Deeper waters are changing less consistently than surface waters in a global analysis of 102 lakes

AbstractGlobally, lake surface water temperatures have warmed rapidly relative to air temperatures, but changes in deepwater temperatures and vertical thermal structure are still largely unknown. We have compiled the most comprehensive data set to date of long-term (1970–2009) summertime vertical temperature profiles in lakes across the world to examine trends and drivers of whole-lake vertical thermal structure. We found significant increases in surface water temperatures across lakes at an average rate of + 0.37 °C decade−1, comparable to changes reported previously for other lakes, and similarly consistent trends of increasing water column stability (+ 0.08 kg m−3 decade−1). In contrast, however, deepwater temperature trends showed little change on average (+ 0.06 °C decade−1), but had high variability across lakes, with trends in individual lakes ranging from − 0.68 °C decade−1 to + 0.65 °C decade−1. The variability in deepwater temperature trends was not explained by trends in either surface water temperatures or thermal stability within lakes, and only 8.4% was explained by lake thermal region or local lake characteristics in a random forest analysis. These findings suggest that external drivers beyond our tested lake characteristics are important in explaining long-term trends in thermal structure, such as local to regional climate patterns or additional external anthropogenic influences.

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Two decades of in-situ temperature measurements in the upper troposphere and lowermost stratosphere from IAGOS long-term routine observation

10.5194/acp-2017-494 ◽

2017 ◽

Author(s):

Florian Berkes ◽

Patrick Neis ◽

Martin G. Schultz ◽

Ulrich Bundke ◽

Susanne Rohs ◽

...

Keyword(s):

Weather Forecast ◽

Global Scale ◽

Temperature Trend ◽

Data Set ◽

Medium Range Weather Forecast ◽

Upper Troposphere ◽

Temperature Trends ◽

Geographical Regions

Abstract. Despite several studies on temperature trends in the tropopause region, a comprehensive understanding of the evolution of temperatures in this climate-sensitive region of the atmosphere remains elusive. Here we present a unique global-scale, long-term data set of high-resolution in-situ temperature data measured aboard passenger aircraft within the European Research Infrastructure IAGOS (In-service Aircraft for a Global Observing System, www.iagos.org). This data set is used to investigate temperature trends within the global upper troposphere and lowermost stratosphere (UTLS) for the period 1995 to 2012 in different geographical regions and vertical layers of the UTLS. The largest amount of observations is available over the North Atlantic. Here, a neutral temperature trend is found within the lowermost stratosphere. This contradicts the temperature trend in the European Centre for Medium Range Weather Forecast (ECMWF) ERA-Interim reanalysis, where a significant (95 % confidence) temperature increase of +0.56 K/decade is obtained. Differences between trends derived from observations and reanalysis data can be traced back to changes in the temperature bias between observation and model data over the studied period. This study demonstrates the value of the IAGOS temperature observations as anchor point for the evaluation of reanalyses and its suitability for independent trend analyses.

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High resolution atmospheric reconstruction for Europe 1948–2012: coastDat2

Earth System Science Data Discussions ◽

10.5194/essdd-6-779-2013 ◽

2013 ◽

Vol 6 (2) ◽

pp. 779-809 ◽

Cited By ~ 2

Author(s):

B. Geyer

Keyword(s):

Climate Model ◽

Numerical Models ◽

Regional Climate ◽

Reanalysis Data ◽

Data Sets ◽

Data Set ◽

Horizontal Grid ◽

Global Reanalysis ◽

Marine Climate

Abstract. The coastDat data sets were produced to give a consistent and homogeneous database mainly for assessing weather statistics and long-term changes for Europe, especially in data sparse regions. A sequence of numerical models was employed to reconstruct all aspects of marine climate (such as storms, waves, surges etc.) over many decades. Here, we describe the atmospheric part of coastDat2 (Geyer and Rockel, 2013, doi:10.1594/WDCC/coastDat-2_COSMO-CLM). It consists of a regional climate reconstruction for entire Europe, including Baltic and North Sea and parts of the Atlantic. The simulation was done for 1948 to 2012 with a regional climate model and a horizontal grid size of 0.22° in rotated coordinates. Global reanalysis data were used as forcing and spectral nudging was applied. To meet the demands on the coastDat data set about 70 variables are stored hourly.

