scholarly journals An analysis of interdecadal variations in the perturbational feedback parameter based on a MIROC6 piControl simulation

2021 ◽  
Author(s):  
Ko Tsuchida ◽  
Takashi Mochizuki ◽  
Ryuichi Kawamura ◽  
Tetsuya Kawano
Keyword(s):  
Surface Temperature ◽  
Southern Oscillation ◽  
Static Stability ◽  
Climate Feedback ◽  
Positive Anomaly ◽  
Feedback Parameter ◽  
Flux Change ◽  
Interannual Fluctuations ◽  
Downward Radiation ◽  
Background State

Abstract The climate feedback parameter is a useful indicator for estimating climate sensitivity relating to anthropogenic forcing. This study defines a new feedback parameter, the Perturbational Feedback Parameter (PFP), and the impacts of internally-generated climate variations are clarified using the MIROC piControl simulation. PFP values are found to vary significantly on interdecadal timescales. The equatorial sea surface temperature (SST) has a positive anomaly in the eastern Pacific and a negative anomaly in the western Pacific, and the thermocline tilts more gently than usual when the PFP is large. The statistical properties of the interannual fluctuations also simultaneously vary, and they correspond to the background state. For example, there is an increase in the El Niño Southern Oscillation (ENSO) amplitude relative to the global mean surface temperature rise, and the equatorial high SST more effectively contributes to the southward shift of the Intertropical Convergence Zone (ITCZ). In addition, a decadal fluctuation that dominates over the extratropical northern Pacific also plays an important role in PFP variations. These fluctuations on broad timescales cooperatively induce increases in lower clouds within the subtropics by strengthening the descending flow and static stability, and the consequential net downward radiation flux change through increases in reflection enhances the PFP. In summary, internal changes in both tropical and extratropical variability corresponding to the background state control the strength of the climate feedback on interdecadal timescales.

scholarly journals On the Accuracy of Deriving Climate Feedback Parameters from Correlations between Surface Temperature and Outgoing Radiation

2010 ◽  
Vol 23 (18) ◽  
pp. 4983-4988 ◽  
Author(s):  
D. M. Murphy ◽  
P. M. Forster
Keyword(s):  
Surface Temperature ◽  
Climate Model ◽  
Mixed Layer Depth ◽  
Box Model ◽  
Climate Feedback ◽  
Time Interval ◽  
Feedback Parameter ◽  
Outgoing Radiation ◽  
The Difference ◽  
Climate Studies

Abstract Changes in outgoing radiation are both a consequence and a cause of changes in the earth’s temperature. Spencer and Braswell recently showed that in a simple box model for the earth the regression of outgoing radiation against surface temperature gave a slope that differed from the model’s true feedback parameter. They went on to select input parameters for the box model based on observations, computed the difference for those conditions, and asserted that there is a significant bias for climate studies. This paper shows that Spencer and Braswell overestimated the difference. Differences between the regression slope and the true feedback parameter are significantly reduced when 1) a more realistic value for the ocean mixed layer depth is used, 2) a corrected standard deviation of outgoing radiation is used, and 3) the model temperature variability is computed over the same time interval as the observations. When all three changes are made, the difference between the slope and feedback parameter is less than one-tenth of that estimated by Spencer and Braswell. Absolute values of the difference for realistic cases are less than 0.05 W m−2 K−1, which is not significant for climate studies that employ regressions of outgoing radiation against temperature. Previously published results show that the difference is negligible in the Hadley Centre Slab Climate Model, version 3 (HadSM3).

scholarly journals The Dependence of Radiative Forcing and Feedback on Evolving Patterns of Surface Temperature Change in Climate Models

2015 ◽  
Vol 28 (4) ◽  
pp. 1630-1648 ◽  
Author(s):  
Timothy Andrews ◽  
Jonathan M. Gregory ◽  
Mark J. Webb
Keyword(s):  
Surface Temperature ◽  
Temperature Change ◽  
Radiative Forcing ◽  
General Circulation ◽  
Climate Feedback ◽  
Climate Feedbacks ◽  
Surface Temperature Change ◽  
Feedback Parameter ◽  
Surface Warming ◽  
Global Mean

