Response of Tropical Precipitation to Global Warming

2011 ◽  
Vol 68 (1) ◽  
pp. 123-138 ◽  
Author(s):  
David M. Romps
Keyword(s):  
Global Warming ◽  
Water Vapor ◽  
High Resolution ◽  
General Circulation ◽  
Co2 Concentration ◽  
General Circulation Models ◽  
Tropical Convection ◽  
Precipitation Extremes ◽  
Tropical Precipitation ◽  
Effective Water

Abstract Using high-resolution cloud-resolving simulations with different CO2 concentrations, local precipitation fluxes are found to obey Clausius–Clapeyron (CC) scaling. Previous studies of the effect of CO2 concentration on precipitation extremes have used general circulation models, which are poor platforms for studying tropical convection because convection is parameterized. In idealized cloud-resolving simulations, it is possible to identify not only the changes in local precipitation fluxes, but also the factors responsible for those changes. There are many properties of convection that can change as the atmosphere warms, each of which could produce deviations from CC scaling. These properties include the effective water-vapor gradient, cloud pressure depth, and cloud velocity. A simple theory is developed that predicts the changes in these properties consistent with CC scaling. Convection in the cloud-resolving simulations is found to change as predicted by this theory, leading to an ∼20% increase in local precipitation fluxes when the CO2 concentration is doubled. Overall, an increase in CO2 leads to more vigorous convection, composed of clouds that are wider, taller, and faster.

scholarly journals Changes in Tropical Cyclone Activity due to Global Warming: Results from a High-Resolution Coupled General Circulation Model

2008 ◽  
Vol 21 (20) ◽  
pp. 5204-5228 ◽  
Author(s):  
S. Gualdi ◽  
E. Scoccimarro ◽  
A. Navarra
Keyword(s):  
Global Warming ◽  
High Resolution ◽  
Tropical Cyclone ◽  
General Circulation Model ◽  
General Circulation ◽  
Large Scale ◽  
Vertical Wind Shear ◽  
Circulation Model ◽  
Co2 Concentration ◽  
Tropical Region

Abstract This study investigates the possible changes that greenhouse global warming might generate in the characteristics of tropical cyclones (TCs). The analysis has been performed using scenario climate simulations carried out with a fully coupled high-resolution global general circulation model. The capability of the model to reproduce a reasonably realistic TC climatology has been assessed by comparing the model results from a simulation of the twentieth century with observations. The model appears to be able to simulate tropical cyclone–like vortices with many features similar to the observed TCs. The simulated TC activity exhibits realistic geographical distribution, seasonal modulation, and interannual variability, suggesting that the model is able to reproduce the major basic mechanisms that link TC occurrence with large-scale circulation. The results from the climate scenarios reveal a substantial general reduction of TC frequency when the atmospheric CO2 concentration is doubled and quadrupled. The reduction appears particularly evident for the tropical western North Pacific (WNP) and North Atlantic (ATL). In the NWP the weaker TC activity seems to be associated with reduced convective instabilities. In the ATL region the weaker TC activity seems to be due to both the increased stability of the atmosphere and a stronger vertical wind shear. Despite the generally reduced TC activity, there is evidence of increased rainfall associated with the simulated cyclones. Finally, the action of the TCs remains well confined to the tropical region and the peak of TC number remains equatorward of 20° latitude in both hemispheres, notwithstanding the overall warming of the tropical upper ocean and the expansion poleward of warm SSTs.

scholarly journals Global distributions of CO<sub>2</sub> volume mixing ratio in the middle and upper atmosphere from MIPAS high resolution spectra

2016 ◽  
Author(s):  
Á. Aythami Jurado-Navarro ◽  
Manuel López-Puertas ◽  
Bernd Funke ◽  
Maya Garcia-Comas ◽  
Angela Gardini ◽  
...  
Keyword(s):  
High Resolution ◽  
General Circulation ◽  
Lower Thermosphere ◽  
Co2 Concentration ◽  
General Circulation Models ◽  
Upper Atmosphere ◽  
Rate Coefficients ◽  
Kinetic Temperature ◽  
Mixing Ratio ◽  
Atmospheric Parameters