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Empirical model for predicting a catchment-scale metric of surface water transit time in streams

Canadian Journal of Fisheries and Aquatic Sciences ◽

10.1139/f04-202 ◽

2005 ◽

Vol 62 (3) ◽

pp. 492-504 ◽

Cited By ~ 4

Author(s):

Erwin E Van Nieuwenhuyse

Keyword(s):

Surface Water ◽

Transit Time ◽

Longitudinal Velocity ◽

Hydraulic Geometry ◽

Catchment Scale ◽

Data Set ◽

Velocity Gradients ◽

Average Water ◽

Bivariate Regression

Estimates of average water velocity (vw) extracted from tracer dye studies (vdye) or calculated from velocitydischarge relationships at continuous-flow gauges (vgage) were combined with catchment area (A) and other readily available data for 111 streams throughout the conterminous United States. The resulting data set (n = 305) represented broad ranges of A (65 62 419 km2), mainstem length (Lmax, 15.6867 km), slope (S, 0.1411.5 m·km1), and daily average discharge (Q, 0.09634 m3·s1). A catchment-scale metric of surface water transit time (Tw, Lmaxvdye1) ranged from 0.3 to 40 days, averaging 7.2 days. A bivariate regression model using log10 A and log10 Q explained 83% of the variation in log10 Tw and predicted Tw with an average precision of ±49%. By contrast, a previously published model based on hydraulic geometry relationships overestimated Tw by 100%. Application of my model to five streams nested in a ninth-order (ω = 9) catchment indicated that under dry (September) and wet (March), long-term (19542001) median flow conditions, vw increased with Q (vw ∝ Q0.3) as far downstream as ω = 8 and then remained constant or declined. The slope of this longitudinal vwQ relationship was three times greater than the expected value. Longitudinal velocity gradients in many streams may thus be much steeper than commonly assumed.

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Developing a Dust Emission Procedure for Central Asia

Air Soil and Water Research ◽

10.1177/1178622117711939 ◽

2017 ◽

Vol 10 ◽

pp. 117862211771193 ◽

Cited By ~ 5

Author(s):

Longlei Li ◽

Irina N Sokolik

Keyword(s):

Central Asia ◽

Regional Climate ◽

Land Use Changes ◽

Dust Emission ◽

Recent Decade ◽

Weather Research And Forecasting ◽

Data Set ◽

Source Regions ◽

Microphysical Processes

Airborne mineral dust is thought to have a significant influence on the climate through absorbing and scattering both shortwave and longwave radiations and affecting cloud microphysical processes. However, a knowledge of long-term dust emissions is limited from both temporal and spatial perspectives. Here, we have developed a quantitative climatology: the column-integrated mass of the dust aerosol loading in Central Asia by incorporating the dust module (DuMo) into the Weather Research and Forecasting coupled with Chemistry (WRF-Chem) model and accounting for regional climate and Land-Cover and Land-Use Changes for the 1950-2010 period in April. This data set is lowly to moderately correlated (0.22-0.48) with the satellite Aerosol Optical Depth in April of the 2000s and lowly correlated (0.02-0.11) with the Absorbing Aerosol Index in April of the 1980s, 1990s, and 2000s. The total dust loading is approximately 207.85 Mton per month in April during the recent decade (2000-2014) over dust source regions. Although only the month of April was simulated, results suggest that trends and magnitudes are captured well, using the WRF-Chem-DuMo.

