Alpine Younger Dryas glaciers as palaeo-precipitation gauges

AbstractMoraines of the Younger Dryas ˚Egesen Stadial", which are widespread features in the Alps, are a valuable terrestrial data source for quantitative palaeoclimatic studies. The depression of the early Younger Dryas (Egesen-I) equilibrium-line altitude (ELA) shows a distinct spatial pattern. It was greatest (about –450 to –500 m vs present day) m areas exposed towards the west and northwest. In the central, more sheltered valleys it was on the order of –300 m or less. Summer temperature depression, which can be derived from the Younger Dryas timberline depression, was on the order of –3.5 K. The stochastic glacier-climate model of Ohmura and others (1992), which relates summer temperature and precipitation at the ELA, is used to infer precipitation change. Results are compared with those obtained from the glacial-meteorological approach of Kuhn (1981a). The two models produce highly similar results. During the early Younger Dryas, climate in the central valleys of the Alps seems to have been considerably drier than today In areas open to the west and northwest, precipitation seems to have been the same as today or even slightly higher. These results, which are based on a rather dense network of data points, agree well with results from permafrost-climate studies and the more qualitative information from palaeobotanical research. They also support the results from atmospheric general circulation models for the Younger Dryas in Europe, which point towards a more zonal type of circulation.

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Reconstructing glacier-based climates of LGM Europe and Russia – Part 1: Numerical modelling and validation methods

Climate of the Past ◽

10.5194/cp-4-235-2008 ◽

2008 ◽

Vol 4 (4) ◽

pp. 235-248 ◽

Cited By ~ 9

Author(s):

R. Allen ◽

M. J. Siegert ◽

A. J. Payne

Keyword(s):

General Circulation ◽

Climate Model ◽

Late Quaternary ◽

Circulation Model ◽

Equilibrium Line Altitude ◽

Geological Evidence ◽

Continental Scale ◽

Temperature And Precipitation ◽

Mountain Environments ◽

Regional Temperature

Abstract. The mountain environments of mid-latitude Europe and Arctic Russia contain widespread evidence of Late-Quaternary glaciers that have been attributed to the Last Glacial Maximum (LGM). This glacial-geological record has yet to be used to quantitatively reconstruct the LGM climate of these regions. Here we describe a simple glacier-climate model that can be used to derive regional temperature and precipitation information from a known glacier distribution. The model was tested against the present day distribution of glaciers in Europe. The model is capable of adequately predicting the spatial distribution, snowline and equilibrium line altitude climate of glaciers in the Alps, Scandinavia, Caucasus and Pyrenees Mountains. This verification demonstrated that the model can be used to investigate former climates such as the LGM. Reconstructions of LGM climates from proxy evidence are an important method of assessing retrospective general circulation model (GCM) simulations. LGM palaeoclimate reconstructions from glacial-geological evidence would be of particular benefit to investigations in Europe and Russia, where to date only fossil pollen data have been used to assess continental-scale GCM simulations.

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Bias correction of temperature and precipitation over China for RCM simulations using the QM and QDM methods

Climate Dynamics ◽

10.1007/s00382-020-05447-4 ◽

2020 ◽

Cited By ~ 2

Author(s):

Yao Tong ◽

Xuejie Gao ◽

Zhenyu Han ◽

Yaqi Xu ◽

Ying Xu ◽

...

Keyword(s):

