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Stanley Q. Kidder and Andrew S. Jones

1. Introduction Forecasters today are faced with many sources of data. What they need is meteorologically significant data fields blended from all available data sources, not numerous maps of observations from individual sources. In this paper we detail our process for blending data for one such meteorological parameter, the total precipitable water (TPW), which is the amount of water vapor in a column from the surface of the earth to space (in kilograms per square meter or, equivalently, in

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É. Gerard, D. G. H. Tan, L. Garand, V. Wulfmeyer, G. Ehret, and P. Di Girolamo

The need for an absolute standard for water vapor observations, in the form of a global dataset with high accuracy and good spatial resolution, has long been recognized. The European Space Agency's Water Vapour Lidar Experiment in Space (WALES) mission aims to meet this need by providing high-quality water vapor profiles, globally and with good vertical resolution, using a differential absorption lidar (DIAL) system in a low earth-orbit satellite. WALES will be the first active system to measure humidity from space routinely. With launch envisaged in the 2008–2010 time frame and a minimum duration of two years, the primary mission goals are to (a) contribute to scientific research and (b) demonstrate the feasibility of longer-term operational missions. This paper assesses the benefits of the anticipated data to NWP through quantitative analysis of information content. Good vertical resolution and low random errors are shown to give substantial improvements in analysis error in one-dimensional variational data assimilation (1DVAR) comparisons with advanced infrared sounders. In addition, the vertical extent of the profiles is shown to reach 16.5 km or ~100 hPa, well above the limit of radiance assimilation (13 km or 200 hPa). Also highlighted are important applications in atmospheric sciences and climate research that would benefit from the low bias promised by spaceborne DIAL data and their complementarity to other types of humidity observations.

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E. M. Weinstock, J. B. Smith, D. Sayres, J. R. Spackman, J. V. Pittman, N. Allen, J. Demusz, M. Greenberg, M. Rivero, L. Solomon, and J. G. Anderson

1. Introduction Accurate measurements of the ice water content (IWC) of cirrus clouds are required for understanding their radiative properties, their impact on the water vapor budget of the upper troposphere and lower stratosphere, and for validation and calibration of satellite-borne instruments that measure cloud properties ( Stephens et al. 2002 ). The critical need for accurate measurements of cloud IWC is succinctly summarized in a statement by the Intergovernmental Panel on Climate

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E. M. Weinstock, J. B. Smith, D. Sayres, J. V. Pittman, N. Allen, and J. G. Anderson

Aeronautics and Space Administration (NASA) WB-57 research aircraft during test flights from Houston, Texas, in May 2001; the Clouds and Water Vapor in the Climate System mission (CWVCS) based out of San Jose, Costa Rica, in the summer of 2001; and the Cirrus Regional Study of Tropical Anvils and Cirrus Layers Florida Area Cirrus Experiment (CRYSTAL FACE) from Key West, Florida, in July 2002. When combined with simultaneous water vapor measurements, instrument accuracy and response time can be evaluated

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Alexandre Couhert, Tapio Schneider, Juilin Li, Duane E. Waliser, and Adrian M. Tompkins

1. Introduction Water vapor plays an essential role in earth’s climate as a mediator of radiative feedbacks in the response of the climate system to perturbations. In particular, the infrared water vapor feedback is strongest in the free troposphere ( Held and Soden 2000 ). Since the infrared radiative forcing associated with changes in atmospheric water vapor concentration scales approximately with relative rather than absolute concentration changes, the subtropical free troposphere has the

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J. W. Hutchings

OCTOBER 1961J. W. HUTCHINGS615WATER-VAPOR TRANSFER OVER THE AUSTRALIAN CONTINENT J. W. Hutchings New Zealand Meteorological Service(Original manuscript received 25 January 1961 ; revised niaiiuscript received 16 March 1961)ABSTRACTFor the calendar year 1956, daily observations of wind and humidity at eight atmospheric levels extendingfrom the earth's surface up to the 400-mb level are used to compute average annual and seasonal verticallyintegrated horizontal water-vapor

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Yu-shu Zhou, Ze-ming Xie, and Xin Liu

-record-breaking heavy rainfall event occurred in the Korla area on 4 June 2012. Floods, landslides, and debris flows caused by torrential rainfall often lead to severe losses of life and property damage and thus have a great impact on the national economy and people’s livelihoods in Xinjiang. Persistent water vapor transport is a necessary condition for the development of torrential rainfall systems ( Gustafsson et al. 2010 ), making the study of water vapor transport and sources for heavy rains important ( Newell

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Stephen Leroy, James Anderson, John Dykema, and Richard Goody

. Slingo and Webb (1997) augmented these points with a simulation of a trend in specific humidity and suggested that the water vapor–longwave feedback might be discernible in trends in the emitted infrared spectrum. They left the question of how one might discern the water vapor–longwave feedback using trend data an open one. Harries et al. (2001) have shown that the difference between two thermal infrared datasets obtained 27 yr apart reveals the increased radiative forcing by individual greenhouse

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Larissa Back, Karen Russ, Zhengyu Liu, Kuniaki Inoue, Jiaxu Zhang, and Bette Otto-Bliesner

warming varies between models. However, the relationship between surface temperature increases and certain hydrological cycle changes is remarkably consistent between models. In this work, we examine whether the hydrological cycle responses are equally robust for slow-global-warming scenarios that occurred naturally in the past by examining a simulation of the climate evolution of the last 22 000 years in a state-of-art climate model ( Liu et al. 2009 ). We find that global water vapor increases

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John R. Hummel

to me sospheric processes. Mesospheric Models and Related Ex periments, G. Fiocco, Ed., Springer-Verlag, 149-159.Bignell, K. J., 1970: The water-vapour infra-red continuum. Quart. J. Roy. Meteor. Soc., 96, 390-403.Bohlander, R. A., R.'J. Emery, D. T. Llewellyn-Jones, G. G. Gim mestad, H. A. Gebbie, O. A. Simpson, J. J. Gallagher and J. Perkowitz, 1980: Excess absorption by water vapor and comparison with theoretical dimer absorption. Atmospheric Water Vapor, A. Deepak, T. D

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