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Mediating the Effects of Climate on the Temperature and Thermal Structure of a Monomictic Reservoir through Use of Hydraulic Facilities

Water ◽

10.3390/w13081128 ◽

2021 ◽

Vol 13 (8) ◽

pp. 1128

Author(s):

Maurice Alfonso Duka ◽

Tetsuya Shintani ◽

Katsuhide Yokoyama

Keyword(s):

Climate Change ◽

Surface Water ◽

Climate Warming ◽

Thermal Structure ◽

Heat Content ◽

Thermal Conditions ◽

Long Term Effects ◽

Air Temperatures ◽

Lower Heat

Climate warming can alter the thermal conditions of reservoirs. However, some hydraulic interventions can be explored to mitigate this impact. This study investigates the long-term effects of climate on the temperature and thermal structure of a monomictic reservoir that has had varying operations from 1959 to 2016. Reservoir progressively operated through three distinct periods, namely, (A) deep penstock withdrawal (DPW; 1959–1991), (B) purely selective withdrawal (SW; 1992–2001), and (C) combination of SW and vertical curtain (VC; 2002–2016). Although annual air temperatures are increasing (+0.15 °C decade−1) in the long term, the reservoir’s surface water temperatures have been found to be decreasing (−0.06 °C decade−1). Periods B and C produced colder profiles and exhibited lower heat content and higher potential energy anomaly than Period A. Furthermore, stronger thermoclines, as indicated by Brunt–Vaisala frequency, were observed in the two latter periods. The results of this study show that varying operations bear a stronger influence on the reservoir’s temperature and thermal structure than climate change itself. Mitigating the thermal impacts of climate warming in reservoirs appears promising with the use of SW and VC.

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Decadal evaluation of regional climate, air quality, and their interactions using WRF/Chem Version 3.6.1

Geoscientific Model Development Discussions ◽

10.5194/gmdd-8-6707-2015 ◽

2015 ◽

Vol 8 (8) ◽

pp. 6707-6756

Author(s):

K. Yahya ◽

K. Wang ◽

P. Campbell ◽

T. Glotfelty ◽

J. He ◽

...

Keyword(s):

Boundary Conditions ◽

Global Analysis ◽

Regional Climate ◽

Model Performance ◽

Cloud Droplet ◽

Meteorological Variables ◽

Cold Bias ◽

Aerosol Cloud ◽

Initial And Boundary Conditions

Abstract. The Weather Research and Forecasting model with Chemistry (WRF/Chem) v3.6.1 with the Carbon Bond 2005 (CB05) gas-phase mechanism is evaluated for its first decadal application during 2001–2010 using the Representative Concentration Pathway (RCP 8.5) emissions to assess its capability and appropriateness for long-term climatological simulations. The initial and boundary conditions are downscaled from the modified Community Earth System Model/Community Atmosphere Model (CESM/CAM5) v1.2.2. The meteorological initial and boundary conditions are bias-corrected using the National Center for Environmental Protection's Final (FNL) Operational Global Analysis data. Climatological evaluations are carried out for meteorological, chemical, and aerosol-cloud-radiation variables against data from surface networks and satellite retrievals. The model performs very well for the 2 m temperature (T2) for the 10 year period with only a small cold bias of −0.3 °C. Biases in other meteorological variables including relative humidity at 2 m, wind speed at 10 m, and precipitation tend to be site- and season-specific; however, with the exception of T2, consistent annual biases exist for most of the years from 2001 to 2010. Ozone mixing ratios are slightly overpredicted at both urban and rural locations but underpredicted at rural locations. PM2.5 concentrations are slightly overpredicted at rural sites, but slightly underpredicted at urban/suburban sites. In general, the model performs relatively well for chemical and meteorological variables, and not as well for aerosol-cloud-radiation variables. Cloud-aerosol variables including aerosol optical depth, cloud water path, cloud optical thickness, and cloud droplet number concentration are generally underpredicted on average across the continental US. Overpredictions of several cloud variables over eastern US result in underpredictions of radiation variables and overpredictions of shortwave and longwave cloud forcing which are important climate variables. While the current performance is deemed to be acceptable, improvements to the bias-correction method for CESM downscaling and the model parameterizations of cloud dynamics and thermodynamics, as well as aerosol-cloud interactions can potentially improve model performance for long-term climate simulations.

