scholarly journals Changes in Interannual Variability and Decadal Potential Predictability under Global Warming

2009 ◽  
Vol 22 (11) ◽  
pp. 3098-3109 ◽  
Author(s):  
G. J. Boer
Keyword(s):  
Global Warming ◽  
Standard Deviation ◽  
Time Scale ◽  
Climate Model ◽  
Decadal Variability ◽  
Climate Change Scenarios ◽  
Potential Predictability ◽  
Temperature And Precipitation ◽  
Mean Temperature ◽  
The Tropics

Abstract Global warming will result in changes in mean temperature and precipitation distributions and is also expected to affect interannual and longer time-scale internally generated variability as a consequence of changes in climate processes and feedbacks. Multimodel estimates of changes in the variability of annual mean temperature and precipitation and in the variability of decadal potential predictability are investigated based on the collection of coupled climate model simulations in the Coupled Model Intercomparison Project phase 3 (CMIP3) data archive. Pooled, multimodel standard deviations of annual mean temperature and precipitation for the unforced preindustrial control climates of the models show good resemblance to observation-based estimates. The internally generated variability of the unforced climate is compared with that of the warmer conditions for simulations with the B1 and A1B climate change scenarios with forcing stabilized at year 2100 values. The standard deviation of annual mean temperature generally decreases with global warming at extratropical latitudes, with the largest percentage decreases over the oceans and largest percentage increases in the tropics and subtropics, although the magnitudes of these increases are smaller. The standard deviation of annual mean precipitation increases almost everywhere, with larger increases in the tropics. Changes are generally larger for the more strongly forced, warmer A1B scenario than for the B1 scenario. The characterization of decadal variability changes in terms of potential predictability stems from the growing interest in producing forecasts for the next decade or several decades. The potential predictability identifies that fraction of the long time-scale variability that is, at least potentially and with enough information, predictable on decadal time scales. There is a general decrease in the internally generated decadal variability of temperature and its potential predictability in the warmer world. The decrease tends to be largest where the decadal potential predictability of the unforced control climate is largest over the high-latitude oceans. The potential predictability of precipitation is small to begin with and generally decreases further. Therefore, there is a potential decrease in the decadal potential predictability of the internally generated component in a warmer world.

Potential predictability of Southwest US rainfall : role of tropical and high-latitude variability

2021 ◽  
pp. 1-45
Keyword(s):  
Time Scale ◽  
Climate Model ◽  
Southern Oscillation ◽  
Seasonal Prediction ◽  
Seasonal Rainfall ◽  
The Arctic ◽  
Sea Ice Concentration ◽  
Potential Predictability ◽  
Subseasonal Variability ◽  
The Tropics

Abstract This study explores the potential predictability of Southwest US (SWUS) precipitation for the November-March season in a set of numerical experiments performed with the Whole Atmospheric Community Climate Model. In addition to the prescription of observed sea surface temperature and sea ice concentration, observed variability from the MERRA-2 reanalysis is prescribed in the tropics and/or the Arctic through nudging of wind and temperature. These experiments reveal how a perfect prediction of tropical and/or Arctic variability in the model would impact the prediction of seasonal rainfall over the SWUS, at various time scales. Imposing tropical variability improves the representation of the observed North Pacific atmospheric circulation, and the associated SWUS seasonal precipitation. This is also the case at the subseasonal time scale due to the inclusion of the Madden-Julian Oscillation (MJO) in the model. When additional nudging is applied in the Arctic, the model skill improves even further, suggesting that improving seasonal predictions in high latitudes may also benefit prediction of SWUS precipitation. An interesting finding of our study is that subseasonal variability represents a source of noise (i.e., limited predictability) for the seasonal time scale. This is because when prescribed in the model, subseasonal variability, mostly the MJO, weakens the El Niño Southern Oscillation (ENSO) teleconnection with SWUS precipitation. Such knowledge may benefit S2S and seasonal prediction as it shows that depending on the amount of subseasonal activity in the tropics on a given year, better skill may be achieved in predicting subseasonal rather than seasonal rainfall anomalies, and conversely.

