A call for new approaches to quantifying biases in observations of sea-surface temperature

Global surface-temperature changes are a fundamental expression of climate change. Recent, much-debated, variations in the observed rate of surface-temperature change have highlighted the importance of uncertainty in adjustments applied to sea-surface temperature (SST) measurements. These adjustments are applied to compensate for systematic biases and changes in observing protocol. Better quantification of the adjustments and their uncertainties would increase confidence in estimated surface-temperature change and provide higher- quality gridded SST fields for use in many applications. Bias adjustments have been based either on physical models of the observing processes or on the assumption of an unchanging relationship between SST and a reference data set such as night marine air temperature. These approaches produce similar estimates of SST bias on the largest space and timescales, but regional differences can exceed the estimated uncertainty. We describe challenges to improving our understanding of SST biases. Overcoming these will require clarification of past observational methods, improved modeling of biases associated with each observing method, and the development of statistical bias estimates that are less sensitive to the absence of metadata regarding the observing method. New approaches are required that embed bias models, specific to each type of observation, within a robust statistical framework. Mobile platforms and rapid changes in observation type require biases to be assessed for individual historic and present-day platforms (i.e., ships or buoys) or groups of platforms. Lack of observational metadata and of high-quality observations for validation and bias model development are likely to remain major challenges

India 1794

Hand colored engraved map. Relief shown pictorially. Includes statement by Andrew Dury to the directors of the East India Company. Prime meridians: Greenwich and Calcutta.Color

Africa 1798

F.d.A G. Ephem, III B. 1st 1799. Taken from the German edition: "Travels in the interior districts of Africa" by Mungo ParkColor1:22,000,00

India 1794

Calcutta meridian.Grayscale

Kiri mr. Booth'ile

Rennell, James, 1742-1830, inglise geograafSoovib laenata kapten Franklini teos

Bengal and Bahar 1779 1922

Original version: [London] : Rennell, 1779.Color

Charte von Ost-Indien : nach des Major J. Rennels General-Charte von 1782

verjüngt gezeichnet von D.F. SotzmannTitelkartusche mit figürlicher Staffage unten rechts. - Maßstableiste oben rechts (Maßstab in graph. Form (Ordinäre Teutsche Meilen, Englische Meilen

INDOSTAN (Península). NE. Mapas generales (1786). 1:1550000

Comprende lo que ocupa actualmente la parte noreste de la India y BangladeshDedicatoria: "To John Stables Esqr. one of the Supreme Council of Bengal. This Map, Engraved from the Original Drawing on the same scale in the Possession of the Honble. East India Company (communicated by him to the late Mr. Dury) is respectfully Inscribed by His obliged and obedient Servant Willm. Faden"Escala gráfica de 100 millas británicas [= 10'4 cm]. Coordenadas referidas además al meridiano de Calcuta (E 9°00'--E 4°50'). Red geográfica de 2° en 2°. Orientado con media lisOrografía de perfilRelación de la división provincial de las posesiones británicas en la península, indicadas por clave cromáticaEn nota se indican los mapas que se han tomado como referencia para trazar algunas carreterasTítulo, autor y editor en cartela con alegoría del Gange

Bengala (India) (Provincia). Mapas generales. 1779

Orientado con lisMárgenes graduadosMeridiano de origen: CalcutaRelieve por montes de perfil y sombreadoRed hidrográfica y de caminosArboladoDivisiones administrativas diferencidas por colorClave por símbolosToponimia abuntanteEn el ángulo superior derecho: Nº IXCopia digital. Madrid : Ministerio de Cultura, 2010En el margen superior del mapa: "Bengal and Bahar