Abstract. Global distributions of the CO2 vmr (volume mixing ratio) in the mesosphere and lower thermosphere (from 70 km up to 142 km) have been derived from high resolution mid-IR spectra. This is the first time that the CO2 vmr has been retrieved in the 120–140 km range. The CO2 vmrs have been retrieved using MIPAS daytime limb emission spectra from the 4.3 µm region in its upper atmosphere (UA) mode (data version v5r_CO2_622). The dataset spans from January 2005 until March 2012. The retrieval of CO2 has been performed jointly with the line of sight (LOS) by using a non-local thermodynamic equilibrium (non-LTE) retrieval scheme. The non-LTE model incorporates the accurate vibrational-vibrational and vibrational-translational collisional rates recently derived from the MIPAS spectra. It also takes advantage of simultaneous MIPAS measurements of other atmospheric parameters, as the kinetic temperature (up to ~100 km) from the CO2 15 µm region, the thermospheric temperature from the NO 5.3 µm emission, and the O3 measurements (up to ~100 km). The latter is very important for the calculations of the non-LTE populations because it strongly constrains the O(1D) concentration below ~100 km. The estimated precision of the retrieved CO2 vmr profiles varies with altitude ranging from ~1 % below 90 km, to 5% around 120 km and larger than 10 % above 130 km. There are some latitudinal and seasonal variations of the precision, which are mainly driven by the solar illumination conditions. The retrieved CO2 profiles have a vertical resolution of about 5–7 km below 120 km and between 10 and 20 km at 120–142 km. We have shown that the inclusion of the LOS as joint fit parameter improves the retrieval of CO2, allowing a clear discrimination between the information of CO2 concentration and the LOS and also leading to significantly smaller systematic errors. The retrieved CO2 has a much better accuracy than previous limb emission measurements, because of the highly accurate rate coefficients recently derived from MIPAS, and the simultaneous MIPAS measurements of other key atmospheric parameters needed for the non-LTE modeling like the kinetic temperature and the O3 concentration. The major systematic error source is the uncertainty of the pressure/temperature profiles, inducing errors of up to 15 % above 100 km, and of ~5% around 80 km at mid-latitude conditions. The errors due to uncertainties in the O(1D) and O(3P) profiles are within 3–4 % in the 100–120 km region, and those due to uncertainties in the gain calibration and in the near-IR solar flux are within ~2 % at all altitudes. The retrieved CO2 shows the major features expected and predicted by general circulation models. In particular, its abrupt decline above 80–90 km and the seasonal change of the latitudinal distribution, with higher CO2 abundances in polar summer from 70 km up to ~95 km and lower CO2 vmr in the polar winter. Above ~95 km, CO2 is more abundant in the polar winter than at mid-latitudes and polar summer regions, caused by the reversal of the mean circulation in that altitude region. Also, the solstice seasonal distribution, with a significant pole-to-pole CO2 gradient, lasts about 2.5 months in each hemisphere, while the seasonal transition occurs quickly.

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 Boundary conditions for the Middle Miocene Climate Transition (MMCT v1.0)

2017 ◽  
Author(s):  
Amanda Frigola ◽  
Matthias Prange ◽  
Michael Schulz
Keyword(s):  
Boundary Conditions ◽  
General Circulation ◽  
Middle Miocene ◽  
Climate Models ◽  
Global Climate ◽  
Co2 Concentration ◽  
General Circulation Models ◽  
Global Climate Models ◽  
Ice Volume ◽  
Climate Transition

Abstract. The Middle Miocene Climate Transition was characterized by major Antarctic ice-sheet expansion and global cooling during the interval ~ 15–13 Ma. Here we present two sets of boundary conditions for global general circulation models characterizing the periods before (Middle Miocene Climatic Optimum; MMCO) and after (Middle Miocene Glaciation; MMG) the transition. These boundary conditions include Middle Miocene global topography, bathymetry and vegetation. Additionally, Antarctic ice volume and geometry, sea-level and atmospheric CO2 concentration estimates for the MMCO and the MMG are reviewed. The boundary-condition files are available for use as input in a wide variety of global climate models and constitute a valuable tool for modeling studies with a focus on the Middle Miocene.

scholarly journals PLASIM-ENTSem: a spatio-temporal emulator of future climate change for impacts assessment

2013 ◽  
Vol 6 (2) ◽  
pp. 3349-3380 ◽  
Author(s):  
P. B. Holden ◽  
N. R. Edwards ◽  
P. H. Garthwaite ◽  
K. Fraedrich ◽  
F. Lunkeit ◽  
...  
Keyword(s):  
Radiative Forcing ◽  
General Circulation ◽  
Coupled Model ◽  
Co2 Concentration ◽  
General Circulation Models ◽  
Climate Impacts ◽  
Future Climate ◽  
Future Climate Change ◽  
Climate Data ◽  
Spatio Temporal

