Are Changes in Global Precipitation Constrained by the Tropospheric Energy Budget?

2009 ◽  
Vol 22 (3) ◽  
pp. 499-517 ◽  
Author(s):  
F. Hugo Lambert ◽  
Myles R. Allen
Keyword(s):  
Greenhouse Gas ◽  
Black Carbon ◽  
Energy Budget ◽  
General Circulation ◽  
Circulation Model ◽  
First Century ◽  
Aerosol Forcing ◽  
Twenty First Century ◽  
Precipitation Changes ◽  
Global Precipitation

Abstract A tropospheric energy budget argument is used to analyze twentieth-century precipitation changes. It is found that global and ocean-mean general circulation model (GCM) precipitation changes can be understood as being due to the competing direct and surface-temperature-dependent effects of external climate forcings. In agreement with previous work, precipitation is found to respond more strongly to anthropogenic and volcanic sulfate aerosol and solar forcing than to greenhouse gas and black carbon aerosol forcing per unit temperature. This is due to the significant direct effects of greenhouse gas and black carbon forcing. Given that the relative importance of different forcings may change in the twenty-first century, the ratio of global precipitation change to global temperature change may be quite different. Differences in GCM twentieth- and twenty-first-century values are tractable via the energy budget framework in some, but not all, models. Changes in land-mean precipitation, on the other hand, cannot be understood at all with the method used here, even if land–ocean heat transfer is considered. In conclusion, the tropospheric energy budget is a useful concept for understanding the precipitation response to different forcings but it does not fully explain precipitation changes even in the global mean.

The Atmospheric Response to Projected Terrestrial Snow Changes in the Late Twenty-First Century

2010 ◽  
Vol 23 (23) ◽  
pp. 6430-6437 ◽  
Author(s):  
Michael A. Alexander ◽  
Robert Tomas ◽  
Clara Deser ◽  
David M. Lawrence
Keyword(s):  
Twentieth Century ◽  
Sea Ice ◽  
Greenhouse Gas ◽  
General Circulation ◽  
Climate Model ◽  
Circulation Model ◽  
Arctic Sea Ice ◽  
First Century ◽  
Model Experiments ◽  
Twenty First Century

Abstract Two atmospheric general circulation model experiments are conducted with specified terrestrial snow conditions representative of 1980–99 and 2080–99. The snow states are obtained from twentieth-century and twenty-first-century coupled climate model integrations under increasing greenhouse gas concentrations. Sea surface temperatures, sea ice, and greenhouse gas concentrations are set to 1980–99 values in both atmospheric model experiments to isolate the effect of the snow changes. The reduction in snow cover in the twenty-first century relative to the twentieth century increases the solar radiation absorbed by the surface, and it enhances the upward longwave radiation and latent and sensible fluxes that warm the overlying atmosphere. The maximum twenty-first-century minus twentieth-century surface air temperature (SAT) differences are relatively small (<3°C) compared with those due to Arctic sea ice changes (∼10°C). However, they are continental in scale and are largest in fall and spring, when they make a significant contribution to the overall warming over Eurasia and North America in the twenty-first century. The circulation response to the snow changes, while of modest amplitude, involves multiple components, including a local low-level trough, remote Rossby wave trains, an annular pattern that is strongest in the stratosphere, and a hemispheric increase in geopotential height.

scholarly journals Predicted Twenty-First-Century Changes in Seasonal Extreme Precipitation Events in the Parallel Climate Model

2004 ◽  
Vol 17 (21) ◽  
pp. 4281-4290 ◽  
Author(s):  
Michael F. Wehner
Keyword(s):  
General Circulation ◽  
Climate Model ◽  
Extreme Values ◽  
Circulation Model ◽  
First Century ◽  
Significant Information ◽  
Extreme Precipitation Events ◽  
Value Changes ◽  
Precipitation Changes ◽  
Return Value

Abstract Twenty-year return values of annual and seasonal maxima of daily precipitation are calculated from a set of transiently forced coupled general circulation model simulations. The magnitude and pattern of return values are found to be highly dependent on the seasonal cycle. A similar dependence is found for projected future changes in return values. The correlation between the spatial pattern of return value changes and mean precipitation changes is found to be low. Hence, the changes in mean precipitation do not provide significant information about changes in precipitation extreme values.

scholarly journals Model Simulation and Projection of European Heat Waves in Present-Day and Future Climates

