A distribution law for free-tropospheric relative humidity

被引:35
作者
Sherwood, Steven C. [1 ]
Kursinski, E. Robert
Read, William G.
机构
[1] Yale Univ, New Haven, CT 06520 USA
[2] Univ Arizona, Tucson, AZ USA
[3] CALTECH, Jet Prop Lab, Pasadena, CA USA
关键词
D O I
10.1175/JCLI3978.1
中图分类号
P4 [大气科学(气象学)];
学科分类号
0706 ; 070601 ;
摘要
The probability distribution of local relative humidity R in the free troposphere is explored by comparing a simple theoretical calculation with observations from the global positioning system (GPS) and the Microwave Limb Sounder (MLS). The calculation is based on a parcel of air that conserves its composition during diabatic subsidence, until it is resaturated by randomly entering a convective system. This simple "advection-condensation" model of relative humidity predicts a probability density for R proportional to Rr-1, where r is the ratio of time scales associated with subsidence drying and random moistening. The observations obey this distribution remarkably well from 600 to 200 hPa in the Tropics and midlatitudes; possible reasons for this are discussed. The lowest values of R are predicted, and observed, to be the most probable. The observed vertical variation of R is well explained by that of the subsidence time scale, which is set by large-scale dynamics and radiation. These results imply that cloud microphysics exerts little control on water vapor's greenhouse effect, but that relatively subtle dynamical changes have the potential to alter the strength of its feedback on climate change.
引用
收藏
页码:6267 / 6277
页数:11
相关论文
共 47 条
[1]  
Arrhenius S., 1896, Philos. Mag., V41, P237
[2]   Simulations of tropical upper tropospheric humidity [J].
Dessler, AE ;
Sherwood, SC .
JOURNAL OF GEOPHYSICAL RESEARCH-ATMOSPHERES, 2000, 105 (D15) :20155-20163
[3]  
Folkins I, 2002, J GEOPHYS RES-ATMOS, V107, DOI 10.1029/2002JD002185
[4]   Early validation analyses of atmospheric profiles from EOS MLS on the Aura satellite [J].
Froidevaux, L ;
Livesey, NJ ;
Read, WG ;
Jiang, YBB ;
Jimenez, C ;
Filipiak, MJ ;
Schwartz, MJ ;
Santee, ML ;
Pumphrey, HC ;
Jiang, JH ;
Wu, DL ;
Manney, GL ;
Drouin, BJ ;
Waters, JW ;
Fetzer, EJ ;
Bernath, PF ;
Boone, CD ;
Walker, KA ;
Jucks, KW ;
Toon, GC ;
Margitan, JJ ;
Sen, B ;
Webster, CR ;
Christensen, LE ;
Elkins, JW ;
Atlas, E ;
Lueb, RA ;
Hendershot, R .
IEEE TRANSACTIONS ON GEOSCIENCE AND REMOTE SENSING, 2006, 44 (05) :1106-1121
[5]   Diagnosis of subtropical humidity dynamics using tracers of last saturation [J].
Galewsky, J ;
Sobel, A ;
Held, I .
JOURNAL OF THE ATMOSPHERIC SCIENCES, 2005, 62 (09) :3353-3367
[6]   Validation of Aqua satellite data in the upper troposphere and lower stratosphere with in situ aircraft instruments [J].
Gettelman, A ;
Weinstock, EM ;
Fetzer, EJ ;
Irion, FW ;
Eldering, A ;
Richard, EC ;
Rosenlof, KH ;
Thompson, TL ;
Pittman, JV ;
Webster, CR ;
Herman, RL .
GEOPHYSICAL RESEARCH LETTERS, 2004, 31 (22) :1-4
[7]   A distribution law for relative humidity in the upper troposphere and lower stratosphere derived from three years of MOZAIC measurements [J].
Gierens, K ;
Schumann, U ;
Helten, M ;
Smit, H ;
Marenco, A .
ANNALES GEOPHYSICAE-ATMOSPHERES HYDROSPHERES AND SPACE SCIENCES, 1999, 17 (09) :1218-1226
[8]   Radioholographic analysis of radio occultation data in multipath zones [J].
Gorbunov, ME .
RADIO SCIENCE, 2002, 37 (01) :14-1
[9]   CHAMP and SAC-C atmospheric occultation results and intercomparisons [J].
Hajj, GA ;
Ao, CO ;
Iijima, BA ;
Kuang, D ;
Kursinski, ER ;
Mannucci, AJ ;
Meehan, TK ;
Romans, LJ ;
Juarez, MD ;
Yunck, TP .
JOURNAL OF GEOPHYSICAL RESEARCH-ATMOSPHERES, 2004, 109 (D6)
[10]   Water vapor feedback and global warming [J].
Held, IM ;
Soden, BJ .
ANNUAL REVIEW OF ENERGY AND THE ENVIRONMENT, 2000, 25 :441-475