scholarly journals Analysis of the Spatio-Temporal Variability of Air Temperature Near the Ground Surface in the Central Baltic Area from 2005 to 2019

Atmosphere ◽  
2020 ◽  
Vol 12 (1) ◽  
pp. 60
Author(s):  
Agu Eensaar
Keyword(s):  
Air Temperature ◽  
Ground Surface ◽  
Surface Air Temperature ◽  
Entire Study ◽  
Significance Level ◽  
Average Surface ◽  
Air Temperatures ◽  
Spatio Temporal ◽  
The Difference ◽  
Baltic Area

In this study, we analyzed the changes in the average daily, monthly, seasonal, and annual surface air temperatures based on the temperature data obtained from seven stations (1 January 2005–31 December 2019; 15 years) belonging to the central Baltic area (Stockholm, Tallinn, Helsinki, Narva, Pärnu, Tartu, and Võru). The statistical analysis revealed that there was a strong correlation between the daily average surface air temperature of the studied cities (range: 0.95–0.99). We analyzed the frequency distribution of the average surface air temperatures in addition to the Kruskal–Wallis and Dunn’s tests (significance level of 0.05) to demonstrate that the difference in air temperatures between Narva, Tallinn, Tartu, and Stockholm are critical. The Welch’s t-test (significance level 0.05), used to study the differences in the average monthly air temperature of the cities in question, showed that the surface air temperatures in Stockholm do not differ from Tallinn air temperatures from May to August. However, the surface air temperatures of Narva were similar to those of Tallinn in September. According to our results, the trends in the changes of monthly average surface air temperatures have a certain course during the year (ranging from 1.8 °C (Stockholm) to 4.5 °C (Võru and Tartu) per decade in February). During the entire study period, in addition to February, the surface air temperature increased in all the studied cities in March, May, June, and December, and the surface air temperature did not increase in January or from July to October. During the study period, the average annual surface air temperature in the cities of the central Baltic area increased by 0.43 °C per decade. The results also confirm that the surface air temperature in the study area is changing differently in different cities. The acceleration of the surface air temperature is very alarming and requires a significant intensification of the measures taken to slow down the temperature rise.

Constructing gridded hourly air temperature dataset

2020 ◽  
Author(s):  
Alexandru Dumitrescu ◽  
Sorin Cheval
Keyword(s):  
Air Temperature ◽  
Land Surface ◽  
Meteorological Data ◽  
Surface Air Temperature ◽  
Shuttle Radar Topography Mission ◽  
National Network ◽  
Research And Innovation ◽  
Air Temperatures ◽  
Spatio Temporal ◽  
Mean Square Errors

<p>Air temperature is one of the most important meteorological element, with major impact on the earth-atmosphere energy balance. The characteristics of the surface air temperature in locations without surface meteorological measurements are usually acquired by employing spatial statistics methods. Gridded surface meteorological data are essential for evaluating the performance of climatological models, for applying statistical downscaling methods and as input data for hydrological and agrometeorological models.</p><p>In this work, we tested two categories of statistical methods (spatial and spatio-temporal) used for interpolating ground-based hourly air temperature data. The main input dataset used in this work was the quality controlled and homogenized hourly air temperatures measured between 2016 and 2017, obtained from four networks: Romanian National Meteorological Administration (ANM), National Network for Monitoring Air Quality (RNMCA), Regional Basic Synoptic Network (RBSN), and Meteorological Terminal Aviation Routine Weather Report network (METAR). </p><p>The principal covariate used in the spatial interpolation procedures was the gap filled hourly LST data over Romania, available between 2016 to 2017, based on MSG-Seviri satellite images, which is an operational product of the Land Surface Analysis – Satellite Application Facility (LSA-SAF).  The other predictors were derived from SRTM (Shuttle Radar Topography Mission) data and from CORINE Land Cover 2018 product. The gridding was performed in a Romanian National Grid (Stereo 70), at 1000 m × 1000 m spatial resolution.</p><p>The results of the tested methods show that the mean absolute errors (MAE) and root mean square errors (RMSE) of space–time predictions are considerably lower than those of the pure spatial estimation.</p><p>This work was supported by a grant of Ministry of Research and Innovation, Romania, CNCS - UEFISCDI, project number PN-III-P1-1.1-PD-2016-1579, within PNCDI III.</p>

scholarly journals The Spatio—Temporal Variation of Pacific Blocking Frequency within Winter Months and Its Relationship with Surface Air Temperature

