scholarly journals Daily vs. hourly simulation for estimating future flood peaks in mesoscale catchments

2021 ◽  
Author(s):  
Marcus Beylich ◽  
Uwe Haberlandt ◽  
Frido Reinstorf
Keyword(s):  
Climate Model ◽  
Time Step ◽  
Flood Peak ◽  
Model Sets ◽  
Modeling Process ◽  
Model Set ◽  
Flood Peaks ◽  
Runoff Hydrographs ◽  
Relative Change ◽  
Climate Studies

Abstract Daily hydrological models are commonly used to study changes in flood peaks due to climate change. Although they often lead to an underestimation of absolute floods, it is assumed that future flood peaks in smaller mesoscale catchments are less underestimated when examining the relative change signal of floods. In this study, the applicability of this hypothesis is investigated by comparing the results of a daily hydrological model set, calibrated on runoff hydrographs, with an hourly model set calibrated on flood peak distributions. For analysis, a daily RCP8.5 climate model ensemble is disaggregated to hourly values and the runoff is simulated on a daily and hourly basis for six mesoscale catchments in Central Germany. Absolute floods and relative flood changes are compared between both model sets. The results show significant differences between the absolute floods of both model sets, in most cases caused by underestimations due to the daily modeling process. In contrast, the differences between the two model sets are not significant for the relative change signal of the floods, especially for higher return periods. To improve results in climate studies with coarse modeling time step, the use of relative change signal of floods instead of absolute values is recommended.

scholarly journals Design of a structure model set for inorganic compounds based on ping-pong balls linked with snap buttons

2021 ◽  
Vol 0 (0) ◽  
Author(s):  
Ryo Horikoshi ◽  
Hiroyuki Higashino ◽  
Yoji Kobayashi ◽  
Hiroshi Kageyama
Keyword(s):  
High School Students ◽  
Coordination Compounds ◽  
Periodic Structures ◽  
Inorganic Compounds ◽  
Structure Model ◽  
School Students ◽  
Model Sets ◽  
Ping Pong ◽  
Hands On ◽  
Model Set

Abstract Structure model sets for inorganic compounds are generally expensive; their distribution to all students in a class is therefore usually impractical. We have therefore developed a structure model set to illustrate inorganic compounds. The set is constructed with inexpensive materials: ping-pong balls, and snap buttons. The structure model set can be used to illustrate isomerism in coordination compounds and periodic structures of ceramic perovskites. A hands-on activity using the structure model set was developed for high school students and was well-received by them. Despite the concepts being slightly advanced for them, the students’ retention of the knowledge gained through the activity was tested a week after they completed the activity and was found to be relatively high, demonstrating the usefulness of the activity based on the structure model set.

scholarly journals Impact of Input Filtering and Architecture Selection Strategies on GRU Runoff Forecasting: A Case Study in the Wei River Basin, Shaanxi, China

Water ◽  
2020 ◽  
Vol 12 (12) ◽  
pp. 3532
Author(s):  
Qianyang Wang ◽  
Yuan Liu ◽  
Qimeng Yue ◽  
Yuexin Zheng ◽  
Xiaolei Yao ◽  
...  
Keyword(s):  
River Basin ◽  
Prediction Accuracy ◽  
Principal Component ◽  
Time Step ◽  
Flood Peak ◽  
Runoff Forecasting ◽  
The Wei River Basin ◽  
The Impact ◽  
Wei River Basin ◽  
Wei River

A gated recurrent unit (GRU) network, which is a kind of artificial neural network (ANN), has been increasingly applied to runoff forecasting. However, knowledge about the impact of different input data filtering strategies and the implications of different architectures on the GRU runoff forecasting model’s performance is still insufficient. This study has selected the daily rainfall and runoff data from 2007 to 2014 in the Wei River basin in Shaanxi, China, and assessed six different scenarios to explore the patterns of that impact. In the scenarios, four manually-selected rainfall or runoff data combinations and principal component analysis (PCA) denoised input have been considered along with single directional and bi-directional GRU network architectures. The performance has been evaluated from the aspect of robustness to 48 various hypermeter combinations, also, optimized accuracy in one-day-ahead (T + 1) and two-day-ahead (T + 2) forecasting for the overall forecasting process and the flood peak forecasts. The results suggest that the rainfall data can enhance the robustness of the model, especially in T + 2 forecasting. Additionally, it slightly introduces noise and affects the optimized prediction accuracy in T + 1 forecasting, but significantly improves the accuracy in T + 2 forecasting. Though with relevance (R = 0.409~0.763, Grey correlation grade >0.99), the runoff data at the adjacent tributary has an adverse effect on the robustness, but can enhance the accuracy of the flood peak forecasts with a short lead time. The models with PCA denoised input has an equivalent, even better performance on the robustness and accuracy compared with the models with the well manually filtered data; though slightly reduces the time-step robustness, the bi-directional architecture can enhance the prediction accuracy. All the scenarios provide acceptable forecasting results (NSE of 0.927~0.951 for T + 1 forecasting and 0.745~0.836 for T + 2 forecasting) when the hyperparameters have already been optimized. Based on the results, recommendations have been provided for the construction of the GRU runoff forecasting model.