scholarly journals Methods for the Design of Climate Change Scenario in Slovakia for the 21St Century

2009 ◽  
Vol 1 (1) ◽  
pp. 77-90 ◽  
Author(s):  
Marian Melo ◽  
Milan Lapin ◽  
Ingrid Damborska
Keyword(s):  
Climate Change ◽  
Time Series ◽  
21St Century ◽  
Climate Change Scenario ◽  
Change Scenario ◽  
Climate Change Scenarios ◽  
Precipitation Time Series ◽  
Impact Studies ◽  
Temperature And Precipitation ◽  
Mean Temperature

Abstract In this paper methods of climate-change scenario projection in Slovakia for the 21st century are outlined. Temperature and precipitation time series of the Hurbanovo Observatory in 1871-2007 (Slovak Hydrometeorological Institute) and data from four global GCMs (GISS 1998, CGCM1, CGCM2, HadCM3) are utilized for the design of climate change scenarios. Selected results of different climate change scenarios (based on different methods) for the region of Slovakia (up to 2100) are presented. The increase in annual mean temperature is about 3°C, though the results are ambiguous in the case of precipitation. These scenarios are required by users in impact studies, mainly from the hydrology, agriculture and forestry sectors.

Temperature and precipitation in Svalbard 1912–2050: measurements and scenarios

Polar Record ◽  
2002 ◽  
Vol 38 (206) ◽  
pp. 225-232 ◽  
Author(s):  
I. Hanssen-Bauer
Keyword(s):  
Climate Model ◽  
Global Climate ◽  
Global Climate Model ◽  
Positive Trend ◽  
Spring Precipitation ◽  
Maximum Increase ◽  
Temperature And Precipitation ◽  
Mean Temperature ◽  
Empirical Downscaling ◽  
The 1960S

AbstractTemperature and precipitation series from Svalbard for the period 1912–2000 were analysed. There was a statistically significant warming from 1912 to the 1930s, a cooling from the 1930s to the 1960s and a warming from the 1960s to present. There was a positive trend in the annual mean temperature during the period 1912–2000, but it was not statistically significant. Spring was the only season when a statistically significant warming was found. For precipitation, statistically significant positive trends during the period 1912–2000 were found on an annual basis and in all seasons except winter. Empirical downscaling was applied on the results from a global climate model to produce scenarios for monthly temperature and precipitation in Svalbard. The 2 m temperature was applied as predictor for temperature. For precipitation, a combination of temperature and sea-level pressure was used. The temperature scenario indicates a warming of about 1°C per decade in winter, and 0.3°C per decade in summer from 1961 to 2050. The projected increase in annual mean temperature is about five times the average warming rate from 1912 to present, and highly significant. The precipitation scenario also indicates that precipitation will increase significantly until 2050. The maximum increase was projected in spring precipitation; however, the trends in seasonal precipitation are quite uncertain.

scholarly journals Long Time-Scale Teleconnection Patterns in the Northern Atlantic and Pacific

2012 ◽  
Vol 25 (1) ◽  
pp. 414-422
Author(s):  
George J. Boer
Keyword(s):  
Time Scale ◽  
Climate Model ◽  
Potential Predictability ◽  
Teleconnection Patterns ◽  
Statistical Robustness ◽  
Model Control ◽  
Long Time ◽  
Total Variability ◽  
Northern Atlantic ◽  
Hadley Centre