Atmosphere ◽  
2020 ◽  
Vol 11 (9) ◽  
pp. 960
Author(s):  
Mingxiang Gao ◽  
Shuangyan Yang ◽  
Tim Li
Keyword(s):  
Air Temperature ◽  
High Latitude ◽  
Surface Air Temperature ◽  
Western Pacific ◽  
The Third ◽  
The Pacific ◽  
Spatio Temporal ◽  
The Difference ◽  
Second Period ◽  
Blocking Index

The spatio–temporal evolution of the Pacific blocking frequency (PBF) that is based on a two–dimensional blocking index is investigated during the recent 40–winter (1979/80–2018/19) months (December–January–February). It is found that maximum PBF appears in January within the key area of 140° E–160° W, 50°–70° N. The key–area Pacific blocking in January is more active during the first (1980–1988) and the third (2009–2019) periods than during the second period (1989–2008). There is a positive 500 hPa–geopotential height (Z500) anomaly over the mid–latitude Pacific and a negative one over the high latitude area between the first two periods (second minus first). This pattern can cause an anomalous westerly circulation over the mid–high Pacific sector, which indicates a weakening of the Pacific blocking activity during the second period. This connects to a positive two–meter air temperature (T2m) anomaly over the northeastern Asia and mid–western Pacific, and a negative one over the high–latitude area. The difference of Z500 between the third and the second periods (third minus first) is opposite to that between the second and the first periods, which leads to more Pacific blocking events during the third period. This is related to a positive T2m anomaly over the high–latitude area and a negative one over the mid–latitude area of Asia and the western Pacific. Furthermore, the correlation coefficient between the variables (Z500, T2m, 200 hPa–zonal wind) and the key–area PBF confirms the above results.

scholarly journals Effects of plantation forest clearfelling on stream temperatures in the Plynlimon experimental catchments, mid-Wales

2000 ◽  
Vol 4 (1) ◽  
pp. 95-104 ◽  
Author(s):  
T. Stott ◽  
S. Marks
Keyword(s):  
Air Temperature ◽  
Ground Surface ◽  
Experimental Period ◽  
Stream Temperature ◽  
Main Stream ◽  
Buffer Strips ◽  
Plantation Forest ◽  
Air Temperatures ◽  
The Difference ◽  
Main Effects

Abstract. Hourly stream temperatures monitored over 28 months, which spanned a 3 month period of environmentally sensitive plot-scale harvesting of 20 ha. (20%) of the Nant Tanllwyth catchment (0.89 km2) on the south side of the main stream in early 1996, resulted in a 0.58°C (p< 0.001) increase in monthly mean stream temperature. Over the same 28 month experimental period, there was no significant increase in the monthly mean air temperature recorded at a nearby automatic weather station. Monthly mean temperatures are highest in July and August in the year before and the year after the clearfelling, and one of the main effects of the clearfelling was to decrease the difference between the monthly mean stream and air temperatures. Despite the air temperatures being cooler in the post-clearfelling year, the stream temperatures still showed an increase in the summer months. Monthly mean maximum stream temperatures, also highest in July and August in the year before and the year after the clearfelling, showed a marked increase of 7.0°C: in July and 5.3°C in August from the pre- to the post-clearfelling years, while monthly mean minimum air temperatures actually showed a slight decrease for the same months. The likely effects on stream fauna are discussed, as are suggestions for, and likely effects of, buffer strips alongside the streams. Keywords: stream temperature; air temperature; ground surface temperature; clearfelling; Plynlimon

scholarly journals Spatio–Temporal Characterization of Land Surface Air Temperature Anomaly over Nigeria