scholarly journals Revision of the convective transport module CVTRANS 2.4 in the EMAC atmospheric chemistry–climate model

2015 ◽  
Vol 8 (8) ◽  
pp. 2435-2445 ◽  
Author(s):  
H. G. Ouwersloot ◽  
A. Pozzer ◽  
B. Steil ◽  
H. Tost ◽  
J. Lelieveld
Keyword(s):  
Atmospheric Chemistry ◽  
Climate Model ◽  
Convective Transport ◽  
Computational Time ◽  
Cloud Base ◽  
Mixing Ratio ◽  
Time Step ◽  
Mixing Ratios ◽  
Time Stepping ◽  
Intermediate Time

Abstract. The convective transport module, CVTRANS, of the ECHAM/MESSy Atmospheric Chemistry (EMAC) model has been revised to better represent the physical flows and incorporate recent findings on the properties of the convective plumes. The modifications involve (i) applying intermediate time stepping based on a settable criterion, (ii) using an analytic expression to account for the intra-time-step mixing ratio evolution below cloud base, and (iii) implementing a novel expression for the mixing ratios of atmospheric compounds at the base of an updraft. Even when averaged over a year, the predicted mixing ratios of atmospheric compounds are affected considerably by the intermediate time stepping. For example, for an exponentially decaying atmospheric tracer with a lifetime of 1 day, the zonal averages can locally differ by more than a factor of 6 and the induced root mean square deviation from the original code is, weighted by the air mass, higher than 40 % of the average mixing ratio. The other modifications result in smaller differences. However, since they do not require additional computational time, their application is also recommended.

Coupling the Earth system model INMCM with the biogeochemical flux model

2018 ◽  
Vol 33 (6) ◽  
pp. 325-331
Author(s):  
Ilya A. Chernov ◽  
Nikolay G. Iakovlev
Keyword(s):  
Climate Model ◽  
World Ocean ◽  
Coupled Model ◽  
Horizontal Resolution ◽  
Ocean Model ◽  
Earth System Model ◽  
System Model ◽  
Earth System ◽  
Time Step ◽  
The Earth

Abstract In the present paper we consider the first results of modelling the World Ocean biogeochemistry system within the framework of the Earth system model: a global atmosphere-ocean-ice-land-biogeochemistry model. It is based on the INMCM climate model (version INMCM39) coupled with the pelagic ecosystem model BFM. The horizontal resolution was relatively low: 2∘ × 2.5∘ for the ‘longitude’ and ‘latitude’ in transformed coordinates with the North Pole moved to land, 33 non-equidistant σ-horizons, 1 hour time step. We have taken into account 54 main rivers worldwide with run–off supplied by the atmosphere submodel. The setup includes nine plankton groups, 60 tracers in total. Some components sink with variable speed. We discuss challenges of coupling the BFM with the σ-coordinate ocean model. The presented results prove that the model output is realistic in comparison with the observed data, the numerical efficiency is high enough, and the coupled model may serve as a basis for further simulations of the long-term climate change.

Uniform Distribution in Model Sets

2002 ◽  
Vol 45 (1) ◽  
pp. 123-130 ◽  
Author(s):  
Robert V. Moody
Keyword(s):  
Uniform Distribution ◽  
Physical Space ◽  
Pure Point ◽  
Internal Space ◽  
Compact Closure ◽  
Related Model ◽  
Model Sets ◽  
Distribution Property ◽  
Distribution Of Points ◽  
Model Set

AbstractWe give a new measure-theoretical proof of the uniform distribution property of points in model sets (cut and project sets). Each model set comes as a member of a family of related model sets, obtained by joint translation in its ambient (the ‘physical’) space and its internal space. We prove, assuming only that the window defining themodel set ismeasurable with compact closure, that almost surely the distribution of points in any model set from such a family is uniform in the sense of Weyl, and almost surely the model set is pure point diffractive.

scholarly journals Decadal changes in summertime reactive oxidized nitrogen and surface ozone over the Southeast United States

2018 ◽  
Vol 18 (3) ◽  
pp. 2341-2361 ◽  
Author(s):  
Jingyi Li ◽  
Jingqiu Mao ◽  
Arlene M. Fiore ◽  
Ronald C. Cohen ◽  
John D. Crounse ◽  
...  
Keyword(s):  
Climate Model ◽  
Surface Ozone ◽  
Regional Scale ◽  
Nox Emissions ◽  
Alkyl Nitrates ◽  
Southeast United States ◽  
Ground Measurement ◽  
Southeast Us ◽  
June July ◽  
Relative Change

