Disentangling the impact of catchment heterogeneity on nitrate export dynamics from event to long‐term time scales

Disentangling the impact of catchment heterogeneity on nitrate export dynamics from event to long-term time scales

10.1002/essoar.10503228.1 ◽

2020 ◽

Author(s):

Carolin Winter ◽

Stefanie Lutz ◽

Andreas Musolff ◽

Rohini Kumar ◽

Michael Weber ◽

...

Keyword(s):

Time Scales ◽

Export Dynamics ◽

Nitrate Export ◽

The Impact

Download Full-text

Disentangling the impact of catchment heterogeneity in a meso-scale catchment on nitrate export dynamics across time scales

10.5194/egusphere-egu2020-13677 ◽

2020 ◽

Author(s):

Carolin Winter ◽

Stefanie Lutz ◽

Andreas Musolff ◽

Michael Weber ◽

Jan H. Fleckenstein

Keyword(s):

Time Scales ◽

Delayed Response ◽

Nitrogen Surplus ◽

Retention Capacity ◽

Transit Times ◽

Nitrate Concentrations ◽

Nitrate Export ◽

Shallow Soils ◽

The Impact

High nitrate concentrations in groundwater and surface water are a long-known but still widespread problem. To most efficiently reduce nitrate pollution, a detailed understanding of catchment organization and the catchment internal processes that drive nitrate mobilization, transport and storage across time scales is needed. Especially in mesoscale catchments (101 &#8211; 10&#179; km&#178;), spatial heterogeneity adds another layer of complexity to these processes compared to headwater catchments. To address this issue, we analyzed seasonal long-term trends (1983 &#8211; 2016) and high frequency event dynamics (2010 &#8211; 2016) of nitrate concentrations, loads and the concentration-discharge relationship (CQ-slope) in three nested catchments within the Selke catchment (Germany). Transit time distributions (TTDs) were calculated for each nested catchment to analyze the response of nitrate export to changes in nitrogen surplus. The upper part of the Selke catchment is dominated by forests with only little agriculture and an overall lower nitrogen surplus, while the lower Selke is dominated by agriculture and a higher nitrogen surplus. Surprisingly, we found a disproportionally high contribution to nitrate loads from the forest-dominated upper Selke (64% of average annual load at the Selke outlet), caused by high nitrate concentrations during wet seasons ( average of 2.5 mg-N L-1 during winter and spring) while dry season nitrate concentrations are relatively low (average of 1.1 mg-N L-1 during summer and autumn). These seasonally high concentrations can be explained by the sub-catchment characteristics such as shallow soils and steeper slopes that lead to a low retention capacity and short effective transit times (peak of TTD after 2 years, indicating a fast response to changes in nitrogen surplus). The increase of nitrate concentrations with discharge resulted in a positive CQ-slope that was consistently observed in long-term dynamics and during events. In the lower Selke, nitrate concentrations are relatively constant across seasons (around 3.1 mg-N L-1). This dynamic is caused by deeper aquifers, long effective transit times (peak of TTD at the Selke outlet after 14 years, indicating a delayed response to changes in nitrogen surplus) and legacy stores of nitrate that constantly release into the Selke River. Consequently, the lower Selke dominates nitrate concentrations and loads exported during dry seasons and is characterized by lower CQ-slopes compared to the upper Selke. Our study shows that the contribution of different sub-catchments to elevated nitrate concentrations can vary greatly between seasons, flow conditions and in their response to changes in nitrogen surplus. It is, therefore, not enough to focus on areas of highest nitrogen surplus &#8211; such as the upper Selke; instead, an assessment of all characteristic sub-catchments, their temporally variable contribution to nitrate export and their specific TTDs is needed to place reduction measures most effectively and to estimate realistic time scales for their success.