Abstract Experiments with CO2 instantaneously quadrupled and then held constant are used to show that the relationship between the global-mean net heat input to the climate system and the global-mean surface air temperature change is nonlinear in phase 5 of the Coupled Model Intercomparison Project (CMIP5) atmosphere–ocean general circulation models (AOGCMs). The nonlinearity is shown to arise from a change in strength of climate feedbacks driven by an evolving pattern of surface warming. In 23 out of the 27 AOGCMs examined, the climate feedback parameter becomes significantly (95% confidence) less negative (i.e., the effective climate sensitivity increases) as time passes. Cloud feedback parameters show the largest changes. In the AOGCM mean, approximately 60% of the change in feedback parameter comes from the tropics (30°N–30°S). An important region involved is the tropical Pacific, where the surface warming intensifies in the east after a few decades. The dependence of climate feedbacks on an evolving pattern of surface warming is confirmed using the HadGEM2 and HadCM3 atmosphere GCMs (AGCMs). With monthly evolving sea surface temperatures and sea ice prescribed from its AOGCM counterpart, each AGCM reproduces the time-varying feedbacks, but when a fixed pattern of warming is prescribed the radiative response is linear with global temperature change or nearly so. It is also demonstrated that the regression and fixed-SST methods for evaluating effective radiative forcing are in principle different, because rapid SST adjustment when CO2 is changed can produce a pattern of surface temperature change with zero global mean but nonzero change in net radiation at the top of the atmosphere (~−0.5 W m−2 in HadCM3).

scholarly journals Estimation of the climate feedback parameter by using radiative fluxes from CERES EBAF

2013 ◽  
Vol 4 (1) ◽  
pp. 25-47
Author(s):  
P. Björnbom
Keyword(s):  
Radiative Forcing ◽  
Phase Plane ◽  
Southern Oscillation ◽  
Radiant Energy ◽  
Radiative Flux ◽  
Climate Feedback ◽  
Time Interval ◽  
Feedback Parameter ◽  
Temperature Anomalies ◽  
Straight Lines

Abstract. Top-of-the-Atmosphere (TOA) net radiative flux anomalies from Clouds and Earth's Radiant Energy Systems (CERES) Energy Balanced and Filled (EBAF) and surface air temperature anomalies from HadCRUT3 were compared for the time interval September 2000–May 2011. In a phase plane plot with the radiative flux anomalies lagging the temperature anomalies with 7 months the phase plane curve approached straight lines during about an eight months long period at the beginning and a five year period at the end of the interval. Both of those periods, but more clearly the latter one, could be connected to the occurrence of distinct El Niño Southern Oscillation (ENSO) episodes. This result is explained by using a hypothesis stating that non-radiative forcing connected to the ENSO is dominating the temperature changes during those two periods and that there is a lag between the temperature change and the radiative flux feedback. According to the hypothesis the slopes of the straight lines equal the value of the climate feedback parameter. By linear regression based on the mentioned five year period the value of the climate feedback parameter was estimated to 5.5 ± 0.6 W m−2 K−1 (± two standard errors).

scholarly journals The Interdecadal Shift of ENSO Properties in 1999/2000: A Review

2020 ◽  
Vol 33 (11) ◽  
pp. 4441-4462 ◽  
Author(s):  
Zeng-Zhen Hu ◽  
Arun Kumar ◽  
Bohua Huang ◽  
Jieshun Zhu ◽  
Michelle L’Heureux ◽  
...  
Keyword(s):  
Surface Temperature ◽  
Sea Surface Temperature ◽  
Regime Shift ◽  
Southern Oscillation ◽  
Static Stability ◽  
Sea Surface ◽  
Water Volume ◽  
Interdecadal Shift ◽  
Subsurface Ocean ◽  
Warm Water Volume