2019 ◽  
pp. 1-9
Author(s):  
O. O. Ajileye ◽  
S. S. Aladodo ◽  
A. B. Rabiu
Keyword(s):  
Air Temperature ◽  
Land Surface ◽  
Temperature Anomaly ◽  
Surface Air Temperature ◽  
Temporal Variations ◽  
Capital City ◽  
Percentage Increase ◽  
Air Temperatures ◽  
Spatio Temporal ◽  
Air Temperature Anomaly

In this study, seventeen gridded stations across the latitude over Nigeria were selected with a view to determine and characterize land surface air temperature anomaly for both minimum and maximum values. The study intends to present graphic illustrations of spatial and temporal variations of land surface air temperature anomaly within a period 2008 – 2013. Long-term averages of minimum and maximum land surface air temperatures were obtained from National Aeronautic and Space Administration satellite meteorological dataset (1983 – 2007). Also, monthly and annual averages of land surface air temperatures were obtained from tutiempo.net to compute monthly anomaly, annual anomaly and percentage departure of minimum and maximum land surface air temperatures within a period of 2008 – 2013. The results showed that Jos had consistently experienced -10.8 and -4 percent decrease in minimum and maximum LSAT anomaly for the period under review. The implication is that Jos is getting colder than usual. The minimum LSAT anomaly declined by -2.8 percent in Lagos. Other stations across Nigeria showed a considerable percentage increase in minimum LSAT anomaly led by Yola (19.5%), Sokoto (18%) and Katsina (15.5%). Inland stations had percentage increase of minimum LSAT anomaly ranging between 5.8% and 10% except in Osogbo where the percentage increase was 1.8%. Osogbo is a less populated capital city of Osun state with active agricultural activities as heat sink. Percentage increase of minimum LSAT anomaly was not significant in Nigerian coastal areas most especially at Port Harcourt (0.5%). The spatial distribution of maximum LSAT anomaly across Nigerian latitudinal belt, unlike minimum LSAT anomaly, reduced in trend except in Lagos, Makurdi, Abuja, Bida, Minna and Kano. The minimum and maximum anomaly for maximum LSAT was observed at Jos and Makurdi respectively. There are 2 stations to be watched in terms of getting colder in the years to ahead namely Jos and Osogbo while Makurdi and Yola are gradually becoming hotspots.

scholarly journals Peculiarities of Long-Term Changes in Air Temperatures Near the Ground Surface in the Central Baltic Coastal Area

Climate ◽  
2019 ◽  
Vol 7 (2) ◽  
pp. 22
Author(s):  
Agu Eensaar
Keyword(s):  
Air Temperature ◽  
Coastal Area ◽  
Ground Surface ◽  
Significance Level ◽  
Frequency Distributions ◽  
Saint Petersburg ◽  
Monthly Average ◽  
Air Temperatures ◽  
Term Change

The peculiarities of the long-term change of the annual and monthly average air temperatures until 2017 in five cities of the coastal area of the Central Baltic region—Stockholm, Tallinn, Riga, Helsinki, and Saint Petersburg—were studied. The anomalies of the annual and monthly average air temperatures in relation to the average characteristics 1961–1990 were analyzed. The trends in the air temperature changes during 1980–2017, which come to 0.5 °C per ten years, have been found in the cities of the Central Baltic coastal area. The average air temperature in the Central Baltic cities has grown faster than the global and northern hemisphere. For the longer period of 1850–2017, the average annual rise of air temperature was within the range of 0.1 °C per ten years. The rise in temperature in different months is different, and the rise of the of the average temperature in the summer period has not occurred (at a significance level of 0.05). With the analysis of the frequency distributions of the average annual air temperatures and Welch’s t-test, it is demonstrated that the air temperature (at a significance level of 0.05) has risen in all the months only in Saint Petersburg during 1901–2017 in comparison to the 19th century. There has been no reliable rise of the air temperature during the century in February and from June to September in Riga, from June to October in Helsinki, from June to September in Stockholm, and in August and September in Tallinn. It was found that the average air temperature trends have a certain annual course. The air temperature has risen most in March and April, reaching 0.09 °C (Stockholm, Tallinn) up to 0.23 °C (Saint Petersburg) per ten years. From June to September, the rise of air temperature is considerably lower, remaining below 0.04 °C per ten years. The changes in air temperature are small during the summer and mid-winter; the air temperature has significantly risen in autumn and spring.

