scholarly journals Impact of deforestation on radiative and thermal regimes of the territory of Ukraine on the base of global climate models data

2021 ◽  
Vol 43 (3) ◽  
pp. 135-160
Author(s):  
L. A. Pysarenko ◽  
S. V. Krakovska
Keyword(s):  
Air Temperature ◽  
Anthropogenic Impact ◽  
Forest Cover ◽  
Climate Models ◽  
Global Climate ◽  
Winter Season ◽  
Warm Season ◽  
Global Climate Models ◽  
Thermal Regimes ◽  
Surface Reflectivity

This paper is dedicated to the influence of partial deforestation with using global retrospective modelling data from The Land Use Model Intercomparison Project (LUMIP) for the territory of Ukraine. This experiment aims to global gradual deforestation and has two phases. The first phase, defined as the pre-industrial period (1850—1899) with constant unchangeable anthropogenic impact. For this period deforestation modelled with further replacement with grass cover with a linear trend 400000 km2/yr or 20 million km2 per 50 years in general. The second phase is next 30 years with no significant changes in forest cover (1900—1929). For conducting this research the data of several global climate models were applied. The results of analysis have demonstrated that a partial deforestation with grass substitution influences the surface reflectivity or albedo and redistribution of shortwave radiative fluxes. In turn, it provokes changes in thermal regime. It was found that the most significant changes in surface reflectivity and the strongest correlation coefficients between albedo and deforestation are in the winter season due to the presence of snow cover. As a result, statistical significant increase of albedo is with maximum values up to 24 %/50 years in some grids in winter. Then in the summer season maximal changes are up to 2.7 %/50 years due to small differences between forest and grass albedos. As a consequence, changes in albedo cause changes in surface and air temperature regimes. Strong dependencies were found in winter between changes in albedo and temperatures with maximum temperature decrease 2.5…2.0 %/50 years. In warm season correlations are weaker in comparison to cold season, but nevertheless, temperatures decrease also take place with maximum values 2.0…1.5 %/50 years. The analysis between deforestation and daily air temperature range has shown that particularly in winter season there is an increase of 0.5...1.5 %/50 years, whereas such tendency is not observed in warm season. Calculations of year air temperature range demonstrated controversial results among climate models, as follows it is hard to make a conclusion about the contribution of forest cover reduction to changes in this index. It was revealed, that global climate models with higher resolution are more sensitive to changes in albedo and, as a consequence to other characteristics than models with coarse ones. It should be noticed that obtained results concern pre-industrial period with minimal anthropogenic impact, when observed a stable snow cover in winter in Ukraine. In the current climate change with significant warming and reduction of snow season duration deforestation can have opposite effects on radiative and thermal regimes that require further studying.

scholarly journals Air Temperature and Precipitation at Wolverine Glacier, Alaska; Glacier Growth in a Warmer, Wetter Climate

1990 ◽  
Vol 14 ◽  
pp. 191-194 ◽  
Author(s):  
L.R. Mayo ◽  
R.S. March
Keyword(s):  
Sea Level ◽  
Air Temperature ◽  
Climate Models ◽  
Global Climate ◽  
Global Climate Models ◽  
Positive Mass ◽  
Temperature And Precipitation ◽  
Warming Climate ◽  
The Common ◽  
Snow Precipitation

Measurements at Wolverine Glacier, Alaska, from 1968 to 1988 indicate unsteady increases of air temperature and precipitation since the early 1970s. These increases were due almost entirely to changes in winter. Variations in annual temperature and precipitation at Wolverine Glacier and at Seward, a nearby climatological station at sea level, correlate positively with global temperature variations and are in general agreement with the changes at high latitudes predicted by five recent general atmospheric circulation models forced by anticipated rises of CO2. A consequence of the air temperature and precipitation increases at Wolverine Glacier was a change to a generally positive mass balance after 1976. Although these observations in the coastal maritime climate of Alaska run against the common, oversimplified notion that in a warming climate glaciers will melt, causing sea level to rise, they are logical and easily understood when the sensitivity of the glacier to the seasonal distribution of the changes is considered. The observed seasonal changes at Wolverine Glacier also are in agreement with global climate models. Snow precipitation and glacier accumulation increased, but at the same time warming affected only these those temperatures below about −5°C, and melting was not altered. The extent of this response is not well known, but the process may be taking place in other important glacierized regions.