2014 ◽  
Vol 27 (10) ◽  
pp. 3713-3730 ◽  
Author(s):  
Ngar-Cheung Lau ◽  
Mary Jo Nath
Keyword(s):  
General Circulation ◽  
Western Europe ◽  
Heat Waves ◽  
Model Simulation ◽  
Wave Train ◽  
Mean Shift ◽  
Circulation Model ◽  
Climate Scenario ◽  
First Century ◽  
Twenty First Century

Abstract The synoptic behavior of present-day heat waves (HW) over Europe is studied using the GFDL high-resolution atmospheric model (HiRAM) with 50-km grid spacing. Three regions of enhanced and coherent temperature variability are identified over western Russia, eastern Europe, and western Europe. The simulated HW characteristics are compared with those derived from Climate Forecast System Reanalysis products. Composite charts for outstanding HW episodes resemble well-known recurrent circulation types. The HW region is overlain by a prominent upper-level anticyclone, which blocks the passage of synoptic-scale transients. The altered eddy vorticity transports in turn reinforce the anticyclone. The anticyclone is part of a planetary-scale wave train. The successive downstream development of this wave train is indicative of Rossby wave dispersion. Additional runs of HiRAM are conducted for the “time slices” of 2026–35 and 2086–95 in the climate scenario corresponding to representative concentration pathway 4.5 (RCP4.5). By the end of the twenty-first century, the average duration and frequency of HW in the three European sites are projected to increase by a factor of 1.4–2.0 and 2.2–4.5, respectively, from the present-day values. These changes can be reproduced by adding the mean shift between the present and future climatological temperatures to the daily fluctuations in the present-day simulation. The output from a continuous integration of a coupled general circulation model through the 1901–2100 period indicates a monotonic increase in severity, duration, and HW days during the twenty-first century.

scholarly journals Impact of Climate Drift on Twenty-First-Century Projection in a Coupled Atmospheric–Ocean General Circulation Model

2013 ◽  
Vol 70 (10) ◽  
pp. 3321-3327 ◽  
Author(s):  
Mao-Chang Liang ◽  
Li-Ching Lin ◽  
Ka-Kit Tung ◽  
Yuk L. Yung ◽  
Shan Sun
Keyword(s):  
General Circulation ◽  
Circulation Model ◽  
General Circulation Models ◽  
Forced Response ◽  
First Century ◽  
Intergovernmental Panel ◽  
Climate Drift ◽  
Ocean General Circulation ◽  
Twenty First Century ◽  
The Impact

Abstract Reducing climate drift in coupled atmosphere–ocean general circulation models (AOGCMs) usually requires 1000–2000 years of spinup, which has not been practical for every modeling group to do. For the purpose of evaluating the impact of climate drift, the authors have performed a multimillennium-long control run of the Goddard Institute for Space Studies model (GISS-EH) AOGCM and produced different twentieth-century historical simulations and subsequent twenty-first-century projections by branching off the control run at various stages of equilibration. The control run for this model is considered at quasi equilibration after a 1200-yr spinup from a cold start. The simulations that branched off different points after 1200 years are robust, in the sense that their ensemble means all produce the same future projection of warming, both in the global mean and in spatial detail. These robust projections differ from the one that was originally submitted to the Intergovernmental Panel on Climate Change (IPCC) Fourth Assessment Report (AR4), which branched off a not-yet-equilibrated control run. The authors test various common postprocessing schemes in removing climate drift caused by a not-yet-equilibrated ocean initial state and find them to be ineffective, judging by the fact that they differ from each other and from the robust results that branched off an equilibrated control. The authors' results suggest that robust twenty-first-century projections of the forced response can be achieved by running climate simulations from an equilibrated ocean state, because memory of the different initial ocean state is lost in about 40 years if the forced run is started from a quasi-equilibrated state.

