Sensitivity of European Temperature to Albedo Parameterization in the Regional Climate Model COSMO-CLM Linked to Extreme Land Use Changes

Previous studies based on observations and models are uncertain about the biophysical impact of af- and deforestation in the northern hemisphere mid-latitude summers, and show either a cooling or warming. The magnitude and direction is still uncertain. In this study, the effect of three different albedo parameterizations in the regional climate model COSMO-CLM (v5.09) is examined performing afforestation experiments at 0.44° horizontal resolution across the EURO-CORDEX domain during 1986-2015. Idealized de- and af-forestation simulations are compared to a simulation with no land cover change. Emphasis is put on the impact of changes in radiation and turbulent fluxes. A clear latitudinal pattern is found, which results partly due to the strong land cover conversion from forest- to grassland in the high latitudes and open land to forest conversion in mid-latitudes. Afforestation warms the climate in winter, and strongest in mid-latitudes. Results are indifferent in summer owing to opposing albedo and evapotranspiration effects of comparable size but different sign. Thus, the net effect is small for summer. Depending on the albedo parameterization in the model, the temperature effect can turn from cooling to warming in mid-latitude summers. The summer warming due to deforestation to grassland is up to 3°C higher than due to afforestation. The cooling by grass or warming by forest is in magnitude comparable and small in winter. The strength of the described near-surface temperature changes depends on the magnitude of the individual biophysical changes in the specific background climate conditions of the region. Thus, the albedo parameterization need to account for different vegetation types. Furthermore, we found that, depending on the region, the land use change effect is more important than the model uncertainty due to albedo parameterization. This is important information for model development

A simplified multi-model statistical approach for predicting the effects of forest management on land surface temperature in Fennoscandia

Forests interact with the local climate through a variety of biophysical mechanisms. Observational and modelling studies have investigated the effects of forested vs. non-forested areas, but the influence of forest management on surface temperature has received far less attention owing to the inherent challenges to adapt climate models to cope with forest dynamics. Further, climate models are complex and highly parameterized, and the time and resource intensity of their use limit applications. The availability of simple yet reliable statistical models based on high resolution maps of forest attributes representative of different development stages can link individual forest management practices to local temperature changes, and ultimately support the design of improved strategies. In this study, we investigate how forest management influences local surface temperature (LSTs) in Fennoscandia through a set of machine learning algorithms. We find that more developed forests are typically associated with higher LST than young or undeveloped forests. The mean multi-model estimates from our statistical system can accurately reproduce the observed LST. Relative to the present state of Fennoscandian forests, fully develop forests are found to induce an annual mean warming of 0.26 °C (0.03/0.69 °C as 5th/95th percentile), and an average cooling effect in the summer daytime from -0.85 to -0.23 °C (depending on the model). On the contrary, a scenario with undeveloped forests induces an annual average cooling of -0.29 °C (-0.61/-0.01 °C), but daytime warming in the summer that can be higher than 1 °C. A weak annual mean cooling of -0.01 °C is attributed to forest harvest from 2015 to 2018, with an increased daytime temperature in summer of about 0.04 °C. Overall, this approach is a flexible option to study effects of forest management on LST that can be applied at various scales and for alternative management scenarios, thereby helping to improve local management strategies with consideration of effects on local climate

Sensitivity of european temperature to albedo parameterization in the regional climate model COSMO-CLM linked to extreme land use changes

