Abstract
Free tropospheric humidity (FTH) is a key parameter of the radiation budget of the Earth. In particular, its distribution over the intertropical belt has been identified as an important contributor to the water vapour feedback. Idealized radiative transfer computations are performed to underscore the need to consider the whole probability distribution function (PDF) rather than the arithmetical mean of the FTH. The analysis confirmed the overwhelming role of the dry end of the PDF in the radiative perturbation of the top of atmosphere longwave budget. The physical and dynamical processes responsible for the maintenance of this dry part of the FTH distribution are reviewed, and the lateral mixing between the tropics and the extra-tropics is revealed as a major element of the dry air dynamics. The evolution of this lateral mixing in the framework of the global warming is discussed, and perspectives of work are listed as a mean of a conclusion.
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Notes
And more recently for the stratospheric water vapour as well (Liu et al. 2010).
Abbreviations
- AC:
-
Advection-condensation
- AIRS:
-
Atmospheric Infrared Sounder
- AR4:
-
Fourth Assessment Report
- BLH:
-
Boundary Layer relative Humidity
- BT:
-
Brightness temperature
- DJF:
-
December, January and February
- ECMWF:
-
European Centre for Medium-Range Weather Forecasts
- ERA-Interim:
-
ECMWF ReAnalyses-interim
- ERA-40:
-
ECMWF ReAnalyses-40
- FIR:
-
Far infrared
- FTH:
-
Free tropospheric humidity
- IPSL:
-
Institut Pierre-Simon Laplace
- ITCZ:
-
Inter Tropical Convergence Zone
- JJA:
-
June, July and August
- NCEP:
-
National Center for Environmental Prediction
- OLR:
-
Outgoing Long wave Radiation
- PDF:
-
probability distribution function
- RH:
-
Relative Humidity
- TS:
-
Temperature of the surface
- TOA:
-
Top of atmosphere
References
Allan RP (2012) The role of water vapour in earth’s energy flows. Surv Geophys. doi:10.1007/s10712-011-9157-8 (this volume)
Allen G, Vaughan G, Brunner D, May TP, Heyes W, Minnis P, Ayers KJ (2009) Modulation of tropical convection by breaking Rossby waves. Quart J R Meteorol Soc 135:125–137. doi:10.1002/qj.349
Aumann HH, Chahine MT, Gautier C, Goldberg M, Kalnay E, McMillin L, Revercomb H, Rosenkranz PW, Smith WL, Staelin DH, Strow L, Susskind J (2003) AIRS/AMSU/HSB on the aqua mission: design, science objectives, data products and processing systems. IEEE Trans Geosci Remote Sensing 41(2):253–264
Berk A, Acharya PK, Bernstein LS, Anderson GP, Chetwynd Jr JH, Hoke ML (2000) Reformulation of the MODTRAN band model for finer spectral resolution. Proceedings of SPIE, vol 4049, Orlando, Florida, April, 2000
Bernstein LS, Berk A, Acharya PK, Robertson DC, Anderson GP, Chetwynd JH, Kimball LM (1996) Very narrow band model calculations of atmospheric fluxes and cooling rates. J Atmos Sci 53(19):2887–2904
Brogniez H, Pierrehumbert R (2007) Intercomparison of tropical tropospheric humidity in GCMs with AMSU-B water vapor data. Geophys Res Lett 34:L17706. doi:10.1029/2007GL030967
Brogniez H, Roca R, Picon L (2006) A clear sky radiances archive from METEOSAT “water vapor” observations. J Geophys Res 111:D21109. doi:10.1029/2006JD007238
Brogniez H, Roca R, Picon L (2009) A study of the free tropospheric humidity interannual variability using meteosat data and an advection-condensation transport model. J Clim 22:6773–6787. doi:10.1175/2009JCLI2963.1
Casey Sean PF, Andrew ED, Courtney S (2009) Five-year climatology of mid troposphere dry air layers in warm tropical ocean regions as viewed by AIRS/Aqua. J Appl Meteor Climatol 48:1831–1842. doi:10.1175/2009JAMC2099.1
Cau P, Methven J, Hoskins B (2007) Origins of dry air in the tropics and subtropics. J Clim 20:2745–2759
Couhert A, Schneider T, Li J, Waliser DE, Tomkins AM (2010) The maintenance of the relative humidity of the subtropical free troposphere. J Clim 23:390–403. doi:10.1175/2009JCLI2952.1
