scholarly journals Disturbances of temperature-depth profiles due to surface climate change and subsurface water flow: 2. An effect of step increase in surface temperature caused by forest clearing in southwest western Australia

1999 ◽  
Vol 35 (5) ◽  
pp. 1519-1529 ◽  
Author(s):  
Makoto Taniguchi ◽  
David R. Williamson ◽  
Adrian J. Peck
Keyword(s):  
Climate Change ◽  
Surface Temperature ◽  
Water Flow ◽  
Western Australia ◽  
Subsurface Water ◽  
Depth Profiles ◽  
Forest Clearing ◽  
Surface Climate ◽  
Temperature Depth

scholarly journals Disturbances of Temperature-Depth Profiles by Surface Warming and Groundwater Flow Convection in Kumamoto Plain, Japan

Geofluids ◽  
2018 ◽  
Vol 2018 ◽  
pp. 1-14 ◽  
Author(s):  
Linyao Dong ◽  
Congsheng Fu ◽  
Jigen Liu ◽  
Yifeng Wang
Keyword(s):  
Groundwater Flow ◽  
Subsurface Water ◽  
Subsurface Temperature ◽  
Flow Perturbation ◽  
Surface Warming ◽  
Heat Flows ◽  
Depth Profiles ◽  
Basin Scale ◽  
Thermal Regimes ◽  
Temperature Depth

Subsurface temperatures depend on climate and groundwater flow. A lack of observations of subsurface temperature collected over decades limits interpretation of the combined influences of surface warming and groundwater flow on subsurface thermal regimes. Subsurface temperature-depth profile data acquired for Kumamoto Plain, Japan, between 1987 and 2012 were collected and analyzed to elucidate regional groundwater and heat flows. The observed and simulated temperature-depth profiles showed the following: subsurface water flows from northeast to southwest in the study area; the combined influence of surface warming and water flow perturbation produces different temporal changes in thermal profiles in recharge, intermediate, and discharge areas; and aquifer thermal properties contribute more than hydraulic parameters to the perturbation of temperature-depth profiles. Spatial and temporal evolution features of subsurface thermal regimes may be utilized to investigate the influence of surface warming events on subsurface water and heat flows at the basin scale.

scholarly journals Selection of borehole temperature depth profiles for regional climate reconstructions

2007 ◽  
Vol 3 (1) ◽  
pp. 121-163 ◽  
Author(s):  
C. Chouinard ◽  
J.-C. Mareschal
Keyword(s):  
Surface Temperature ◽  
Joint Inversion ◽  
Regional Climate ◽  
Ground Surface ◽  
Temperature History ◽  
Data Set ◽  
Ground Surface Temperature ◽  
Depth Profiles ◽  
Borehole Temperature ◽  
Temperature Depth

Abstract. Borehole temperature depth profiles are commonly used to infer time variations in the ground surface temperature on centennial time scales. We compare different procedures to obtain a regional ground surface temperature history (GSTH) from an ensemble of borehole temperature depth profiles. We address in particular the question of selecting profiles that are not contaminated by non climatic surface perturbations and we compare the joint inversion of all the profiles with the average of individual inversions. We show that the resolution and the stability of the inversion of selected profiles are much improved over those for a complete data set. When profiles have been selected, the average GSTH of individual inversions and the GSTH of the joint inversion are almost identical. This is not observed when the entire data set is inverted: the average of individual inversions is different from the joint inversion. We also show that the joint inversion of very noisy data sets does not improve the resolution but, on the contrary, causes strong instabilities in the inversion. When the profiles that are affected by noise can not be eliminated, averaging of the individual inversions yields the most stable result, but with very poor resolution.

scholarly journals Selection of borehole temperature depth profiles for regional climate reconstructions

2007 ◽  
Vol 3 (2) ◽  
pp. 297-313 ◽  
Author(s):  
C. Chouinard ◽  
J.-C. Mareschal
Keyword(s):  
Surface Temperature ◽  
Joint Inversion ◽  
Regional Climate ◽  
Ground Surface ◽  
Temperature History ◽  
Data Set ◽  
Ground Surface Temperature ◽  
Depth Profiles ◽  
Borehole Temperature ◽  
Temperature Depth

Abstract. Borehole temperature depth profiles are commonly used to infer time variations in the ground surface temperature on centennial time scales. We compare different procedures to obtain a regional ground surface temperature history (GSTH) from an ensemble of borehole temperature depth profiles. We address in particular the question of selecting profiles that are not contaminated by non climatic surface perturbations and we compare the joint inversion of all the profiles with the average of individual inversions. Very few profiles of the Canadian data set meet the selection criteria (e.g. only 13 out of 73 profiles in Manitoba and Saskatchewan were retained). We show that the resolution and the stability of the inversion of selected profiles are much improved over those for a complete data set. When profiles have been selected, the average GSTH of individual inversions and the GSTH of the joint inversion are almost identical. This is not observed when the entire data set is inverted: the average of individual inversions is different from the joint inversion. We also show that the joint inversion of very noisy data sets does not improve the resolution but, on the contrary, causes strong instabilities in the inversion. When the profiles that are affected by noise can not be eliminated, averaging of the individual inversions yields the most stable result, but with very poor resolution.