Bias Correction ◽

General Circulation ◽

Climate Model ◽

Regional Climate ◽

General Circulation Models ◽

Grid Spacing ◽

Quantile Mapping ◽

Temperature And Precipitation ◽

June July August ◽

June July

Abstract Two different bias correction methods, the quantile mapping (QM) and quantile delta mapping (QDM), are applied to simulated daily temperature and precipitation over China from a set of 21st century regional climate model (the ICTP RegCM4) projections. The RegCM4 is driven by five different general circulation models (GCMs) under the representative concentration pathway RCP4.5 at a grid spacing of 25 km using the CORDEX East Asia domain. The focus is on mean temperature and precipitation in December–January–February (DJF) and June–July–August (JJA). The impacts of the two methods on the present day biases and future change signals are investigated. Results show that both the QM and QDM methods are effective in removing the systematic model biases during the validation period. For the future changes, the QDM preserves the temperature change signals well, in both magnitude and spatial distribution, while the QM artificially modifies the change signal by decreasing the warming and modifying the patterns of change. For precipitation, both methods preserve the change signals well but they produce greater magnitude of the projected increase, especially the QDM. We also show that the effects of bias correction are variable- and season-dependent. Our results show that different bias correction methods can affect in different way the simulated change signals, and therefore care has to be taken in carrying out the bias correction process.

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Approaches to attribution of extreme temperature and precipitation events using multi-model and single-member ensembles of general circulation models

Advances in Statistical Climatology Meteorology and Oceanography ◽

10.5194/ascmo-5-133-2019 ◽

2019 ◽

Vol 5 (2) ◽

pp. 133-146 ◽

Cited By ~ 1

Author(s):

Sophie C. Lewis ◽

Sarah E. Perkins-Kirkpatrick ◽

Andrew D. King

Keyword(s):

General Circulation ◽

Climate Model ◽

Extreme Event ◽

Extreme Temperature ◽

General Circulation Models ◽

Cmip5 Models ◽

Spatial And Temporal Scales ◽

Temperature And Precipitation ◽

Event Attribution ◽

Precipitation Events

Abstract. Extreme temperature and precipitation events occurring in Australia in recent decades have caused significant socio-economic and environmental impacts, and thus determining the factors contributing to these extremes is an active area of research. Many recently occurring record-breaking temperature and rainfall events have now been examined from an extreme event attribution (EEA) perspective. This paper describes a set of studies that have examined the causes of extreme climate events using various general circulation models (GCMs), presenting a comprehensive methodology for GCM-based attribution of extremes of temperature and precipitation observed on large spatial and temporal scales in Australia. First, we review how Coupled Model Intercomparison Project Phase 5 (CMIP5) models have been used to examine the changing odds of observed extremes. Second, we review how a large perturbed initial condition ensemble of a single climate model (CESM) has been used to quantitatively examine the changing characteristics of Australian heat extremes. For each approach, methodological details and applications are provided and limitations highlighted. The conclusions of this methodological review discuss the limitations and uncertainties associated with this approach and identify key unexplored applications of GCM-based attribution of extremes. Ideally, this information will be useful for the application of the described extreme event attribution approaches elsewhere.

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Reconstructing glacier-based climates of LGM Europe and Russia – Part 1: Numerical modelling and validation methods

Climate of the Past Discussions ◽

10.5194/cpd-3-1133-2007 ◽

2007 ◽

Vol 3 (5) ◽

pp. 1133-1166 ◽

Cited By ~ 4

Author(s):

R. Allen ◽

M. J. Siegert ◽

A. J. Payne

Keyword(s):

General Circulation ◽

Climate Model ◽

Late Quaternary ◽

Circulation Model ◽

Equilibrium Line Altitude ◽

Geological Evidence ◽

Continental Scale ◽

Temperature And Precipitation ◽

Mountain Environments ◽

Regional Temperature

Abstract. The mountain environments of mid-latitude Europe and Arctic Russia contain widespread evidence of Late-Quaternary glaciers that have been prescribed to the Last Glacial Maximum (LGM). This glacial-geological record has yet to be used to quantitatively reconstruct the LGM climate of these regions. Here we describe a simple glacier-climate model that can be used to derive regional temperature and precipitation information from a known glacier distribution. The model was tested against the present day distribution of glaciers in Europe. The model is capable of adequately predicting the spatial distribution, snowline and equilibrium line altitude climate of glaciers in the Alps, Scandinavia, Caucasus and Pyrenees Mountains. This verification demonstrated that the model can be used to investigate former climates such as the LGM. Reconstructions of LGM climates from proxy evidence are an important method of assessing retrospective general circulation model (GCM) simulations. LGM palaeoclimate reconstructions from glacial-geological evidence would be of particular benefit to investigations in Europe and Russia, where to date only fossil pollen data have been used to assess continental-scale GCM simulations.