AbstractFollowing the interdecadal shift of El Niño–Southern Oscillation (ENSO) properties that occurred in 1976/77, another regime shift happened in 1999/2000 that featured a decrease of variability and an increase in ENSO frequency. Specifically, the frequency spectrum of Niño-3.4 sea surface temperature shifted from dominant variations at quasi-quadrennial (~4 yr) periods during 1979–99 to weaker fluctuations at quasi-biennial (~2 yr) periods during 2000–18. Also, the spectrum of warm water volume (WWV) index had almost no peak in 2000–18, implying a nearly white noise process. The regime shift was associated with an enhanced zonal gradient of the mean state, a westward shift in the atmosphere–ocean coupling in the tropical Pacific, and an increase in the static stability of the troposphere. This shift had several important implications. The whitening of the subsurface ocean temperature led to a breakdown of the relationship between WWV and ENSO, reducing the efficacy of WWV as a key predictor for ENSO and thus leading to a decrease in ENSO prediction skill. Another consequence of the higher ENSO frequency after 1999/2000 was that the forecasted peak of sea surface temperature anomaly often lagged that observed by several months, and the lag increased with the lead time. The ENSO regime shift may have altered ENSO influences on extratropical climate. Thus, the regime shift of ENSO in 1999/2000 as well as the model default may account for the higher false alarm and lower skill in predicting ENSO since 1999/2000.

scholarly journals Carbon-Cycle Feedbacks Operating in the Climate System

2019 ◽  
Vol 5 (4) ◽  
pp. 282-295 ◽  
Author(s):  
Richard G. Williams ◽  
Anna Katavouta ◽  
Philip Goodwin
Keyword(s):  
Carbon Cycle ◽  
Surface Temperature ◽  
Climate System ◽  
Climate Forcing ◽  
Climate Feedback ◽  
Direct Response ◽  
Feedback Parameter ◽  
Ocean Carbon ◽  
Carbon Stores ◽  
Climate Responses

AbstractClimate change involves a direct response of the climate system to forcing which is amplified or damped by feedbacks operating in the climate system. Carbon-cycle feedbacks alter the land and ocean carbon inventories and so act to reduce or enhance the increase in atmospheric CO2 from carbon emissions. The prevailing framework for carbon-cycle feedbacks connect changes in land and ocean carbon inventories with a linear sum of dependencies on atmospheric CO2 and surface temperature. Carbon-cycle responses and feedbacks provide competing contributions: the dominant effect is that increasing atmospheric CO2 acts to enhance the land and ocean carbon stores, so providing a negative response and feedback to the original increase in atmospheric CO2, while rising surface temperature acts to reduce the land and ocean carbon stores, so providing a weaker positive feedback for atmospheric CO2. The carbon response and feedback of the land and ocean system may be expressed in terms of a combined carbon response and feedback parameter, λcarbon in units of W m− 2K− 1, and is linearly related to the physical climate feedback parameter, λclimate, revealing how carbon and climate responses and feedbacks are inter-connected. The magnitude and uncertainties in the carbon-cycle response and feedback parameter are comparable with the magnitude and uncertainties in the climate feedback parameter from clouds. Further mechanistic insight needs to be gained into how the carbon-cycle feedbacks are controlled for the land and ocean, particularly to separate often competing effects from changes in atmospheric CO2 and climate forcing.

scholarly journals The Climate Sensitivity and Its Components Diagnosed from Earth Radiation Budget Data

2006 ◽  
Vol 19 (1) ◽  
pp. 39-52 ◽  
Author(s):  
Piers Mde F. Forster ◽  
Jonathan M. Gregory
Keyword(s):  
Climate Change ◽  
Time Series ◽  
Surface Temperature ◽  
Climate Sensitivity ◽  
Radiative Forcing ◽  
Radiation Budget ◽  
Climate Feedback ◽  
Feedback Parameter ◽  
Earth Radiation Budget ◽  
Earth Radiation

Abstract One of the major uncertainties in the ability to predict future climate change, and hence its impacts, is the lack of knowledge of the earth’s climate sensitivity. Here, data are combined from the 1985–96 Earth Radiation Budget Experiment (ERBE) with surface temperature change information and estimates of radiative forcing to diagnose the climate sensitivity. Importantly, the estimate is completely independent of climate model results. A climate feedback parameter of 2.3 ± 1.4 W m−2 K−1 is found. This corresponds to a 1.0–4.1-K range for the equilibrium warming due to a doubling of carbon dioxide (assuming Gaussian errors in observable parameters, which is approximately equivalent to a uniform “prior” in feedback parameter). The uncertainty range is due to a combination of the short time period for the analysis as well as uncertainties in the surface temperature time series and radiative forcing time series, mostly the former. Radiative forcings may not all be fully accounted for; however, an argument is presented that the estimate of climate sensitivity is still likely to be representative of longer-term climate change. The methodology can be used to 1) retrieve shortwave and longwave components of climate feedback and 2) suggest clear-sky and cloud feedback terms. There is preliminary evidence of a neutral or even negative longwave feedback in the observations, suggesting that current climate models may not be representing some processes correctly if they give a net positive longwave feedback.