Download Full-text

Evaluating the impacts of environmental factors on soil moisture temporal dynamics at different time scales

Journal of Water and Climate Change ◽

10.2166/wcc.2020.011 ◽

2020 ◽

Author(s):

Qi Chai ◽

Tiejun Wang ◽

Chongli Di

Keyword(s):

Soil Moisture ◽

Environmental Factors ◽

Time Scales ◽

Temporal Dynamics ◽

Soil Moisture Dynamics ◽

Temporal Variance ◽

The Impact ◽

Moisture Dynamics ◽

Different Time Scales

Abstract Soil moisture displays complex spatiotemporal patterns across scales, making it important to disentangle the impacts of environmental factors on soil moisture temporal dynamics at different time scales. This study evaluated the factors affecting soil moisture dynamics at different time scales using long-term soil moisture data obtained from Nebraska and Utah. The empirical mode decomposition method was employed to decompose soil moisture time series into different temporal components with several intrinsic mode functions (IMFs) and one residual component. Results showed that the percent variance contribution (PVC) of IMFs to the total soil moisture temporal variance tended to increase for the IMFs with longer time periods. It indicated that the long-term soil moisture variations in study regions were mainly determined by low-temporal frequency signals related to seasonal climate and vegetation variations. Besides, the PVCs at short- and medium-temporal ranges were positively correlated with climate dryness, while negatively at longer temporal ranges. Moreover, the results suggested that the impact of climate on soil moisture dynamics at different time scales might vary across different climate zones, while soil effect was comparatively less in both regions. It provides additional insights into understanding soil moisture temporal dynamics in regions with contrasting climatic conditions.

Download Full-text

Rankings of extreme and widespread dry and wet events in the Iberian Peninsula between 1901–2016

10.5194/esd-2020-46 ◽

2020 ◽

Author(s):

Margarida L. R. Liberato ◽

Irene Montero ◽

Célia Gouveia ◽

Ana Russo ◽

Alexandre M. Ramos ◽

...

Keyword(s):

Iberian Peninsula ◽

Time Scales ◽

Extreme Events ◽

Potential Evapotranspiration ◽

Grid Point ◽

Research Unit ◽

Climatic Research Unit ◽

The Impact ◽

Monteith Equation

Abstract. Extensive, longstanding dry and wet episodes are one of the most frequent climatic extreme events in the Iberian Peninsula. Here, we present a method for ranking regional extremes of persistent, widespread drought and wet events, considering different time scales. The method is based on the multiscalar Standardized Precipitation Evapotranspiration Index (SPEI) gridded dataset for the Iberian Peninsula. SPEI was computed using the Climatic Research Unit (CRU) between 1901 and 2016 using a log-logistic probability distribution function. The Potential Evapotranspiration (PET) was computed through the Penmann-Monteith equation. The ranking classification method is based on the evaluation of the magnitude of an event, which is obtained after considering both the area affected respectively by the dryness or wetness – defined by SPEI values over a certain threshold – and its intensity in each grid point. A sensitivity analysis on the impact of different thresholds to define dry and wet events is performed. A comprehensive dataset of rankings of the most extreme, prolonged, widespread dry and wet periods in the Iberian Peninsula is presented, for aggregated time scales of 6, 12, 18 and 24 months. Results show that in the Iberian Peninsula there is not a region more prone to the occurrence of any of these long-term (dry and/or wet) most extreme events.

Download Full-text

Impact of Exports on the Exporter’s Domestic Market

Экономическая наука современной России ◽

10.33293/1609-1442-2021-4(95)-49-67 ◽

2021 ◽

pp. 49-67

Author(s):

Konstantin G. Borodin

Keyword(s):

