Diagnosis of Radiosonde Vertical Temperature Trend Profiles: Comparing the Influence of Data Homogenization versus Model Forcings

2007 ◽  
Vol 20 (21) ◽  
pp. 5356-5364 ◽  
Author(s):  
John R. Lanzante
Keyword(s):  
Climate Model ◽  
Temperature Response ◽  
Volcanic Eruptions ◽  
Human Influence ◽  
Vertical Temperature ◽  
Upper Troposphere ◽  
Temperature Trends ◽  
Versus Model ◽  
Time Period ◽  
Climate Forcings

Abstract Measurements from radiosonde temperatures have been used in studies that seek to identify the human influence on climate. However, such measurements are known to be contaminated by artificial inhomogeneities introduced by changes in instruments and recording practices that have occurred over time. Some simple diagnostics are used to compare vertical profiles of temperature trends from the observed data with simulations from a GCM driven by several different sets of forcings. Unlike most earlier studies of this type, both raw (i.e., fully contaminated) as well as adjusted observations (i.e., treated to remove some of the contamination) are utilized. The comparisons demonstrate that the effect of observational data adjustment can be as important as the inclusion of some major climate forcings in the model simulations. The effects of major volcanic eruptions critically influence temperature trends, even over a time period nearly four decades in length. In addition, it is seen that the adjusted data show consistently better agreement than the unadjusted data, with simulations from a climate model for 1959–97. Particularly noteworthy is the fact that the adjustments supply missing warming in the tropical upper troposphere that has been attributed to model error in a number of earlier studies. Finally, an evaluation of the fidelity of the model’s temperature response to major volcanic eruptions is conducted. Although the major conclusions of this study are unaffected by shortcomings of the simulations, they highlight the fact that even using a fairly long period of record (∼40 yr), any such shortcomings can have an important impact on trends and trend comparisons.

The vertical profile of tropical temperature trends: Persistent model biases in the context of forced and internal variability

2020 ◽  
Author(s):  
Dann Mitchell ◽  
Eunice Lo ◽  
William Seviour ◽  
Lorenzo Polvani
Keyword(s):  
Vertical Profile ◽  
Climate Models ◽  
Internal Variability ◽  
Montreal Protocol ◽  
Upper Troposphere ◽  
Temperature Trends ◽  
The Rich ◽  
Climate Forcings ◽  
Stratospheric Cooling ◽  
Middle Stratosphere

<p>Tropospheric and stratospheric tropical temperature trends in recent decades have been notoriously hard to simulate using climate models, notably in the upper troposphere.  Aside from the warming signal itself, this has broader implications, e.g. atmospheric circulation trends depend on latitudinal temperature gradients. In this study, tropical temperature trends in the CMIP6 models are examined, from 1979 to 2014, and contrasted with trends from the RICH/RAOBCORE radiosondes, and the ERA5/5.1 reanalysis.  Confirming previous studies, we find considerable warming biases in the CMIP6 modeled trends, and show that these biases are linked to biases in surface temperature (the models warm too much).  We also uncover previously undocumented biases in the lower-middle stratosphere: the CMIP6 models appear unable to capture the time evolution of stratospheric cooling, which is non-monotonic owing to the Montreal Protocol. This troposphere-warming, stratospheric-cooling fingerprint of climate change is therefore not well captured in CMIP6 models. Finally, we quantify the relative roles of individual climate forcings in tropspheric and stratospheric temperatures, including that of internal variability.</p>

scholarly journals A timescale analysis of the NH temperature response to volcanic and solar forcing in the past millenium

2005 ◽  
Vol 1 (2) ◽  
pp. 137-153 ◽  
Author(s):  
S. L. Weber
Keyword(s):  
Climate Model ◽  
Temperature Response ◽  
Volcanic Eruptions ◽  
Time Interval ◽  
Solar Forcing ◽  
Model Driven ◽  
Reconstructed Temperature ◽  
Volcanic Forcing ◽  
Temperature Records ◽  
Recent Claim

