Water vapor and lapse rate feedbacks in the climate system

Abstract There are discrepancies between global climate models regarding the evolution of the tropical tropopause layer (TTL) and also whether changes in ozone impact the surface under climate change. We use a 1D clear-sky radiative–convective equilibrium model to determine how a variety of factors can affect the TTL and how they influence surface climate. We develop a new method of convective adjustment, which relaxes the temperature profile toward the moist adiabat and allows for cooling above the level of neutral buoyancy. The TTL temperatures in our model are sensitive to CO2 concentration, ozone profile, the method of convective adjustment, and the upwelling velocity, which is used to calculate a dynamical cooling rate in the stratosphere. Moreover, the temperature response of the TTL to changes in each of the above factors sometimes depends on the others. The surface temperature response to changes in ozone and upwelling at and above the TTL is also strongly amplified by both stratospheric and tropospheric water vapor changes. With all these influencing factors, it is not surprising that global models disagree with regard to TTL structure and evolution and the influence of ozone changes on surface temperatures. On the other hand, the effect of doubling CO2 on the surface, including just radiative, water vapor, and lapse-rate feedbacks, is relatively robust to changes in convection, upwelling, or the applied ozone profile.

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The Atmospheric Energy Constraint on Global-Mean Precipitation Change

Journal of Climate ◽

10.1175/jcli-d-13-00163.1 ◽

2014 ◽

Vol 27 (2) ◽

pp. 757-768 ◽

Cited By ~ 109

Author(s):

Angeline G. Pendergrass ◽

Dennis L. Hartmann

Keyword(s):

Water Vapor ◽

Temperature Increase ◽

Longwave Radiation ◽

Surface Fluxes ◽

Lapse Rate ◽

Specific Humidity ◽

Radiative Cooling ◽

Rate Of Increase ◽

Precipitation Increase ◽

Global Mean

Abstract Models from phase 5 of the Coupled Model Intercomparison Project (CMIP5) robustly predict that the rate of increase in global-mean precipitation with global-mean surface temperature increase is much less than the rate of increase of water vapor. The goal of this paper is to explain in detail the mechanisms by which precipitation increase is constrained by radiative cooling. Changes in clear-sky atmospheric radiative cooling resulting from changes in temperature and humidity in global warming simulations are in good agreement with the multimodel, global-mean precipitation increase projected by GCMs (~1.1 W m−2 K−1). In an atmosphere with fixed specific humidity, radiative cooling from the top of the atmosphere (TOA) increases in response to a uniform temperature increase of the surface and atmosphere, while atmospheric cooling by exchange with the surface decreases because the upward emission of longwave radiation from the surface increases more than the downward longwave radiation from the atmosphere. When a fixed relative humidity (RH) assumption is made, however, uniform warming causes a much smaller increase of cooling at the TOA, and the surface contribution reverses to an increase in net cooling rate due to increased downward emission from water vapor. Sensitivity of precipitation changes to lapse rate changes is modest when RH is fixed. Carbon dioxide reduces TOA emission with only weak effects on surface fluxes, and thus suppresses precipitation. The net atmospheric cooling response and thereby the precipitation response to CO2-induced warming at fixed RH are mostly contributed by changes in surface fluxes. The role of clouds is discussed. Intermodel spread in the rate of precipitation increase across the CMIP5 simulations is attributed to differences in the atmospheric cooling.

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Consistent Differences in Climate Feedbacks between Atmosphere–Ocean GCMs and Atmospheric GCMs with Slab-Ocean Models*

Journal of Climate ◽

10.1175/jcli-d-12-00519.1 ◽

2013 ◽

Vol 26 (12) ◽

pp. 4264-4281 ◽

Cited By ~ 8

Author(s):

Karen M. Shell

Keyword(s):

Water Vapor ◽

General Circulation ◽

Ocean Dynamics ◽

Lapse Rate ◽

Climate Feedbacks ◽

Temperature Changes ◽

Model Type ◽

Global Average ◽

Ocean Models ◽

Slab Ocean

Abstract Climate sensitivity is generally studied using two types of models. Atmosphere–ocean general circulation models (AOGCMs) include interactive ocean dynamics and detailed heat uptake. Atmospheric GCMs (AGCMs) with slab ocean models (SOMs) cannot fully simulate the ocean’s response to and influence on climate. However, AGCMs are computationally cheaper and thus are often used to quantify and understand climate feedbacks and sensitivity. Here, physical climate feedbacks are compared between AOGCMs and SOM-AGCMs from the Coupled Model Intercomparison Project phase 3 (CMIP3) using the radiative kernel technique. Both the global-average (positive) water vapor and (negative) lapse-rate feedbacks are consistently stronger in AOGCMs. Water vapor feedback differences result from an essentially constant relative humidity and peak in the tropics, where temperature changes are larger for AOGCMs. Differences in lapse-rate feedbacks extend to midlatitudes and correspond to a larger ratio of tropical- to global-average temperature changes. Global-average surface albedo feedbacks are similar between models types because of a near cancellation of Arctic and Antarctic differences. In AOGCMs, the northern high latitudes warm faster than the southern latitudes, resulting in interhemispheric differences in albedo, water vapor, and lapse-rate feedbacks lacking in the SOM-AGCMs. Meridional heat transport changes also depend on the model type, although there is a large intermodel spread. However, there are no consistent global or zonal differences in cloud feedbacks. Effects of the forcing scenario [Special Report on Emissions Scenarios A1B (SRESa1b) or the 1% CO2 increase per year to doubling (1%to2x) experiments] on feedbacks are model dependent and generally of lesser importance than the model type. Care should be taken when using SOM-AGCMs to understand AOGCM feedback behavior.