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Interhemispheric differences of mesosphere/lower thermosphere winds and tides investigated from three whole atmosphere models and meteor radar observations

10.5194/acp-2021-142 ◽

2021 ◽

Author(s):

Gunter Stober ◽

Ales Kuchar ◽

Dimitry Pokhotelov ◽

Huixin Liu ◽

Han-Li Liu ◽

...

Keyword(s):

General Circulation ◽

Climate Models ◽

Climate Model ◽

Lower Thermosphere ◽

Winter Season ◽

General Circulation Models ◽

Meteor Radar ◽

Radar Observations ◽

Seasonal Characteristics

Abstract. Long-term and continuous observations of mesospheric/lower thermospheric winds are rare, but they are important to investigate climatological changes at these altitudes on time scales of several years, covering a solar cycle and longer. Such long time series are a natural heritage of the mesosphere/lower thermosphere climate, and they are valuable to compare climate models or long term runs of general circulation models (GCMs). Here we present a climatological comparison of wind observations from six meteor radars at two conjugate latitudes to validate the corresponding mean winds and atmospheric diurnal and semidiurnal tides from three GCMs, namely Ground-to-Topside Model of Atmosphere and Ionosphere for Aeronomy (GAIA), Whole Atmosphere Community Climate Model Extension (Specified Dynamics) (WACCM-X(SD)) and Upper Atmosphere ICOsahedral Non-hydrostatic (UA-ICON) model. Our results indicate that there are interhemispheric differences in the seasonal characteristics of the diurnal and semidiurnal tide. There also are some differences in the mean wind climatologies of the models and the observations. Our results indicate that GAIA shows a reasonable agreement with the meteor radar observations during the winter season, whereas WACCM-X(SD) shows a better agreement with the radars for the hemispheric zonal summer wind reversal, which is more consistent with the meteor radar observations. The free running UA-ICON tends to show similar winds and tides compared to WACCM-X(SD).

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Panama’s Current Climate Replicability in a Non-Hydrostatic Regional Climate Model Nested in an Atmospheric General Circulation Model

Atmosphere ◽

10.3390/atmos12121543 ◽

2021 ◽

Vol 12 (12) ◽

pp. 1543

Author(s):

Reinhardt Pinzón ◽

Noriko N. Ishizaki ◽

Hidetaka Sasaki ◽

Tosiyuki Nakaegawa

Keyword(s):

Regional Climate Model ◽

Air Temperature ◽

General Circulation ◽

Climate Model ◽

Regional Climate ◽

Surface Air Temperature ◽

Circulation Model ◽

Horizontal Resolution ◽

Temperature And Precipitation ◽

Current Climate

To simulate the current climate, a 20-year integration of a non-hydrostatic regional climate model (NHRCM) with grid spacing of 5 and 2 km (NHRCM05 and NHRCM02, respectively) was nested within the AGCM. The three models did a similarly good job of simulating surface air temperature, and the spatial horizontal resolution did not affect these statistics. NHRCM02 did a good job of reproducing seasonal variations in surface air temperature. NHRCM05 overestimated annual mean precipitation in the western part of Panama and eastern part of the Pacific Ocean. NHRCM05 is responsible for this overestimation because it is not seen in MRI-AGCM. NHRCM02 simulated annual mean precipitation better than NHRCM05, probably due to a convection-permitting model without a convection scheme, such as the Kain and Fritsch scheme. Therefore, the finer horizontal resolution of NHRCM02 did a better job of replicating the current climatological mean geographical distributions and seasonal changes of surface air temperature and precipitation.