Abstract Long time-scale teleconnection patterns, with common features in both the northern Atlantic and Pacific regions, are identified. The teleconnection patterns arise in an investigation of the internally generated variability in a multimodel ensemble of coupled climate model control simulations. The large amount of data involved offers statistical robustness and the benefits of combining results across models. Maxima of decadal potential predictability identify regions where long time-scale variability is an appreciable fraction of the total variability and serve as index regions for the teleconnection analysis. Annual, 5-yr, and decadal mean temperatures over these Atlantic and Pacific index regions are correlated with corresponding temperatures and precipitation rates over the globe. The resulting teleconnection patterns are reasonably similar despite the different long time-scale variability mechanisms thought to exist in the two ocean basins. Although lacking statistical robustness, some aspects of the temperature teleconnection patterns are obtained based on the Hadley Centre Sea Ice and Sea Surface Temperature (HadISST) dataset. The similarity of the teleconnection patterns in the two northern ocean regions suggests that common variability mechanisms may be involved.

scholarly journals The response of precipitation characteristics to global warming from climate projections

2019 ◽  
Vol 10 (1) ◽  
pp. 73-89 ◽  
Author(s):  
Filippo Giorgi ◽  
Francesca Raffaele ◽  
Erika Coppola
Keyword(s):  
Global Warming ◽  
Climate Model ◽  
Regional Climate ◽  
Climate Projections ◽  
Potential Predictability ◽  
Precipitation Characteristics ◽  
Dry Spell ◽  
The Difference ◽  
Light Precipitation ◽  
Precipitation Events

Abstract. We revisit the issue of the response of precipitation characteristics to global warming based on analyses of global and regional climate model projections for the 21st century. The prevailing response we identify can be summarized as follows: increase in the intensity of precipitation events and extremes, with the occurrence of events of “unprecedented” magnitude, i.e., a magnitude not found in the present-day climate; decrease in the number of light precipitation events and in wet spell lengths; and increase in the number of dry days and dry spell lengths. This response, which is mostly consistent across the models we analyzed, is tied to the difference between precipitation intensity responding to increases in local humidity conditions and circulations, especially for heavy and extreme events, and mean precipitation responding to slower increases in global evaporation. These changes in hydroclimatic characteristics have multiple and important impacts on the Earth's hydrologic cycle and on a variety of sectors. As examples we investigate effects on potential stress due to increases in dry and wet extremes, changes in precipitation interannual variability, and changes in the potential predictability of precipitation events. We also stress how the understanding of the hydroclimatic response to global warming can provide important insights into the fundamental behavior of precipitation processes, most noticeably tropical convection.

scholarly journals Increasing potential for intense tropical and subtropical thunderstorms under global warming

2017 ◽  
Vol 114 (44) ◽  
pp. 11657-11662 ◽  
Author(s):  
Martin S. Singh ◽  
Zhiming Kuang ◽  
Eric D. Maloney ◽  
Walter M. Hannah ◽  
Brandon O. Wolding
Keyword(s):  
Global Warming ◽  
Theoretical Model ◽  
Climate Models ◽  
Climate Model ◽  
Convective Available Potential Energy ◽  
Thunderstorm Activity ◽  
Lapse Rate ◽  
Climate Projections ◽  
Entrainment Rate ◽  
The Tropics

Intense thunderstorms produce rapid cloud updrafts and may be associated with a range of destructive weather events. An important ingredient in measures of the potential for intense thunderstorms is the convective available potential energy (CAPE). Climate models project increases in summertime mean CAPE in the tropics and subtropics in response to global warming, but the physical mechanisms responsible for such increases and the implications for future thunderstorm activity remain uncertain. Here, we show that high percentiles of the CAPE distribution (CAPE extremes) also increase robustly with warming across the tropics and subtropics in an ensemble of state-of-the-art climate models, implying strong increases in the frequency of occurrence of environments conducive to intense thunderstorms in future climate projections. The increase in CAPE extremes is consistent with a recently proposed theoretical model in which CAPE depends on the influence of convective entrainment on the tropospheric lapse rate, and we demonstrate the importance of this influence for simulated CAPE extremes using a climate model in which the convective entrainment rate is varied. We further show that the theoretical model is able to account for the climatological relationship between CAPE and a measure of lower-tropospheric humidity in simulations and in observations. Our results provide a physical basis on which to understand projected future increases in intense thunderstorm potential, and they suggest that an important mechanism that contributes to such increases may be present in Earth’s atmosphere.

scholarly journals Will Global Warming Suppress North Atlantic Tripole Decadal Variability?

