Diana Rechid

Evaluation and Bias Correction of Regional Climate Model Results Using Model Evaluation Measures

AbstractFor the assessment of regional climate change the reliability of the regional climate models needs to be known. The main goal of this paper is to evaluate the quality of climate model data that are used for impact research. Temperature, precipitation, total cloud cover, relative humidity, and wind speed simulated by the regional climate models Climate Local Model (CLM) and Regional Model (REMO) are evaluated for the metropolitan region of Hamburg in northern Germany for the period 1961–2000. The same evaluation is performed for the global climate model ECHAM5 that is used to force the regional climate models. The evaluation is based on comparison of the simulated and observed climatological annual cycles and probability density functions of daily averages. Several model evaluation measures are calculated to assure an objective model evaluation. As a very selective model evaluation measure, the hit rate of the percentiles is introduced for the evaluation of daily averages. The influence of interann...

Influence of monthly varying vegetation on the simulated climate in Europe

In this study the regional climate model of the German Max-Planck-Institute for Meteorology (REMO) is used to analyse the effect of monthly varying vegetation on the simulated climate in Europe. For this investigation the annual cycle of vegetation is implemented in the land surface parameterization scheme of REMO. As input data source a new global dataset of land surface parameters is used. It contains monthly varying vegetation parameter values for leaf area index, fractional vegetation cover and background surface albedo. This dataset is adapted to both standard REMO model domains at 0.5 degree and 0.16 degree horizontal resolution focusing Europe. For both resolutions present-day climate simulations are performed to examine the sensitivity of REMO to the modified vegetation parameterization. The simulation results are compared to corresponding reference simulations where vegetation parameter values are held constant in time. A validation is done by the comparison of the model results with several gridded observational datasets. A significant influence of monthly varying vegetation on the regional climate can be demonstrated. Vertical surface fluxes, near surface temperature and precipitation are strongly affected. The temporal analysis of the results reveals that the vegetation effect on the simulated climate occurs mainly in the summer season. In general, the simulated near-surface climate becomes cooler and wetter during the growing season. Concerning the spatial resolution, main effects can be detected in eastern Europe and the Hungarian lowlands. In these regions the more realistic vegetation treatment improves the simulated mean annual cycles of 2 m temperature and precipitation with respect to the observations.

Case study for the assessment of the biogeophysical effects of a potential afforestation in Europe

BackgroundA regional-scale sensitivity study has been carried out to investigate the climatic effects of forest cover change in Europe. Applying REMO (regional climate model of the Max Planck Institute for Meteorology), the projected temperature and precipitation tendencies have been analysed for summer, based on the results of the A2 IPCC-SRES emission scenario simulation. For the end of the 21st century it has been studied, whether the assumed forest cover increase could reduce the effects of the greenhouse gas concentration change.ResultsBased on the simulation results, biogeophysical effects of the hypothetic potential afforestation may lead to cooler and moister conditions during summer in most parts of the temperate zone. The largest relative effects of forest cover increase can be expected in northern Germany, Poland and Ukraine, which is 15–20% of the climate change signal for temperature and more than 50% for precipitation. In northern Germany and France, potential afforestation may enhance the effects of emission change, resulting in more severe heavy precipitation events. The probability of dry days and warm temperature extremes would decrease.ConclusionsLarge contiguous forest blocks can have distinctive biogeophysical effect on the climate on regional and local scale. In certain regions of the temperate zone, climate change signal due to greenhouse gas emission can be reduced by afforestation due to the dominant evaporative cooling effect during summer. Results of this case study with a hypothetical land cover change can contribute to the assessment of the role of forests in adapting to climate change. Thus they can build an important basis of the future forest policy.

