Faculty Opinions recommendation of Highly variable Northern Hemisphere temperatures reconstructed from low- and high-resolution proxy data.

The spectral composition of temporal variations in the Northern Hemisphere mean surface air temperature is estimated and compared in 2000-year paleoclimatic reconstructions. Continuous wavelet transforms of these reconstructions are used for the stable estimation of energy spectra. It is found that low-frequency parts of the spectra (the periods of temperature variations of more than 100 years) based on such high-resolution paleoclimatic indicators as tree rings, corals, etc., are similar to the spectrum of white noise, that is never observed in nature. This seems unrealistic. The famous reconstruction called “Hockey Stick” is among such unrealistic reconstructions. Reconstructions based not only on high-resolution but also on low-resolution indicators seem to be more realistic, since the low-frequency parts of their spectra have the pattern of red noise. They include the “Boomerang” reconstruction showing that some warm periods close to the present-day one were observed in the past.

Download Full-text

VARDA (VArved sediments DAtabase) – providing and connecting proxy data from annually laminated lake sediments

10.5194/essd-2020-55 ◽

2020 ◽

Author(s):

Arne Ramisch ◽

Alexander Brauser ◽

Mario Dorn ◽

Cecile Blanchet ◽

Brian Brademann ◽

...

Keyword(s):

High Resolution ◽

Lake Sediments ◽

Climate Models ◽

Detailed Comparison ◽

High Temporal Resolution ◽

Proxy Data ◽

Varved Sediments ◽

Proxy Records ◽

Data Compilation ◽

Varved Lake Sediments

Abstract. Varved lake sediments provide long climatic records with high temporal resolution and low associated age uncertainty. Robust and detailed comparison of well-dated and annually laminated sediment records is crucial for reconstructing abrupt and regionally time-transgressive changes as well as validation of spatial and temporal trajectories of past climatic changes. The VARved sediments DAtabase (VARDA) presented here is the first data compilation for varve chronologies and associated palaeoclimatic proxy records. The current version 1.0 allows detailed comparison of published varve records from 95 lakes. VARDA is freely accessible and was created to assess outputs from climate models with high-resolution terrestrial palaeoclimatic proxies. VARDA additionally provides a technical environment that enables to explore the database of varved lake sediments using a connected data-model and can generate a state-of-the-art graphic representation of multi-site comparison. This allows to reassess existing chronologies and tephra events to synchronize and compare even distant varved lake records. Furthermore, the present version of VARDA permits to explore varve thickness data. In this paper, we report in detail on the data mining and compilation strategies for the identification of varved lakes and assimilation of high-resolution chronologies as well as the technical infrastructure of the database. Additional paleoclimate proxy data will be provided in forthcoming updates. The VARDA graph-database and user interface can be accessed online at https://varve.gfz-potsdam.de, all datasets of version 1.0 are available at http://doi.org/10.5880/GFZ.4.3.2019.003 (Ramisch et al., 2019).

Download Full-text

High Resolution Spectroscopy of Symbiotic Stars

International Astronomical Union Colloquium ◽

10.1017/s0252921100069062 ◽

1990 ◽

Vol 122 ◽

pp. 444-445

Author(s):

Hugo E. Schwarz ◽

Hilmar W. Duerbeck ◽

Waltraut C. Seitter

Keyword(s):

High Resolution ◽

Southern Hemisphere ◽

Northern Hemisphere ◽

High Resolution Spectroscopy ◽

Symbiotic Stars ◽

Current Interest ◽

Echelle Spectrograph ◽

La Palma ◽

Recurrent Nova ◽

The Uk

A high resolution spectroscopy survey of symbiotic stars is conducted in the southern hemisphere by the authors, using the Coudé Echelle Spectrograph (CES), equipped with a CCD at the ESO Coudé Auxiliary Telescope (CAT), and concurrently in the northern hemisphere by Bode, Evans, Meaburn and collaborators, using the UK facilities at La Palma. So far, more than 400 spectra of about 70 stars have been obtained, mostly during 1988 and 1989. The southern part of the work will be described below.The discussion of symbiotic stars in the context of novae is not far-fetched. A number of symbiotics are known to have nova-like outbursts, and several novae are not easily distinguished from symbiotic stars. A noteworthy example is the most recently recognized recurrent nova, V745 Sco, first observed by Liller on July 24, 1989. It is described here, both because in late decline it represents a link between novae and symbiotic stars, and because of its current interest.