Twenty-First-Century Multimodel Subtropical Precipitation Declines Are Mostly Midlatitude Shifts

2012 ◽  
Vol 25 (12) ◽  
pp. 4330-4347 ◽  
Author(s):  
Jack Scheff ◽  
Dargan Frierson
Keyword(s):  
General Circulation ◽  
Storm Track ◽  
First Century ◽  
Intergovernmental Panel ◽  
Common Framework ◽  
Tropical Areas ◽  
Twenty First Century ◽  
Thermodynamic Mechanism ◽  
Precipitation Changes ◽  
Poleward Expansion

Abstract Declines in subtropical precipitation are a robust response to modeled twenty-first-century global warming. Two suggested mechanisms are the “dry-get-drier” intensification of existing subtropical dry zones due to the thermodynamic increase in vapor transport and the poleward expansion of these same dry zones due to poleward shifts in the modeled general circulation. Here, subtropical drying in the Intergovernmental Panel on Climate Change (IPCC) Fourth Assessment Report multimodel archive is compared to each of these two mechanisms. Each model’s particular, biased, and seasonally and zonally varying mean state is considered relative to the location of that model’s predicted changes, and these relationships are recorded in a common framework that can be compared across models. The models have a strong tendency to reduce precipitation along the subtropical flanks of their existing midlatitude cyclonic precipitation belts. This broad result agrees with the poleward expansion mechanism and with a poleward storm-track shift in particular. In contrast, the models have no clear tendency to reduce precipitation in the central nor equatorward portions of their subtropical dry zones, implying that the thermodynamic mechanism is broadly unimportant for the precipitation reductions. This is unlike the response of precipitation minus evaporation, which robustly declines in large portions of these regions, especially over the oceans. The models also tend to increase precipitation in their wet deep tropical areas, but this is not as robust as the above reduction in the subtropical midlatitudes. High-latitude precipitation increases are the most robust precipitation changes of all in this framework.

Mechanisms of Forced Tropical Meridional Energy Flux Change

2015 ◽  
Vol 28 (5) ◽  
pp. 1725-1742 ◽  
Author(s):  
Spencer A. Hill ◽  
Yi Ming ◽  
Isaac M. Held
Keyword(s):  
Spatial Pattern ◽  
Greenhouse Gas ◽  
Energy Flux ◽  
General Circulation ◽  
Energy Transport ◽  
Circulation Model ◽  
Hadley Cell ◽  
Energy Fluxes ◽  
Hadley Cells ◽  
Sst Anomalies

Abstract Anthropogenically forced changes to the mean and spatial pattern of sea surface temperatures (SSTs) alter tropical atmospheric meridional energy transport throughout the seasonal cycle—in total, its partitioning between the Hadley cells and eddies and, for the Hadley cells, the relative roles of the mass flux and the gross moist stability (GMS). The authors investigate this behavior using an atmospheric general circulation model forced with SST anomalies caused by either historical greenhouse gas or aerosol forcing, dividing the SST anomalies into two components: the tropical mean SST anomaly applied uniformly and the full SST anomalies minus the tropical mean. For greenhouse gases, the polar-amplified SST spatial pattern partially negates enhanced eddy poleward energy transport driven by mean warming. Both SST components weaken winter Hadley cell circulation and alter GMS. The Northern Hemisphere–focused aerosol cooling induces northward energy flux anomalies in the deep tropics, which manifest partially via strengthened northern and weakened southern Hadley cell overturning. Aerosol-induced GMS changes also contribute to the northward energy fluxes. A simple thermodynamic scaling qualitatively captures these changes, although it performs less well for the greenhouse gas simulations. The scaling provides an explanation for the tight correlation demonstrated in previous studies between shifts in the intertropical convergence zone and cross-equatorial energy fluxes.

scholarly journals Probabilistic Projections of Climate Change over China under the SRES A1B Scenario Using 28 AOGCMs

2011 ◽  
Vol 24 (17) ◽  
pp. 4741-4756 ◽  
Author(s):  
Weilin Chen ◽  
Zhihong Jiang ◽  
Laurent Li
Keyword(s):  
Climate Change ◽  
Interannual Variability ◽  
General Circulation ◽  
Regional Scale ◽  
First Century ◽  
Climate System Model ◽  
Huai River ◽  
Twenty First Century ◽  
The Impact ◽  
A1b Scenario

