scholarly journals Process-evaluation of tropospheric humidity simulated by general circulation models using water vapor isotopologues: 1. Comparison between models and observations

2012 ◽  
Vol 117 (D5) ◽  
pp. n/a-n/a ◽  
Author(s):  
Camille Risi ◽  
David Noone ◽  
John Worden ◽  
Christian Frankenberg ◽  
Gabriele Stiller ◽  
...  
Keyword(s):  
Water Vapor ◽  
Process Evaluation ◽  
General Circulation ◽  
General Circulation Models

scholarly journals Review on Applications of 17O in Hydrological Cycle

Molecules ◽  
2021 ◽  
Vol 26 (15) ◽  
pp. 4468
Author(s):  
Yalalt Nyamgerel ◽  
Yeongcheol Han ◽  
Minji Kim ◽  
Dongchan Koh ◽  
Jeonghoon Lee
Keyword(s):  
Water Vapor ◽  
General Circulation ◽  
Hydrological Cycle ◽  
General Circulation Models ◽  
Convective Precipitation ◽  
Subsurface Water ◽  
Polar Regions ◽  
Sea Ice Concentration ◽  
Moisture Source ◽  
Depositional Processes

The triple oxygen isotopes (16O, 17O, and 18O) are very useful in hydrological and climatological studies because of their sensitivity to environmental conditions. This review presents an overview of the published literature on the potential applications of 17O in hydrological studies. Dual-inlet isotope ratio mass spectrometry and laser absorption spectroscopy have been used to measure 17O, which provides information on atmospheric conditions at the moisture source and isotopic fractionations during transport and deposition processes. The variations of δ17O from the developed global meteoric water line, with a slope of 0.528, indicate the importance of regional or local effects on the 17O distribution. In polar regions, factors such as the supersaturation effect, intrusion of stratospheric vapor, post-depositional processes (local moisture recycling through sublimation), regional circulation patterns, sea ice concentration and local meteorological conditions determine the distribution of 17O-excess. Numerous studies have used these isotopes to detect the changes in the moisture source, mixing of different water vapor, evaporative loss in dry regions, re-evaporation of rain drops during warm precipitation and convective storms in low and mid-latitude waters. Owing to the large variation of the spatial scale of hydrological processes with their extent (i.e., whether the processes are local or regional), more studies based on isotopic composition of surface and subsurface water, convective precipitation, and water vapor, are required. In particular, in situ measurements are important for accurate simulations of atmospheric hydrological cycles by isotope-enabled general circulation models.

scholarly journals The MJO Transition from Shallow to Deep Convection in CloudSat/CALIPSO Data and GISS GCM Simulations

2012 ◽  
Vol 25 (11) ◽  
pp. 3755-3770 ◽  
Author(s):  
Anthony D. Del Genio ◽  
Yonghua Chen ◽  
Daehyun Kim ◽  
Mao-Sung Yao
Keyword(s):  
Water Vapor ◽  
General Circulation ◽  
Deep Convection ◽  
General Circulation Models ◽  
Lapse Rate ◽  
Shallow Convection ◽  
Large Variability ◽  
Earth Observing System ◽  
Upper Level ◽  
Goddard Institute

The relationship between convective penetration depth and tropospheric humidity is central to recent theories of the Madden–Julian oscillation (MJO). It has been suggested that general circulation models (GCMs) poorly simulate the MJO because they fail to gradually moisten the troposphere by shallow convection and simulate a slow transition to deep convection. CloudSat and Cloud–Aerosol Lidar and Infrared Pathfinder Satellite Observations (CALIPSO) data are analyzed to document the variability of convection depth and its relation to water vapor during the MJO transition from shallow to deep convection and to constrain GCM cumulus parameterizations. Composites of cloud occurrence for 10 MJO events show the following anticipated MJO cloud structure: shallow and congestus clouds in advance of the peak, deep clouds near the peak, and upper-level anvils after the peak. Cirrus clouds are also frequent in advance of the peak. The Advanced Microwave Scanning Radiometer for Earth Observing System (EOS) (AMSR-E) column water vapor (CWV) increases by ~5 mm during the shallow–deep transition phase, consistent with the idea of moisture preconditioning. Echo-top height of clouds rooted in the boundary layer increases sharply with CWV, with large variability in depth when CWV is between ~46 and 68 mm. International Satellite Cloud Climatology Project cloud classifications reproduce these climatological relationships but correctly identify congestus-dominated scenes only about half the time. A version of the Goddard Institute for Space Studies Model E2 (GISS-E2) GCM with strengthened entrainment and rain evaporation that produces MJO-like variability also reproduces the shallow–deep convection transition, including the large variability of cloud-top height at intermediate CWV values. The variability is due to small grid-scale relative humidity and lapse rate anomalies for similar values of CWV.

scholarly journals Spectroscopic Imaging of Sub-Kilometer Spatial Structure in Lower Tropospheric Water Vapor

