Exploring the ingredients required to successfully model the placement, generation, and evolution of ice streams in the British-Irish Ice Sheet

Ice stream evolution is a major uncertainty in projections of the future of the Greenland and Antarctic Ice sheets. Accurate simulation of ice stream evolution requires an understanding of a number of “ingredients” that control the location and behaviour of ice stream flow. Here, we test the influence of geothermal heat flux, grid resolution, and bed hydrology on simulated ice streaming. The palaeo-record provides snapshots of ice stream evolution, with a particularly well constrained ice sheet being the British-Irish Ice Sheet (BIIS). We implement a new basal sliding scheme coupled with thermo-mechanics into the BISICLES ice sheet model, to simulate the evolution of the BIIS ice streams. We find that the simulated location and spacing of ice streams matches well with the empirical reconstructions of ice stream flow in terms of position and direction when simple bed hydrology is included. We show that the new basal sliding scheme allows the accurate simulation for the majority of BIIS ice streams. The extensive empirical record of the BIIS has allowed the testing of model inputs, and has helped demonstrate the skill of the ice sheet model in simulating the evolution of the location, spacing, and migration of ice streams through millennia. Simulated ice streams also prompt new empirical mapping of features indicative of streaming in the North Channel region. Ice sheet model development has allowed accurate simulation of the palaeo record, and allows for improved modelling of future ice stream behaviour

Biological flora of Central europe: Baldellia ranunculoides (Alismataceae)

Baldellia ranunculoides (L.) Parl. (Alismataceae) is a taxonomically problematic aquatic plant with an historically ill-defined distribution and global conservation status. This paper finds morphological, ecological and molecular evidence for two distinct taxa, probably best described as subspecies: (1) B. ranunculoides subsp. ranunculoides and (2) B. ranunculoides subsp. repens and provides detailed distribution data on their overlapping range, in different habitats, across the cool, high rainfall areas of western Europe and west Mediterranean. The two subspecies are amongst the relatively large number of threatened European and north Africa aquatic plants and this paper provides a systematic review of their relative conservation pressures and management needs, with particular emphasis on the status of both taxa in central Europe. Other observations indicate probable evolutionary relationships within B. ranunculoides s.l. and its associated taxa and the review points out where these and other research topics could potentially be pursued

Strandlingsgesellschaften seichter Gewässer in Irland (Littorelletea) : Arbeiten aus dem Botanischen Institut der Universität Nijmengen, Niederlande

von Margarita Schoof-van Pelt und V. Westhof

Strandlingsgesellschaften seichter Gewässer in Irland (Littorelletea) : Arbeiten aus dem Botanischen Institut der Universität Nijmengen, Niederlande

von Margarita Schoof-van Pelt und V. Westhof

Dynamic Response of a High Arctic Glacier to Melt and Runoff Variations

The dynamic response of High Arctic glaciers to increased runoff in a warming climate remains poorly understood. We analyze a 10-year record of continuous velocity data collected at multiple sites on Nordenskiöldbreen, Svalbard, and study the connection between ice flow and runoff within and between seasons. During the melt season, the sensitivity of ice motion to runoff at sites in the ablation and lower accumulation zone drops by a factor of 3 when cumulative runoff exceeds a local threshold, which is likely associated with a transition from inefficient (distributed) to efficient (channelized) drainage. Average summer (June-August) velocities are found to increase with summer ablation, while subsequent fall (September-November) velocities decrease. Spring (March-May) velocities are largely insensitive to summer ablation, which suggests a short-lived impact of summer melt on ice flow during the cold season. The net impact of summer ablation on annual velocities is found to be insignificant

Fotografía de Carmen Martín Gaite en El Boalo.

En 1960 José Martín López, padre de Carmen, compra un terreno en El Boalo (a 50 km de Madrid, al pie de la Sierra de Navacerrada), y edifica una casa con la piedra del lugar. La finca será bautizada como Los Prados y se convertirá en un lugar importantísimo para Carmen Martín Gaite, su familia y sus amigos. Será el fondo de muchas de las imágenes que componen este conjunto fotográfico.Sumario: En el vuelto de la misma aparece el sello de la tienda de fotografía con la fecha del revelado: "Aug.1978"Metodología: Esta fotografía pertenece al Sobre número 2 de la Caja número 6 de Carmen Martín Gaite titulado: "Doña Carmen, Anita con sus padres, Marta, fiesta familiar"