Probabilistic projection of climate change consists of formulating the climate change information in a probabilistic manner at either global or regional scale. This can produce useful results for studies of the impact of climate change impact and change mitigation. In the present study, a simple yet effective approach is proposed with the purpose of producing probabilistic results of climate change over China for the middle and end of the twenty-first century under the Special Report on Emissions Scenarios A1B (SRES A1B) emission scenario. Data from 28 coupled atmosphere–ocean general circulation models (AOGCMs) are used. The methodology consists of ranking the 28 models, based on their ability to simulate climate over China in terms of two model evaluation metrics. Different weights were then given to the models according to their performances in present-day climate. Results of the evaluation for the current climate show that five models that have relatively higher resolutions—namely, the Istituto Nazionale di Geofisica e Vulcanologia ECHAM4 (INGV ECHAM4), the third climate configuration of the Met Office Unified Model (UKMO HadCM3), the CSIRO Mark version 3.5 (Mk3.5), the NCAR Community Climate System Model, version 3 (CCSM3), and the Model for Interdisciplinary Research on Climate 3.2, high-resolution version [MIROC3.2 (hires)]—perform better than others over China. Their corresponding weights (normalized to 1) are 0.289, 0.096, 0.058, 0.048, and 0.044, respectively. Under the A1B scenario, surface air temperature is projected to increase significantly for both the middle and end of the twenty-first century, with larger magnitude over the north and in winter. There are also significant increases in rainfall in the twenty-first century under the A1B scenario, especially for the period 2070–99. As far as the interannual variability is concerned, the most striking feature is that there are high probabilities for the future intensification of interannual variability of precipitation over most of China in both winter and summer. For instance, over the Yangtze–Huai River basin (28°–35°N, 105°–120°E), there is a 60% probability of increased interannual standard deviation of precipitation by 20% in summer, which is much higher than that of the mean precipitation. In general there are small differences between weighted and unweighted projections, but the uncertainties in the projected changes are reduced to some extent after weighting.

scholarly journals Fire emission heights in the climate system – Part 2: Impact on transport, black carbon concentrations and radiation

2015 ◽  
Vol 15 (13) ◽  
pp. 7173-7193 ◽  
Author(s):  
A. Veira ◽  
S. Kloster ◽  
N. A. J. Schutgens ◽  
J. W. Kaiser
Keyword(s):  
Black Carbon ◽  
Radiative Forcing ◽  
General Circulation ◽  
Circulation Model ◽  
Atmospheric Radiation ◽  
Orthogonal Polarization ◽  
Plume Height ◽  
Near Surface ◽  
The Impact ◽  
Emission Height

Abstract. Wildfires represent a major source for aerosols impacting atmospheric radiation, atmospheric chemistry and cloud micro-physical properties. Previous case studies indicated that the height of the aerosol–radiation interaction may crucially affect atmospheric radiation, but the sensitivity to emission heights has been examined with only a few models and is still uncertain. In this study we use the general circulation model ECHAM6 extended by the aerosol module HAM2 to investigate the impact of wildfire emission heights on atmospheric long-range transport, black carbon (BC) concentrations and atmospheric radiation. We simulate the wildfire aerosol release using either various versions of a semi-empirical plume height parametrization or prescribed standard emission heights in ECHAM6-HAM2. Extreme scenarios of near-surface or free-tropospheric-only injections provide lower and upper constraints on the emission height climate impact. We find relative changes in mean global atmospheric BC burden of up to 7.9±4.4 % caused by average changes in emission heights of 1.5–3.5 km. Regionally, changes in BC burden exceed 30–40 % in the major biomass burning regions. The model evaluation of aerosol optical thickness (AOT) against Moderate Resolution Imaging Spectroradiometer (MODIS), AErosol RObotic NETwork (AERONET) and Cloud–Aerosol Lidar with Orthogonal Polarization (CALIOP) observations indicates that the implementation of a plume height parametrization slightly reduces the ECHAM6-HAM2 biases regionally, but on the global scale these improvements in model performance are small. For prescribed emission release at the surface, wildfire emissions entail a total sky top-of-atmosphere (TOA) radiative forcing (RF) of −0.16±0.06 W m−2. The application of a plume height parametrization which agrees reasonably well with observations introduces a slightly stronger negative TOA RF of −0.20±0.07 W m−2. The standard ECHAM6-HAM2 model in which 25 % of the wildfire emissions are injected into the free troposphere (FT) and 75 % into the planetary boundary layer (PBL), leads to a TOA RF of −0.24±0.06 W m−2. Overall, we conclude that simple plume height parametrizations provide sufficient representations of emission heights for global climate modeling. Significant improvements in aerosol wildfire modeling likely depend on better emission inventories and aerosol process modeling rather than on improved emission height parametrizations.

Sign in / Sign up

Export Citation Format

Share Document