Abstract. The Northern Hemisphere temperature response to volcanic and solar forcing is studied using first a set of simulations with an intermediate-complexity climate model, driven by reconstructed forcings. Results are than compared with those obtained from the seven high-resolution reconstructed temperature records for the last millenium that are at present available. Focus of the analysis is on the timescale dependence of the response. Results between the model and the proxy-based reconstructions are remarkably consistent. The response to solar forcing is found to equilibrate at interdecadal timescales, reaching an equilibrium value for the regression of 0.2-0.3°C per W/m2. The time interval between volcanic eruptions is typically shorter than the dissipation timescale of the climate system, so that the response to volcanic forcing never equilibrates. As a result, the regression on the volcanic forcing is always lower than the equilibrium value and goes to zero for the longest temporal scales. The trends over the pre-anthropogenic period are found to be relatively large in all reconstructed temperature records compared to their interdecadal-centennial variability. This is at variance with a recent claim that reconstructed temperature records underestimate climatic variations at multi-centennial scales.

scholarly journals Global temperature response to the major volcanic eruptions in multiple reanalysis datasets

2015 ◽  
Vol 15 (9) ◽  
pp. 13315-13346 ◽  
Author(s):  
M. Fujiwara ◽  
T. Hibino ◽  
S. K. Mehta ◽  
L. Gray ◽  
D. Mitchell ◽  
...  
Keyword(s):  
Lower Stratosphere ◽  
Temperature Response ◽  
Volcanic Eruptions ◽  
Global Temperature ◽  
Quasi Biennial Oscillation ◽  
Mount Pinatubo ◽  
Upper Troposphere ◽  
El Chichón ◽  
Pinatubo Eruption ◽  
El Chichon

Abstract. Global temperature response to the eruptions of Mount Agung in 1963, El Chichón in 1982 and Mount Pinatubo in 1991 is investigated using nine reanalysis datasets (JRA-55, MERRA, ERA-Interim, NCEP-CFSR, JRA-25, ERA-40, NCEP-1, NCEP-2, and 20CR). Multiple linear regression is applied to the zonal and monthly mean time series of temperature for two periods, 1979–2009 (for eight reanalysis datasets) and 1958–2001 (for four reanalysis datasets), by considering explanatory factors of seasonal harmonics, linear trends, Quasi-Biennial Oscillation, solar cycle, and El Niño Southern Oscillation. The residuals are used to define the volcanic signals for the three eruptions separately. In response to the Mount Pinatubo eruption, most reanalysis datasets show strong warming signals (up to 2–3 K for one-year average) in the tropical lower stratosphere and weak cooling signals (down to −1 K) in the subtropical upper troposphere. For the El Chichón eruption, warming signals in the tropical lower stratosphere are somewhat smaller than those for the Mount Pinatubo eruption. The response to the Mount Agung eruption is asymmetric about the equator with strong warming in the Southern Hemisphere midlatitude upper troposphere to lower stratosphere. The response to three other smaller-scale eruptions in the 1960s and 1970s is also investigated. Comparison of the results from several different reanalysis datasets confirms the atmospheric temperature response to these major eruptions qualitatively, but also shows quantitative differences even among the most recent reanalysis datasets.

scholarly journals Understanding the Atmospheric Temperature Adjustment to CO2 Perturbation at the Process Level

2020 ◽  
Vol 33 (3) ◽  
pp. 787-803 ◽  
Author(s):  
Yuwei Wang ◽  
Yi Huang
Keyword(s):  
Large Scale ◽  
Climate Model ◽  
Temperature Response ◽  
Lower Troposphere ◽  
Atmospheric Temperature ◽  
Climate Simulation ◽  
Large Scale Circulation ◽  
Upper Troposphere ◽  
Rapid Adjustment ◽  
Process Level