Recent trends of groundwater temperatures in Bavaria, Germany

2020 ◽  
Author(s):  
Hannes Hemmerle ◽  
Peter Bayer
Keyword(s):  
Climate Change ◽  
Air Temperature ◽  
Ground Surface ◽  
Temperature History ◽  
Seasonal Temperature ◽  
Subsurface Temperature ◽  
Temperature Variations ◽  
Depth Profiles ◽  
Recent Climate ◽  
Temperature Depth

<p>Surface temperature variations have been well shown to transfer their thermal signature into the subsurface. This continuous heat transfer manifests in altered thermal conditions in the subsurface where temperature variations over a long lapse of time are more pronounced than shorter ones. Hence, repeated temperature depth profiles allow to investigate the effects of recent climate change on the subsurface. In this study we present recent temperature trends in more than 40 observation wells in Bavaria, Germany. Temperature depth profiles have been quarterly measured for one year between 1992-1994 and measurements have been repeated two times in 2019. The quarterly measurements reveal that the periodic seasonal temperature signal dampens to around 0.1 K at a depth of 15 m below ground surface. This implies that temperature variations below this depth can be used as climate archives as they store the temperature history of multiple years. The measurements span a time period of almost 30 years which is the most common period of reference for deriving climate normals according to the World Meteorological Organization. Therefore, the findings of recent subsurface temperature variations are assessed versus and complemented by 22 air temperature stations. Preliminary results show, that the linear regression of the annual mean air temperature since 1990 yields a slope of 0.35 ± 0.11 K 10a<sup>-1</sup>. In the subsurface, median temperature differences of the respective baselines from 1992-94 period and 2019 are 0.26, 0.13 and 0.07 K 10a<sup>-1 </sup>at 20, 40 and 60 m depth below surface, accordingly. Despite the common magnitude and continuous downward decrease, subsurface temperature differences exhibit a much higher variance compared to air temperature changes. This is due to local effects, such as varying thermal conductivities of the subsurface, latent heat transport caused by evapotranspiration, lateral and vertical groundwater flow, and anthropogenic influences. Our contribution will feature a comparison of this temperature change in response to recent atmospheric climate change in Bavaria and link these results with perceptions gained by similar investigations on local scale in other European regions.</p>

scholarly journals Complete genomes of two extinct New Zealand passerines show responses to climate fluctuations but no evidence for genomic erosion prior to extinction

2019 ◽  
Vol 15 (9) ◽  
pp. 20190491 ◽  
Author(s):  
Nicolas Dussex ◽  
Johanna von Seth ◽  
Michael Knapp ◽  
Olga Kardailsky ◽  
Bruce C. Robertson ◽  
...  
Keyword(s):  
Climate Change ◽  
New Zealand ◽  
Human Impacts ◽  
Oceanic Islands ◽  
Genomic Diversity ◽  
Climate Fluctuations ◽  
Forest Clearing ◽  
Mammalian Predators ◽  
Demographic Trajectories ◽  
Human Climate

Human intervention, pre-human climate change (or a combination of both), as well as genetic effects, contribute to species extinctions. While many species from oceanic islands have gone extinct due to direct human impacts, the effects of pre-human climate change and human settlement on the genomic diversity of insular species and the role that loss of genomic diversity played in their extinctions remains largely unexplored. To address this question, we sequenced whole genomes of two extinct New Zealand passerines, the huia ( Heteralocha acutirostris ) and South Island kōkako ( Callaeas cinereus ). Both species showed similar demographic trajectories throughout the Pleistocene. However, the South Island kōkako continued to decline after the last glaciation, while the huia experienced some recovery. Moreover, there was no indication of inbreeding resulting from recent mating among closely related individuals in either species. This latter result indicates that population fragmentation associated with forest clearing by Maōri may not have been strong enough to lead to an increase in inbreeding and exposure to genomic erosion. While genomic erosion may not have directly contributed to their extinctions, further habitat fragmentation and the introduction of mammalian predators by Europeans may have been an important driver of extinction in huia and South Island kōkako.

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