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Water vapor and temperature lapse rate feedbacks in the mid-latitude seasonal cycle

Geophysical Research Letters ◽

10.1029/96gl01669 ◽

1996 ◽

Vol 23 (14) ◽

pp. 1761-1764 ◽

Cited By ~ 5

Author(s):

Haijun Hu

Keyword(s):

Water Vapor ◽

Seasonal Cycle ◽

Lapse Rate ◽

Temperature Lapse Rate

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Preface [to special section on Water Vapor in the Climate System (WVCS)]

Journal of Geophysical Research Atmospheres ◽

10.1029/2000jd900345 ◽

2001 ◽

Vol 106 (D6) ◽

pp. 5197-5197

Author(s):

Rebecca Ross ◽

Dian Gaffen ◽

John Gille

Keyword(s):

Water Vapor ◽

Special Section ◽

Climate System

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Balloon-borne measurements of temperature, water vapor, ozone and aerosol backscatter at the southern slopes of the Himalayas during StratoClim 2016-2017

10.5194/acp-2018-222 ◽

2018 ◽

Author(s):

Simone Brunamonti ◽

Teresa Jorge ◽

Peter Oelsner ◽

Sreeharsha Hanumanthu ◽

Bhupendra B. Singh ◽

...

Keyword(s):

Water Vapor ◽

Lower Stratosphere ◽

Monsoon Season ◽

Deep Convection ◽

Lapse Rate ◽

Boreal Summer ◽

Aerosol Layer ◽

Vertical Distributions ◽

Aerosol Backscatter ◽

Temperature Water

Abstract. The Asian summer monsoon anticyclone (ASMA) is a major meteorological system of the upper troposphere-lower stratosphere (UTLS) during boreal summer. It is known to be enriched in tropospheric trace gases and aerosols, due to rapid lifting from the boundary layer by deep convection and subsequent horizontal confinement. Given its dynamical structure, the ASMA offers a very efficient pathway for the transport of pollutants to the global stratosphere. Detailed understanding of the ASMA structure and processes requires accurate in-situ measurements. Here we present balloon-borne measurements of temperature, water vapor, ozone and aerosol backscatter conducted within the StratoClim project from two stations at the southern slopes of the Himalayas. In total we performed 63 balloon soundings during two main monsoon-season campaigns, in August 2016 in Nainital, India (NT16AUG) and July–August 2017 in Dhulikhel, Nepal (DK17), and one brief post-monsoon campaign in Nainital in November 2016 (NT16NOV). These measurements provide unprecedented insights into the ASMA thermal structure and its relations to the vertical distributions of water vapor, ozone and aerosols. To study the structure of the UTLS during the monsoon season, we adopt the thermal definition of tropical tropopause layer (TTL), and define the region of altitudes between the lapse rate minimum (LRM) and the cold-point tropopause (CPT) as the Asian Tropopause Transition Layer (ATTL). Further, based on air mass trajectories, we define the Top of Confinement (TOC) level of ASMA, which divides the lower stratosphere (LS) into a Confined LS (CLS), below the TOC and above the CPT, and a Free LS (FLS), above the TOC. Using these thermodynamically-significant boundaries, our analysis reveals that the composition of the UTLS is affected by deep convection up to altitudes 1.5–2 km above the CPT due to the horizontal confinement effect of ASMA. This is shown by enhanced water vapor mixing ratios in the Confined LS compared to background stratospheric values in the Free LS, observed in both NT16AUG (+0.5 ppmv) and DK17 (+0.75 ppmv), and by enhanced aerosol backscatter of the Asian tropopause aerosol layer (ATAL) extending into the Confined LS, as observed in NT16AUG. The CPT was 600 m higher in altitude and 5 K colder in DK17 compared to NT16AUG and strong ozone depletion was found in the ATTL and CLS in DK17, suggesting stronger convective activity during DK17 compared to NT16AUG. An isolated water vapor maximum in the Confined LS, about 1 km above the CPT, was also found in DK17, which we argue is due to overshooting convection hydrating the CLS. These evidence show that the vertical distributions and variability of water vapor, ozone and aerosols in the Asian UTLS are controlled by the top height of the anticyclonic confinement in ASMA, rather than by CPT height as in the conventional understanding of TTL, and suggest that the ASMA contributes to moistening the global stratosphere and to increase its aerosol burden.

