Recent Near-surface Temperature Trends in the Antarctic Peninsula from Observed,Reanalysis and Regional Climate Model Data

This study investigates the recent near-surface temperature trends over the Antarctic Peninsula.We make use of available surface observations,ECMWF’s ERA5 and its predecessor ERA-Interim,as well as numerical simulations,allowing us to contrast different data sources.We use hindcast simulations performed with Polar-WRF over the Antarctic Peninsula on a nested domain configuration at 45 km(PWRF-45)and 15 km(PWRF-15)spatial resolutions for the period 1991?2015.In addition,we include hindcast simulations of KNMI-RACMO21P obtained from the CORDEX-Antarctica domain(~50 km)for further comparisons.Results show that there is a marked windward warming trend except during summer.This windward warming trend is particularly notable in the autumn season and likely to be associated with the recent deepening of the Amundsen/Bellingshausen Sea low and warm advection towards the Antarctic Peninsula.On the other hand,an overall summer cooling is characterized by the strengthening of the Weddell Sea low as well as an anticyclonic trend over the Amundsen Sea accompanied by northward winds.The persistent cooling trend observed at the Larsen Ice Shelf station is not captured by ERA-Interim,whereas hindcast simulations indicate that there is a clear pattern of windward warming and leeward cooling.Furthermore,larger temporal correlations and lower differences exhibited by PWRF-15 illustrate the existence of the added value in the higher spatial resolution simulation.     

Interacting Ricci-like holographic dark energy

In a flat Friedmann–Lemaitre–Robertson–Walker background, a scheme of dark matter–dark energy interaction is studied considering a holographic Ricci-like model for the dark energy. Without giving a priori some specific model for the interaction function, we show that this function can experience a change of sign during the cosmic evolution. The parameters involved in the holographic model are adjusted with Supernova data and we obtained results compatible with the observable universe.     

TiN PRODUCTION IN A GLOW DISCHARGE

We have been studying direct current glow discharges aiming at the production of different paint of coatings on steel substrates. In a set of preliminary experiments, long lasting (hours) discharges performed in a Nitrogen atmosphere between a stell anode (holding the substrates) and a titanium cathode separated by a small gap (few mm) produced very thin coatings of the substrates whose colour depend on the parameter of (interelectrodes gap, gas pressure, discharge current and time duration). In some conditions, the coatings showed a golden colour, typical of the Nti compound. A discussion of the results is given.     

Anisotropic four loop superstring cosmologies

A spatially-homogenous and anisotropic cosmological model in self-creation theory of gravitation proposed by Barber is obtained when the source of gravitational field is a perfect fluid and the metric is of Marder's cyclindrically-symmetric form. Some properties of the model are discussed.     

The inverse compton effect in the electrons of the Van Allen radiation belt

A first estimate of the energy that reaches the Earth's surface and is produced by the inverse Compton effect between the electrons in the Van Allen belt and the solar flux was made. Since in the belt there are electrons with energies between 0.5 and 7 MeV, it was possible to use the Klein-Nishina formula in an approximate form and estimate the energy that is Compton scattered by all the electrons in the Van Allen belt by using Vette, Lucero and Bright's model. The result was compared (a) with the measurements of the continuum in the regions of soft X-rays, and (b) with the energy that is produced by the trapped electrons through the synchrotron mechanism.This paper was presented at the COSPAR meeting held in leningrad on May 20–29, 1970.     

An upgraded version of the Eta model

Upgrades implemented over a number of years in an open source version of the Eta model, posted at the CPTEC web site http://etamodel.cptec.inpe.br/, are summarized and examples of benefits are shown. The version originates from the NCEP’s Workstation Eta code posted on the NCEP web site http://www.emc.ncep.noaa.gov/mmb/wrkstn_eta, which differs from the NCEP’s latest operational Eta by having the WRF-NMM nonhydrostatic option included. Most of the upgrades made resulted from attention paid to less than satisfactory performance noted in several Eta results, and identification of the reasons for the problem. Others came from simple expectation that including a feature that is physically justified but is missing in the code should help. The most notable of the upgrades are the introduction of the so-called sloping steps, or discretized shaved cells topography; piecewise-linear finite-volume vertical advection of dynamic variables; vapor and hydrometeor loading in the hydrostatic equation, and changes aimed at refining the convection schemes available in the Eta. Several other modifications have to do with the calculation of exchange coefficients, conservation in the vertical diffusion, and diagnostic calculation of 10-m winds. Several examples showing improved performance resulting from the dynamics changes are given. One includes a case of unrealistically low temperatures in several mountain basins generated by a centered vertical advection difference scheme’s unphysical advection from below ground, removed by its replacement with a finite-volume scheme. Another is that of increased katabatic winds in the Terra Nova Bay Antarctica region. Successful forecast of the severe downslope zonda wind case in the lee of the highest peaks of the Andes is also shown, and some of the recent successful verification results of the use of the upgraded model are pointed out. The code is used at numerous places, and along with setup information it is available for outside users at the CPTEC Eta web site given above.     

Downscaling of South America present climate driven by 4-member HadCM3 runs

The objective of this work is to evaluate climate simulations over South America using the regional Eta Model driven by four members of an ensemble of the UK Met Office Hadley Centre HadCM3 global model. The Eta Model has been modified with the purpose of performing long-term decadal integrations and has shown to reproduce “present climate”—the period 1961–1990—reasonably well when forced by HadCM3. The global model lateral conditions with a resolution of 2.5° latitude?×?3.75° longitude were provided at a frequency of 6?h. Each member of the global model ensemble has a different climate sensitivity, and the four members were selected to span the range of uncertainty encompassed by the ensemble. The Eta Model nested in the HadCM3 global model was configured with 40-km horizontal resolution and 38 layers in the vertical. No large-scale internal nudging was applied. Results are shown for austral summer and winter at present climate defined as 1961–90. The upper and low-level circulation patterns produced by the Eta-CPTEC/HadCM3 experiment set-up show good agreement with reanalysis data and the mean precipitation and temperature with CRU observation data. The spread in the downscaled mean precipitation and temperature is small when compared against model errors. On the other hand, the benefits in using an ensemble is clear in the improved representation of the seasonal cycle by the ensemble mean over any one realization. El Ni?o and La Ni?a years were identified in the HadCM3 member runs based on the NOAA Climate Prediction Center criterion of sea surface temperature anomalies in the Ni?o 3.4 area. The frequency of the El Ni?o and La Ni?a events in the studied period is underestimated by HadCM3. The precipitation and temperature anomalies typical of these events are reproduced by most of the Eta-CPTEC/HadCM3 ensemble, although small displacements of the positions of the anomalies occur. This experiment configuration is the first step on the implementation of Eta-CPTEC/HadCM3 upcoming experiments on climate change studies that are discussed in a companion paper.