Jonas Bhend

MeteoSwiss · Analysis and Forecasting

Statistical postprocessing is applied in operational forecasting to correct systematic errors of numerical weather prediction models (NWP) and to automatically produce calibrated local forecasts for end-users. Postprocessing is particularly relevant in complex terrain, where even state-of-the-art high-resolution NWP systems cannot resolve many of t...

Probabilistic weather forecasts from ensemble systems require statistical postprocessing to yield calibrated and sharp predictive distributions. This paper presents an area-covering postprocessing method for ensemble precipitation predictions. We rely on the ensemble model output statistics (EMOS) approach, which generates probabilistic forecasts w...

Statistical postprocessing techniques are nowadays key components of the forecasting suites in many national meteorological services (NMS), with, for most of them, the objective of correcting the impact of different types of errors on the forecasts. The final aim is to provide optimal, automated, seamless forecasts for end users. Many techniques ar...

Seasonal forecasts of variables like near-surface temperature or precipitation are becoming increasingly important for a wide range of stakeholders. Due to the many possibilities of recalibrating, combining, and verifying ensemble forecasts, there are ambiguities of which methods are most suitable. To address this we compare approaches how to proce...

Statistical postprocessing is routinely applied to correct systematic errors of numerical weather prediction models (NWP) and to automatically produce calibrated local forecasts for end-users. Postprocessing is particularly relevant in complex terrain, where even state-of-the-art high-resolution NWP systems cannot resolve many of the small-scale pr...

Statistical postprocessing techniques are nowadays key components of the forecasting suites in many National Meteorological Services (NMS), with for most of them, the objective of correcting the impact of different types of errors on the forecasts. The final aim is to provide optimal, automated, seamless forecasts for end users. Many techniques are...

The present paper is a follow-on of the work presented in Manzanas et al. (Clim Dyn 53(3–4):1287–1305, 2019) which provides a comprehensive intercomparison of alternatives for the post-processing (statistical adjustment, calibration and downscaling) of seasonal forecasts for a particularly interesting region, Southeast Asia. To answer the questions...

Seasonal predictions have a great socio-economic potential if they are reliable and skillful. In this study, we assess the prediction performance of SEAS5, version 5 of the seasonal prediction system of the European Centre for Medium-Range Weather Forecasts (ECMWF), over South America against homogenized station data. For temperature, we find highe...

Probabilistic weather forecasts from ensemble systems require statistical postprocessing to yield calibrated and sharp predictive distributions. This paper presents an area-covering postprocessing method for ensemble precipitation predictions. We rely on the ensemble model output statistics (EMOS) approach, which generates probabilistic forecasts w...

Floods in the Alpine region can be destructive and cause large economic losses. Many rivers and lakes in Switzerland are regulated and flood damage can be mitigated through an optimal management of lake levels and runoff. This requires high-quality forecasts of atmospheric flood precursors extending beyond short-range (forecast days 1–5) prediction...

This work presents a comprehensive intercomparison of different alternatives for the calibration of seasonal forecasts, ranging from simple bias adjustment (BA) -e.g. quantile mapping- to more sophisticated ensemble recalibration (RC) methods -e.g. non-homogeneous Gaussian regression,- which build on the temporal correspondence between the climate...

Subseasonal predictions bridge the gap between medium-range weather forecasts and seasonal climate predictions. This time horizon is of crucial importance for many planning purposes, including energy production and agriculture. The verification of such predictions is normally done for areal averages of upper-air parameters. Only few studies exist t...

Near-term climate predictions such as decadal climate forecasts are increasingly being used to guide adaptation measures. For near-term probabilistic predictions to be useful, systematic errors of the forecasting systems have to be corrected. While methods for the calibration of probabilistic forecasts are readily available, these have to be adapte...

Within the FP7 EUPORIAS project we have assessed the utility of dynamical and statistical downscaling to provide seasonal forecast for impact modelling in eastern Africa. An ensemble of seasonal hindcasts was generated by the global climate model (GCM) EC-EARTH and then downscaled by four regional climate models and by two statistical methods over...

Near-term climate predictions such as decadal climate forecasts are increasingly being used to guide adaptation measures. For near-term probabilistic predictions to be useful, systematic errors of the forecasting systems have to be corrected. While methods for the calibration of probabilistic forecasts are readily available, these have to be adapte...

Climatic variations at decadal scales such as phases of accelerated warming or weak monsoons have profound effects on society and economy. Studying these variations requires insights from the past. However, most current reconstructions provide either time series or fields of regional surface climate, which limit our understanding of the underlying...