Download Full-text

A 300-Year High-Resolution Greenland Ice Record of Large-Scale Atmospheric Pollution by Arsenic in the Northern Hemisphere

Environmental Science & Technology ◽

10.1021/acs.est.9b01805 ◽

2019 ◽

Vol 53 (22) ◽

pp. 12999-13008 ◽

Cited By ~ 3

Author(s):

Khanghyun Lee ◽

Changhee Han ◽

Sang-Bum Hong ◽

Seong-Joon Jun ◽

Yeongcheol Han ◽

...

Keyword(s):

High Resolution ◽

Northern Hemisphere ◽

Atmospheric Pollution ◽

Large Scale

Download Full-text

Evaluation of a Unique Approach to High-Resolution Climate Modelling using the Model for Prediction Across Scales (MPAS) version 5.1

10.5194/gmd-2019-34 ◽

2019 ◽

Author(s):

Allison C. Michaelis ◽

Gary M. Lackmann ◽

Walter A. Robinson

Keyword(s):

Climate Change ◽

High Resolution ◽

Sea Ice ◽

Northern Hemisphere ◽

General Circulation ◽

Southern Oscillation ◽

Spatial Scales ◽

General Circulation Models ◽

Climate Modelling ◽

Northern Hemispheric

Abstract. We present multi-seasonal simulations representative of present-day and future thermodynamic environments using the global Model for Prediction Across Scales-Atmosphere (MPAS) version 5.1 with high resolution (15 km) throughout the Northern Hemisphere. We select ten simulation years with varying phases of El Niño-Southern Oscillation (ENSO) and integrate each for 14.5 months. We use analysed sea surface temperature (SST) patterns for present-day simulations. For the future climate simulations, we alter present-day SSTs by applying monthly-averaged temperature changes derived from a 20-member ensemble of Coupled Model Intercomparison Project Phase 5 (CMIP5) general circulation models (GCMs) following the Representative Concentration Pathway (RCP) 8.5 emissions scenario. Daily sea ice fields, obtained from the monthly-averaged CMIP5 ensemble mean sea ice, are used for present-day and future simulations. The present-day simulations provide a reasonable reproduction of large-scale atmospheric features in the Northern Hemisphere such as the wintertime midlatitude storm tracks, upper-tropospheric jets, and maritime sea-level pressure features as well as annual precipitation patterns across the tropics. The simulations also adequately represent tropical cyclone (TC) characteristics such as strength, spatial distribution, and seasonal cycles for most of Northern Hemispheric basins. These results demonstrate the applicability of these model simulations for future studies examining climate change effects on various Northern Hemispheric phenomena, and, more generally, the utility of MPAS for studying climate change at spatial scales generally unachievable in GCMs.

Download Full-text

The Baseline Metrology System of the USNO Astrometric Interferometer

Symposium - International Astronomical Union ◽

10.1017/s007418090010751x ◽

1994 ◽

Vol 158 ◽

pp. 174-176 ◽

Cited By ~ 1

Author(s):

Nicholas M. Elias ◽

Donald J. Hutter

Keyword(s):

High Resolution ◽

Northern Hemisphere ◽

Three Dimensional ◽

Optical Interferometer ◽

Laser Metrology ◽

Under Construction ◽

Metrology System ◽

Better Than

The USNO Astrometric Interferometer (USNOAI; a subarray of the Navy Prototype Optical Interferometer at Lowell Observatory) is presently under construction and expected to begin limited operations within a year. The main goal of the USNOAI observations is to provide a northern hemisphere catalog of several thousand stars with positions known to a few mas. In order to meet this requirement, a baseline laser metrology system must be employed to measure the three-dimensional motions of the baselines with an accuracy better than ~ 0.1 μm. The metrology scheme, as presently conceived, represents the largest and most complex high-resolution laser metrology system ever attempted.

Download Full-text