scholarly journals Intercomparison of Surface Temperatures from AIRS, MERRA, and MERRA-2 with NOAA and GC-Net Weather Stations at Summit, Greenland

2018 ◽  
Vol 57 (5) ◽  
pp. 1231-1245 ◽  
Author(s):  
Thomas J. Hearty ◽  
Jae N. Lee ◽  
Dong L. Wu ◽  
Richard Cullather ◽  
John M. Blaisdell ◽  
...  
Keyword(s):  
Surface Temperature ◽  
Air Temperature ◽  
Surface Air Temperature ◽  
Cold Season ◽  
Near Surface ◽  
Surface Temperatures ◽  
Air Temperatures ◽  
Weather Stations ◽  
The Difference ◽  
Temperature Inversions

AbstractThe surface skin and air temperatures reported by the Atmospheric Infrared Sounder/Advanced Microwave Sounding Unit-A (AIRS/AMSU-A), the Modern-Era Retrospective Analysis for Research and Applications (MERRA), and MERRA-2 at Summit, Greenland, are compared with near-surface air temperatures measured at National Oceanic and Atmospheric Administration (NOAA) and Greenland Climate Network (GC-Net) weather stations. The AIRS/AMSU-A surface skin temperature (TS) is best correlated with the NOAA 2-m air temperature (T2M) but tends to be colder than the station measurements. The difference may be the result of the frequent near-surface temperature inversions in the region. The AIRS/AMSU-A surface air temperature (SAT) is also correlated with the NOAA T2M but has a warm bias during the cold season and a larger standard error than the surface temperature. The extrapolation of the temperature profile to calculate the AIRS SAT may not be valid for the strongest inversions. The GC-Net temperature sensors are not held at fixed heights throughout the year; however, they are typically closer to the surface than the NOAA station sensors. Comparing the lapse rates at the two stations shows that it is larger closer to the surface. The difference between the AIRS/AMSU-A SAT and TS is sensitive to near-surface inversions and tends to measure stronger inversions than both stations. The AIRS/AMSU-A may be sampling a thicker layer than either station. The MERRA-2 surface and near-surface temperatures show improvements over MERRA but little sensitivity to near-surface temperature inversions.

scholarly journals Changes in Frequency of Precipitation Types Associated with Surface Air Temperature over Northern Eurasia during 1936–90

2008 ◽  
Vol 21 (22) ◽  
pp. 5807-5819 ◽  
Author(s):  
Hengchun Ye
Keyword(s):  
Air Temperature ◽  
High Latitude ◽  
Surface Air Temperature ◽  
Northern Eurasia ◽  
Precipitation Frequency ◽  
Warming Climate ◽  
Air Temperatures ◽  
Threshold Temperatures ◽  
Hydrological Cycles ◽  
Former Ussr

Abstract Potential benefits or disadvantages of increasing precipitation in high-latitude regions under a warming climate are dependent on how and in what form the precipitation occurs. Precipitation frequency and type are equally as important as quantity and intensity to understanding the seasonality of hydrological cycles and the health of the ecosystem in high-latitude regions. This study uses daily historical synoptic observation records during 1936–90 over the former USSR to reveal associations between the frequency of precipitation types (rainfall, snowfall, mixed solid and liquid, and wet days of all types) and surface air temperatures to determine potential changes in precipitation characteristics under a warming climate. Results from this particular study show that the frequency of precipitation of all types generally increases with air temperature during winter. However, both solid and liquid precipitation days predominantly decrease with air temperature during spring with a reduction in snowfall days being most significant. During autumn, snowfall days decrease while rainfall days increase resulting in overall decreases in wet days as air temperature increases. The data also reveal that, as snowfall days increase in relationship to increasing air temperatures, this increase may level out or even decrease as mean surface air temperature exceeds −8°C in winter. In spring and autumn, increasing rainfall days switch to decreasing when the mean surface air temperature goes above 6°C. The conclusion of this study is that changes in the frequency of precipitation types are highly dependent on the location’s air temperature and that threshold temperatures exist beyond which changes in an opposite direction occur.

