A5043973894- Atmospheric and Environmental Gas Dynamics
- Climate variability and models
- Atmospheric Ozone and Climate
- Meteorological Phenomena and Simulations
- Arctic and Antarctic ice dynamics
- Atmospheric chemistry and aerosols
- Climate change and permafrost
- Cryospheric studies and observations
- Oceanographic and Atmospheric Processes
- Atmospheric aerosols and clouds
- Methane Hydrates and Related Phenomena
- Hydrological Forecasting Using AI
- Tropical and Extratropical Cyclones Research
- Ionosphere and magnetosphere dynamics
- Geological Studies and Exploration
- Air Quality Monitoring and Forecasting
- Solar and Space Plasma Dynamics
- Plant Water Relations and Carbon Dynamics
- Aerospace Engineering and Energy Systems
- Fish Ecology and Management Studies
- Hydrology and Watershed Management Studies
- Peatlands and Wetlands Ecology
- Marine and coastal ecosystems
- Wind and Air Flow Studies
- Ocean Acidification Effects and Responses
Finnish Meteorological Institute
2016-2025
University of Virginia
2024
Bureau of Meteorology
2021
Hebrew University of Jerusalem
2021
NOAA Chemical Sciences Laboratory
2021
National Oceanic and Atmospheric Administration
2021
University of Helsinki
2019
Max Planck Institute for Meteorology
2017
University of East Anglia
2008-2011
British Antarctic Survey
2009
Abstract In recent decades, the warming in Arctic has been much faster than rest of world, a phenomenon known as amplification. Numerous studies report that is either twice, more or even three times fast globe on average. Here we show, by using several observational datasets which cover region, during last 43 years nearly four globe, higher ratio generally reported literature. We compared observed amplification with simulated state-of-the-art climate models, and found four-fold over...
Abstract The stratosphere can have a significant impact on winter surface weather subseasonal to seasonal (S2S) timescales. This study evaluates the ability of current operational S2S prediction systems capture two important links between and troposphere: (1) changes in probabilistic skill extratropical by precursors tropics troposphere (2) predictability extratropics after stratospheric weak strong vortex events. Probabilistic exists for events when including tropospheric over North Pacific...
Abstract We investigate seasonal forecasts of the winter North Atlantic Oscillation (NAO) and their relationship with stratosphere. Climatological frequencies sudden stratospheric warming (SSW) strong polar vortex (SPV) events are well represented predicted risk varies between 25 90% from to winter, indicating predictability beyond deterministic range. The SSW SPV relates NAO as expected, shifts −6.5 +4.8 hPa in forecast members containing events. Most striking all is that skill surface...
Major sudden stratospheric warmings ( SSWs ) are striking phenomena of wintertime circulation usually defined as a reversal zonal mean from westerlies to easterlies. often have significant impact on tropospheric and cause anomalies in surface climate lasting for up 2 months. For this reason, dynamics predictability SSW receive considerable attention. It is however well‐known that not all significant, long‐lasting the troposphere. In order explain differences impacts following , several...
Abstract The stratosphere has been identified as an important source of predictability for a range processes on subseasonal to seasonal (S2S) time scales. Knowledge about S2S within the is however still limited. This study evaluates what extent in extratropical exists hindcasts operational prediction systems database. found exhibit extended compared troposphere. Prediction with higher stratospheric skill tend also analysis includes assessment events, including early and midwinter sudden...
Future changes in the stratospheric circulation could have an important impact on northern winter tropospheric climate change, given that sea level pressure (SLP) responds not only to variations but also vertically coherent troposphere-stratosphere circulation. Here we assess change and its potential influence surface Coupled Model Intercomparison Project-Phase 5 (CMIP5) multimodel ensemble. In stratosphere at high latitudes, easterly zonally averaged zonal wind is found for majority of...
Abstract Sudden stratospheric warmings (SSWs) are significant source of enhanced subseasonal predictability, but whether this is untapped in operational models remains an open question. Here we report on the prediction SSW 12 February 2018, its dynamical precursors, and surface climate impacts by ensemble forecast models. The from 1 predicted 3 times increased odds compared to climatology, although lead time for varied among individual Errors location a Ural high underestimated magnitude...
The internal variability and coupling between the stratosphere troposphere in CCMVal‐2 chemistry‐climate models are evaluated through analysis of annular mode patterns variability. Computation modes long data sets with secular trends requires refinement standard definition mode, a more robust procedure that allows for slowly varying is established verified. spatial temporal structure models’ then compared reanalyses. As whole, capture key features observed intraseasonal variability,...
Using an international, multi‐model suite of historical forecasts from the World Climate Research Programme (WCRP) Climate‐system Historical Forecast Project (CHFP), we compare seasonal prediction skill in boreal wintertime between models that resolve stratosphere and its dynamics (‘high‐top’) do not (‘low‐top’). We evaluate hindcasts are initialized November, examine model biases how they relate to (December–March) forecast skill. unable detect more high‐top ensemble‐mean than low‐top...
Abstract Surface weather patterns related to 35 major sudden stratospheric warmings (SSWs) in 1958–2010 are analyzed based on reanalysis data. Similar analyses conducted with data from seven stratosphere‐resolving Earth system models. The carried out separately for displacement and splitting SSWs. On the basis of observational analysis, it is shown that northern Eurasia, cold anomalies linked SSWs tend be stronger more widespread before central date than during first 2 months after event...
