ALBERT

Beschreibung: The chemical composition of sediments from the Reykjanes Ridge is controlled by allochthonous and autochthonous processes. The surface sediments are characterized by relatively high contents of calciumoxide and strontium. Calcium and strontium dominate in the carbonate phase due to the high content of biogenic carbonate. A high percentage of iron and manganese are bound to oxides and hydroxides. An indication of hydrothermal activity was not observed. A considerable portion of adsorbed barium is transported in clay minerals. The higher amounts of aluminium in glacial sequences indicate an enhanced input of terrigenous material; the increase of stable bonding elemen~s points toward the large influence of detrital minerals. The distinct differences in the bonding characteristics of elements in these marine sediments in comparison to fluvial and coastal - deposits could be due to the different environmental conditions.

Beschreibung: The seasonal cycle over the tropical Pacific simulated by 11 coupled ocean–atmosphere general circulation models (GCMs) is examined. Each model consists of a high-resolution ocean GCM of either the tropical Pacific or near-global means coupled to a moderate- or high-resolution atmospheric GCM, without the use of flux correction. The seasonal behavior of sea surface temperature (SST) and eastern Pacific rainfall is presented for each model. The results show that current state-of-the-art coupled GCMs share important successes and troublesome systematic errors. All 11 models are able to simulate the mean zonal gradient in SST at the equator over the central Pacific. The simulated equatorial cold tongue generally tends to be too strong, too narrow, and extend too far west. SSTs are generally too warm in a broad region west of Peru and in a band near 10°S. This is accompanied in some models by a double intertropical convergence zone (ITCZ) straddling the equator over the eastern Pacific, and in others by an ITCZ that migrates across the equator with the seasons; neither behavior is realistic. There is considerable spread in the simulated seasonal cycles of equatorial SST in the eastern Pacific. Some simulations do capture the annual harmonic quite realistically, although the seasonal cold tongue tends to appear prematurely. Others overestimate the amplitude of the semiannual harmonic. Nonetheless, the results constitute a marked improvement over the simulations of only a few years ago when serious climate drift was still widespread and simulated zonal gradients of SST along the equator were often very weak.

Beschreibung: he distribution of evaporation and precipitation over the ocean (its hydrologic cycle) is one of the least understood elements of the climate system. However, it is now considered one of the most important, especially for ocean circulation changes on decadal to millennial time-scales. The ocean covers 70% of the Earth's surface and contains nearly all (97%) of its free water, thus, it plays a dominant role in the global water cycle. The atmosphere only holds a few centimeters of liquid water, or 0.001% of the total. However, most discussions of the water cycle focus on the rather small component associated with terrestrial processes [Chahine, 1992]. This is understandable, since the water cycle is so vital to agriculture and all of man's activities. Yet current estimates indicate that 86% of global evaporation and 78% of global precipitation occurs over the oceans [Baumgartner and Reichel, 1975]; (Figure 1 ). Since the oceans are the source of most rainwater, it behooves us to work toward a better understanding of the ocean hydrologic cycle; small changes in ocean evaporation and precipitation patterns may have dramatic consequences for the much smaller terrestrial water cycle. For example, if less than 1% of the rain falling on the Atlantic Ocean were to be concentrated in the central US, it would double the discharge of the Mississippi river!