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Tracking Scheme Dependence of Simulated Tropical Cyclone Response to Idealized Climate Simulations

Journal of Climate ◽

10.1175/jcli-d-14-00200.1 ◽

2014 ◽

Vol 27 (24) ◽

pp. 9197-9213 ◽

Cited By ~ 53

Author(s):

Michael Horn ◽

Kevin Walsh ◽

Ming Zhao ◽

Suzana J. Camargo ◽

Enrico Scoccimarro ◽

...

Keyword(s):

Tropical Cyclone ◽

Tropical Cyclones ◽

General Circulation ◽

Climate Model ◽

Circulation Model ◽

General Circulation Models ◽

Tropical Cyclone Activity ◽

Model Data ◽

Cyclone Activity ◽

Sensitivity Testing

Abstract Future tropical cyclone activity is a topic of great scientific and societal interest. In the absence of a climate theory of tropical cyclogenesis, general circulation models are the primary tool available for investigating the issue. However, the identification of tropical cyclones in model data at moderate resolution is complex, and numerous schemes have been developed for their detection. The influence of different tracking schemes on detected tropical cyclone activity and responses in the Hurricane Working Group experiments is examined herein. These are idealized atmospheric general circulation model experiments aimed at determining and distinguishing the effects of increased sea surface temperature and other increased CO2 effects on tropical cyclone activity. Two tracking schemes are applied to these data and the tracks provided by each modeling group are analyzed. The results herein indicate moderate agreement between the different tracking methods, with some models and experiments showing better agreement across schemes than others. When comparing responses between experiments, it is found that much of the disagreement between schemes is due to differences in duration, wind speed, and formation-latitude thresholds. After homogenization in these thresholds, agreement between different tracking methods is improved. However, much disagreement remains, accountable for by more fundamental differences between the tracking schemes. The results indicate that sensitivity testing and selection of objective thresholds are the key factors in obtaining meaningful, reproducible results when tracking tropical cyclones in climate model data at these resolutions, but that more fundamental differences between tracking methods can also have a significant impact on the responses in activity detected.

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Performance Assessment of General Circulation Model in Simulating Daily Precipitation and Temperature Using Multiple Gridded Datasets

Water ◽

10.3390/w10121793 ◽

2018 ◽

Vol 10 (12) ◽

pp. 1793 ◽

Cited By ~ 34

Author(s):

Najeebullah Khan ◽

Shamsuddin Shahid ◽

Kamal Ahmed ◽

Tarmizi Ismail ◽

Nadeem Nawaz ◽

...

Keyword(s):

General Circulation ◽

Coupled Model ◽

Circulation Model ◽

General Circulation Models ◽

Daily Maximum ◽

Gridded Data ◽

Max Planck ◽

Meteorological Forcing ◽

Temperature And Precipitation ◽

Feature Selection Approach

The performance of general circulation models (GCMs) in a region are generally assessed according to their capability to simulate historical temperature and precipitation of the region. The performance of 31 GCMs of the Coupled Model Intercomparison Project Phase 5 (CMIP5) is evaluated in this study to identify a suitable ensemble for daily maximum, minimum temperature and precipitation for Pakistan using multiple sets of gridded data, namely: Asian Precipitation–Highly-Resolved Observational Data Integration Towards Evaluation (APHRODITE), Berkeley Earth Surface Temperature (BEST), Princeton Global Meteorological Forcing (PGF) and Climate Prediction Centre (CPC) data. An entropy-based robust feature selection approach known as symmetrical uncertainty (SU) is used for the ranking of GCM. It is known from the results of this study that the spatial distribution of best-ranked GCMs varies for different sets of gridded data. The performance of GCMs is also found to vary for both temperatures and precipitation. The Commonwealth Scientific and Industrial Research Organization, Australia (CSIRO)-Mk3-6-0 and Max Planck Institute (MPI)-ESM-LR perform well for temperature while EC-Earth and MIROC5 perform well for precipitation. A trade-off is formulated to select the common GCMs for different climatic variables and gridded data sets, which identify six GCMs, namely: ACCESS1-3, CESM1-BGC, CMCC-CM, HadGEM2-CC, HadGEM2-ES and MIROC5 for the reliable projection of temperature and precipitation of Pakistan.

