Precipitation δ<sup>18</sup>O over the Himalaya‐Tibet orogen from ECHAM5‐wiso simulations: Statistical analysis of temperature, topography and precipitation

Ehlers, Todd A.; Li, Jingmin; Steger, Christian; Paeth, Heiko; Werner, Martin; Poulsen, Christopher J.

doi:10.1002/2016jd024856

Cited by 18 publications

(30 citation statements)

References 58 publications

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“…[] using the same resolution ECHAM5‐wiso model outputs as this study. Thus, the model resolution used in this study agrees with reanalysis data and the different reanalysis data sets agree with each other [ Mutz et al ., ]. Furthermore, our study uses a T63 resolution ECHAM5 model.…”

Section: Resultsmentioning

confidence: 99%

“…This information is important for paleoclimatology and paleoaltimetry studies when interpolating proxy data for the Tibetan Plateau. This SE to the NW direction of δ 18 O p zones and the climate controls on it have been independent of this study identified by a cluster analysis of δ 18 O p [ Mutz et al ., ]. The standard deviation ( σ ) in δ 18 O p was calculated from 90 monthly means of predicted δ 18 O p (30 simulation years × 3 month in a season).…”

Section: Resultsmentioning

confidence: 99%

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Modern precipitation δ¹⁸O and trajectory analysis over the Himalaya‐Tibet Orogen from ECHAM5‐wiso simulations

Ehlers

Steger

et al. 2016

JGR Atmospheres

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Variations in oxygen isotope ratios (δ18O) measured from modern precipitation and geologic archives provide a promising tool for understanding modern and past climate dynamics and tracking elevation changes over geologic time. In areas of extreme topography, such as the Tibetan Plateau, the interpretation of δ18O has proven challenging. This study investigates the climate controls on temporal (daily and 6 h intervals) and spatial variations in present‐day precipitation δ18O (δ18Op) across the Tibetan Plateau using a 30 year record produced from the European Centre/Hamburg ECHAM5‐wiso global atmospheric general circulation model (GCM). Results indicate spatial and temporal agreement between model‐predicted δ18Op and observations. Large daily δ18Op variations of −25 to +5‰ occur over the Tibetan Plateau throughout the 30 simulation years, along with interannual δ18Op variations of ~2‰. Analysis of extreme daily δ18Op indicates that extreme low values coincide with extreme highs in precipitation amount. During the summer, monsoon vapor transport from the north and southwest of the plateau generally corresponds with high δ18Op, whereas vapor transport from the Indian Ocean corresponds with average to low δ18Op. Thus, vapor source variations are one important cause of the spatial‐temporal differences in δ18Op. Comparison of GCM and Rayleigh Distillation Model (RDM)‐predicted δ18Op indicates a modest agreement for the Himalaya region (averaged over 86°–94°E), confirming application of the simpler RDM approach for estimating δ18Op lapse rates across Himalaya.

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Section: Resultsmentioning

confidence: 99%

Section: Resultsmentioning

confidence: 99%

Modern precipitation δ¹⁸O and trajectory analysis over the Himalaya‐Tibet Orogen from ECHAM5‐wiso simulations

Ehlers

Steger

et al. 2016

JGR Atmospheres

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“…Similarly, u-wind and v-wind speeds during (January) and outside (July) the monsoon season in South America are added to the list of considered variables to take into account the South American Monsoon System (SASM) in the cluster analysis for this region. The long-term monthly means of those variables are used in a hierarchical clustering method, followed by a non-hierarchical k-means correction with randomised regroupment (Mutz et al, 2016;Wilks, 2011;Paeth, 2004;Bahrenberg et al, 1992). The hierarchical part of the clustering procedure starts with as many clusters as there are elements (ni), then iteratively combines the most similar clusters to form a new cluster using centroids for the linkage procedure for clusters containing multiple elements.…”

Section: Cluster Analysis To Document Temporal and Spatial Changes Inmentioning

confidence: 99%

Estimates of late Cenozoic climate change relevant to Earth surface processes in tectonically active orogens

et al. 2018

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Abstract. The denudation history of active orogens is often interpreted in the context of modern climate gradients. Here we address the validity of this approach and ask what are the spatial and temporal variations in palaeoclimate for a latitudinally diverse range of active orogens? We do this using high-resolution (T159, ca. 80 × 80 km at the Equator) palaeoclimate simulations from the ECHAM5 global atmospheric general circulation model and a statistical cluster analysis of climate over different orogens (Andes, Himalayas, SE Alaska, Pacific NW USA). Time periods and boundary conditions considered include the Pliocene (PLIO, ∼ 3 Ma), the Last Glacial Maximum (LGM, ∼ 21 ka), mid-Holocene (MH, ∼ 6 ka), and pre-industrial (PI, reference year 1850). The regional simulated climates of each orogen are described by means of cluster analyses based on the variability in precipitation, 2 m air temperature, the intra-annual amplitude of these values, and monsoonal wind speeds where appropriate. Results indicate the largest differences in the PI climate existed for the LGM and PLIO climates in the form of widespread cooling and reduced precipitation in the LGM and warming and enhanced precipitation during the PLIO. The LGM climate shows the largest deviation in annual precipitation from the PI climate and shows enhanced precipitation in the temperate Andes and coastal regions for both SE Alaska and the US Pacific Northwest. Furthermore, LGM precipitation is reduced in the western Himalayas and enhanced in the eastern Himalayas, resulting in a shift of the wettest regional climates eastward along the orogen. The cluster-analysis results also suggest more climatic variability across latitudes east of the Andes in the PLIO climate than in other time slice experiments conducted here. Taken together, these results highlight significant changes in late Cenozoic regional climatology over the last ∼ 3 Myr. Comparison of simulated climate with proxy-based reconstructions for the MH and LGM reveal satisfactory to good performance of the model in reproducing precipitation changes, although in some cases discrepancies between neighbouring proxy observations highlight contradictions between proxy observations themselves. Finally, we document regions where the largest magnitudes of late Cenozoic changes in precipitation and temperature occur and offer the highest potential for future observational studies that quantify the impact of climate change on denudation and weathering rates.