The skill of the Arctic stratospheric retrospective ensemble forecasts (hindcasts) European Centre for Medium-Range Weather Forecasts extended-range system is analyzed with a focus on predictability major sudden warmings (SSWs) during period 1993–2016. Thirteen SSWs took place this period. It found that initialized 10–15 days before show worse in stratosphere than normal conditions terms root-mean-square errors but not anomaly correlation. Using spread members to estimate forecasted SSW...
Abstract Simulated stratospheric temperatures over the period 1979–2016 in models from Chemistry‐Climate Model Initiative are compared with recently updated and extended satellite data sets. The multimodel mean global temperature trends 1979–2005 −0.88 ± 0.23, −0.70 0.16, −0.50 0.12 K/decade for Stratospheric Sounding Unit (SSU) channels 3 (~40–50 km), 2 (~35–45 1 (~25–35 respectively (with 95% confidence intervals). These within uncertainty bounds of observed two reprocessed SSU In lower...
Abstract Observations taken over the last few decades indicate that dramatic changes are occurring in Arctic‐Boreal Zone (ABZ), which having significant impacts on ABZ inhabitants, infrastructure, flora and fauna, economies. While suitable for detecting overall change, current capability is inadequate systematic monitoring improving process‐based large‐scale understanding of integrated components ABZ, includes cryosphere, biosphere, hydrosphere, atmosphere. Such knowledge will lead to...
Abstract We investigate factors influencing European winter (DJFM) air temperatures for the period 1979–2015 with focus on changes during recent of rapid Arctic warming (1998–2015). employ meteorological reanalyses analysed a combination correlation analysis, two pattern clustering techniques, and back‐trajectory airmass identification. In all five selected regions, severe cold events lasting at least 4 days are significantly correlated warm episodes. Relationships opposite conditions...
Abstract. Over recent years there have been concomitant advances in the development of stratosphere-resolving numerical models, our understanding stratosphere–troposphere interaction, and extension long-range forecasts to explicitly include stratosphere. These are now allowing for new improved capability prediction. We present an overview this show how inclusion stratosphere forecast systems aids monthly, seasonal, annual-to-decadal climate predictions multidecadal projections. end with...
Abstract Projected changes in the Northern Hemisphere stratospheric polar vortex are analyzed using Climate Model Intercomparison Project Phase 6 experiments. Previous studies showed that projections of wintertime zonally averaged strength diverge widely between climate models with no agreement on sign change, and this uncertainty contributes to regional change uncertainty. Here, we show there remains large projected experiments global warming levels ranging from moderate (SSP245 runs)...
Abstract Solar driven energetic particle precipitation (EPP) is an important factor in polar atmospheric ozone balance and has been linked to ground-level regional climate variability. However, the linking mechanism remained ambiguous. The observed simulated changes start well before processes from main candidate, so-called EPP-indirect effect, would start. Here we show that initial reduction of mesospheric resulting change heating rapidly couples dynamics, transferring signal downwards,...
[1] This paper evaluates global mean radiatively important properties of chemistry climate models (CCMs). We evaluate stratospheric temperatures and their 1980–2000 trends, January clear sky irradiances, heating rates, greenhouse gas radiative forcings from an offline comparison CCM radiation codes with line-by-line models, CCMs' representation the solar cycle. change can give indication errors in transfer and/or atmospheric composition. Biases temperature climatology are generally small,...
The role of the stratosphere in tropospheric climate response to increased concentrations greenhouse gases during Northern Hemisphere winter is addressed by performing and analyzing a set simulations with atmosphere general circulation model ECHAM5. Attention paid difference doubled CO 2 concentration associated sea surface temperature ice anomaly between low‐top stratosphere‐resolving version. We find larger decrease Arctic level pressure late when compared one. Such dependence on...
Record Arctic ozone loss in spring 2011 occurred concert with record positive values of the tropospheric Northern Annular Mode (NAM) index raising question about role stratospheric driver on this climate event. A set 50 years long simulations by atmospheric general circulation model European Centre/Hamburg version 5 (ECHAM5) is carried out and responses to observed anomalies (O3) sea surface temperatures (SST) separately also response combined SST O3 forcing (ALL) are analyzed. In all three...
Public attention has recently focused on high-impact extreme weather events in midlatitudes that originate the sub-Arctic. We investigate movements of stratospheric polar vortex (SPV) and related changes lower atmospheric circulation during February-March 2018 “Beast from East” cold winter event dramatically affected much Europe north-central North America. This study demonstrates movement SPV is a key linkage late subarctic northern midlatitude events. February–March saw two types...
Abstract The winter of 2019–2020 was dominated by an extremely strong stratospheric polar vortex and positive tropospheric Arctic Oscillation (AO). Here, we analyze forecasts from six different prediction systems contributing to the C3S seasonal forecast database. Most performed very strongly, with consistently high skill for January–March 2020 launched through October–December 2019. Although magnitude anomalies underestimated, performance most a AO relative common hindcast climate. Ensemble...
Abstract. The stratosphere can be a source of predictability for surface weather on timescales several weeks to months. However, the potential predictive skill gained from stratospheric variability limited by biases in representation processes and coupling with climate forecast systems. This study provides first systematic identification model across wide range subseasonal It is found that many systems considered exhibit warm global-mean temperature lower middle stratosphere, too strong/cold...