced by the general circulation models. The new data and method of evaluating the statistical significance of bimodality confirm bimodal probability distributions of RH at large tropospheric scales, notably in the ascending branch of ...

[1]  Lena Iredell,et al.  Interannual variability of outgoing longwave radiation as observed by AIRS and CERES , 2012 .

[2]  An assessment of climate feedback processes using satellite observations of clear‐sky OLR , 2010 .

[3]  V. Ramanathan,et al.  Observational determination of the greenhouse effect , 1989, Nature.

[4]  B. Mapes.  Water's two height scales: The moist adiabat and the radiative troposphere , 2001 .

[5]  A. Dessler,et al.  A Determination of the Cloud Feedback from Climate Variations over the Past Decade , 2010, Science.

[6]  T. Igusa,et al.  PDFs of Tropical Tropospheric Humidity: Measurements and Theory , 2009 .

[7]  F. Bretherton,et al.  Upper tropospheric relative humidity from the GOES 6.7 μm channel: method and climatology for July 1987 , 1993 .

[8]  V. Ramaswamy,et al.  Observed Dependence of Outgoing Longwave Radiation on Sea Surface Temperature and Moisture. , 1994 .

[9]  D. P. Brown,et al.  Process-evaluation of tropospheric humidity simulated by general circulation models using water vapor isotopic observations: 2. Using isotopic diagnostics to understand the mid and upper tropospheric moist bias in the tropics and subtropics , 2012 .

[10]  K. Trenberth,et al.  A Less Cloudy Future: The Role of Subtropical Subsidence in Climate Sensitivity , 2012, Science.

[11]  S. Bony,et al.  Sea Surface Temperature and Large-Scale Circulation Influences on Tropical Greenhouse Effect and Cloud Radiative Forcing , 1997 .

[12]  Roy W. Spencer,et al.  How dry is the tropical free troposphere? : Implications for global warming theory , 1997 .

[13]  I. Held,et al.  Using Relative Humidity as a State Variable in Climate Feedback Analysis , 2012 .

[14]  J. Hartigan,et al.  The Dip Test of Unimodality , 1985 .

[15]  H. Yang,et al.  Production of Dry Air by Isentropic Mixing , 1994 .

[16]  Jonathon S. Wright,et al.  Diagnosis of zonal mean relative humidity changes in a warmer climate. , 2010 .

[17]  S. Sherwood,et al.  A Distribution Law for Free-Tropospheric Relative Humidity , 2006 .

[18]  J. Marron,et al.  SiZer for Exploration of Structures in Curves , 1999 .

[19]  Zhibo Zhang,et al.  An analysis of the dependence of clear-sky top-of-atmosphere outgoing longwave radiation on atmospheric temperature and water vapor , 2008 .

[20]  E. Fetzer,et al.  Cloudy and clear‐sky relative humidity in the upper troposphere observed by the A‐train , 2009 .

[21]  N. Graham,et al.  Comparison of the Highly Reflective Cloud and Outgoing Longwave Radiation Datasets for Use in Estimating Tropical Deep Convection. , 1993 .

[22]  Lance E. Christensen,et al.  Aura Microwave Limb Sounder upper tropospheric and lower stratospheric H2O and relative humidity with respect to ice validation , 2007 .

[23]  R. Allan,et al.  The dependence of clear‐sky outgoing long‐wave radiation on surface temperature and relative humidity , 1999 .

[24]  B. Soden,et al.  WATER VAPOR FEEDBACK AND GLOBAL WARMING 1 , 2003 .

[25]  Johannes Schmetz,et al.  Upper tropospheric humidity observations from Meteosat compared with short-term forecast fields , 1994 .

[26]  H. Aumann,et al.  On the Surface Temperature Sensitivity of the Reflected Shortwave, Outgoing Longwave, and Net Incident Radiation , 2011 .

[27]  Y. Tsushima,et al.  Relative humidity changes in a warmer climate , 2010 .

[28]  Dong L. Wu,et al.  Enhanced positive water vapor feedback associated with tropical deep convection: New evidence from Aura MLS , 2006 .

[29]  M. McElroy,et al.  A model for the energy budget of the atmosphere: Comparison with data from the Earth Radiation Budget Experiment , 1992 .

[30]  S. Fueglistaler,et al.  Statistical analysis of global variations of atmospheric relative humidity as observed by AIRS , 2012 .

[31]  Govindasamy Bala,et al.  Climatology of Upper-Tropospheric Relative Humidity from the Atmospheric Infrared Sounder and Implications for Climate , 2006 .

[32]  Syukuro Manabe,et al.  Thermal Equilibrium of the Atmosphere with a Given Distribution of Relative Humidity , 1967 .

[33]  Anand K. Inamdar,et al.  Physics of greenhouse effect and convection in warm Oceans , 1994 .

[34]  J. Peixoto,et al.  The Climatology of Relative Humidity in the Atmosphere , 1996 .

[35]  Brian E. Mapes,et al.  Bimodality in tropical water vapour , 2003 .

[36]  D. Waliser.  Formation and Limiting Mechanisms for Very High Sea Surface Temperature: Linking the Dynamics and the Thermodynamics , 1996 .

[37]  Andrew E. Dessler,et al.  Water Vapor Feedback in the Tropical Upper Troposphere: Model Results and Observations , 2004 .