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Pan-European groundwater to atmosphere terrestrial systems climatology from a physically consistent simulation

Scientific Data ◽

10.1038/s41597-019-0328-7 ◽

2019 ◽

Vol 6 (1) ◽

Cited By ~ 2

Author(s):

Carina Furusho-Percot ◽

Klaus Goergen ◽

Carl Hartick ◽

Ketan Kulkarni ◽

Jessica Keune ◽

...

Keyword(s):

Land Surface ◽

Climate Models ◽

Water Cycle ◽

Regional Climate ◽

Regional Climate Models ◽

Data Set ◽

Groundwater Dynamics ◽

Terrestrial System ◽

Terrestrial Water

AbstractApplying the Terrestrial Systems Modeling Platform, TSMP, this study provides the first simulated long-term (1996–2018), high-resolution (~12.5 km) terrestrial system climatology over Europe, which comprises variables from groundwater across the land surface to the top of the atmosphere (G2A). The data set offers an unprecedented opportunity to test hypotheses related to short- and long-range feedback processes in space and time between the different interacting compartments of the terrestrial system. The physical consistency of simulated states and fluxes in the terrestrial system constitutes the uniqueness of the data set: while most regional climate models (RCMs) have a tendency to simplify the soil moisture and groundwater representation, TSMP explicitly simulates a full 3D soil- and groundwater dynamics, closing the terrestrial water cycle from G2A. As anthopogenic impacts are excluded, the dataset may serve as a near-natural reference for global change simulations including human water use and climate change. The data set is available as netCDF files for the pan-European EURO-CORDEX domain.

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Global data set of long-term summertime vertical temperature profiles in 153 lakes

Scientific Data ◽

10.1038/s41597-021-00983-y ◽

2021 ◽

Vol 8 (1) ◽

Author(s):

Rachel M. Pilla ◽

Elizabeth M. Mette ◽

Craig E. Williamson ◽

Boris V. Adamovich ◽

Rita Adrian ◽

...

Keyword(s):

Time Series ◽

Thermal Structure ◽

Ecological Change ◽

Thermal Gradients ◽

Temperature Profiles ◽

Vertical Temperature ◽

Data Set ◽

Long Term Trends

AbstractClimate change and other anthropogenic stressors have led to long-term changes in the thermal structure, including surface temperatures, deepwater temperatures, and vertical thermal gradients, in many lakes around the world. Though many studies highlight warming of surface water temperatures in lakes worldwide, less is known about long-term trends in full vertical thermal structure and deepwater temperatures, which have been changing less consistently in both direction and magnitude. Here, we present a globally-expansive data set of summertime in-situ vertical temperature profiles from 153 lakes, with one time series beginning as early as 1894. We also compiled lake geographic, morphometric, and water quality variables that can influence vertical thermal structure through a variety of potential mechanisms in these lakes. These long-term time series of vertical temperature profiles and corresponding lake characteristics serve as valuable data to help understand changes and drivers of lake thermal structure in a time of rapid global and ecological change.

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In situ temperature measurements in the upper troposphere and lowermost stratosphere from 2 decades of IAGOS long-term routine observation

Atmospheric Chemistry and Physics ◽

10.5194/acp-17-12495-2017 ◽

2017 ◽

Vol 17 (20) ◽

pp. 12495-12508 ◽

Cited By ~ 8

Author(s):

Florian Berkes ◽

Patrick Neis ◽

Martin G. Schultz ◽

Ulrich Bundke ◽

Susanne Rohs ◽

...