The Role of Forests in Mitigating Climate Change - a Case Study for Europe

Abstract - A regional-scale case study has been carried out to assess the possible climatic benefits of forest cover increase in Europe. For the end of the 21st century (2071-2090) it has been investigated, whether the projected climate change could be reduced assuming potential afforestation of the continent. The magnitude of the biogeophysical effects of enhanced forest cover on temperature and precipitation means and extremes have been analyzed relative to the magnitude of the climate change signal applying the regional climate model REMO. The simulation results indicate that in the largest part of the temperate zone potential afforestation may reduce the projected climate change through cooler and moister conditions, thus could contribute to the mitigation of the projected climate change for the entire summer period. The largest relative effect of forest cover increase can be expected in northern Germany, Poland and Ukraine. Here, the projected precipitation decrease could be fully compensated, the temperature increase could be relieved by up to 0.5 °C, and the probability of extremely warm and dry days could be reduced. Results can help to identify the areas, where forest cover increase could be the most effective from climatic point of view. Thus they can build an important basis of the future adaptation strategies and forest policy. Kivonat - Esettanulmány az erdők klímavédelmi szerepének vizsgálatára Európában. Az esettanulmány célja az erdőterület növekedés éghajlati hatásainak, a klímaváltozás mérsékelésében betöltött szerepének számszerűsítése Európában. A REMO regionális klímamodell segítségével vizsgáltuk, hogy a feltételezett potenciális erdőtelepítéssel milyen irányban és mértékben befolyásolhatók a 2071-2090-es időszakra előrevetített hőmérséklet- és csapadéktendenciák. A modellszimulációk eredményei alapján, potenciális erdőtelepítés feltételezésével nyáron a mérsékelt övi területek döntő része hűvösebb, csapadékosabb lehet. A legnagyobb hatás Németország és Lengyelország északi részén, valamint az ukrán-belorusz-orosz határvidéken várható. Ezeken a területeken az erdőtelepítés hatása a hőmérsékletre egy nagyságrenddel kisebb, mint az üvegházgáz koncentráció változásáé. A klímaváltozással járó csapadékmennyiség-csökkenés azonban szinte teljes egészében kiegyenlíthető lenne, és a szélsőségesen meleg és száraz napok gyakorisága csökkenhet. Az erdő-klíma kölcsönhatások számszerűsítése nem csak az erdők klímavédelmi szerepéről ad információt, hanem az éghajlatváltozás következményeinek megelőzését, enyhítését célzó stratégiák alapja is lehet.

Erratum to: EURO-CORDEX: new high-resolution climate change projections for European impact research

Daniela Jacob • Juliane Petersen • Bastian Eggert • Antoinette Alias • Ole Bossing Christensen • Laurens M. Bouwer • Alain Braun • Augustin Colette • Michel Deque • Goran Georgievski • Elena Georgopoulou • Andreas Gobiet • Laurent Menut • Grigory Nikulin • Andreas Haensler • Nils Hempelmann • Colin Jones • Klaus Keuler • Sari Kovats • Nico Kroner • Sven Kotlarski • Arne Kriegsmann • Eric Martin • Erik van Meijgaard • Christopher Moseley • Susanne Pfeifer • Swantje Preuschmann • Christine Radermacher • Kai Radtke • Diana Rechid • Mark Rounsevell • Patrick Samuelsson • Samuel Somot • Jean-Francois Soussana • Claas Teichmann • Riccardo Valentini • Robert Vautard • Bjorn Weber • Pascal Yiou

Globale Sicht des Klimawandels

Klimamodelle ermoglichen mathematisch-physikalisch basierte und quantitative Aussagen uber die Anderungen des Klimas. Neben Atmosphare und Ozean berucksichtigen sie auch das Eis, die Landoberflachen, biologische Prozesse und die Variabilitat der Sonneneinstrahlung. Globale Klimamodelle tragen dazu bei, Natur und Ursachen des globalen Klimawandels zu verstehen und mogliche zukunftige Entwicklungen abzubilden. Diese Modelle beschreiben die Entwicklung des Klimas unter der Annahme eines Szenarios kunftiger Emissionen von Treibhausgasen und Aerosolen. Das Kapitel gibt Einblick in die Moglichkeiten und Grenzen der globalen Klimamodellierung. Es beschreibt, inwiefern sich die im aktuellen Weltklimabericht benutzten Szenarien deutlich von fruheren Szenarien unterscheiden. Im Vordergrund stehen die globalen Veranderungen im Klimasystem, die mit Hilfe von Projektionen - basierend auf unterschiedlichen Szenarien - bis zum Ende des 21. Jahrhunderts ermittelt werden.