Surface air–soil temperature relationship and shallow soil thermal regime: a case study using a soil temperature observational dataset for Spain.

2021 ◽  
Author(s):  
Camilo Melo Aguilar ◽  
Fidel González Rouco ◽  
Norman Steinert ◽  
Elena García Bustamante ◽  
Felix García Pereira ◽  
...  
Keyword(s):  
Surface Temperature ◽  
Soil Temperature ◽  
Air Temperature ◽  
Thermal Regime ◽  
Ground Surface ◽  
Surface Air Temperature ◽  
Environmental Variable ◽  
Chemical Processes ◽  
Strong Connection ◽  
Shallow Subsurface

&lt;p&gt;The land-atmosphere interactions via the energy and water exchanges at the ground surface generally translate into a strong connection between the surface air temperature (SAT) and the ground surface temperature (GST). In turn, the surface temperature affects the amount of heat flowing into the soil, thus controlling the subsurface temperature profile. As soil temperature (ST) is a key environmental variable that controls various physical, biological and chemical processes, understanding the relationship between SAT and GST and STs is important.&lt;/p&gt;&lt;p&gt;In situ ST measurements represent the most adequate source&amp;#160;of information to evaluate the distribution of temperature in soils and to address its influence on soil biological and chemical processes as well as on climate feedbacks. However, ST observations are scarce both in space and time. Therefore, the development of ST observational datasets is of great interest to promote analyses regarding the soil thermodynamics and the response to atmospheric warming.&lt;/p&gt;&lt;p&gt;We have developed a quality-controlled dataset of Soil Temperature Observations for Spain (SoTOS). The ST data are obtained from the Spanish meteorological agency (AEMET), including ST at different layers down to a depth of 1 m (i.e., 0.05, 0.1, 0.2, 0.5 and 1 m depth) for 39 observatories for the 1985&amp;#8211;2018 period. Likewise, 2m air temperature has also been included for the same 39 sites.&lt;/p&gt;&lt;p&gt;SoTOS is employed to evaluate the shallow subsurface thermal regime and the SAT&amp;#8211;GST relationship on interannual to multidecadal timescales. The results show that thermal conduction is the main heat transfer mechanism that controls the distribution of soil temperatures in the shallow subsurface. Regarding the SAT-GST relationship, there is a strong connection between SAT and GST. However, the SAT&amp;#8211;GST coupling may be disrupted on seasonal to multidecadal timescales due to variations in the surface energy balance in response to decreasing soil moisture conditions over the last decade at some SoTOS sites. This results in larger GST warming relative to SAT. Such a response may have implications for climate studies that assume a strong connection between SAT and GST such as air temperature estimations from remote sensing products or even for palaeoclimatic analyses.&lt;/p&gt;

scholarly journals Influence of radiative forcing factors on ground–air temperature coupling during the last millennium: implications for borehole climatology

2018 ◽  
Vol 14 (11) ◽  
pp. 1583-1606 ◽  
Author(s):  
Camilo Melo-Aguilar ◽  
J. Fidel González-Rouco ◽  
Elena García-Bustamante ◽  
Jorge Navarro-Montesinos ◽  
Norman Steinert
Keyword(s):  
Air Temperature ◽  
Land Surface ◽  
Radiative Forcing ◽  
Spatial Scales ◽  
Ground Surface ◽  
Surface Air Temperature ◽  
Small Variation ◽  
Last Millennium ◽  
Reconstruction Methods

