Trends and periodicities in the Canadian Drought Code and their relationships with atmospheric circulation for the southern Canadian boreal forest

2004 ◽  
Vol 34 (1) ◽  
pp. 103-119 ◽  
Author(s):  
Martin-Philippe Girardin ◽  
Jacques Tardif ◽  
Mike D Flannigan ◽  
B Mike Wotton ◽  
Yves Bergeron
Keyword(s):  
Boreal Forest ◽  
Gulf Of Alaska ◽  
Drought Severity ◽  
Severe Drought ◽  
Summer Drought ◽  
Eastern Canada ◽  
The North ◽  
Circulation Patterns ◽  
Decadal Scale ◽  
Canadian Boreal Forest

Trends and periodicities in summer drought severity are investigated on a network of Canadian Drought Code (CDC) monthly average indices extending from central Quebec to western Manitoba and covering the instrumental period 1913–1998. The relationship and coherency between CDC indices and ocean–atmosphere circulation patterns are also examined. Trend analyses indicate that drought severity is unchanged in eastern and central Canada. Composite analyses indicate that for most of the corridor, severe drought seasons occur with a combination of positive 500-hPa geopotential height anomalies centered over the Gulf of Alaska and over the Baffin Bay. Additional severe drought seasons develop across the corridor in the presence of positive height anomalies located over or upstream of the affected regions. According to spectral analyses, the North Atlantic and the North Pacific circulation patterns modulate the drought variability at the decadal scale. Our results lead us to conclude that climate warming and the increases in the amount and frequency of precipitation in eastern Canada during the last century had no significant impact on summer drought severity. It is unlikely that linear climate change contributed to the change in the boreal forest dynamics observed over the past 150 years.

Stress-testing groundwater and baseflow drought sensitivity to recharge

2021 ◽  
Author(s):  
Jost Hellwig ◽  
Michael Stoelzle ◽  
Kerstin Stahl
Keyword(s):  
Fractured Rock ◽  
Drought Severity ◽  
Severe Drought ◽  
Stress Tests ◽  
Drought Sensitivity ◽  
The North ◽  
Groundwater Response ◽  
Dry Spells ◽  
Groundwater Drought ◽  
Fractured Rock Aquifers

<p>Groundwater is the main source of freshwater and maintains streamflow during drought. Potential future groundwater and baseflow drought hazards depend on the systems' sensitivity to altered recharge conditions. We performed groundwater model experiments using three different generic stress tests to estimate the groundwater- and baseflow drought sensitivity to changes in recharge. The stress tests stem from a stakeholder co-design process that specifically followed the idea of altering known drought events from the past, i.e. asking whether altered recharge could have made a particular event worse. Here we show that groundwater responses to the stress tests are highly heterogeneous across Germany with groundwater heads in the North more sensitive to long-term recharge and in the Central German Uplands to short-term recharge variations. Baseflow droughts are generally more sensitive to intra-annual dynamics and baseflow responses to the stress tests are smaller compared to the groundwater heads. The groundwater drought recovery time is mainly driven by the hydrogeological conditions with slow (fast) recovery in the porous (fractured rock) aquifers. In general, a seasonal shift of recharge (i.e., less summer recharge and more winter recharge) will therefore have low effects on groundwater and baseflow drought severity. A lengthening of dry spells might cause much stronger responses, especially in regions with slow groundwater response to precipitation. Water management may need to consider the spatially different sensitivities of the groundwater system and the potential for more severe groundwater droughts in the large porous aquifers following prolonged meteorological droughts, particularly in the context of climate change projections indicating stronger seasonality and more severe drought events.</p>

scholarly journals Standardized Drought Indices for Pre-Summer Drought Assessment in Tropical Areas

Atmosphere ◽  
2020 ◽  
Vol 11 (11) ◽  
pp. 1209
Author(s):  
David Romero ◽  
Eric Alfaro ◽  
Roger Orellana ◽  
Maria-Engracia Hernandez Cerda
Keyword(s):  
Vegetation Index ◽  
Temporal Variations ◽  
Climatic Conditions ◽  
Drought Indices ◽  
Drought Severity ◽  
Severe Drought ◽  
Summer Drought ◽  
Tropical Zone ◽  
Drought Assessment ◽  
The Impact

The main climatic indices used for the determination of pre-summer drought severity were developed for temperate zones with very different climatic conditions from those found in the tropical climate zones, particularly with respect to seasonal rainfall variations. The temporal evolution of pre-summer drought leads the authors to compute the indices for each year over a defined period according to the climatic normals of each meteorological station and to consider the months inside the dry episode differently, according to the law of emptying the water reserves. As a function of this, standardized drought indices are proposed for the evaluation of the pre-summer drought in tropical zone. Two new indices were tested: one developed from precipitation and the other also considering temperature. These indices were validated by correlation with Advanced very-high-resolution radiometer (AVHRR) normalized difference vegetation index (NDVI) time series and used to identify the most severe drought conditions in the Yucatan Peninsula. The comparison between the indices and their temporal variations highlighted the importance of temperature in the most critical events and left indications of the impact of global warming on the phenomenon.