2012 ◽  
Vol 25 (6) ◽  
pp. 2040-2055 ◽  
Author(s):  
Yun Yang ◽  
Lixin Wu ◽  
Changfang Fang
Keyword(s):  
Global Warming ◽  
North Atlantic ◽  
Time Scale ◽  
Decadal Variability ◽  
Buoyancy Frequency ◽  
The North ◽  
Ocean Atmosphere ◽  
The North Atlantic ◽  
Partial Blocking ◽  
Partial Coupling

Abstract In this paper, the modulations of the North Atlantic tripole (NAT) decadal variability from global warming are studied by conducting a series of coupled ocean–atmosphere experiments using the Fast Ocean Atmosphere Model (FOAM). The model reasonably captures the observed NAT decadal variability with a preferred time scale of about 11 years. With the aid of partial-blocking and partial-coupling experiments, it is found that the NAT decadal cycle can be attributed to oceanic planetary wave adjustment in the subtropical basin and ocean–atmosphere coupling over the North Atlantic. In a doubled CO2 experiment, the spatial pattern of the NAT is preserved; however, the decadal cycle is significantly suppressed. This suppression appears to be associated with the acceleration of oceanic planetary waves due to an increase of buoyancy frequency in global warming. This shortens the time from a decadal to an interannual time scale for the first-mode baroclinic Rossby waves to cross the subtropical North Atlantic basin, the primary memory for the NAT decadal variability in the model. The modeling study also found that the global warming does not modulate the North Atlantic air–sea coupling significantly, but it may be model dependent.

scholarly journals Large-scale emergence of regional changes in year-to-year temperature variability by the end of the 21st century

2021 ◽  
Vol 12 (1) ◽  
Author(s):  
Dirk Olonscheck ◽  
Andrew P. Schurer ◽  
Lucie Lücke ◽  
Gabriele C. Hegerl
Keyword(s):  
Global Warming ◽  
Large Scale ◽  
Climate Model ◽  
Climate Extremes ◽  
Temperature Variability ◽  
High Latitudes ◽  
Large Ensembles ◽  
Proxy Reconstructions ◽  
Instrumental Records ◽  
The Tropics

AbstractGlobal warming is expected to not only impact mean temperatures but also temperature variability, substantially altering climate extremes. Here we show that human-caused changes in internal year-to-year temperature variability are expected to emerge from the unforced range by the end of the 21st century across climate model initial-condition large ensembles forced with a strong global warming scenario. Different simulated changes in globally averaged regional temperature variability between models can be explained by a trade-off between strong increases in variability on tropical land and substantial decreases in high latitudes, both shown by most models. This latitudinal pattern of temperature variability change is consistent with loss of sea ice in high latitudes and changes in vegetation cover in the tropics. Instrumental records are broadly in line with this emerging pattern, but have data gaps in key regions. Paleoclimate proxy reconstructions support the simulated magnitude and distribution of temperature variability. Our findings strengthen the need for urgent mitigation to avoid unprecedented changes in temperature variability.

scholarly journals Implications of Both Statistical Equilibrium and Global Warming Simulations with CCSM3. Part I: On the Decadal Variability in the North Pacific Basin

2009 ◽  
Vol 22 (20) ◽  
pp. 5277-5297 ◽  
Author(s):  
Marc d’Orgeville ◽  
W. Richard Peltier
Keyword(s):  
Global Warming ◽  
North Pacific ◽  
Time Scale ◽  
Decadal Variability ◽  
Sea Surface ◽  
The North ◽  
Sst Variability ◽  
Pacific Decadal Variability ◽  
The North Pacific ◽  
North Pacific Basin