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Net effect of the QBO in a chemistry climate model

Atmospheric Chemistry and Physics ◽

10.5194/acp-8-6505-2008 ◽

2008 ◽

Vol 8 (21) ◽

pp. 6505-6525 ◽

Cited By ~ 11

Author(s):

H. J. Punge ◽

M. A. Giorgetta

Keyword(s):

General Circulation ◽

Climate Models ◽

Climate Model ◽

Middle Atmosphere ◽

Meridional Circulation ◽

Vortex Formation ◽

General Circulation Models ◽

Quasi Biennial Oscillation ◽

The Mean ◽

The Tropics

Abstract. The quasi-biennial oscillation (QBO) of zonal wind is a prominent mode of variability in the tropical stratosphere. It affects not only the meridional circulation and temperature over a wide latitude range but also the transport and chemistry of trace gases such as ozone. Compared to a QBO less circulation, the long-term climatological means of these quantities are also different. These climatological net effects of the QBO can be studied in general circulation models that extend into the middle atmosphere and have a chemistry and transport component, so-called Chemistry Climate Models (CCMs). In this work we show that the CCM MAECHAM4-CHEM can reproduce the observed QBO variations in temperature and ozone mole fractions when nudged towards observed winds. In particular, it is shown that the QBO signal in transport of nitrogen oxides NOx plays an important role in reproducing the observed ozone QBO, which features a phase reversal slightly below the level of maximum of the ozone mole fraction in the tropics. We then compare two 20-year experiments with the MAECHAM4-CHEM model that differ by including or not including the QBO. The mean wind fields differ between the two model runs, especially during summer and fall seasons in both hemispheres. The differences in the wind field lead to differences in the meridional circulation, by the same mechanism that causes the QBO's secondary meridional circulation, and thereby affect mean temperatures and the mean transport of tracers. In the tropics, the net effect on ozone is mostly due to net differences in upwelling and, higher up, the associated temperature change. We show that a net surplus of up to 15% in NOx in the tropics above 10 hPa in the experiment that includes the QBO does not lead to significantly different volume mixing ratios of ozone. We also note a slight increase in the southern vortex strength as well as earlier vortex formation in northern winter. Polar temperatures differ accordingly. Differences in the strength of the Brewer-Dobson circulation and in further trace gas concentrations are analysed. Our findings underline the importance of a representation of the QBO in CCMs.

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Hadley Cell Widening: Model Simulations versus Observations

Journal of Climate ◽

10.1175/2008jcli2620.1 ◽

2009 ◽

Vol 22 (10) ◽

pp. 2713-2725 ◽

Cited By ~ 227

Author(s):

Celeste M. Johanson ◽

Qiang Fu

Keyword(s):

Twentieth Century ◽

General Circulation ◽

Large Scale ◽

General Circulation Models ◽

Hadley Cell ◽

Climate Projections ◽

The West ◽

Model Simulations ◽

Stratospheric Cooling ◽

Future Climate Projections

Abstract Observations show that the Hadley cell has widened by about 2°–5° since 1979. This widening and the concomitant poleward displacement of the subtropical dry zones may be accompanied by large-scale drying near 30°N and 30°S. Such drying poses a risk to inhabitants of these regions who are accustomed to established rainfall patterns. Simple and comprehensive general circulation models (GCMs) indicate that the Hadley cell may widen in response to global warming, warming of the west Pacific, or polar stratospheric cooling. The combination of these factors may be responsible for the recent observations. But there is no study so far that has compared the observed widening to GCM simulations of twentieth-century climate integrated with historical changes in forcings. Here the Hadley cell widening is assessed in current GCMs from historical simulations of the twentieth century as well as future climate projections and preindustrial control runs. The authors find that observed widening cannot be explained by natural variability. This observed widening is also significantly larger than in simulations of the twentieth and twenty-first centuries. These results illustrate the need for further investigation into the discrepancy between the observed and simulated widening of the Hadley cell.

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