Redistribution of meridional atmospheric energy transport caused by polar amplification on an aqua planet

This thesis analyses the alterations of vertically integrated atmospheric meridional energy transport due to polar amplification on an aqua planet. We analyse the energy transport of sensible heat, latent energy, potential energy and kinetic energy. We also cover the energy flux of the mean meridional circulation, transient eddies and stationary eddies. In addition, we also address the response of the zonal mean air temperature, zonal mean zonal wind, zonal mean meridional wind, zonal mean stream function and zonal mean specific humidity. Numerical model experiments were carried out with OpenIFS in its aqua planet configuration. A control (CTRL) and a polar amplification (PA) simulation was set up forced by different SST (sea surface temperature) patterns. We detected tropospheric warming and atmospheric specific humidity increase 15-90° N/S and reduction of the meridional temperature gradient throughout the troposphere. We also found reduced strength of the subtropical jet stream and slowdown of the mean meridional circulation. Important changes were identified in the Hadley cell: the rising branch shifted poleward and caused reduced lifting in equatorial areas. Regarding the total atmospheric vertically integrated meridional energy transport, we found reduction in case of the mean meridional circulation and transient eddies in all latitudes. The largest reduction was shown by the Hadley cell transport (-15%) and by midlatitude transient eddy flux (-23%). Unlike most studies, we did not observe that meridional latent energy transport increases by polar amplification. Therefore, it is stated that the increased moisture content of the atmosphere does not imply increased meridional latent energy transport, and hence there is no compensation for the decrease of meridional dry static energy transport. Lastly, we did not detect stationary eddies in our simulations which is caused by the simplified surface boundary (i.e. the water-covered Earth surface). The main finding of this thesis is that polar amplification causes decreasing poleward energy transport on an aqua planet

Assessment of the Urban Impact on Surface and Screen-Level Temperature in the ALADIN-Climate Driven SURFEX Land Surface Model for Budapest

Land surface models with detailed urban parameterization schemes provide adequate tools to estimate the impact of climate change in cities, because they rely on the results of the regional climate model, while operating on km scale at low cost. In this paper, the SURFEX land surface model driven by the evaluation and control runs of ALADIN-Climate regional climate model is validated over Budapest from the aspect of urban impact on temperature. First, surface temperature of SURFEX with forcings from ERA-Interim driven ALADIN-Climate was compared against the MODIS land surface temperature for a 3-year period. Second, the impact of the ARPEGE global climate model driven ALADIN-Climate was assessed on the 2 m temperature of SURFEX and was validated against measurements of a suburban station for 30 years. The spatial extent of surface urban heat island (SUHI) is exaggerated in SURFEX from spring to autumn, because the urbanized gridcells are generally warmer than their rural vicinity, while the observed SUHI extent is more variable. The model reasonably simulates the seasonal means and diurnal cycle of the 2 m temperature in the suburban gridpoint, except summer when strong positive bias occurs. However, comparing the two experiments from the aspect of nocturnal UHI, only minor differences arose. The thorough validation underpins the applicability of SURFEX driven by ALADIN-Climate for future urban climate projections.Peer reviewe

Excitation of mixed Rossby-gravity waves by wave-mean flow interactions on the sphere

The equatorial mixed Rossby-gravity wave (MRGW) is an important contributor to tropical variability. Its excitation mechanism capable of explaining the observed MRGW variance peak at synoptic scales remains elusive. This study investigates wave-mean flow interactions as a generation process for the MRGWs using the barotropic version of the global Transient Inertia-Gravity And Rossby wave dynamics model (TIGAR), which employs Hough harmonics as the basis of spectral expansion, thereby representing MRGWs as prognostic variables. High accuracy numerical simulations manifest that interactions between waves emanating from a tropical heat source and zonal mean jets in the subtropics generate MRGWs with the variance spectra resembling the one observed in the tropical troposphere. Quantification of spectral tendencies associated with the MRGW energy growth underscores the significance of wave-mean flow interactions in comparison to excitation mechanisms driven by external forcing and wave-wave interactions. The MRGW growth and amplitude depend on the asymmetry in the zonal mean flow that may explain not only seasonal variability but also differences between the troposphere and the middle atmosphere.Comment: 20 pages, 13 figures, 1 table, submitted to Quarterly Journal of the Royal Meteorological Societ

Numerical modelling for analysis of the effect of different urban green spaces on urban heat load patterns in the present and in the future

