At King's Cross Amalia Pica’s ‘Semaphores’

Amalia Pica’s installation Semaphores, currently on display behind King’s Cross Station, consists of three brightly coloured signalling devices, one on the ground, next to the Regent’s Canal, the other two on the rooftops of nearby buildings. Candy-striped and chequered in contrasting colours, they seem made for play and nostalgia, a kind of mechanical bunting. The device at ground level is operated by passers-by. Pulling on its cables causes differently shaped and patterned discs to flip from horizontal to vertical, composing a message. It looks like a giant toy, but it also pays homage to a more distant predecessor: George Murray’s shutter semaphore system, invented in 1795, which allowed information to be sent at great speed (London could contact Portsmouth in just seven and a half minutes). A panel next to Pica’s semaphore provides the code, so that messages can be spelled out, letter by letter, although I doubt many people bother; it’s surprisingly labour-intensive. I hope some do, however, because it’s at this point that Pica’s work departs from the cheery aesthetic that characterises the regeneration zone behind King’s Cross, with its astroturf and glossy shops. Whatever message we send won’t be returned. There are no further shutter signal posts to send it down the line or reply. The three pieces in Pica’s installation are based on two distinct historical semaphore systems, operating independently of each other. The paired rooftop works, which emulate a communication system developed in France in 1792 by Claude Chappe, a former priest, speak an entirely different language

At the National Gallery

Louis-Léopold Boilly’s long life – his career began during the Ancien Régime and lasted until the final years of the July Monarchy – makes it hard not to view his work in parallel with the huge transformations that took place in French society during that period. Born near Lille in 1761, he received no formal training, but his early paintings impressed a local bishop, who arranged for him to work and study in Arras. When he arrived in Paris in 1785, Boilly specialised in cabinet paintings for private collectors. Two Young Women Kissing (c.1790), on display at the National Gallery’s small exhibition of his paintings (until 19 May), was previously catalogued as The Friends and Two Sisters, kidding absolutely nobody. These early works, heavy in innuendo and set in fashionable interiors, are far removed from the crowded Parisian street scenes that later became his stock in trade. Boilly’s concentration on frivolous or licentious topics pandering to the tastes of the Ancien Régime made him the subject of suspicion during the Terror, when he was denounced as a counter-revolutionary by a fellow artist Jean-Baptiste Wicar, and accused of making paintings that ‘dirty the walls of the Republic’. Forced to defend himself before the Société Populaire et Républicaine des Arts, Boilly was exonerated, largely due to his canny submission of a painting representing The Triumph of Marat (1794) and several other revolutionary works. It was lucky he could paint quickly

Historical analogues of the recent extreme minima observed in the Atlantic meridional overturning circulation at 26°N

Observations of the Atlantic meridional overturning circulation (AMOC) by the RAPID 26°N array show a pronounced minimum in the northward transport over the winter of 2009/10, substantially lower than any observed since the initial deployment in April 2004. It was followed by a second minimum in the winter of 2010/2011. We demonstrate that ocean models forced with observed surface fluxes reproduce the observed minima. Examining output from five ocean model simulations we identify several historical events which exhibit similar characteristics to those observed in the winter of 2009/10, including instances of individual events, and two clear examples of pairs of events which happened in consecutive years, one in 1969/70 and another in 1978/79. In all cases the absolute minimum, associated with a short, sharp reduction in the Ekman component, occurs in winter. AMOC anomalies are coherent between the Equator and 50°N and in some cases propagation attributable to the poleward movement of the anomaly in the wind field is observed. We also observe a low frequency (decadal) mode of variability in the anomalies, associated with the North Atlantic Oscillation (NAO). Where pairs of events have occurred in consecutive years we find that atmospheric conditions during the first winter correspond to a strongly negative Arctic Oscillation (AO) index. Atmospheric conditions during the second winter are indicative of a more regional negative NAO phase, and we suggest that this persistence is linked to re-emergence of sea surface temperature anomalies in the North Atlantic for the events of 1969/70 and 2009/10. The events of 1978/79 do not exhibit re-emergence, indicating that the atmospheric memory for this pair of events originates elsewhere. Observation of AO patterns associated with cold winters over northwest Europe may be indicative for the occurrence of a second extreme winter over northwest Europe