Del Genio AD (2011) Representing the sensitivity of convective cloud systems to tropospheric humidity in general circulation models. Surv Geophys. doi:10.1007/s10712-011-9148-9
Del Genio AD, Kovari W (2002) Climatic properties of tropical precipitating convection under varying environmental conditions. J Clim 15:2597–2615. doi:10.1175/1520-0442(2002)015<2597:CPOTPC>2.0.CO;2
Dessler AE, Minschwaner K (2007) An analysis of the regulation of tropical tropospheric water vapor. J Geophys Res 112:D10120. doi:10.1029/2006JD007683
Dessler AE, Sherwood SC (2000) Simulations of tropical upper tropospheric humidity. J Geophys Res 105:20155–20163
Fetzer EJ, McMillin L, Tobin D, Aumann HH, Gunson MR, McMillan WW, Hagan DE, Hofstadter MD, Yoe J, Whiteman D, Barnes J, Bennartz R, Vemel H, Walden V, Newchurch M, Minnett P, Atlas R, Schmidlin F, Olsen ET, Goldberg M, Zhou S, Ding H, Smith W, Revercomb SRH (2003) AIRS/AMSU/HSB validation. IEEE Trans Geosci Remote Sens 41:418–431
Galewsky J, Sobel A, Held I (2005) Diagnosis of subtropical humidity dynamics using tracers of last saturation. J Atmos Sci 62:3353–3367
Guzman R, Picon L, Roca R (2012) A simple model of outgoing longwave radiation for the tropical ocean, land and desert. J Geophys Res (in preparation)
Harries J, Carli B, Rizzi R, Serio C, Mlynczak M, Palchetti L, Maestri T, Brindley H, Masiello G (2008) The far infrared earth. Rev Geophys 46:RG4004. doi:10.1029/2007RG000233
Held IM, Soden BJ (2000) Water vapor feedback and global warming. Annu Rev Energy Environ 25:441–475
Hurley JV, Galewsky J (2010a) A last saturation analysis of ENSO humidity variability in the subtropical Pacific. J Clim 23:918–931
Hurley JV, Galewsky J (2010b) A last-saturation diagnosis of subtropical water vapor response to global warming. Geophys Res Lett 37:L06702
Inamdar AK, Ramanathan V (1998) Tropical and global scale interactions among water vapor, atmospheric greenhouse effect, and surface temperature. J Geophys Res 103:32177–32194
John VO, Holl G, Allan RP, Buehler SA, Parker DE, Soden BJ (2011) Clear-sky biases in satellite infrared estimates of upper tropospheric humidity and its trends. J Geophys Res 116:D14108. doi:10.1029/2010JD015355
Lemond J (2009) Climatologie et variabilité de l’air sec de la troposphère libre intertropicale: analyse du climat actuel et de son évolution. PhD thesis, University Pierre and Marie Curie, Paris, France
Liu YS, Fueglistaler S, Haynes PH (2010) Advection-condensation paradigm for stratospheric water vapor. J Geophys Res 115:D24307. doi:10.1029/2010JD014352
Marti GE (2005) The new IPSL climate system model: IPSL-CM4. Report no 26, Institute Pierre Simon Laplace, Paris
O’Gorman PA, Schneider T (2008) The hydrological cycle over a wide range of climates simulated with an idealized GCM. J Clim 21:3815–3832
O’Gorman PA, Lamquin N, Schneider T, Singh MS (2011) The relative humidity in an isentropic advection–condensation model: limited poleward influence and properties of subtropical minima. J Atmos Sci 68:3079–3093. doi:10.1175/JAS-D-11-067.1
Peixoto JP, Oort AH (1996) The climatology of relative humidity in the atmosphere. J Clim 9(12):3443–3463
Pierrehumbert RT (1995) Thermostats, radiator fins, and the local runaway greenhouse. J Atmos Sci 52:1784–1806
Pierrehumbert RT (1998) Lateral mixing as a source of subtropical water vapor. Geophys Res Lett 25:151–154
Pierrehumbert RT, Roca R (1998) Evidence for control of Atlantic subtropical humidity by large scale advection. Geophys Res Lett 25:4537–4540
Pierrehumbert R, Yang H (1993) Global chaotic mixing on isentropic surfaces. J Atmos Sci 50:2462–2480
Pierrehumbert RT, Brogniez H, Roca R (2007) On the relative humidity of the atmosphere. In: Schneider T, Sobel AH (eds) The global circulation of the atmosphere. Princeton, Princeton University Press, pp 143–185