The projected warming of surface air temperature at the global and regional scale by the end of the century is directly related to emissions and Earth’s climate sensitivity. Projections are typically produced using an ensemble of climate models such as CMIP5, however the range of climate sensitivity in models doesn’t cover the entire range consider...

Seasonal forecasting models are increasingly being used to forecast application-relevant aspects of upcoming climatic conditions, often summarised by climate indices. Little is known, however, on how the predictive skill of such forecasts of climate indices relates to the predictive skill in forecasting seasonal mean conditions. Here we analyse for...

A new suite of national Swiss climate scenarios “CH2018” is currentlybeing prepared and expected to be released in 2018. CH2018 exploits the latestCMIP5 and CORDEX climate projections and employs empirical-statisticaldownscaling and bias correction (ESDBC) techniques to produce climate scenariosfor the local scale. The applied ESDBC techniques shou...

Der Schweizer Sommer 2015 geht als Zweitwärmster in die 152-jährige Mess-Geschichte ein. Das Schweizer Temperaturmittel war im Vergleich zur Normperiode 1981–2010 2.4 Grad höher. Damit liegt der Sommer 2015 mehr als ein Grad über allen bisherigen Rekordsommern, mit Ausnahme des legendären Hitzesommers 2003, der nochmals rund ein Grad wärmer war als...

There is a high degree of variation in rainfall projections for later this century for Australia's eastern seaboard, partly because of how different climate models represent the relevant physical processes. These processes include local environmental conditions, synoptic phenomena and large-scale atmospheric and oceanic modes of variability. We rev...

The eruption of Mount Tambora (Indonesia) in April 1815 is the largest documented volcanic eruption in history. It is associated with a large global cooling during the following year, felt particularly in parts of Europe and North America, where the year 1816 became known as the "year without a summer". This paper describes an effort made to collec...

The eruption of Mount Tambora (Indonesia) in April 1815 is the largest documented volcanic eruption in history. It caused a large global cooling during the following year, felt particularly in parts of Europe and North America, where the year 1816 became known as the "year without a summer". This paper describes an effort made to collect surface me...

This chapter starts by introducing the complex nature of atmospheric aerosols, their sources, formation and properties and describes how they interact with clouds . This is important background information for discussing how aerosols affect climate, both directly and indirectly by affecting the radiative properties of clouds. The complexity of the...

This chapter assesses to what extent the factors causing global warming affect the Baltic Sea area. Summertime near-surface warming in northern Europe exceeds natural internal variability of the climate system, and the observed warming cannot be explained without human influence. Regional changes in extreme temperatures, growing-season length and t...

The Australian eastern seaboard is a distinct climate entity from the interior of the continent, with different climatic influences on each side of the Great Dividing Range. Therefore, it is plausible that downscaling of global climate models could reveal meaningful regional detail, or 'added value', in the climate change signal of mean rainfall ch...

A projected drying of the extra-tropics under enhanced levels of atmospheric greenhouse gases has large implications for natural systems and water security across southern Australia. The drying is driven by well studied changes to the atmospheric circulation and is consistent across climate models, providing a strong basis from which adaptation pla...

Model evaluation is an important tool to help rate confidence in climate model simulations. This can add to the overall confidence assessment for future projections of the Australian climate. Additionally it can highlight significant model deficiencies that may affect the selection of a subset of models for use in impact assessment. Here we present...

The ability to reproduce recent observed climate change in climate models is a pertinent prerequisite for trust in climate projections. Also, information on the consistency of simulated and observed recent changes helps users to interpret near-term climate change projections. A comprehensive assessment of simulated regional trends, however, is ofte...

This Report provides an assessment of observed climate change in Australia and its causes, and details projected future changes over the 21st century. This document, produced by CSIRO and the Australian Bureau of Meteorology, underpins extensive climate change projections for Australia provided as part of a larger package of products developed with...

Climate warming has large implications for rainfall patterns, and identifying the most plausible pattern of rainfall change over the next century among various model projections would be valuable for future planning. The spatial pattern of projected sea surface temperature change has a key influence on rainfall changes in the tropical Pacific Ocean...

Strong tropical volcanic eruptions have significant effects on global and regional temperatures. Their effects on precipitation, however, are less well understood. Analyzing hydroclimatic anomalies after 14 strong eruptions during the last 400 years in climate reconstructions and model simulations, a reduction of the Asian and African summer monsoo...

Background and AimsClimate is a key consideration for winegrowers, so information regarding projected climate change and the relative global impacts are of great interest. Methods and ResultsThis climate analogue approach compares and contrasts future to current climate among the regions. Warming was projected for all regions, with greater warming...