Previous studies based on observations and models are uncertain about the biophysical impact of af- and deforestation in the northern hemisphere mid-latitude summers, and show either a cooling or warming. The spatial distribution, magnitude and direction are still uncertain. In this study, the effect of three different albedo parameterizations in the regional climate model COSMO-CLM (v5.09) is examined performing idealized experiments at 0.44° horizontal resolution across the EURO-CORDEX domain during 1986–2015. De- and af-forestation simulations are compared to a simulation with no land cover change. Emphasis is put on the impact of changes in radiation and turbulent fluxes. A clear latitudinal pattern is found, which results partly due to the strong land cover conversion from forest- to grassland in the high latitudes and open land to forest conversion in mid-latitudes. Afforestation warms the climate in winter, and strongest in mid-latitudes. Results are indifferent in summer owing to opposing albedo and evapotranspiration effects of comparable size but different sign. Thus, the net effect is small for summer. Depending on the albedo parameterization in the model, the temperature effect can turn from cooling to warming in mid-latitude summers. The summer warming due to deforestation to grassland is up to 3°C higher than due to afforestation. The cooling by grass or warming by forest is in magnitude comparable and small in winter. The strength of the described near-surface temperature changes depends on the magnitude of the individual biophysical changes in the specific background climate conditions of the region. Thus, the albedo parameterization need to account for different vegetation types. Furthermore, we found that, depending on the region, the land cover change effect is more important than the model uncertainty due to albedo parameterization. This is important information for model development

The influence of biosphere change in the pannonian basin on local and regional climate during spring, summer and autumn months

Uticaj kopnene vegetacije na fizičke procese u površinskom i planetarnom graničnom sloju atmosfere je od velikog značaja za izučavanje vremenskih i klimatskih uslova u klimatskom sistemu Zemlje. Kopnena vegetacija, kao sastavni deo klimatskog sistema Zemlje, ima veliki uticaj na razmenu energije između kopna i atmosfere, a usled toga i značajnu ulogu u definisanju vremenskih i klimatskih obrazaca, kako na globalnom, tako i na regionalnom i lokalnom nivou. Međutim, usled konstantnog antropogenog uticaja, ali i zbog sopstvene dinamike, ovaj vegetacioni sistem se stalno menja i veoma ga je komplikovano predstaviti, kao i njegov uticaj na klimatski sistem Zemlje. Cilj ovog istraživanja je proučavanje uticaja regionalne promene vegetacije na sezonsku temperaturu vazduha u blizini Zemljine površine. Istraživanje je urađeno upotrebom globalnog klimatskog modela MPI-ESM (Max Planck Institute - Earth System Model). Oblast ovog istraživanja je smeštena u Panonskom basenu koji predstavlja jedan od mnogih regiona u kome je antropogeni uticaj na geofizičke promene životne sredine veliki. Vremenski okvir unutar koga su rađeni numerički eksperimenti MPI-ESM modelom je pokrivao period od 2002. do 2011. godine. Izmena zastupljenosti tipova šumske, travnate i poljoprivredne vegetacije koja je izvedena u istraživanju nedvosmisleno pokazuje da je došlo do povećanja dekadnih vrednosti srednjih sezonskih temperatura vazduha u blizini Zemljine površine (T2m) i temperature vazduha u nižim slojevima atmosfere (Tlev), kako na lokalnom tako i na regionalnom nivou. Međutim, došlo je i do značajnih promena u trendovima srednjih sezonskih vrednosti: temperature vazduha u blizini Zemljine površine (YT2m), fluksa osetne toplote (YFh), fluksa latentne toplote (YFl), površinskog albeda (Ya) i oblačnosti (YOb). Postignut je trend hlađenja vazduha u letnjoj sezoni, dok je u prolećnoj postignut trend zagrevanja prizemnog vazduha, a za jesenju sezonu dobijeni su trendovi zagrevanja i hlađenja vazduha. Promena trenda YT2m je uglavnom dobijena usled promene u površinskom albedu, kao i usled promene oblačnosti. Trend hlađenja vazduha za letnju sezonu je zastupljen uglavnom u severnim i centralnim oblastima Panonskog basena dok je u južnoj oblasti zabeležen trend zagrevanja. Ovim istraživanjem je postignut postavljeni cilj, odnosno potvrđeno je da postoji značajan antropogeni uticaj na promenu klimatskih uslova, kako na lokalnom, tako i na regionalnom nivou, usled geofizičkih uticaja na kopnenu vegetaciju. Pokazalo se da izmenom vegetacije na površini možemo ublažiti zagrevanje u letnjoj sezoni, kao i da ubrzamo povećanje prizemne temperature vazduha u prolećnoj sezoni, dok je za jesenju sezonu postignuto i hlađenje i zagrevanje.The influence of terrestrial vegetation on developments in the surface and planetary boundary layer of the atmosphere has great importance for the study of weather and climatic conditions in the Earth's climate system. Terrestrial vegetation as an integral part of the Earth's climate system has a great influence on the exchange of energy between the land and the atmosphere and consequently a significant role in defining weather and climate patterns globally, regionally and locally. However, due to the constant anthropogenic impact, this vegetation system is constantly changing and it is very complicated to present it during research as well as its impact on the Earth's Climate System. The aim of this study is to study the impact of regional vegetation change on the seasonal air temperature near the Earth's surface and was performed using the global climate model MPI-ESM (Max Planck Institute - Earth System Model). The region of our research is located in the Pannonian basin and is one of many regions in which the anthropogenic impact on geophysical changes in the environment is great. The research was conducted for a ten-year period from 2002 to 2011. The change in the concentration of CF types that we performed in our study unequivocally shows that it has led to an increase in decadal values of mean seasonal air temperatures: near the Earth's surface (T2m) and air temperature in the lower atmosphere (Tlev) both locally and at the regional level. However, there were also significant changes in the trends of average seasonal values: air temperature near the Earth's surface (YT2m), sensory heat flux (YFh), latent heat flux (YFl), surface albedo (Ya), cloud cover (YOb) and soil water content (YSW). We managed to achieve the trend of air cooling in the summer season, while in the spring we got the trend of heating the ground air, and for the autumn season we got the trend of heating and cooling the air. The change in the YT2m trend was mainly due to a change in surface albedo as well as due to a change in cloud cover. The trend of air cooling that we received for the summer season is represented mainly in the northern and central areas of the Pannonian basin, while for the southern area we received a trend of warming. For the spring season, we mainly obtained a mean positive linear correlation between the mean monthly values of air temperature T2m and the mean monthly values of the sensory heat flux Fh. For the summer season we mostly got that medium and strong linear correlation while for the autumn season we got weak positive and weak negative linear correlation. Through our research, we have achieved the set goal and shown that there is a significant anthropogenic impact on climate change at both local and regional levels. We have shown that we can mitigate warming in the summer season as well as accelerate the increase in ground air temperature in the spring season while we have achieved both cooling and warming for the autumn season..