Linkages between atmospheric circulation, climate and streamflow in the northern North Atlantic: research prospects

2006 ◽  
Vol 30 (2) ◽  
pp. 143-174 ◽  
Author(s):  
D. G. Kingston ◽  
D. M. Lawler ◽  
G. R. McGregor
Keyword(s):  
Atmospheric Circulation ◽  
North Atlantic ◽  
Analytical Techniques ◽  
Eastern Canada ◽  
Natural Systems ◽  
Atmospheric Circulation Patterns ◽  
The North ◽  
Circulation Patterns ◽  
Northwest Europe ◽  
The North Atlantic Oscillation

This paper evaluates the relationships between atmospheric circulation, climate and streamflow in the northern North Atlantic region over the last century and especially the last 50 years. Improved understanding of climatic influences on streamflow is vital given the great importance of fluvial processes to natural systems and water resources, especially in the light of recent and predicted climate change. The main focus lies with climatic and hydrologic implications of the major circulation patterns in the northern North Atlantic, namely the North Atlantic Oscillation (NAO) and Arctic Oscillation (AO). The studies reviewed here reveal key relationships between circulation, climate and streamflow across the northern North Atlantic, allowing the construction of a simple conceptual model for this system. Generally positive NAO/AO-streamflow relationships are found in northwest Europe and northeast USA, with both positive and negative NAO/AO-streamflow linkages apparent for parts of eastern Canada. To help promote a better understanding of the system, several research gaps are identified and critically examined, including: the spatial scope and coverage of investigations; data quality and homogeneity; appropriateness of analytical techniques; and the need for greater knowledge and technique sharing between hydrology and climatology, particularly regarding the rigorous characterization of atmospheric circulation patterns. Among these, the development of seasonally varying, or mobile, NAO indices, to capture variations in subseasonal, seasonal and annual movements in the centres of action, and the need to develop analyses of more hydrologically meaningful climate variables beyond conventional time averaged statistics, are deemed particularly important.

scholarly journals Synoptic-Scale Atmospheric Circulation and Boreal Canada Summer Drought Variability of the Past Three Centuries

2006 ◽  
Vol 19 (10) ◽  
pp. 1922-1947 ◽  
Author(s):  
Martin-Philippe Girardin ◽  
Jacques C. Tardif ◽  
Mike D. Flannigan ◽  
Yves Bergeron
Keyword(s):  
Atmospheric Circulation ◽  
North Pacific ◽  
Land Surface ◽  
Fire Regimes ◽  
Global Ocean ◽  
Summer Drought ◽  
Eastern Canada ◽  
Meridional Component ◽  
The Past ◽  
Decadal Scale

Abstract Five independent multicentury reconstructions of the July Canadian Drought Code and one reconstruction of the mean July–August temperature were developed using a network of 120 well-replicated tree-ring chronologies covering the area of the eastern Boreal Plains to the eastern Boreal Shield of Canada. The reconstructions were performed using 54 time-varying reconstruction submodels that explained up to 50% of the regional drought variance during the period of 1919–84. Spatial correlation fields on the six reconstructions revealed that the meridional component of the climate system from central to eastern Canada increased since the mid–nineteenth century. The most obvious change was observed in the decadal scale of variability. Using 500-hPa geopotential height and wind composites, this zonal to meridional transition was interpreted as a response to an amplification of long waves flowing over the eastern North Pacific into boreal Canada, from approximately 1851 to 1940. Composites with NOAA Extended Reconstructed SSTs indicated a coupling between the meridional component and tropical and North Pacific SST for a period covering at least the past 150 yr, supporting previous findings of a summertime global ocean–atmosphere–land surface coupling. This change in the global atmospheric circulation could be a key element toward understanding the observed temporal changes in the Canadian boreal forest fire regimes over the past 150 yr.

scholarly journals Groundwater and baseflow drought responses to synthetic recharge stress tests