scholarly journals Interannual Variability and Trends in Sea Surface Temperature, Lower and Middle Atmosphere Temperature at Different Latitudes for 1980–2019

Atmosphere ◽  
2021 ◽  
Vol 12 (4) ◽  
pp. 454
Author(s):  
Andrew R. Jakovlev ◽  
Sergei P. Smyshlyaev ◽  
Vener Y. Galin
Keyword(s):  
Surface Temperature ◽  
Sea Surface Temperature ◽  
Lower Stratosphere ◽  
Middle Atmosphere ◽  
Southern Oscillation ◽  
Lower Troposphere ◽  
Reanalysis Data ◽  
Sea Surface ◽  
The Arctic ◽  
The Impact

The influence of sea-surface temperature (SST) on the lower troposphere and lower stratosphere temperature in the tropical, middle, and polar latitudes is studied for 1980–2019 based on the MERRA2, ERA5, and Met Office reanalysis data, and numerical modeling with a chemistry-climate model (CCM) of the lower and middle atmosphere. The variability of SST is analyzed according to Met Office and ERA5 data, while the variability of atmospheric temperature is investigated according to MERRA2 and ERA5 data. Analysis of sea surface temperature trends based on reanalysis data revealed that a significant positive SST trend of about 0.1 degrees per decade is observed over the globe. In the middle latitudes of the Northern Hemisphere, the trend (about 0.2 degrees per decade) is 2 times higher than the global average, and 5 times higher than in the Southern Hemisphere (about 0.04 degrees per decade). At polar latitudes, opposite SST trends are observed in the Arctic (positive) and Antarctic (negative). The impact of the El Niño Southern Oscillation phenomenon on the temperature of the lower and middle atmosphere in the middle and polar latitudes of the Northern and Southern Hemispheres is discussed. To assess the relative influence of SST, CO2, and other greenhouse gases’ variability on the temperature of the lower troposphere and lower stratosphere, numerical calculations with a CCM were performed for several scenarios of accounting for the SST and carbon dioxide variability. The results of numerical experiments with a CCM demonstrated that the influence of SST prevails in the troposphere, while for the stratosphere, an increase in the CO2 content plays the most important role.

Humboldt penguins outmanoeuvring El Nino

2000 ◽  
Vol 203 (15) ◽  
pp. 2311-2322 ◽  
Author(s):  
B. Culik ◽  
J. Hennicke ◽  
T. Martin
Keyword(s):  
Surface Temperature ◽  
Sea Surface Temperature ◽  
Chlorophyll A ◽  
Wind Direction ◽  
El Niño ◽  
El Nino ◽  
Southern Oscillation ◽  
Dive Duration ◽  
Sea Surface ◽  
Day Length

We satellite-tracked five Humboldt penguins during the strong 1997/98 El Nino Southern Oscillation (ENSO) from their breeding island Pan de Azucar (26 degrees 09′S, 70 degrees 40′W) in Northern Chile and related their activities at sea to satellite-derived information on sea surface temperature (SST), sea surface temperature anomaly (SSTA), wind direction and speed, chlorophyll a concentrations and statistical data on fishery landings. We found that Humboldt penguins migrated by up to 895 km as marine productivity decreased. The total daily dive duration was highly correlated with SSTA, ranging from 3.1 to 12.5 h when the water was at its warmest (+4 degrees C). Birds travelled between 2 and 116 km every day, travelling further when SSTA was highest. Diving depths (maximum 54 m), however, were not increased with respect to previous years. Two penguins migrated south and, independently of each other, located an area of high chlorophyll a concentration 150 km off the coast. Humboldt penguins seem to use day length, temperature gradients, wind direction and olfaction to adapt to changing environmental conditions and to find suitable feeding grounds. This makes Humboldt penguins biological in situ detectors of highly productive marine areas, with a potential use in the verification of trends detected by remote sensors on board satellites.

Sign in / Sign up

Export Citation Format

Share Document