Impact of deforestation on surface radiative properties and temperature characteristics in Ukraine based on LUMIP CMIP6 datasets

2021 ◽  
Author(s):  
Larysa Pysarenko ◽  
Svitlana Krakovska
Keyword(s):  
Air Temperature ◽  
Forest Cover ◽  
Winter Season ◽  
Warm Season ◽  
Radiative Properties ◽  
Shortwave Radiation ◽  
Model Intercomparison ◽  
Temperature Changes ◽  
Intercomparison Project ◽  
The Impact

<p>The impact of temperate forests on climate still has open questions about their quantitative effect on radiative and thermal properties of the territory. The study addresses some of these questions and the analysis is based on the data from the Land-Use Model Intercomparison Project (LUMIP), which is the part of Coupled Model Intercomparison Project Phase 6 (CMIP6). The main aim of CMIP is to study climate on different periods of time from the past to the future with help of observations and Earth System Models (ESM).</p><p>LUMIP belongs to historical experiments and implies gradual deforestation with linear trend up to 1% all over the world during 50 years in pre-industrial period (1850-1899) and next 30 years with no change in forest cover. The goal of this experiment is to reveal the contribution of forest cover reduction on climate characteristics under quasi-constant anthropogenic forcing. This experiment was based on ESM simulations and the dataset of 8 ESM was retrieved for calculations of different climatic characteristics for the territory of Ukraine. These models have different spatial resolution, the initial and the final forest cover in grid cells respectively. Therefore, we analysed ESMs one-by-one and summarised the results over latitudinal zones. To analyse radiative regime we used monthly data of downwelling and upwelling shortwave radiation, which affect thermal regime estimated via surface and 2-m air temperature changes as well as mean daily and annual ranges. Anomalies of each characteristics were obtained over the base averages of the first 20 years of deforestation (1850-1869), which were further smoothed using the 5-year running mean.</p><p>It is known that the forest cover influences the ratio of surface downwelling and upwelling shortwave radiation, particularly, via albedo. We found the highest changes in albedo in winter season, most probably due to the presence of snow cover. Increase of albedo is well correlated with deforestation and the maximal rate of 18%/50 years was found in the Carpathians in winter. There were much less changes in warm season with rates up to 2%/50 years due to small difference between values of forest (~3-10%) with grass (~10-30%) than snow albedo (~40-90%).</p><p>These changes in radiative properties cause shifts in temperature regime with moderate and strong negative correlations between albedo and both surface and air temperatures. Higher albedo in winter season caused the decrease of mean monthly surface temperature up to -0.4℃/10 years in winter and -0.3℃/10 years in warm season. Values of changes of mean monthly air temperature corresponded to surface temperature changes and they were -0.4℃/10 years in winter and -0.2℃/10 years in warm season. Based on mean maximum and minimum monthly temperatures we found that deforestation also affected mean daily air temperature range only in winter with tendency up to 0.1–0.3℃/ 10 years. Meanwhile the models showed controversial results for annual air temperature range. One of the essential research outcomes we found that the impact of gradual deforestation on the thermal regime was shifted on approximately 20 years and diminished after stopping land cover change.</p>

Air Temperature and Precipitation at Wolverine Glacier, Alaska; Glacier Growth in a Warmer, Wetter Climate

1990 ◽  
Vol 14 ◽  
pp. 191-194 ◽  
Author(s):  
L.R. Mayo ◽  
R.S. March
Keyword(s):  
Sea Level ◽  
Air Temperature ◽  
Climate Models ◽  
Global Climate ◽  
Global Climate Models ◽  
Positive Mass ◽  
Temperature And Precipitation ◽  
Warming Climate ◽  
The Common ◽  
Snow Precipitation