2021 ◽  
Vol 25 (2) ◽  
pp. 1053-1068
Author(s):  
Jost Hellwig ◽  
Michael Stoelzle ◽  
Kerstin Stahl
Keyword(s):  
Fractured Rock ◽  
Drought Severity ◽  
Severe Drought ◽  
Stress Tests ◽  
The North ◽  
Groundwater Response ◽  
Dry Spells ◽  
Groundwater Drought ◽  
Fractured Rock Aquifers

Abstract. Groundwater is the main source of freshwater and maintains streamflow during drought. Potential future groundwater and baseflow drought hazards depend on the systems' sensitivity to altered recharge conditions. We performed groundwater model experiments using three different generic stress tests to estimate the groundwater and baseflow drought sensitivity to changes in recharge. The stress tests stem from a stakeholder co-design process that specifically followed the idea of altering known drought events from the past, i.e. asking whether altered recharge could have made a particular event worse. Across Germany, groundwater responses to the stress tests are highly heterogeneous, with groundwater heads in the north more sensitive to long-term recharge and in the Central German Uplands to short-term recharge variations. Baseflow droughts are generally more sensitive to intra-annual dynamics, and baseflow responses to the stress tests are smaller compared to the groundwater heads. The groundwater drought recovery time is mainly driven by the hydrogeological conditions, with slow (fast) recovery in the porous (fractured rock) aquifers. In general, a seasonal shift of recharge (i.e. less summer recharge and more winter recharge) will have lesser effects on groundwater and baseflow drought severity. A lengthening of dry spells might cause much stronger responses, especially in regions with slow groundwater response to precipitation. Water management may need to consider the spatially different sensitivities of the groundwater system and the potential for more severe groundwater droughts in the large porous aquifers following prolonged meteorological droughts, particularly in the context of climate change projections indicating stronger seasonality and more severe drought events.

scholarly journals Tree-Ring-Recorded Drought Variability in the Northern Daxing’anling Mountains of Northeastern China

Forests ◽  
2018 ◽  
Vol 9 (11) ◽  
pp. 674 ◽  
Author(s):  
Jian Yu ◽  
Sher Shah ◽  
Guang Zhou ◽  
Zhenzhao Xu ◽  
Qijing Liu
Keyword(s):  
Correlation Analysis ◽  
Tree Ring ◽  
Large Scale ◽  
Southern Oscillation ◽  
Ring Width ◽  
Principal Component ◽  
Severity Index ◽  
Drought Severity ◽  
Severe Drought ◽  
The North

We developed two tree-ring width chronologies of Mongolian Scots pine (Pinus sylvestris var. mongolica) from the low elevation forest of the northern Daxing’anling Mountains of Inner Mongolia. Although the two chronologies come from different sampling sites, significant correlations existed among the chronologies (r = 0.318), and the first principal component (PC1) accounted for 65.9% of total variance over their common period 1792–2016. Climate-growth correlation analysis revealed that the previous June and July Palmer drought severity index (PDSIp6-7) was the main climatic factor controlling tree-ring growth. Using a linear regression model, we reconstructed the PDSIp6-7 for the past 225 years (1792–2016). The reconstruction satisfied required statistical calibration and validation tests, and represented 38.6% of the PDSI variance recorded by instruments over the period 1955–2016. Six wet and five dry periods were revealed during these 225 years. The drought of 1903–1927 was the most severe drought in the study area in the last 225 years. Comparison with other tree-ring-based moisture-sensitive sequences from nearby regions confirmed a high degree of confidence in our reconstruction. The results of a spatial climate correlation analysis with a gridded PDSI dataset revealed that our reconstructions contained strong regional drought signals for the southern Stanovoy Range and the northern Daxing’anling Mountains. The power spectrum revealed the existence of significant frequency cycles, which may be linked to large-scale atmospheric-oceanic variability, such as the El Niño-Southern Oscillation, solar activity, and the North Atlantic Oscillation.

scholarly journals Spatial variation of trends in wildfire and summer drought in British Columbia, Canada, 1920 - 2000

2010 ◽  
Vol 19 (3) ◽  
pp. 272 ◽  
Author(s):  
Andrea Meyn ◽  
Sebastian Schmidtlein ◽  
Stephen W. Taylor ◽  
Martin P. Girardin ◽  
Kirsten Thonicke ◽  
...  
Keyword(s):  
British Columbia ◽  
Spatial Variation ◽  
Boreal Forests ◽  
Aridity Index ◽  
Severity Index ◽  
Drought Severity ◽  
Summer Drought ◽  
North East ◽  
The North ◽  
The Relationship