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Temperature and Moisture Gradients under Low Stratus Clouds*

Bulletin of the American Meteorological Society ◽

10.1175/1520-0477-33.10.403 ◽

1952 ◽

Vol 33 (10) ◽

pp. 403-408 ◽

Cited By ~ 1

Author(s):

Peter E. Kraght

Keyword(s):

Steady State ◽

Water Vapor ◽

Equilibrium State ◽

Dew Point ◽

Lapse Rate ◽

Stratus Clouds ◽

A Value ◽

Statistical Sample

The lapse rate of dew point is developed from thermodynamic relations. It is shown to have varied values depending on the flux of water vapor but to have a value of nearly 1.0F° per 1,000 feet for steady state. The lapse rate of temperature is developed after a method suggested by Priestley and Swinbank. Approximately 10,000 cases of ceiling heights, temperatures and dew points observed simultaneously are used as a statistical sample to represent an equilibrium state for a layer 1,000 feet or less thick. The results suggest the ratio of the equilibrium lapse rate to the dry adiabatic lapse rate is nearly 0.80.

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

Journal of Climate ◽

10.1175/jcli-d-11-00384.1 ◽

2012 ◽

Vol 25 (11) ◽

pp. 3755-3770 ◽

Cited By ~ 139

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.

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A Gaussian process emulator for simulating ice sheet-climate interactions on a multi-million year timescale

10.5194/egusphere-egu2020-11471 ◽

2020 ◽

Author(s):

Jonas Van Breedam ◽

Philippe Huybrechts ◽

Michel Crucifix

Keyword(s):

Gaussian Process ◽

Climate Model ◽

Ice Sheet ◽

Climate System ◽

Lapse Rate ◽

Coupled Models ◽

Climate Interactions ◽

Coupling Time ◽

Fully Coupled ◽

Gaussian Process Emulator

Fully coupled state-of-the-art Atmosphere-Ocean General Circulation Models are the best tool to investigate feedbacks between the different components of the climate system on a decadal to centennial timescale. On millennial to multi-millennial timescales, Earth System Models of Intermediate Complexity are used to explore the feedbacks in the climate system between the ice sheets, the atmosphere and the ocean. Those fully coupled models, even at coarser resolution, are computationally very expensive and other techniques have been proposed to simulate ice sheet-climate interactions on a million-year timescale. The asynchronous coupling technique proposes to run a climate model for a few decades and subsequently an ice sheet model for a few millennia. Another, more efficient method is the use of a matrix look-up table where climate model runs are performed for end-members and intermediate climatic states are linearly interpolated.In this study, a novel coupling approach is presented where a Gaussian Process emulator applied to the climate model HadSM3 is coupled to the ice sheet model AISMPALEO. We have tested the sensitivity of the formulation of the ice sheet parameter and of the coupling time to the evolution of the ice sheet over time. Additionally, we used different lapse rate adjustments between the relatively coarse climate model and the much finer ice sheet model topography. It is shown that the ice sheet evolution over a million year timescale is strongly sensitive to the choice of the coupling time and to the implementation of the lapse rate adjustment. With the new coupling procedure, we provide a more realistic and computationally efficient framework for ice sheet-climate interactions on a multi-million year timescale.&#160;

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A Robust Constraint on the Temperature and Height of the Extratropical Tropopause

Journal of Climate ◽

10.1175/jcli-d-18-0339.1 ◽

2018 ◽

Vol 32 (2) ◽

pp. 273-287 ◽

Cited By ~ 2

Author(s):

David W. J. Thompson ◽

Paulo Ceppi ◽

Ying Li

Keyword(s):

Global Warming ◽

Water Vapor ◽

General Circulation ◽

Circulation Model ◽

Lapse Rate ◽

Radiative Cooling ◽

Vapor Pressures ◽

Strong Constraint ◽

Surface Temperatures ◽

Extratropical Tropopause

Abstract In a recent study, the authors hypothesize that the Clausius–Clapeyron relation provides a strong constraint on the temperature of the extratropical tropopause and hence the depth of mixing by extratropical eddies. The hypothesis is a generalization of the fixed-anvil temperature hypothesis to the global atmospheric circulation. It posits that the depth of robust mixing by extratropical eddies is limited by radiative cooling by water vapor—and hence saturation vapor pressures—in areas of sinking motion. The hypothesis implies that 1) radiative cooling by water vapor constrains the vertical structure and amplitude of extratropical dynamics and 2) the extratropical tropopause should remain at roughly the same temperature and lift under global warming. Here the authors test the hypothesis in numerical simulations run on an aquaplanet general circulation model (GCM) and a coupled atmosphere–ocean GCM (AOGCM). The extratropical cloud-top height, wave driving, and lapse-rate tropopause all shift upward but remain at roughly the same temperature when the aquaplanet GCM is forced by uniform surface warming of +4 K and when the AOGCM is forced by RCP8.5 scenario emissions. “Locking” simulations run on the aquaplanet GCM further reveal that 1) holding the water vapor concentrations input into the radiation code fixed while increasing surface temperatures strongly constrains the rise in the extratropical tropopause, whereas 2) increasing the water vapor concentrations input into the radiation code while holding surface temperatures fixed leads to robust rises in the extratropical tropopause. Together, the results suggest that roughly invariant extratropical tropopause temperatures constitutes an additional “robust response” of the climate system to global warming.

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