AbstractClimate model comparisons show that there is considerable uncertainty in the atmospheric temperature response to CO2 perturbation. The uncertainty results from both the rapid adjustment that occurs before SST changes and the slow feedbacks that occur after SST changes. The analysis in this paper focuses on the rapid adjustment. We use a novel method to decompose the temperature change in AMIP-type climate simulation in order to understand the adjustment at the process level. We isolate the effects of different processes, including radiation, convection, and large-scale circulation in the temperature adjustment, through a set of numerical experiments using a hierarchy of climate models. We find that radiative adjustment triggers and largely controls the zonal mean atmospheric temperature response pattern. This pattern is characterized by stratospheric cooling, lower-tropospheric warming, and a warming center near the tropical tropopause. In contrast to conventional views, the warming center near the tropopause is found to be critically dependent on the shortwave absorption of CO2. The dynamical processes largely counteract the effect of the radiative process that increases the vertical temperature gradient in the free troposphere. The effect of local convection is to move atmospheric energy vertically, which cools the lower troposphere and warms the upper troposphere. The adjustment due to large-scale circulation further redistributes energy along the isentropic surfaces across the latitudes, which cools the low-latitude lower troposphere and warms the midlatitude upper troposphere and stratosphere. Our results highlight the importance of the radiative adjustment in the overall adjustment and provide a potential method to understand the spread in the models.

scholarly journals The role of tropical volcanic eruptions in exacerbating Indian droughts

2021 ◽  
Vol 11 (1) ◽  
Author(s):  
Suvarna Fadnavis ◽  
Rolf Müller ◽  
Tanusri Chakraborty ◽  
T. P. Sabin ◽  
Anton Laakso ◽  
...  
Keyword(s):  
El Niño ◽  
Climate Model ◽  
El Nino ◽  
Volcanic Eruptions ◽  
Summer Monsoon Rainfall ◽  
Indian Region ◽  
Volcanic Plume ◽  
Kelvin Wave ◽  
Central Pacific ◽  
Climate Model Simulations

AbstractThe Indian summer monsoon rainfall (ISMR) is vital for the livelihood of millions of people in the Indian region; droughts caused by monsoon failures often resulted in famines. Large volcanic eruptions have been linked with reductions in ISMR, but the responsible mechanisms remain unclear. Here, using 145-year (1871–2016) records of volcanic eruptions and ISMR, we show that ISMR deficits prevail for two years after moderate and large (VEI > 3) tropical volcanic eruptions; this is not the case for extra-tropical eruptions. Moreover, tropical volcanic eruptions strengthen El Niño and weaken La Niña conditions, further enhancing Indian droughts. Using climate-model simulations of the 2011 Nabro volcanic eruption, we show that eruption induced an El Niño like warming in the central Pacific for two consecutive years due to Kelvin wave dissipation triggered by the eruption. This El Niño like warming in the central Pacific led to a precipitation reduction in the Indian region. In addition, solar dimming caused by the volcanic plume in 2011 reduced Indian rainfall.

scholarly journals Constructing Damage Indices Based on Publicly Available Spatial Data: Exemplified by Earthquakes and Volcanic Eruptions in Indonesia

2021 ◽  
Author(s):  
Emmanuel Skoufias ◽  
Eric Strobl ◽  
Thomas Tveit
Keyword(s):  
Spatial Data ◽  
Volcanic Ash ◽  
Satellite Images ◽  
Fragility Curves ◽  
Volcanic Eruptions ◽  
Damage Indices ◽  
Damage Indicator ◽  
Time Period ◽  
Peak Ground Motion

AbstractThis article demonstrates the construction of earthquake and volcano damage indices using publicly available remote sensing sources and data on the physical characteristics of events. For earthquakes we use peak ground motion maps in conjunction with building type fragility curves to construct a local damage indicator. For volcanoes we employ volcanic ash data as a proxy for local damages. Both indices are then spatially aggregated by taking local economic exposure into account by assessing nightlight intensity derived from satellite images. We demonstrate the use of these indices with a case study of Indonesia, a country frequently exposed to earthquakes and volcanic eruptions. The results show that the indices capture the areas with the highest damage, and we provide overviews of the modeled aggregated damage for all provinces and districts in Indonesia for the time period 2004 to 2014. The indices were constructed using a combination of software programs—ArcGIS/Python, Matlab, and Stata. We also outline what potential freeware alternatives exist. Finally, for each index we highlight the assumptions and limitations that a potential practitioner needs to be aware of.

scholarly journals The HAMMONIA Chemistry Climate Model: Sensitivity of the Mesopause Region to the 11-Year Solar Cycle and CO2 Doubling