2020 ◽  
Author(s):  
David R. Thompson ◽  
Brian H. Kahn ◽  
Philip G. Brodrick ◽  
Matthew D. Lebsock ◽  
Mark Richardson ◽  
...  
Keyword(s):  
Water Vapor ◽  
Spatial Variability ◽  
General Circulation ◽  
Imaging Spectroscopy ◽  
General Circulation Models ◽  
Order Structure ◽  
Scaling Properties ◽  
Observation Network ◽  
Airborne Imaging ◽  
Shortwave Infrared

Abstract. Understanding the subgrid spatial variability of water vapor is important for parameterizing and simulating cloud processes in General Circulation Models (GCMs). This study maps sub-kilometer spatial structures in total atmospheric column water vapor with Visible to Shortwave Infrared (VSWIR) imaging spectroscopy. We describe our inversion approach and validate its accuracy with coincident measurements by airborne imaging spectrometers and the AERONET ground-based observation network. Next, data from NASA’s AVIRIS-NG spectrometer enables the highest resolution measurement to date of water vapor’s spatial variability and scaling properties. We find second order structure function scaling exponents consistent with prior studies of convective atmospheres. Finally, we conclude by discussing the implications of these measurements and paths toward future campaigns to build upon these results.

scholarly journals The global impact of supersaturation in a coupled chemistry-climate model

2007 ◽  
Vol 7 (6) ◽  
pp. 1629-1643 ◽  
Author(s):  
A. Gettelman ◽  
D. E. Kinnison
Keyword(s):  
Water Vapor ◽  
Radiative Forcing ◽  
General Circulation ◽  
Climate Model ◽  
General Circulation Models ◽  
Boreal Summer ◽  
Boreal Winter ◽  
Strong Impact ◽  
Small Component ◽  
Enhanced Production

Abstract. Ice supersaturation is important for understanding condensation in the upper troposphere. Many general circulation models however do not permit supersaturation. In this study, a coupled chemistry climate model, the Whole Atmosphere Community Climate Model (WACCM), is modified to include supersaturation for the ice phase. Rather than a study of a detailed parameterization of supersaturation, the study is intended as a sensitivity experiment, to understand the potential impact of supersaturation, and of expected changes to stratospheric water vapor, on climate and chemistry. High clouds decrease and water vapor in the stratosphere increases at a similar rate to the prescribed supersaturation (20% supersaturation increases water vapor by nearly 20%). The stratospheric Brewer-Dobson circulation slows at high southern latitudes, consistent with slight changes in temperature likely induced by changes to cloud radiative forcing. The cloud changes also cause an increase in the seasonal cycle of near tropopause temperatures, increasing them in boreal summer over boreal winter. There are also impacts on chemistry, with small increases in ozone in the tropical lower stratosphere driven by enhanced production. The radiative impact of changing water vapor is dominated by the reduction in cloud forcing associated with fewer clouds (~+0.6 Wm−2) with a small component likely from the radiative effect (greenhouse trapping) of the extra water vapor (~+0.2 Wm−2), consistent with previous work. Representing supersaturation is thus important, and changes to supersaturation resulting from changes in aerosol loading for example, might have a modest impact on global radiative forcing, mostly through changes to clouds. There is no evidence of a strong impact of water vapor on tropical tropopause temperatures.

On Cirrus Modeling for General Circulation and Climate Models

Cirrus ◽  
2002 ◽  
Author(s):  
Hilding Sundqvist
Keyword(s):  
Water Vapor ◽  
General Circulation ◽  
Climate Models ◽  
Numerical Models ◽  
General Circulation Models ◽  
Cirrus Clouds ◽  
Energy Budgets ◽  
Water Ice ◽  
Physically Based ◽  
Ice Content

Cirrus clouds are significant regulators of the earth's radiation budget. Cirrus generally have low ice water content, leading to partial transparency to radiation, and a variety of ice crystal types constitutes the cloud. As a consequence, cirrus have complex optical qualities, which are discussed in other chapters of this book. In this chapter, I discuss the appearance and behavior of the cirrus clouds per se and discuss approaches to include those features in numerical models by parameterization. The number of general circulation models (GCMs) containing physically based parameterizations of cloud processes with prognostic equations for water/ice content increased remarkably during the 1990s. Model simulations of the general circulation of the atmosphere have shown a pronounced sensitivity to modeled optical properties of cirrus (e.g., Ramanathan et al. 1983; Senior and Mitchell 1993; Mitchell 1994b; Fowler and Randall 1996a,b; Kristjansson et al. 1998). Most studies with GCMs and climate models have focused on features of radiation and energy budgets and the modulation of these budgets as a consequence of changes in cloudiness quality or other conditions. Much less attention has been paid to the characteristics and realism of the model cloudiness itself (e.g., Liou 1992). Only meager discussions are generally found on these topics from studies in this context. In most cases, zonally averaged and/or bird's-eyeview cloudiness are reported. The reason for this is the sparseness of observational data, which makes it difficult to conduct a detailed verification of the simulated cloud fields. Many papers on model experimentation on this topic do indeed contain statements that uncertainties in cloud behavior constitute a severe weakness of the simulations (Senior and Mitchell 1993; Mitchell 1994). It is also emphasized that substantial improvement in our understanding of the behavior of clouds (not least cirrus) is required for satisfactory confidence in simulations of different climate scenarios. The critical need for high-accuracy measurements of upper-tropospheric water vapor is emphasized for example, in a paper by Stephens et al. (1996) discussing satellite measurements of water vapor. Clouds also have an indirect effect on climatology because their appearance and disappearance (evaporation) modulate the distribution of water vapor in the atmosphere.