Renno N, Stoneet PH, Emanuel KA (1994) Radiative-convective model with an explicit hydrologic cycle 2. Sensitivity to large changes in solar forcing. J Geophys Res 99:17001–17020
Roca R (2011) The Megha-tropiques mission. MT special issue in QJRMS (in preparation)
Roca R, Brogniez H, Picon L, Desbois M (2003) Free tropospheric humidity observations from METEOSAT water vapor data, 83 AMS annual meeting, Long Beach, California, USA, in the CDROM, 9–13 February 2003
Roca R, Louvet S, Picon L, Desbois M (2004) A study of convective systems, water vapor and top of the atmosphere cloud radiative forcing over the Indian Ocean using INSAT-1B and ERBE data. Meteorol Atmos Phys. doi:10.1007/s00703-004-0098-3
Roca R, Lafore JP, Piriou C, Redelsperger JL (2005) Extratropical dry air intrusions into the West African monsoon mid troposphere: an important factor for the convective activity over the Sahel. J Atmos Sci 62:390–407
Ryoo JM, Ugasa T, Waugh DW (2009) PDFs of tropospheric humidity. J Clim 22:3357–3373
Salathé EP, Hartmann DL (1997) A trajectory analysis of tropical upper tropospheric moisture and convection. J Clim 10:2533–2547
Schneider T, Smith KL, O’Gorman PA, Walker CC (2006) A climatology of tropospheric zonal-mean water vapor fields and fluxes in isentropic coordinates. J Clim 19:5918–5933
Schneider T, O’Gorman PA, Levine XJ (2010) Water vapor and the dynamics of climate changes. Rev Geophys 48:RG3001. doi:10.1029/2009RG000302
Sherwood SC (1996) Maintenance of the free tropospheric tropical water vapor distribution, part II: simulation by large scale advection. J Clim 9:2919–2934
Sherwood SC, Kursinski ER, Read WG (2006) A distribution law for free tropospheric relative humidity. J Clim 19:6267–6277
Sherwood SC, Roca R, Weckwerth TM, Andronova NG (2010a) Tropospheric water vapor, convection, and climate. Rev Geophys 48:RG2001. doi:10.1029/2009RG00030
Sherwood SC, Ingram W, Tsushima Y, Satoh M, Roberts M, Vidale PL, O’Gorman PA (2010b) Relative humidity changes in a warmer climate. J Geophys Res 115:D09104
Shine KP, Ptashnik IV, Radel G (2012) The water vapour continuum: brief history and recent developments. Surv Geophys (this volume)
Sohn BJ, Bennartz R (2008) Contribution of water vapor to observational estimates of longwave cloud radiative forcing. J Geophys Res 113:D20107. doi:10.1029/2008JD01005
Sohn BJ, Schmetz J (2004) Water vapor-induced OLR variations associated with high cloud changes over the tropics: a study from meteosat-5 observations. J Clim 17:1987–1996
Sohn B-J, Schmetz J, Chung E-S (2008) Moistening processes in the tropical upper troposphere observed from meteosat measurements. J Geophys Res 113:D13109. doi:10.1029/2007JD009527
Spencer R, Braswell WD (1997) How dry is the tropical free troposphere? Implications for global warming theory. Bull Am Meteorol Soc 78:1097–1106
Su H, Read WG, Jiang JH, Waters JW, Wu DL, Fetzer EJ (2006) Enhanced positive water vapor feedback associated with tropical deep convection: new evidence from Aura MLS. Geophys Res Lett 33:L05709. doi:10.1029/2005GL025505
Waugh DW (2005) Impact of potential vorticity intrusions on subtropical upper tropospheric humidity. J Geophys Res 110:D11305. doi:10.1029/2004JD005664
Wright JS, Sobel A, Galewsky J (2010) Diagnosis of zonal mean relative humidity changes in a warmer climate. J Clim 23(17):4556–4569
Yang H, Pierrehumbert RT (1994) Production of dry air by isentropic mixing. J Atmos Sci 51:3437–3454
Yoneyama K, Parsons DB (1999) A proposed mechanism for the intrusion of dry air into the tropical western Pacific region. J Atmos Sci 56:1524–1546
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Roca, R., Guzman, R., Lemond, J. et al. Tropical and Extra-Tropical Influences on the Distribution of Free Tropospheric Humidity Over the Intertropical Belt. Surv Geophys 33, 565–583 (2012). https://doi.org/10.1007/s10712-011-9169-4
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DOI: https://doi.org/10.1007/s10712-011-9169-4