Local Effects of Forests on Temperatures across Europe

Forests affect local climate through biophysical processes in terrestrial ecosystems. Due to the spatial and temporal heterogeneity of ecosystems in Europe, climate responses to forests vary considerably with diverse geographic and seasonal patterns. Few studies have used an empirical analysis to examine the effect of forests on temperature and the role of the background climate in Europe. In this study, we aimed to quantitatively determine the effects of forest on temperature in different seasons with MODIS (MODerate-resolution Imaging Spectroradiometer) land surface temperature (LST) data and in situ air temperature measurements. First, we compared the differences in LSTs between forests and nearby open land. Then, we paired 48 flux sites with nearby weather stations to quantify the effects of forests on surface air temperature. Finally, we explored the role of background temperatures on the above forests effects. The results showed that (1) forest in Europe generally increased LST and air temperature in northeastern Europe and decreased LST and air temperature in other areas; (2) the daytime cooling effect was dominate and produced a net cooling effect from forests in the warm season. In the cold season, daytime and nighttime warming effects drove the net effect of forests; (3) the effects of forests on temperatures were mainly negatively correlated with the background temperatures in Europe. Under extreme climate conditions, the cooling effect of forests will be stronger during heatwaves or weaker during cold spring seasons; (4) the background temperature affects the spatiotemporal distribution of differences in albedo and evapotranspiration (forest minus open land), which determines the spatial, seasonal and interannual effects of forests on temperature. The extrapolation of the results could contribute not only to model validation and development but also to appropriate land use policies for future decades under the background of global warming