Monthly, seasonal and annual temperature reconstructions for Central Europe derived from documentary evidence and instrumental records since AD 1500

Monthly temperature series for Central Europe back to AD 1500 are developed from documentary index series from Germany, Switzerland and the Czech Republic (1500-1854) and 11 instrumental temperature records (1760-2007). Documentary evidence from the Low Countries, the Carpathian Basin and Poland are used for cross-checking for earlier centuries. The instrumental station records are corrected for inhomogeneities, including insufficient radiation protection of early thermometers and the urban heat island effect. For overlapping period (1760-1854), the documentary data series correlate with instrumental temperatures, most strongly in winter (86% explained variance in January) and least in autumn (56% in September). For annual average temperatures, 81% of the variance is explained. Verification statistics indicate high reconstruction skill for most months and seasons. The last 20 years (since 1988) stand out as very likely the warmest 20-year period, accounting for the calibration uncertainty and decreases in proxy data quality before the calibration period. The new reconstruction displays a previously unobserved long-term decrease in DJF, MAM and JJA temperature variability over last five centuries. Compiled monthly, seasonal and annual series can be used to improve the robustness of gridded large-scale European temperature reconstructions and possible impact studies. Further improvement of the reconstruction would be achieved if documentary data from other European countries are further developed.</p

Circulation dynamics and its influence on European and Mediterranean January-April climate over the past half millennium: results and insights from instrumental data, documentary evidence and coupled climate models

We use long instrumental temperature series together with available field reconstructions of sea-level pressure (SLP) and three-dimensional climate model simulations to analyze relations between temperature anomalies and atmospheric circulation patterns over much of Europe and the Mediterranean for the late winter/early spring (January-April, JFMA) season. A Canonical Correlation Analysis (CCA) investigates interannual to interdecadal covariability between a new gridded SLP field reconstruction and seven long instrumental temperature series covering the past 250 years. We then present and discuss prominent atmospheric circulation patterns related to anomalous warm and cold JFMA conditions within different European areas spanning the period 1760-2007. Next, using a data assimilation technique, we link gridded SLP data with a climate model (EC-Bilt-Clio) for a better dynamical understanding of the relationship between large scale circulation and European climate. We thus present an alternative approach to reconstruct climate for the pre-instrumental period based on the assimilated model simulations. Furthermore, we present an independent method to extend the dynamic circulation analysis for anomalously cold European JFMA conditions back to the sixteenth century. To this end, we use documentary records that are spatially representative for the long instrumental records and derive, through modern analogs, large-scale SLP, surface temperature and precipitation fields. The skill of the analog method is tested in the virtual world of two three-dimensional climate simulations (ECHO-G and HadCM3). This endeavor offers new possibilities to both constrain climate model into a reconstruction mode (through the assimilation approach) and to better asses documentary data in a quantitative way.</p

Typologie clonale des tissus laticifères chez l'Hevea brasiliensis

Certaines caractéristiques physiologiques du latex ont été étudiées chez 12 clones d'Hevea brasiliensis d'une plantation polyclonale. En plus des paramètres classiques : extrait sec, teneur en saccharose, phosphore minéral, magnésium, thiols, activité des phosphatases acides totales, indice d'éclatement et pH, cinq acides organiques du cytosol ont été dosés : le citrate, le malate, l'acronitate, le pyruvate et le fumarate. Les teneurs de ces cinq acides organiques sont différentes selon les clones et peuvent être utilisées comme critère de typologie. Leur signification sur le plan métabolique a été analysée. Associés aux autres paramètres, ils permettent d'établir une typologie de fonctionnement des systèmes laticifères en exploitation des différents clones étudiés. L'intensité de l'activité métabolique des laticifères caractérisant tel ou tel clone apparaît comme un facteur majeur de production. L'étude de la réponse à la stimulation de 3 clones présentant des caractéristiques très différentes permet de conforter le modèle de typologie de fonctionnement propos

Climate of the Carpathian Region in the period 1961–2010: climatologies and trends of 10 variables

The Carpathians are the largest mountain range in Europe and they represent a geographic barrier between Central Europe, Eastern Europe, and the Balkans. In order to investigate the climate of the area, the CARPATCLIM project members compiled the Climate Atlas of the Carpathian Region, which consists of high-resolution daily grids (0.1˚ x 0.1˚) of sixteen meteorological variables and many derived indicators related to 1961-2010. We computed the gridded climatologies for 1961-2010 for eight variables (air pressure, cloudiness, precipitation, relative humidity, minimum and maximum temperature, sunshine duration, and wind speed) and we discuss their spatial patterns. For each variable, we calculated the gridded linear trends related to 1961-2010 both on annual and seasonal basis. In general, temperature was found to increase in every season in 1986-2010, confirming the trends occurring in Europe in the last decades. On the other way, wind speed decreased in every season. Cloudiness and relative humidity decreased in spring, summer, and winter, and increased in autumn, whilst sunshine duration, as expected, behaved in the opposite way. Precipitation slightly increased and air pressure showed no significant trend, except of a few grid points. Then, we dealt with the correlation between the variables: excluding the high elevation points, the most correlated are sunshine duration and temperature. In particular, positive and negative sunshine duration anomalies are found to be respectively correlated with positive and negative temperature anomalies during the global dimming (60’s and 70’s) and brightening (90’s and 2000’s) periods.JRC.H.7-Climate Risk Managemen