This paper focuses on urban green spaces in terms of climate and human thermal comfort containing their effect on heat load mitigation. It incorporates a modelling study in which the role of green spaces was investigated in terms of heat stress modification by applying MUKLIMO_3 model. During the experiment, the thermal effects of dense trees, scattered trees, grasslands and mixed green infrastructure has been investigated in the case of Szeged (Hungary) and assessed using different climate indices. The investigations encompassed 3 climatological time periods (1981-2010, 2021-2050 and 2071-2100) and two emission scenarios for future climate (RCP4.5 and RCP8.5). It was found that urban green spaces (e.g. parks) generally cool the environment, although, the cooling potential of the different green types differs. The highest reduction of heat load was found in the case of large urban parks comprising of dense trees near the downtown. The spatial extension of detected cooling was found small. However, it would increase during the future, especially in the case of grasslands. For urban planners, it is highly recommended to introduce new green sites within a city and to increase the spatial extension of the existing ones to mitigate and adapt to the impacts of climate change in the urban environment.Peer reviewe

Estrogens regulate neuroinflammatory genes via estrogen receptors α and β in the frontal cortex of middle-aged female rats

ABSTRACT: BACKGROUND: Estrogens exert anti-inflammatory and neuroprotective effects in the brain mainly via estrogen receptors alpha (ERalpha) and beta (ERbeta). These receptors are members of the nuclear receptor superfamily of ligand-dependent transcription factors. This study was aimed at the elucidation of the effects of ERalpha and ERbeta agonists on the expression of neuroinflammatory genes in the frontal cortex of aging female rats. METHODS: To identify estrogen-responsive immunity/inflammation genes, we treated middle-aged, ovariectomized rats with 17beta-estradiol (E2), ERalpha agonist 16alpha-lactone-estradiol (16alpha-LE2) and ERbeta agonist diarylpropionitrile (DPN), or vehicle by Alzet minipump delivery for 29 days. Then we compared the transcriptomes of the frontal cortex of estrogen-deprived versus ER agonist-treated animals using Affymetrix Rat230 2.0 expression arrays and TaqMan-based quantitative real-time PCR. Microarray and PCR data were evaluated by using Bioconductor packages and the RealTime StatMiner software, respectively. RESULTS: Microarray analysis revealed the transcriptional regulation of 21 immunity/inflammation genes by 16alpha-LE2. The subsequent comparative real-time PCR study analyzed the isotype specific effects of ER agonists on neuroinflammatory genes of primarily glial origin. E2 regulated the expression of sixteen genes, including down-regulation of complement C3 and C4b, Ccl2, Tgfb1, macrophage expressed gene Mpeg1, RT1-Aw2, Cx3cr1, Fcgr2b, Cd11b, Tlr4 and Tlr9, and up-regulation of defensin Np4 and RatNP-3b, IgG-2a, Il6 and ER gene Esr1. Similar to E2, both 16alpha-LE2 and DPN evoked up-regulation of defensins, IgG-2a and Il6, and down-regulation of C3 and its receptor Cd11b, Ccl2, RT1-Aw2 and Fcgr2b. CONCLUSIONS: These findings provide evidence that E2, 16alpha-LE2 and DPN modulate the expression of neuroinflammatory genes in the frontal cortex of middle-aged female rats via both ERalpha and ERbeta. We propose that ERbeta is a promising target to suppress regulatory functions of glial cells in the E2-deprived female brain and in various neuroinflammatory diseases

Palladium-catalyzed diaminocarbonylation: synthesis of androstene dimers containing 3,3’ - or 17,17’-dicarboxamide spacers

Novel androstene-based dimers linked through A- and D-ring with 3,3′- and 17,17′-dicarboxamide spacers, were synthesized via palladium-catalyzed aminocarbonylation. Androstane derivatives possessing either 3-iodo-3,5-diene or 17-iodo-16-ene functionality were used as substrates in the presence of palladium-phosphine in situ catalysts and aliphatic and aromatic diamines as N-nucleophiles. Since androst-4-ene-3,17-dione was used as starting material, a multistep synthesis including protection/deprotection of one of the keto functionalities (3-one or 17-one) as ethylene ketals, transformation of the other keto group to iodoalkene functionality via its hydrazone, and palladium-catalyzed aminocarbonylation of the iodoalkene functionality was used. In this way, new dimeric compounds possessing a keto functionality were obtained in moderate-to-good isolated yields, via highly chemoselective reactions, under relatively mild conditions