Keyword(s):

Global Scale ◽

Reanalysis Data ◽

Temperature Trend ◽

Data Set ◽

Upper Troposphere ◽

The North ◽

Temperature Trends ◽

Geographical Regions

Abstract. Despite several studies on temperature trends in the tropopause region, a comprehensive understanding of the evolution of temperatures in this climate-sensitive region of the atmosphere remains elusive. Here we present a unique global-scale, long-term data set of high-resolution in situ temperature data measured aboard passenger aircraft within the European Research Infrastructure IAGOS (In-service Aircraft for a Global Observing System; http://www.iagos.org). This data set is used to investigate temperature trends within the global upper troposphere and lowermost stratosphere (UTLS, <  13 km) for the period of 1995–2012 in different geographical regions and vertical layers of the UTLS. The largest number of observations is available over the North Atlantic. Here, a neutral temperature trend is found within the lowermost stratosphere. This contradicts the temperature trend in the European Centre for Medium-Range Weather Forecasts (ECMWF) ERA-Interim reanalysis, in which a significant (95 % confidence) temperature increase of +0.56 K decade−1 is found. Differences between trends derived from observations and reanalysis data can be traced back to changes in the temperature difference between observation and model data over the period studied. This study underpins the value of the IAGOS temperature observations as an anchor point for the evaluation of reanalyses and its suitability for independent trend analyses.

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Long-term assessment of floodplain reconnection as a stream restoration approach for managing nitrogen in ground and surface waters

Urban Ecosystems ◽

10.1007/s11252-021-01199-z ◽

2022 ◽

Author(s):

Paul M. Mayer ◽

Michael J. Pennino ◽

Tammy A. Newcomer-Johnson ◽

Sujay S. Kaushal

Keyword(s):

Surface Water ◽

Surface Waters ◽

Stream Restoration ◽

Specific Conductance ◽

Data Set ◽

N Transformations ◽

Total N ◽

Floodplain Reconnection ◽

Over Time

AbstractStream restoration is a popular approach for managing nitrogen (N) in degraded, flashy urban streams. Here, we investigated the long-term effects of stream restoration involving floodplain reconnection on riparian and in-stream N transport and transformation in an urban stream in the Chesapeake Bay watershed. We examined relationships between hydrology, chemistry, and biology using a Before/After-Control/Impact (BACI) study design to determine how hydrologic flashiness, nitrate (NO3−) concentrations (mg/L), and N flux, both NO3− and total N (kg/yr), changed after the restoration and floodplain hydrologic reconnection to its stream channel. We examined two independent surface water and groundwater data sets (EPA and USGS) collected from 2002–2012 at our study sites in the Minebank Run watershed. Restoration was completed during 2004 and 2005. Afterward, the monthly hydrologic flashiness index, based on mean monthly discharge, decreased over time from 2002 and 2008. However, from 2008–2012 hydrologic flashiness returned to pre-restoration levels. Based on the EPA data set, NO3− concentration in groundwater and surface water was significantly less after restoration while the control site showed no change. DOC and NO3− were negatively related before and after restoration suggesting C limitation of N transformations. Long-term trends in surface water NO3− concentrations based on USGS surface water data showed downward trends after restoration at both the restored and control sites, whereas specific conductance showed no trend. Comparisons of NO3− concentrations with Cl− concentrations and specific conductance in both ground and surface waters suggested that NO3− reduction after restoration was not due to dilution or load reductions from the watershed. Modeled NO3− flux decreased post restoration over time but the rate of decrease was reduced likely due to failure of restoration features that facilitated N transformations. Groundwater NO3− concentrations varied among stream features suggesting that some engineered features may be functionally better at creating optimal conditions for N retention. However, some engineered features eroded and failed post restoration thereby reducing efficacy of the stream restoration to reduce flashiness and NO3− flux. N management via stream restoration will be most effective where flashiness can be reduced and DOC made available for denitrifiers. Stream restoration may be an important component of holistic watershed management including stormwater management and nutrient source control if stream restoration and floodplain reconnection can be done in a manner to resist the erosive effects of large storm events that can degrade streams to pre-restoration conditions. Long-term evolution of water quality functions in response to degradation of restored stream channels and floodplains from urban stressors and storms over time warrants further study, however.

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