Theoretical Model ◽

Equilibrium Model ◽

Domestic Market ◽

Partial Equilibrium ◽

Short Term ◽

Export Dynamics ◽

Supply Shock ◽

Partial Equilibrium Model ◽

The Impact

This paper developed a theoretical model of partial equilibrium of the export-oriented market for a short-term period, as well as outlined the main approaches to modeling equilibrium in a long-term period. Thus, the competition between the producers of the selected exporting country and its global competitor in the external import-dependent market is considered. In the partial equilibrium model, for the first time, the domestic and foreign sales markets are presented together. The analysis of the theoretical model made it possible to obtain the following results for the short-term period: in a state close to equilibrium, external supplies of the exporting country are positively related to their own production volumes and negatively – with the production volumes of the global exporter; the price of the domestic market of the exporting country is negatively related to the volume of its own production and the volume of production of the global exporter. The paper analyzes three scenarios that allow checking the adequacy of the partial equilibrium model for different conditions of its application. The first scenario considers a negative supply shock associated with a drop in production in a global exporter. The second analyzes the impact of the pandemic on the global exporter and exporting country. The third scenario is devoted to assessing the impact of a demand shock on a designated exporting country. The scenarios confirmed the adequacy of the model. The approach to modeling an export-oriented market for a long-term period is based on the assumption that the exporter's price will converge with the price of the domestic market over time and, ultimately, will differ from it only by the amount of additional costs associated with the export of a unit of production. It was established that, while maintaining exogenous conditions for positive long-term export dynamics, the price of the domestic market of the exporting country will decrease in case of an increase in the incremental values of exports and production volumes of the global exporter. The consequences of the positive dynamics of exports for the domestic demand of the exporting country are considered. The established relationships between exports and sales in the exporter's domestic market were empirically confirmed by the example of the Russian sunflower oil market.

Download Full-text

Modulation of Atlantic Basin Tropical Cyclone Activity by the Madden–Julian Oscillation (MJO) from 1905 to 2011

Journal of Climate ◽

10.1175/jcli-d-14-00509.1 ◽

2014 ◽

Vol 28 (1) ◽

pp. 204-217 ◽

Cited By ~ 32

Author(s):

Philip J. Klotzbach ◽

Eric C. J. Oliver

Keyword(s):

Tropical Cyclone ◽

Time Scales ◽

El Niño ◽

El Nino ◽

Southern Oscillation ◽

Atlantic Multidecadal Oscillation ◽

Madden Julian Oscillation ◽

Atlantic Basin ◽

The Impact

Abstract The Madden–Julian oscillation (MJO) has been demonstrated to play a role in tropical cyclone (TC) activity around the globe in a number of recent studies. While the impact of the MJO on TCs in the Atlantic basin since the mid-1970s has been well documented, a newly developed 107-yr-long index for the MJO allows for additional analysis of the impacts of the MJO on Atlantic TC activity. TC activity in the Atlantic increases when MJO-related convection is enhanced over Africa and the Indian Ocean, while TC activity in the Atlantic is suppressed when the MJO enhances convection over the western Pacific. This long-term record of the MJO also allows for the analysis of how the MJO’s impacts may be modulated by other climate modes, such as the El Niño–Southern Oscillation (ENSO) over interannual time scales and the Atlantic multidecadal oscillation (AMO) over multidecadal time scales. When climatologically unfavorable conditions such as an El Niño event or a negative AMO phase are present, even TC-favorable MJO conditions are not enough to generate statistically significant increases in TC activity from the long-term average across the Atlantic basin. However, climatologically favorable conditions during a La Niña event or a warm AMO phase act to enhance the modulation of TC activity over the Atlantic basin by the MJO.

Download Full-text

Suppressed, but Not Forgotten

Swiss Journal of Psychology ◽

10.1024/1421-0185/a000033 ◽

2011 ◽

Vol 70 (1) ◽

pp. 5-11 ◽

Cited By ~ 8

Author(s):

Beat Meier ◽

Anja König ◽

Samuel Parak ◽

Katharina Henke

Keyword(s):

Memory Trace ◽

Thought Suppression ◽

Test Phase ◽

Indirect Test ◽

Final Test ◽

Test Experiment ◽

And Control ◽

Cue Words ◽

The Impact

This study investigates the impact of thought suppression over a 1-week interval. In two experiments with 80 university students each, we used the think/no-think paradigm in which participants initially learn a list of word pairs (cue-target associations). Then they were presented with some of the cue words again and should either respond with the target word or avoid thinking about it. In the final test phase, their memory for the initially learned cue-target pairs was tested. In Experiment 1, type of memory test was manipulated (i.e., direct vs. indirect). In Experiment 2, type of no-think instructions was manipulated (i.e., suppress vs. substitute). Overall, our results showed poorer memory for no-think and control items compared to think items across all experiments and conditions. Critically, however, more no-think than control items were remembered after the 1-week interval in the direct, but not in the indirect test (Experiment 1) and with thought suppression, but not thought substitution instructions (Experiment 2). We suggest that during thought suppression a brief reactivation of the learned association may lead to reconsolidation of the memory trace and hence to better retrieval of suppressed than control items in the long term.

Download Full-text