Owing to large climatic and orographic variation, British Columbia covers a variety of ecosystems extending from temperate rainforests on the Pacific coast to boreal forests in the north-east. The aim of this study is to investigate the spatial variation of trends in wildfire activity and their relationship to summer drought for the entire province of British Columbia. Time series of annual wildfire extent and occurrence, summer self-calibrating Palmer Drought Severity Index and summer Aridity Index were derived from spatially explicit data. Sixteen landscape regions according to the provincial Biogeoclimatic Ecosystem Classification system served as spatial reference. The regional series for 1920–2000 were subjected to trend analysis. Correlations between area burned and summer drought were assessed and tested for significance. The observed decrease in wildfire activity is significantly related to wetter summers with the strength of the relationship considerably varying between British Columbia’s landscapes. Our results suggest that aggregated statistics for large regions with complex topography and climate can hide the spatial variation in direction and strength of changes and may accordingly obscure the relationship between fire and drought. Based on high-spatial-resolution data, our study is the first to provide a differentiated picture for British Columbia.

A molluscan perspective on hydrological cycle dynamics in northwestern Europe

2010 ◽  
Vol 89 (1) ◽  
pp. 51-60 ◽  
Author(s):  
E.A.A. Versteegh ◽  
H.B. Vonhof ◽  
S.R. Troelstra ◽  
D. Kroon
Keyword(s):  
Environmental Conditions ◽  
Hydrological Cycle ◽  
Dominant Mode ◽  
Warm Period ◽  
Drought Severity ◽  
Rhine River ◽  
The North ◽  
Precipitation Regimes ◽  
Decadal Scale ◽  
The North Atlantic Oscillation

AbstractShell aragonite δ180 values of unionid freshwater mussels are applied as a proxy for past river discharges in the rivers Rhine and Meuse, using a set of nine shells from selected climatic intervals during the late Holocene. A single Meuse shell derives from the Subboreal and its δ180 values are similar to modern values. The Rhine specimens represent the Subboreal, the Roman Warm Period and the Medieval Warm Period (MWP). These shells also show averages and ranges of aragonite δ180 values similar to modern specimens. This indicates that environmental conditions such as Rhine river dynamics, Alpine meltwater input and drought severity during these intervals were similar to the 20th century. These shells do not record subtle centennial to millennial climatic variation due to their relatively short lifespan and the large inter-annual and intra-seasonal variation in environmental conditions. However, they are very suitable for studying seasonal to decadal scale climate variability. The two shells with the longest lifespan appear to show decadal scale variability in reconstructed water δ180 values during the MWP, possibly forced by the North Atlantic Oscillation (NAO), which is the dominant mode of variability influencing precipitation regimes over Europe.

scholarly journals Past and projected future changes in moisture conditions in the Canadian boreal forest

2014 ◽  
Vol 90 (05) ◽  
pp. 678-691 ◽  
Author(s):  
Yonghe Wang ◽  
Edward H. Hogg ◽  
David T. Price ◽  
Jason Edwards ◽  
Tim Williamson
Keyword(s):  
Forest Management ◽  
Boreal Forest ◽  
Spatial Data ◽  
General Circulation ◽  
General Circulation Models ◽  
Drought Severity ◽  
Linear Regression Models ◽  
Moisture Index ◽  
Forest Management Planning ◽  
Canadian Boreal Forest

Spatial data for the Climate Moisture Index and the Palmer Drought Severity Index were generated from gridded temperature and precipitation data for the Canadian boreal zone over the period 1951–2010. Annual values for the indices for 2011–2100 were generated from projections of future climate derived from four general circulation models forced by three greenhouse gas emissions scenarios. Linear regression models between the indices and time were fitted to examine long-term trends. Results indicated that several large regions of the Canadian boreal forest experienced substantial drying during 1951–2010. Future projections indicated a general trend toward drier conditions during the 21st century. Overall, the analysis indicated more frequent and/or more severe droughts across managed western and central portions of the boreal forest in coming decades. These projections of indices are relevant to forest management because soil moisture availability is an important determinant of forest distribution, tree health, and regeneration success. Knowledge of the range of potential future changes in drought occurrence and intensity will aid forest managers and decisionmakers in incorporating climate change considerations into forest management planning and practices.

scholarly journals Massive mortality of aspen following severe drought along the southern edge of the Canadian boreal forest

2010 ◽  
Vol 17 (6) ◽  
pp. 2084-2094 ◽  
Author(s):  
MICHAEL MICHAELIAN ◽  
EDWARD H. HOGG ◽  
RONALD J. HALL ◽  
ERIC ARSENAULT
Keyword(s):  
Boreal Forest ◽  
Severe Drought ◽  
Canadian Boreal Forest
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