2006 ◽  
Vol 19 (16) ◽  
pp. 3903-3931 ◽  
Author(s):  
H. Schmidt ◽  
G. P. Brasseur ◽  
M. Charron ◽  
E. Manzini ◽  
M. A. Giorgetta ◽  
...  
Keyword(s):  
Carbon Dioxide ◽  
Solar Cycle ◽  
General Circulation ◽  
Climate Model ◽  
Temperature Response ◽  
Circulation Model ◽  
Max Planck ◽  
Dynamical Processes ◽  
Mesopause Region ◽  
Height Range

Abstract This paper introduces the three-dimensional Hamburg Model of the Neutral and Ionized Atmosphere (HAMMONIA), which treats atmospheric dynamics, radiation, and chemistry interactively for the height range from the earth’s surface to the thermosphere (approximately 250 km). It is based on the latest version of the ECHAM atmospheric general circulation model of the Max Planck Institute for Meteorology in Hamburg, Germany, which is extended to include important radiative and dynamical processes of the upper atmosphere and is coupled to a chemistry module containing 48 compounds. The model is applied to study the effects of natural and anthropogenic climate forcing on the atmosphere, represented, on the one hand, by the 11-yr solar cycle and, on the other hand, by a doubling of the present-day concentration of carbon dioxide. The numerical experiments are analyzed with the focus on the effects on temperature and chemical composition in the mesopause region. Results include a temperature response to the solar cycle by 2 to 10 K in the mesopause region with the largest values occurring slightly above the summer mesopause. Ozone in the secondary maximum increases by up to 20% for solar maximum conditions. Changes in winds are in general small. In the case of a doubling of carbon dioxide the simulation indicates a cooling of the atmosphere everywhere above the tropopause but by the smallest values around the mesopause. It is shown that the temperature response up to the mesopause is strongly influenced by changes in dynamics. During Northern Hemisphere summer, dynamical processes alone would lead to an almost global warming of up to 3 K in the uppermost mesosphere.

Why does the climate response to greenhouse warming and greenhouse cooling differ? 

2021 ◽  
Author(s):  
Jennifer Kay ◽  
Jason Chalmers
Keyword(s):  
Carbon Dioxide ◽  
Radiative Forcing ◽  
Climate Model ◽  
Temperature Response ◽  
Greenhouse Warming ◽  
Climate Response ◽  
Cloud Feedbacks ◽  
Surface Climate ◽  
Carbon Dioxide Concentrations ◽  
Radiative Feedbacks

<p>While the long-standing quest to constrain equilibrium climate sensitivity has resulted in intense scrutiny of the processes controlling idealized greenhouse warming, the processes controlling idealized greenhouse cooling have received less attention. Here, differences in the climate response to increased and decreased carbon dioxide concentrations are assessed in state-of-the-art fully coupled climate model experiments. One hundred and fifty years after an imposed instantaneous forcing change, surface global warming from a carbon dioxide doubling (abrupt-2xCO2, 2.43 K) is larger than the surface global cooling from a carbon dioxide halving (abrupt-0p5xCO2, 1.97 K). Both forcing and feedback differences explain these climate response differences. Multiple approaches show the radiative forcing for a carbon dioxide doubling is ~10% larger than for a carbon dioxide halving. In addition, radiative feedbacks are less negative in the doubling experiments than in the halving experiments. Specifically, less negative tropical shortwave cloud feedbacks and more positive subtropical cloud feedbacks lead to more greenhouse 2xCO2 warming than 0.5xCO2 greenhouse cooling. Motivated to directly isolate the influence of cloud feedbacks on these experiments, additional abrupt-2xCO2 and abrupt-0p5xCO2 experiments with disabled cloud-climate feedbacks were run. Comparison of these “cloud-locked” simulations with the original “cloud active” simulations shows cloud feedbacks help explain the nonlinear global surface temperature response to greenhouse warming and greenhouse cooling. Overall, these results demonstrate that both radiative forcing and radiative feedbacks are needed to explain differences in the surface climate response to increased and decreased carbon dioxide concentrations.</p>

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