Measurements at Wolverine Glacier, Alaska, from 1968 to 1988 indicate unsteady increases of air temperature and precipitation since the early 1970s. These increases were due almost entirely to changes in winter. Variations in annual temperature and precipitation at Wolverine Glacier and at Seward, a nearby climatological station at sea level, correlate positively with global temperature variations and are in general agreement with the changes at high latitudes predicted by five recent general atmospheric circulation models forced by anticipated rises of CO2.A consequence of the air temperature and precipitation increases at Wolverine Glacier was a change to a generally positive mass balance after 1976. Although these observations in the coastal maritime climate of Alaska run against the common, oversimplified notion that in a warming climate glaciers will melt, causing sea level to rise, they are logical and easily understood when the sensitivity of the glacier to the seasonal distribution of the changes is considered. The observed seasonal changes at Wolverine Glacier also are in agreement with global climate models. Snow precipitation and glacier accumulation increased, but at the same time warming affected only these those temperatures below about −5°C, and melting was not altered. The extent of this response is not well known, but the process may be taking place in other important glacierized regions.

scholarly journals Multi-model ensemble of statistically downscaled GCMs over southeastern South America: historical evaluation and future projections of daily precipitation with focus on extremes

2021 ◽  
Author(s):  
Matias Ezequiel Olmo ◽  
Rocio Balmaceda-Huarte ◽  
Maria Laura Bettolli
Keyword(s):  
South America ◽  
Climate Models ◽  
Linear Models ◽  
Dynamical Downscaling ◽  
Daily Precipitation ◽  
Global Climate ◽  
Warm Season ◽  
Global Climate Models ◽  
Added Value ◽  
Model Ensemble

Abstract High-resolution climate information is required over southeastern South America (SESA) for a better understanding of the observed and projected climate changes due to their strong socio-economic and hydrological impacts. Thereby, this work focuses on the construction of an unprecedented multi-model ensemble of statistically downscaled global climate models (GCMs) for daily precipitation, considering different statistical techniques - including analogs, generalized linear models and neural networks - and a variety of CMIP5 and CMIP6 models. The skills and shortcomings of the different downscaled models were identified. Most of the methods added value in the representation of the main features of daily precipitation, especially in the spatial and intra-annual variability of extremes. The statistical methods showed to be sensitive to the driver GCMs, although the ESD family choice also introduced differences in the simulations. The statistically downscaled projections depicted increases in mean precipitation associated with a rising frequency of extreme events - mostly during the warm season - following the registered trends over SESA. Change rates were consistent among downscaled models up to the middle 21st century when model spread started to emerge. Furthermore, these projections were compared to the available CORDEX-CORE RCM simulations, evidencing a consistent agreement between statistical and dynamical downscaling procedures in terms of the sign of the changes, presenting some differences in their intensity. Overall, this study evidences the potential of statistical downscaling in a changing climate and contributes to its undergoing development over SESA.

Precipitation Associated with Cyclogenetic Hotspot Regions in the Extratropical Southern Hemisphere: CORDEX-CORE Projections

2020 ◽  
Author(s):  
Michelle Reboita ◽  
Marco Reale ◽  
Rosmeri da Rocha ◽  
Graziano Giuliani ◽  
Erika Coppola ◽  
...  
Keyword(s):  
Southern Hemisphere ◽  
Climate Models ◽  
Climate Model ◽  
Global Climate ◽  
Regional Climate ◽  
Winter Season ◽  
Coupled Model ◽  
Global Climate Models ◽  
Precipitation Intensity ◽  
Southeastern Australia

<p>Projections of the precipitation associated with cyclones in the main cyclogenetic regions of the Extratropical Southern Hemisphere domains (Africa - AFR, Australia - AUS and South America - SAM) are here analyzed during the winter season (JJA). The projections were obtained with the Regional Climate Model version 4 (RegCM4) nested in three global climate models (GCMs) from the Coupled Model Intercomparison Project phase 5 (CMIP5) under the Representative Concentration Pathway 8.5. RegCM4 simulations were executed with horizontal grid spacing of 25 km and for the period 1979-2100. As reference period, we consider the interval 1995-2014 and as future climate, the period 2080-2099. Cyclones are identified using an algorithm based on the neighbor nearest approach applied to 6 hourly mean sea level pressure (SLP) fields. In SAM and AUS domains, two hotspot regions for cyclogenesis are selected while for AFR only one is considered. First, in each hotspot region, the cyclogeneses are identified and, then, the mean precipitation from the previous day (day<sub>-1</sub>) to the day after (day<sub>+1</sub>) of these processes is calculated. A general negative trend in the cyclone's frequency is projected for the period 2080-2099. However, for the same period, it is projected an increase of precipitation intensity for AFR domain, mainly near the southwestern coast of the continent. In AUS the increase is observed between southeastern Australia and New Zeland, and over north New Zealand. For SAM there is an expansion of the area with a maximum precipitation intensity close to southern Brazil and Uruguay and to the east of 60<sup>o</sup>W near 40<sup>o</sup>S. Summarizing, the precipitation associated with individual cyclones will increase on average in the future (for example 30% in the SAM domain), being the storms less frequent but more intense.</p>