Abstract. Past climate variations may be uncovered via reconstruction methods that use proxy data as predictors. Among them, borehole reconstruction is a well-established technique to recover the long-term past surface air temperature (SAT) evolution. It is based on the assumption that SAT changes are strongly coupled to ground surface temperature (GST) changes and transferred to the subsurface by thermal conduction. We evaluate the SAT–GST coupling during the last millennium (LM) using simulations from the Community Earth System Model LM Ensemble (CESM-LME). The validity of such a premise is explored by analyzing the structure of the SAT–GST covariance during the LM and also by investigating the evolution of the long-term SAT–GST relationship. The multiple and single-forcing simulations in the CESM-LME are used to analyze the SAT–GST relationship within different regions and spatial scales and to derive the influence of the different forcing factors on producing feedback mechanisms that alter the energy balance at the surface. The results indicate that SAT–GST coupling is strong at global and above multi-decadal timescales in CESM-LME, although a relatively small variation in the long-term SAT–GST relationship is also represented. However, at a global scale such variation does not significantly impact the SAT–GST coupling, at local to regional scales this relationship experiences considerable long-term changes mostly after the end of the 19th century. Land use land cover changes are the main driver for locally and regionally decoupling SAT and GST, as they modify the land surface properties such as albedo, surface roughness and hydrology, which in turn modifies the energy fluxes at the surface. Snow cover feedbacks due to the influence of other external forcing are also important for corrupting the long-term SAT–GST coupling. Our findings suggest that such local and regional SAT–GST decoupling processes may represent a source of bias for SAT reconstructions from borehole measurement, since the thermal signature imprinted in the subsurface over the affected regions is not fully representative of the long-term SAT variations.

Analysis of methodological and physical bias on borehole temperature reconstructions from a pseudo-proxy approach.

2020 ◽  
Author(s):  
Camilo Melo Aguilar ◽  
Fidel González Rouco ◽  
Elena García Bustamante ◽  
Norman Steinert ◽  
Jorge Navarro ◽  
...  
Keyword(s):  
Grid Point ◽  
Ground Surface ◽  
Temporal Distribution ◽  
Surface Air Temperature ◽  
Internal Variability ◽  
Last Millennium ◽  
Subsurface Temperature ◽  
Borehole Logs ◽  
Spatio Temporal

&lt;p&gt;The analysis of subsurface temperature measurements from boreholes is a well established approach for reconstructing last millennium (LM) surface air temperature (SAT). It is based on the assumption that SAT variations are strongly coupled to ground surface temperature (GST) variations and transferred to the subsurface by thermal conduction. We have evaluated the long-term SAT-GST coupling over the LM using an ensemble of both full- and single-forcing simulations form the Community Earth System Model-Last Millennium Ensemble (CESM-LME). Such a premise is explored by investigating the evolution of the long-term SAT&amp;#8211;GST relationship. The results indicate that SAT&amp;#8211;GST coupling is strong at global and above multi-decadal timescales in CESM-LME. However, at local to regional scales this relationship experiences considerable long-term changes mostly after the end of the 19th century. Land use land cover (LULC) changes stand as the main driver for locally and regionally decoupling SAT and GST, due to the changes in the energy fluxes at the surface. Snow cover feedbacks due to the influence of GHG forcing are also important for corrupting the long-term SAT&amp;#8211;GST coupling. These processes may represent a source of bias for SAT reconstructions from GST borehole profiles. In light of these findings, we subsequently assessed the potential effects on SAT reconstructions from the borehole method in pseudo-proxy experiments that make use of the same set of simulations from the CESM-LME. First, a heat-conduction forward model has been used to estimate subsurface temperature-anomaly profiles using simulated GST as boundary conditions. Subsequently, singular value decomposition inversion (SVD) has been applied to reconstruct LM GST variations from the simulated profiles. We implemented and ideal scenario in which it is assumed the existence of borehole logs at every model grid point. Further, this scenario considers that all boreholes are logged homogenously at the same time. In addition, we implemented a more realistic approach in which the real-world spatio-temporal distribution of the global borehole network is considered. Results show that the SVD inversion is able to retrieve the long-term GST variations over the LM when an appropriated coverture of borehole logs is available. However, due to the limited spatio-temporal distribution of the actual borehole network, there is a lost in the accuracy to retrieve the simulated GST 20th century trends, with the temporal logging of the BTPs as the main sampling issue. Furthermore, in the surrogate reality of the CESM-LME the SAT-GST decoupling, due to the influence of LULC and GHG forcings, leads to a slightly underestimation of SAT warming during the industrial period across the CESM-LME. The level of impact is, however, highly depended on the realization of internal variability.&lt;/p&gt;

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