Abstract. Many applications in the evaluation of climate impacts and environmental policy require detailed spatio-temporal projections of future climate. To capture feedbacks from impacted natural or socio-economic systems requires interactive two-way coupling but this is generally computationally infeasible with even moderately complex general circulation models (GCMs). Dimension reduction using emulation is one solution to this problem, demonstrated here with the GCM PLASIM-ENTS. Our approach generates temporally evolving spatial patterns of climate variables, considering multiple modes of variability in order to capture non-linear feedbacks. The emulator provides a 188-member ensemble of decadally and spatially resolved (~ 5° resolution) seasonal climate data in response to an arbitrary future CO2 concentration and radiative forcing scenario. We present the PLASIM-ENTS coupled model, the construction of its emulator from an ensemble of transient future simulations, an application of the emulator methodology to produce heating and cooling degree-day projections, and the validation of the results against empirical data and higher-complexity models. We also demonstrate the application to estimates of sea-level rise and associated uncertainty.

Atmospheric response to Gulf Stream SST front shifting: impact of horizontal resolution in an ensemble of global climate models

2021 ◽  
Author(s):  
Luca Famooss Paolini ◽  
Alessio Bellucci ◽  
Paolo Ruggieri ◽  
Panos Athanasiadis ◽  
Silvio Gualdi
Keyword(s):  
High Resolution ◽  
Gulf Stream ◽  
General Circulation ◽  
Diabatic Heating ◽  
Storm Track ◽  
General Circulation Models ◽  
Horizontal Resolution ◽  
Atmospheric Response ◽  
Sst Front ◽  
Pressure Anomaly

&lt;p&gt;Western boundary currents transport a large amount of heat from the Tropics toward higher latitudes; furthermore they are characterized by a strong sea surface temperature (SST) gradient, which anchors zones of intense upward motion extending up to the upper-troposphere and shapes zones of intense baroclinic eddy activity (storm tracks). For such reasons they have been shown to be fundamental in influencing the climate of the Northern Hemisphere and its variability, and a potentially relevant source of atmospheric predictability.&amp;#160;&lt;/p&gt;&lt;p&gt;&amp;#160;&lt;/p&gt;&lt;p&gt;General circulation models show deficiencies in simulating the observed atmospheric response to SST front variability. The atmospheric horizontal resolution has been recently proposed as a key element in understanding such differences. However, the number of studies on this subject is still limited. Furthermore, a multi-model analysis to systematically investigate differences between low-resolution and high-resolution atmospheric response to oceanic forcing is still lacking.&amp;#160;&lt;/p&gt;&lt;p&gt;&amp;#160;&lt;/p&gt;&lt;p&gt;The present work has the objective to fill this gap, analysing the atmospheric response to Gulf Stream SST front shifting using data from recent High Resolution Model Intercomparison Project (HighResMIP). This project was designed with the specific objective of investigating the impact of increased model horizontal resolution on the representation of the observed climate. Ensembles of historical simulations performed with three atmospheric general circulation models (AGCMs) have been analysed, each conducted with a low-resolution (LR, about 1&amp;#176;) and a high-resolution (HR, about 0.25&amp;#176;) configuration. AGCMs have been forced with observed SSTs (HadISST2 dataset), available at daily frequency on a 0.25&amp;#176; grid, during 1950&amp;#8211;2014.&amp;#160;&lt;/p&gt;&lt;p&gt;&lt;br&gt;Results show atmospheric responses to the SST-induced diabatic heating anomalies that are strongly resolution dependent. In LR simulations a low-pressure anomaly is present downstream of the SST anomaly, while the diabatic heating anomaly is mainly balanced by meridional advection of air coming from higher latitudes, as expected for an extra-tropical shallow heat source. In contrast, HR simulations generate a high-pressure anomaly downstream of the SST anomaly, thus driving positive temperature advection from lower latitudes (not balancing diabatic heating). Along the vertical direction, both in LR and HR simulation, the diabatic heating in the interior of the atmosphere is balanced by upward motion south of GS SST front and downward motion north and further south of the Gulf Stream. Finally, LR simulations show a reduction in storm-track activity over the North Atlantic, whereas HR simulations show a meridional displacement of the storm-track considerably larger (yet in the same direction) than that of the SST front. HR simulations reproduce the atmospheric response obtained from observations, albeit weaker. This is a hint for the existence of a positive feedback between ocean and atmosphere, as proposed in previous studies. These findings are qualitatively consistent with previous results in literature and, leveraging on recent coordinated modelling efforts, shed light on the effective role of atmospheric horizontal resolution in modelling the atmospheric response to extra-tropical oceanic forcing.&lt;/p&gt;

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