scholarly journals Atmospheric stilling and warming air temperatures drive long‐term changes in lake stratification in a large oligotrophic lake

2020 ◽  
Author(s):  
Jonathan T. Stetler ◽  
Scott Girdner ◽  
Jeremy Mack ◽  
Luke A. Winslow ◽  
Taylor H. Leach ◽  
...  
Keyword(s):  
Oligotrophic Lake ◽  
Air Temperatures ◽  
Long Term Changes ◽  
Lake Stratification

Analysis of Long-term Changes of Days with 25℃ or Higher Air Temperatures in Jeju

2016 ◽  
Vol 7 (1) ◽  
pp. 31 ◽  
Author(s):  
Jae-Won Choi ◽  
Yumi Cha ◽  
Jeoung-Yun Kim ◽  
Cheol-Hong Park
Keyword(s):  
Air Temperatures ◽  
Long Term Changes

scholarly journals Interannual and long-term changes in the trophic state of a multibasin lake: effects of morphology, climate, winter aeration, and beaver activity

2016 ◽  
Vol 73 (3) ◽  
pp. 445-460 ◽  
Author(s):  
Dale M. Robertson ◽  
William J. Rose ◽  
Paul C. Reneau
Keyword(s):  
Water Quality ◽  
Trophic State ◽  
Secchi Depth ◽  
Climatic Changes ◽  
Main Flow ◽  
Temperature And Precipitation ◽  
Air Temperatures ◽  
Long Term Changes ◽  
P Sources

Little St. Germain Lake (LSG), a relatively pristine multibasin lake in Wisconsin, USA, was examined to determine how morphologic (internal), climatic (external), anthropogenic (winter aeration), and natural (beaver activity) factors affect the trophic state (phosphorus, P; chlorophyll, CHL; and Secchi depth, SD) of each of its basins. Basins intercepting the main flow and external P sources had highest P and CHL and shallowest SD. Internal loading in shallow, polymictic basins caused P and CHL to increase and SD to decrease as summer progressed. Winter aeration used to eliminate winterkill increased summer internal P loading and decreased water quality, while reductions in upstream beaver impoundments had little effect on water quality. Variations in air temperature and precipitation affected each basin differently. Warmer air temperatures increased productivity throughout the lake and decreased clarity in less eutrophic basins. Increased precipitation increased P in the basins intercepting the main flow but had little effect on the isolated deep West Bay. These relations are used to project effects of future climatic changes on LSG and other temperate lakes.

scholarly journals Dynamic response of an Arctic epishelf lake to seasonal and long-term forcing: implications for ice shelf thickness

2017 ◽  
Author(s):  
Andrew K. Hamilton ◽  
Bernard E. Laval ◽  
Derek R. Mueller ◽  
Warwick F. Vincent ◽  
Luke Copland
Keyword(s):  
Seasonal Variation ◽  
Canadian Arctic ◽  
The Arctic ◽  
Ice Shelf ◽  
Ice Shelves ◽  
Air Temperatures ◽  
Long Term Changes ◽  
Episodic Mixing ◽  
Outflow Pathway

Abstract. Changes in the depth of the freshwater-seawater interface in epishelf lakes have been used to infer long-term changes in the thickness of ice shelves, however, little is known about the dynamics of epishelf lakes and what other factors may influence their depth. Continuous observations collected between 2011 and 2014 in the Milne Fiord epishelf lake, in the Canadian Arctic, showed that the depth of the halocline varied seasonally by up to 3.3 m, which was comparable to interannual variability. The seasonal depth variation was controlled by the magnitude of surface meltwater inflow and the hydraulics of the inferred outflow pathway, a narrow basal channel in the Milne Ice Shelf. When seasonal variation and an episodic mixing of the halocline were accounted for, long-term records of depth indicated there was no significant change in thickness of ice along the basal channel from 1983 to 2004, followed by a period of steady thinning at 0.50 m a-1 between 2004 and 2011. Rapid thinning at 1.15 m a-1 then occurred from 2011 to 2014, corresponded to a period of warming regional air temperatures. Continued warming is expected to lead to the breakup of the ice shelf and the imminent loss of the last known epishelf lake in the Arctic.

Long-term changes in the water quality of a deep temperate oligotrophic lake in response to catchment disturbance: evidence from sediment cores

2019 ◽  
Vol 53 (4) ◽  
pp. 571-587 ◽  
Author(s):  
Alfred Theodore N. K. Kpodonu ◽  
David P. Hamilton ◽  
Christopher H. Lusk ◽  
Adam Hartland ◽  
Daniel C. Laughlin ◽  
...  
Keyword(s):  
Water Quality ◽  
Sediment Cores ◽  
Oligotrophic Lake ◽  
Catchment Disturbance ◽  
Long Term Changes

scholarly journals Assessment of long-term changes in the surface air temperature from the High Arctic archipelago Franz Joseph Land from 1929 to the present (2017)

2021 ◽  
Vol 11 (1) ◽  
pp. 114-133
Author(s):  
Boris Ivanov ◽  
Tatiana Karandasheva ◽  
Valery Demin ◽  
Anastasiia Revina ◽  
Pavel Sviashchennikov ◽  
...  
Keyword(s):  
Temperature Increase ◽  
Maximum Rate ◽  
Winter Season ◽  
Surface Air Temperature ◽  
High Arctic ◽  
Data Series ◽  
Regression Equations ◽  
Air Temperatures ◽  
Long Term Changes