scholarly journals Niche squeeze induced by climate change of the cold-tolerant subtropical montane Podocarpus parlatorei

2018 ◽  
Vol 5 (11) ◽  
pp. 180513 ◽  
Author(s):  
María Paula Quiroga ◽  
Andrea C. Premoli ◽  
Thomas Kitzberger
Keyword(s):  
Climate Models ◽  
Global Climate ◽  
Warm Season ◽  
Global Climate Models ◽  
High Mountain ◽  
Environmental Niche ◽  
Temperature And Precipitation ◽  
Cold Tolerant ◽  
Suitable Habitats ◽  
Surrounding Areas

Under changing climates, the persistence of montane subtropical taxa may be threatened as suitable habitats decrease with elevation. We developed future environmental niche models (ENNMs) for Podocarpus parlatorei, the only conifer from southern Yungas in South America, and projected it onto two greenhouse gas concentration scenarios based on 13 global climate models for the years 2050 and 2070. Modelling identified that P. parlatorei is sensitive and restricted to a relatively narrow range of both warm season temperature and precipitation. By the mid-late twenty-first century areas of high suitability for P. parlatorei will not migrate but overall suitability will become substantially reduced across its whole range and surrounding areas. Despite extensive areas in high mountain ranges where the species may encounter thermally optimal conditions to potentially allow upward local migration, these same areas will likely become strongly aridified under future conditions. On the other hand, in lowland locations where rainfall levels will not change substantially (e.g. northern range), excessive warming will likely generate abiotic and biotic restrictions (e.g. competition with lowland species) for this cold-tolerant species. Urgent measures should be developed for the local long-term preservation of the gene pool of the unique conifer that characterizes Yungas forests for reasons of biodiversity conservation and ecosystem services.

scholarly journals A New Perspective on Coastally Trapped Disturbances Using Data from the Satellite Era

2019 ◽  
Vol 100 (4) ◽  
pp. 631-651 ◽  
Author(s):  
Timothy W. Juliano ◽  
Zachary J. Lebo ◽  
Gregory Thompson ◽  
David A. Rahn
Keyword(s):  
Climate Models ◽  
Marine Boundary Layer ◽  
Global Climate ◽  
Warm Season ◽  
Cloud Droplet ◽  
Global Climate Models ◽  
Spatial Inhomogeneity ◽  
Radiation Budget ◽  
Stratiform Clouds ◽  
New Perspective

Abstract The ability of global climate models to simulate accurately marine stratiform clouds continues to challenge the atmospheric science community. These cloud types, which account for a large uncertainty in Earth’s radiation budget, are generally difficult to characterize due to their shallowness and spatial inhomogeneity. Previous work investigating marine boundary layer (MBL) clouds off the California coast has focused on clouds that form under the typical northerly flow regime during the boreal warm season. From about June through September, however, these northerly winds may reverse and become southerly as part of a coastally trapped disturbance (CTD). As the flow surges northward, it is accompanied by a broad cloud deck. Because these events are difficult to forecast, in situ observations of CTDs are few and far between, and little is known about their cloud physical properties. A climatological perspective of 23 CTD events—spanning the years from 2004 to 2016—is presented using several data products, including model reanalyses, buoys, and satellites. For the first time, satellite retrievals suggest that CTD cloud decks may play a unique role in the radiation budget due to a combination of aerosol sources that enhance cloud droplet number concentration and reduce cloud droplet effective radius. This particular type of cloud regime should therefore be treated differently than that which is more commonly found in the summertime months over the northeast Pacific Ocean. The potential influence of a coherent wind stress cycle on sea surface temperatures and sea salt aerosol is also explored.

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