Abstract In the low-resolution version of the Community Climate System Model, version 3 (CCSM3), the modeled North Pacific decadal variability is demonstrated to be independent of the epoch for which a statistically steady control simulation is constructed, either preindustrial or modern; however, it is demonstrated to be significantly affected by the different global warming scenarios investigated. In the control simulations, the North Pacific basin is shown to be dominated by sea surface temperature (SST) variability with a time scale of approximately 20 yr. This mode of variability is in close accord with the observed characteristics of the Pacific decadal oscillation (PDO). A detailed analysis of the statistical equilibrium runs is performed based on other model variables as well [sea surface salinity (SSS), barotropic circulation, freshwater and heat fluxes, wind stress curl, sea ice, and snow coverage]. These analyses confirm that the underlying mechanism of the PDO involves a basin-scale mode of ocean adjustment to changes of the atmospheric forcing associated with the Aleutian low pressure system. However, they also suggest that the observed sign reversal of the PDO arises from a feedback in the northern part of the basin. In this novel hypothesis, the advection to the Bering Sea of “spice” anomalies formed in the central and western Pacific sets up a typical 10-yr time scale for the triggering of the PDO reversal. In all of the global warming simulations described in this paper, the signal represented by the detrended SST variability in the North Pacific displays significant power at multidecadal frequencies. In these simulations, the natural North Pacific decadal variability, as characterized in the control simulations (the PDO), remains the leading mode of variability only for moderate forcing. If the warming is too strong, then the typical 20-yr time scale of the canonical PDO can no longer be detected, except in terms of SSS variability and only prior to a significant change that occurs in the Bering Strait Throughflow.

scholarly journals Simulating the temperature and precipitation signal in an Alpine ice core

2013 ◽  
Vol 9 (4) ◽  
pp. 2013-2022 ◽  
Author(s):  
S. Brönnimann ◽  
I. Mariani ◽  
M. Schwikowski ◽  
R. Auchmann ◽  
A. Eichler
Keyword(s):  
Climate Models ◽  
Climate Model ◽  
Meteorological Data ◽  
Ice Core ◽  
Ice Cores ◽  
Irregular Sampling ◽  
Temperature And Precipitation ◽  
Mean Temperature ◽  
Ice Core Record ◽  
Precipitation Events

Abstract. Accumulation and δ18O data from Alpine ice cores provide information on past temperature and precipitation. However, their correlation with seasonal or annual mean temperature and precipitation at nearby sites is often low. This is partly due to the irregular sampling of the atmosphere by the ice core (i.e. ice cores almost only record precipitation events and not dry periods) and the possible incongruity between annual layers and calendar years. Using daily meteorological data from a nearby station and reanalyses, we replicate the ice core from the Grenzgletscher (Switzerland, 4200 m a.s.l.) on a sample-by-sample basis by calculating precipitation-weighted temperature (PWT) over short intervals. Over the last 15 yr of the ice core record, accumulation and δ18O variations can be well reproduced on a sub-seasonal scale. This allows a wiggle-matching approach for defining quasi-annual layers, resulting in high correlations between measured quasi-annual δ18O and PWT. Further back in time, the agreement deteriorates. Nevertheless, we find significant correlations over the entire length of the record (1938–1993) of ice core δ18O with PWT, but not with annual mean temperature. This is due to the low correlations between PWT and annual mean temperature, a characteristic which in ERA-Interim reanalysis is also found for many other continental mid-to-high-latitude regions. The fact that meteorologically very different years can lead to similar combinations of PWT and accumulation poses limitations to the use of δ18O from Alpine ice cores for temperature reconstructions. Rather than for reconstructing annual mean temperature, δ18O from Alpine ice cores should be used to reconstruct PWT over quasi-annual periods. This variable is reproducible in reanalysis or climate model data and could thus be assimilated into conventional climate models.

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