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“…Despite consistent forcings, experiments carried out with different GCMs and model resolutions yield different results due to GCM specific parameterisation. Mutz et al (2018) conducted PMIP-style palaeoclimate experiments with the same GCM (ECHAM5) and resolution, which removes the GCM parameterisation related signal in the differences between simulated palaeoclimates. This experiment framework comprises climate simulations for the pre-industrial (PI, reference year 1850), Mid-Holocene (MH, ∼ 6 ka), Last Glacial Maximum (LGM, ∼ 21 ka) and Pliocene (PLIO, ∼ 3 Ma).…”

Section: Introductionmentioning

confidence: 99%

Detection and explanation of spatiotemporal patterns in Late Cenozoic palaeoclimate change relevant to Earth surface processes

Ehlers

2019

Earth Surf. Dynam.

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Abstract. Detecting and explaining differences between palaeoclimates can provide valuable insights for Earth scientists investigating processes that are affected by climate change over geologic time. In this study, we describe and explain spatiotemporal patterns in palaeoclimate change that are relevant to Earth surface scientists. We apply a combination of multivariate cluster and discriminant analysis techniques to a set of high-resolution palaeoclimate simulations. The simulations were conducted with the ECHAM5 climate model and consistent setup. A pre-industrial (PI) climate simulation serves as the control experiment, which is compared to a suite of simulations of Late Cenozoic climates, namely a Mid-Holocene (MH, approximately 6.5 ka), Last Glacial Maximum (LGM, approximately 21 ka) and Pliocene (PLIO, approximately 3 Ma) climate. For each of the study regions (western South America, Europe, South Asia and southern Alaska), differences in climate are subjected to geographical clustering to identify dominant modes of climate change and their spatial extent for each time slice comparison (PI–MH, PI–LGM and PI–PLIO). The selection of climate variables for the cluster analysis is made on the basis of their relevance to Earth surface processes and includes 2 m air temperature, 2 m air temperature amplitude, consecutive freezing days, freeze–thaw days, maximum precipitation, consecutive wet days, consecutive dry days, zonal wind speed and meridional wind speed. We then apply a two-class multivariate discriminant analysis to simulation pairs PI–MH, PI–LGM and PI–PLIO to evaluate and explain the discriminability between climates within each of the anomaly clusters. Changes in ice cover create the most distinct and stable patterns of climate change, and create the best discriminability between climates in western Patagonia. The distinct nature of European palaeoclimates is statistically explained mostly by changes in 2 m air temperature (MH, LGM, PLIO), consecutive freezing days (LGM) and consecutive wet days (PLIO). These factors typically contribute 30 %–50 %, 10 %–40 % and 10 %–30 %, respectively, to climate discriminability. Finally, our results identify regions particularly prone to changes in precipitation-induced erosion and temperature-dependent physical weathering.

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Precipitation δ¹⁸O over the Himalaya‐Tibet orogen from ECHAM5‐wiso simulations: Statistical analysis of temperature, topography and precipitation

Cited by 18 publications

References 58 publications

Modern precipitation δ¹⁸O and trajectory analysis over the Himalaya‐Tibet Orogen from ECHAM5‐wiso simulations

Modern precipitation δ¹⁸O and trajectory analysis over the Himalaya‐Tibet Orogen from ECHAM5‐wiso simulations

Estimates of late Cenozoic climate change relevant to Earth surface processes in tectonically active orogens

Detection and explanation of spatiotemporal patterns in Late Cenozoic palaeoclimate change relevant to Earth surface processes

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Precipitation δ18O over the Himalaya‐Tibet orogen from ECHAM5‐wiso simulations: Statistical analysis of temperature, topography and precipitation

Cited by 18 publications

References 58 publications

Modern precipitation δ18O and trajectory analysis over the Himalaya‐Tibet Orogen from ECHAM5‐wiso simulations

Modern precipitation δ18O and trajectory analysis over the Himalaya‐Tibet Orogen from ECHAM5‐wiso simulations

Estimates of late Cenozoic climate change relevant to Earth surface processes in tectonically active orogens

Detection and explanation of spatiotemporal patterns in Late Cenozoic palaeoclimate change relevant to Earth surface processes

Contact Info

Product

Resources

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Precipitation δ¹⁸O over the Himalaya‐Tibet orogen from ECHAM5‐wiso simulations: Statistical analysis of temperature, topography and precipitation

Modern precipitation δ¹⁸O and trajectory analysis over the Himalaya‐Tibet Orogen from ECHAM5‐wiso simulations

Modern precipitation δ¹⁸O and trajectory analysis over the Himalaya‐Tibet Orogen from ECHAM5‐wiso simulations