Two questions motivated this study: 1) Will meteorological droughts become more frequent and severe during the twenty-first century? 2) Given the projected global temperature rise, to what extent does the inclusion of temperature (in addition to precipitation) in drought indicators play a role in future meteorological droughts? To answer, we analyzed the changes in drought frequency, severity, and historically undocumented extreme droughts over 1981–2100, using the standardized precipitation index (SPI; including precipitation only) and standardized precipitation-evapotranspiration index (SPEI; indirectly including temperature), and under two representative concentration pathways (RCP4.5 and RCP8.5). As input data, we employed 103 high-resolution (0.44°) simulations from the Coordinated Regional Climate Downscaling Experiment (CORDEX), based on a combination of 16 global circulation models (GCMs) and 20 regional circulation models (RCMs). This is the first study on global drought projections including RCMs based on such a large ensemble of RCMs. Based on precipitation only, ~15% of the global land is likely to experience more frequent and severe droughts during 2071–2100 versus 1981–2010 for both scenarios. This increase is larger (~47% under RCP4.5, ~49% under RCP8.5) when precipitation and temperature are used. Both SPI and SPEI project more frequent and severe droughts, especially under RCP8.5, over southern South America, the Mediterranean region, southern Africa, southeastern China, Japan, and southern Australia. A decrease in drought is projected for high latitudes in Northern Hemisphere and Southeast Asia. If temperature is included, drought characteristics are projected to increase over North America, Amazonia, central Europe and Asia, the Horn of Africa, India, and central Australia; if only precipitation is considered, they are found to decrease over those areas.

The Mediterranean Basin is one of the regions that shall be affected most by the impacts of the future climate changes on hydrology and water resources. In this study, projected future changes in mean air temperature and precipitation climatology and inter‐annual variability over the Mediterranean region were studied. For performing this aim, the future changes in annual and seasonal averages for the future period of 2070–2100 with respect to the period from 1970 to 2000 were investigated. Global climate model outputs of the World Climate Research Program's Coupled Model Intercomparison Project Phase 3 multi‐model dataset were used in this work. Intergovernmental Panel on Climate Change SRES A2, A1B and B1 emission scenarios' outputs were used in future climate model projections. Future surface mean air temperatures of the larger Mediterranean basin increase mostly in summer and least in winter, and precipitation amounts decrease in all seasons at almost all parts of the basin. Future climate signals for air temperature and total precipitation values are much larger than the inter‐model standard deviation. Inter‐annual temperature variability increases evidently in summer season and decreases in the northern part of the domain in the winter season, while precipitation variability increases in almost all parts of domain. Probability distribution functions are found to be shifted and flattened for future period compared to the reference period. This indicates that the occurrence of frequency and intensity of high temperatures and heavy precipitation events will likely increase in the future period.

We study the reversible aggregation of polystyrene latex spheres (PLS) in one phase mixtures of 2,6 lutidine plus water at temperatures and solvent compositions near the solvent mixture's critical point. The aggregation occurs only on the side of the critical composition rich in the liquid component which is nonpreferred when the system is in the solvent s two-phase region. The liquid that is preferred can be changed by changing the surface charge density of the PLS. The aggregation region extends to temperatures well beyond the wetting temperature, and dynamic light scattering shows no evidence of a thick layer building up on individual particles before they join aggregates.

It is well-known that the fraction of cadmium salt incorporated into arachidic acid Langmuir−Blodgett (LB) films deposited from a dilute CdCl2 subphase increases from 0 to 1 over the pH range of about 4.8 to 6.2. We report a systematic change in the surface morphology of such LB multilayers over this pH range using atomic force microscopy (AFM). At pH ≤ 5.0 (low pH) the surface displays increasing coverage of stripes (ridges), 0.6 ± 0.2 nm above the surrounding area, aligned in the dipping direction. At pH = 5.8 (high pH), the surface is pockmarked with irregular but compact indentations about 1.2 ± 0.3 nm deep (in addition to numerous monolayer and bilayer deep holes). At intermediate pH values, the surface is covered by alternating bands (perpendicular to the dipping direction) of the low- and high-pH textures. These bands represent an example of “substrate-mediated condensation”. When films are soaked in benzene, dissolving away the free acid, ridges 2−2.5 nm high remain in the low-pH films; however, structures 5−6 nm high remain in the high-pH structure. Also, the low-pH structure is easily damaged by AFM scanning, while the high-pH structure is more robust and molecular resolution images are obtained. This implies that, at low pH, correlations are only within the top monolayer; however, at high pH, structures are correlated with those in the neighboring layer.

We have observed the surface-pressure driven flow of an arachidic ͑eicosanoic͒ acid Langmuir monolayer through a narrow channel using Brewster angle microscopy. By following distinctive features of the monolayer domain morphology we determined the velocity profile across the channel for various values of surface pressure over a wide range of flow rates. At low surface pressure within the L 2 mesophase, the velocity profile is parabolic for low flow rates. This implies that the surface viscosity dominates the coupling to the aqueous subphase as a source of dissipation and that the monolayer behaves as a Newtonian fluid. At extremely high shear rates, a flattened velocity profile is observed, similar to plug flow. At higher surface pressure (у20 mN/m) the velocity profile is again parabolic for low flow rates. However, as the flow rate is increased the velocity profile is observed to gradually sharpen, eventually becoming triangular. The critical shear rate for the onset of this flow profile is 0.2 s Ϫ1 . In a typical fluid, such a profile would indicate shear thickening. However, measurement of the surface pressure drop along the channel versus flow rate indicates that macroscopic surface viscosity actually decreases with shear rate in this regime. The sharp change in interfacial rheology at ϭ20 mN/m suggests the presence of a monolayer phase transition. ͓S1063-651X͑97͒14409-9͔

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The Coordinated Regional Climate Downscaling Experiment (CORDEX) is a framework designed to coordinate international efforts on regional climate simulations. CORDEX domains encompass the majority of land areas of the world. Region 8 of the CORDEX basically covers Central Asia, with the corners of the domain at 54. 76°N, 11.05°E; 56.48°N, 139.13°E; 18.34°N, 42.41°E; and 19.39°N, 108.44°E and with a horizontal resolution of 50 km. In the present study, the results of an experiment with the ICTP regional climate RegCM 4.0 model that was run for seasonal mean air temperature and precipitation total series are presented. The experiment consists of one simulation from 1989 to 2010 using ERA-Interim reanalysis data as the boundary condition, another simulation for the period 1970−2000 using the global climate model ECHAM5 A1B scenario data for forcing, and finally a simulation for the period 2070−2100 using the ECHAM5 A1B scenario projection data for forcing. Between these 3 simulations we determined the temperature and precipitation climatology obtained from RegCM 4.0 downscaling for Region 8 of the CORDEX framework. In spite of the diverse topography of the region, the temperature and precipitation climatology obtained by RegCM 4.0 from hindcast data captures the general characteristics of the climate of Central Asia. In winter, the warm temperature bias of the forcing data is slightly decreased by regional downscaling. The influences of the Indian monsoon system are well represented, as this region covers a large area towards the southern boundary of Region 8, even though the focus of this work was to capture the general characteristics of the whole region.