The Role of the Water Vapor Feedback in the ITCZ Response to Hemispherically Asymmetric Forcings

2018 ◽  
Vol 31 (9) ◽  
pp. 3659-3678 ◽  
Author(s):  
Spencer K. Clark ◽  
Yi Ming ◽  
Isaac M. Held ◽  
Peter J. Phillipps
Keyword(s):  
Water Vapor ◽  
General Circulation ◽  
General Circulation Models ◽  
Convection Scheme ◽  
Water Vapor Absorption ◽  
Control Distribution ◽  
Model Yield ◽  
Water Vapor Feedback ◽  
Vapor Absorption

In comprehensive and idealized general circulation models, hemispherically asymmetric forcings lead to shifts in the latitude of the intertropical convergence zone (ITCZ). Prior studies using comprehensive GCMs (with complicated parameterizations of radiation, clouds, and convection) suggest that the water vapor feedback tends to amplify the movement of the ITCZ in response to a given hemispherically asymmetric forcing, but this effect has yet to be elucidated in isolation. This study uses an idealized moist model, coupled to a full radiative transfer code, but without clouds, to examine the role of the water vapor feedback in a targeted manner. In experiments with interactive water vapor and radiation, the ITCZ latitude shifts roughly twice as much off the equator as in cases with the water vapor field seen by the radiation code prescribed to a static hemisperically symmetric control distribution. Using energy flux equator theory for the latitude of the ITCZ, the amplification of the ITCZ shift is attributed primarily to the longwave water vapor absorption associated with the movement of the ITCZ into the warmer hemisphere, further increasing the net column heating asymmetry. Local amplification of the imposed forcing by the shortwave water vapor feedback plays a secondary role. Experiments varying the convective relaxation time, an important parameter in the convection scheme used in the idealized moist model, yield qualitatively similar results, suggesting some degree of robustness to the model physics; however, the sensitivity experiments do not preclude that more extreme modifications to the convection scheme could lead to qualitatively different behavior.

Atmosphere and climate

2010 ◽  
Author(s):  
Ned Horning ◽  
Julie A. Robinson ◽  
Eleanor J. Sterling ◽  
Woody Turner ◽  
Sacha Spector
Keyword(s):  
Water Vapor ◽  
General Circulation ◽  
Batrachochytrium Dendrobatidis ◽  
Regional Climate ◽  
General Circulation Models ◽  
Global Scale ◽  
Daily Maximum ◽  
Air Temperatures ◽  
Conservation Concern ◽  
Highland Forests

There is a compelling need for environmental managers to consider atmospheric and climatic impacts upon the systems they manage. Pounds et al. (2006) linked dramatic losses of frog species in the neotropical genus Atelopus to regional climate effects on the temperature and relative humidity of highland forests. They related frog disappearances to tropical air temperatures, finding that ~80 percent of the missing species were lost after relatively warm years. The strength of association between warm years and disappearing frogs was independent of elevation, latitude, or range size. Such an association of extinctions with warmer years leads to a paradox: the believed cause of death of the Atelopine frogs is chytridiomycosis due to outbreaks of the fungus Batrachochytrium dendrobatidis, but Batrachochytrium becomes more pathogenic at lower rather than higher temperatures. Pounds et al. posited a resolution to this paradox by coupling higher temperatures to increased evaporation rates resulting in more water vapor in the atmosphere. Higher atmospheric water vapor drives increased cloud cover over Monteverde and other sites where scientists observed disappearances. In this case, more clouds led to cooler days, because they reflected more solar radiation, but also to warmer nights as they decreased heat loss to the atmosphere. The net result was that the range of daily maximum and minimum temperatures was not only less but less in a way that favored chytrid fungi (which grow best at 17–25 °C). Preventing it from getting too hot by day or too cold at night, the increased clouds during warmer years kept the temperature “just right” for Batrachochytrium to infect frogs. Conservation biologists recognize the significant impact that regional shifts in climate may have on populations of conservation concern (Hannah et al. 2005). However, much of the remote sensing work on the atmosphere and climate addresses global-scale phenomena, such as general circulation models (GCMs) of the atmosphere. Moving from these global scales to scales more appropriate to conservation work continues to be a significant challenge.

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