Electronic archives of data from standard meteorological observations (mean daily/monthly surface air temperatures - SAT) at the meteorological stations at Bukhta Tikhaya (Hooker Island, 1929-1960) and Krenkel Observatory (Hayes Island, 1957-2017) on Franz Josef Land (FJL) are presented. Parallel data series of SAT made in 1958 and 1959 on both meteorological stations were analyzed. Linear regression equations used for extrapolation of observational data representative for Krenkel Observatory for the period 1929-1957 are also presented. The assessment of long-term changes in SAT on FJL was carried out based on the analysis of the obtained series (1929-2017). The main conclusions that follow from our study are: (1) The total warming in the FJL archipelago was 1.6-1.8°C (0.2°C/decade) for the entire available period of instrumental observations (1929-2017); (2) The highest rates of warming were recorded in March-April and amounted to 0.6°C/decade; (3) A particular strong warming has been observed since the 1990s. The annual temperature increased by 6.3°C (2.2°C/decade) for the period 1990-2017 and 5.2°C (2.9°C/decade) for the period 2000-2017; (4) For the period 1990-2017 the maximum rate of warming occurred between October to February with 4.4°C/decade; (5) For the period 2000-2017 the maximum rate of warming occurred between January to April and from November to December with 5.6°C/decade; (6) The dominant seasons of the year are winter (November-April), spring (May), summer (June-September) and autumn (October); (7) Over the entire observation period the largest temperature increase was observed in the winter season. During the period of modern warming (1990-2017), the largest temperature increase was observed in winter and autumn.

scholarly journals Changes of Extreme Climate Events in Latvia

2012 ◽  
Vol 9 (1) ◽  
pp. 4-11 ◽  
Author(s):  
Zanita Avotniece ◽  
Maris Klavins ◽  
Valerijs Rodinovs
Keyword(s):  
Spatial Heterogeneity ◽  
Extreme Precipitation ◽  
Negative Temperature ◽  
Temperature Extremes ◽  
Extreme Climate Events ◽  
Extreme Climate ◽  
Air Temperatures ◽  
Long Term Changes ◽  
Climate Events

Abstract Extreme climate events are increasingly recognized as a threat to human health, agriculture, forestry and other sectors. To assess the occurrence and impacts of extreme climate events, we have investigated the changes of indexes characterizing positive and negative temperature extremes and extreme precipitation as well as the spatial heterogeneity of extreme climate events in Latvia. Trend analysis of long-term changes in the frequency of extreme climate events demonstrated a significant increase in the number of days with extremely high air temperatures and extreme precipitation, and a decrease in the number extremely cold days.

scholarly journals Long-term changes in precipitation phase in Czechia

Geografie ◽  
2019 ◽  
Vol 124 (1) ◽  
pp. 41-55
Author(s):  
Martin Hynčica ◽  
Radan Huth
Keyword(s):  
Air Temperature ◽  
Daily Precipitation ◽  
Sharp Decrease ◽  
Total Precipitation ◽  
Solid Precipitation ◽  
The Past ◽  
Air Temperatures ◽  
Long Term Changes ◽  
Precipitation Phase

Long-term changes in precipitation phase are investigated at ten stations in Czechia. Trends are calculated from 1983 to 2018 for the period between November and April. Daily SYNOP reports and daily precipitation totals are used at every station, where number and occurrence of specific codes in SYNOP report determine daily precipitation totals as solid, combined (which represents, to a large extent, category of mixed precipitation), or liquid. Thereafter, it is possible to calculate trends of all precipitation phases as well as the proportion of solid to total precipitation (S/P; in %). The average S/P trend over all Czech stations is significantly negative (−0.60%·year-1) and accompanied by a sharp decrease in solid precipitation (−1.66 mm·year-1) and an increase in combined precipitation (1.50 mm·year-1). Thus, our results show a ship of precipitation phase from solid to combined. Because of the dependence of S/P on air temperature, we suppose that the current S/P decline is a manifestation of rising air temperatures in the past decades.

scholarly journals Dynamic response of an Arctic epishelf lake to seasonal and long-term forcing: implications for ice shelf thickness

2017 ◽  
Vol 11 (5) ◽  
pp. 2189-2211 ◽  
Author(s):  
Andrew K. Hamilton ◽  
Bernard E. Laval ◽  
Derek R. Mueller ◽  
Warwick F. Vincent ◽  
Luke Copland
Keyword(s):  
Canadian Arctic ◽  
The Arctic ◽  
Ice Shelf ◽  
Minimum Thickness ◽  
Ice Shelves ◽  
Air Temperatures ◽  
Long Term Changes ◽  
Episodic Mixing ◽  
Outflow Pathway

Abstract. Changes in the depth of the freshwater–seawater interface in epishelf lakes have been used to infer long-term changes in the minimum thickness of ice shelves; however, little is known about the dynamics of epishelf lakes and what other factors may influence their depth. Continuous observations collected between 2011 and 2014 in the Milne Fiord epishelf lake, in the Canadian Arctic, showed that the depth of the halocline varied seasonally by up to 3.3 m, which was comparable to interannual variability. The seasonal depth variation was controlled by the magnitude of surface meltwater inflow and the hydraulics of the inferred outflow pathway, a narrow basal channel in the Milne Ice Shelf. When seasonal variation and an episodic mixing of the halocline were accounted for, long-term records of depth indicated there was no significant change in thickness of ice along the basal channel from 1983 to 2004, followed by a period of steady thinning at 0.50 m a−1 between 2004 and 2011. Rapid thinning at 1.15 m a−1 then occurred from 2011 to 2014, corresponding to a period of warming regional air temperatures. Continued warming is expected to lead to the breakup of the ice shelf and the imminent loss of the last known epishelf lake in the Arctic.

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