We present a vertically resolved zonal mean monthly mean global ozone data set spanning the period 1901 to 2007, called HISTOZ.1.0. It is based on a new approach that combines information from an ensemble of chemistry climate model (CCM) simulations with historical total column ozone information. The CCM simulations incorporate important external d...

We analyze the impact of stratospheric volcanic aerosols on the diurnal temperature range (DTR) over Europe using long-term sub-daily station records. We compare the results with a 28-member ensemble of ECHAM5.4 general circulation model simulations. Eight stratospheric volcanic eruptions during the instrumental period are investigated. Seasonal al...

There is increasing pressure from stakeholders for highly localised climate change projections. A comprehensive assessment of climate model performance at the grid box scale in simulating recent change, however, is not available at present. Therefore, we compare observed changes in near-surface temperature, sea level pressure (SLP) and precipitatio...

We present a vertically resolved (with pressure as the vertical coordinate) zonal mean monthly mean global ozone data set spanning the period 1900 to 2008, called HISTOZ.1.0. It is based on a new approach that combines information from an ensemble of chemistry climate model (CCM) simulations with historical total ozone information. The CCM simulati...

Data assimilation is a promising approach to obtain climate reconstructions that are both consistent with observations of the past and with our understanding of the physics of the climate system as represented in the climate model used. Here, we investigate the use of ensemble square root filtering (EnSRF) - a technique used in weather forecasting...

Trends in phenological phases associated with climate change are widely reported--yet attribution remains rare. Attribution research in biological systems is critical in assisting stakeholders to develop adaptation strategies, particularly if human factors may be exacerbating impacts. Detailed, quantified attribution helps to effectively target ada...

In this study we assess the role of anthropogenic forcing (greenhouse gases and sulphate aerosols, GS) in recently observed precipitation trends over the Mediterranean region. We investigate whether the observed precipitation trends (1966–2005 and 1979–2008) are consistent with what 22 models project as response of precipitation to GS forcing. Sign...

Data assimilation is a promising approach to obtain climate reconstructions that are both consistent with observations of the past and with our understanding of the physics of the climate system as represented in the climate model used. Here, we investigate the use of Ensemble Square Root Filtering (EnSRF) - a technique used in weather forecasting...

We examine the possibility that anthropogenic forcing (Greenhouse gases and Sulfate aerosols, GS) is a plausible explanation for the observed near-surface temperature trends over the Mediterranean area. For this purpose, we compare annual and seasonal observed trends in near-surface temperature over the period from 1980 to 2009 with the response to...

Past climate states are usually reconstructed based on the empirical relationship between climate proxy records and climate variables during the past century. This approach, however, is applicable only to a small set of climate variables for which robust linear relationships with climate proxies can be found. Furthermore, climate proxies are spatia...

We investigate the detection and attribution of a potential anthropogenic effect on regional-scale temperature and precipitation changes in Northern Europe. The generally decreasing signal-to-noise ratio with decreasing area of aggregation as well as the shortcomings of present-day climate models in simulating regional climate limit successful dete...

We investigate if anthropogenic forcing is a plausible explanation for the observed warming in the Baltic Sea catchment area. Therefore, we compare the most recent trends in surface temperature over land with anthropogenic climate change pro- jections from regional climate model simulations. We analyze patterns of change with different spatio-tempo...

Often it is claimed that the recent changes in northern European climate are at least partly anthropogenic even though a human influence has not yet been successfully detected. Hence we investigate whether the recent changes are consistent with regional climate change projections. Therefore, trends in winter (DJF) mean precipitation in northern Eur...

Often it is claimed that recent changes in northern European climate are at least partly anthropogenic even though a human influence has not yet been successfully detected. Increasing variability with decreasing scale of aggregation (and thus in general decreasing signal-to-noise ratios) as well as limitations in the ability of present day climate...

,University of Lecce, Italy (piero. lionello@unile. it),University of Bern, Switzerland (bhend@giub. unibe. ch, dmarta@giub. unibe. ch),ISAC-CNR, Italy (A. Buzzi@isac. cnr. it),Tel Aviv University, Israel (shimon@cyclone. tau. ac. il),INM Spain (jansa@inm. es),University of Thessalonoki, Greece (maheras@geo. auth. gr),ARPA, Piemonte, Italy (antonel...

When investigating a human contribution to the observed climate change, often de- tection and attribution studies are sought after. However, for regional scale climate change, a human influence is often not detectable due to the increasing variability with decreasing spatial aggregation and limitations in modelling regional scale cli- mate. Neverth...