Abstract. Widespread efforts to abate ozone (O3) smog have significantly reduced emissions of nitrogen oxides (NOx) over the past 2 decades in the Southeast US, a place heavily influenced by both anthropogenic and biogenic emissions. How reactive nitrogen speciation responds to the reduction in NOx emissions in this region remains to be elucidated. Here we exploit aircraft measurements from ICARTT (July–August 2004), SENEX (June–July 2013), and SEAC4RS (August–September 2013) and long-term ground measurement networks alongside a global chemistry–climate model to examine decadal changes in summertime reactive oxidized nitrogen (RON) and ozone over the Southeast US. We show that our model can reproduce the mean vertical profiles of major RON species and the total (NOy) in both 2004 and 2013. Among the major RON species, nitric acid (HNO3) is dominant (∼ 42–45 %), followed by NOx (31 %), total peroxy nitrates (ΣPNs; 14 %), and total alkyl nitrates (ΣANs; 9–12 %) on a regional scale. We find that most RON species, including NOx, ΣPNs, and HNO3, decline proportionally with decreasing NOx emissions in this region, leading to a similar decline in NOy. This linear response might be in part due to the nearly constant summertime supply of biogenic VOC emissions in this region. Our model captures the observed relative change in RON and surface ozone from 2004 to 2013. Model sensitivity tests indicate that further reductions of NOx emissions will lead to a continued decline in surface ozone and less frequent high-ozone events.

Occasional floods on the Russian Plain: types, frequency and conditions for the origin in the face of changing climate

2020 ◽  
Author(s):  
Maria Kireeva ◽  
Ekaterina Rets ◽  
Frolova Natalia ◽  
Gorbarenko Artem
Keyword(s):  
Discharge Rate ◽  
Geographic Location ◽  
Low Flow ◽  
Russian Plain ◽  
Amur River Basin ◽  
Russian Science ◽  
Unit Discharge ◽  
Flood Peak ◽  
Natural Zones ◽  
Flood Peaks

<p>In the last decade, floods on the rivers of Russia have become one of the most terrifying natural disasters. Among the catastrophic events, historical flood in Krymsk (2012), Amur River basin (2013), Veliky Ustyug (2016), floods in the Voronezh and Volgograd Region (2018) and Irkutsk and Novgorod Region (2019) can be called.</p><p>Floods on the rivers of the Russian Plain are divided into three main genetic types: rain, snowmelt and mixed. There is also a classification by seasons in which they can be observed. The seasonality of the flood peaks passage depends on the geographic location of the catchment and it’s local features. For most of the rivers of Central Russia, it was traditionally believed that occasional floods are mainly observed in the summer-autumn low flow period. In the summer, they are most often associated with intensive rainfall, and in the fall, with prolonged and drizzling rains. The influence of climate change on the processes of runoff formation has led to a transformation of the conditions for the occurrence of flood peaks and the need to rethink traditional ideas.</p><p>In this work, we analyzed the daily discharge time-series and highlighted flood peaks at 60 hydrological stations located in different natural zones of the European territory of Russia. Occasional flood peaks were divided into 5 classes, taking into account the time of their formation and genesis: a) thaw peaks during the winter low flow period, b) mixed peaks during the winter low flow period, c) mixed peaks during the rise of the main seasonal (snowmelt) wave, d) rain peaks during the decline of the main seasonal (snowmelt) wave, e) rain peaks during the summer-autumn low flow period.</p><p>The total number of peaks, the maximum peak discharge and its unit discharge rate, the beginning, end and duration of the flood peak, the total runoff volume of the flood, the relative stability of the low-flow period were estimated.</p><p>On average, the number of flood peaks in the rivers of the study area varies from 1 to 8 events per year. The greatest number of flood peaks is characteristic of the foothills of the Caucasus and the rivers of the Kola Peninsula, as well as the most western regions - the upper reaches of the Seversky Donets, Dnieper, and Western Dvina. The maximum unit discharges of rain floods on average is from 5 to 50 and more and thaw from 2 to 20 l/s*km<sup>2</sup>. The spatial pattern shows that higher unit discharges are typical for the windward western slopes of the hills, and relatively low ones are observed on the leeward, eastern slopes. In general, unit discharge rats increase from southwest to east, northeast.</p><p>In recent decades, the seasonality of flood peaks has changed significantly, they began to be observed in almost any period of the year, the number of events in the pre-flood period increased, as well as in the autumn period, at the time of transition to negative air temperatures.</p><p>The study was supported by the Russian Science Foundation grant No.19-77-10032</p>

scholarly journals Detection and Correction of Diurnal Sampling Bias in HIRS/2 Brightness Temperatures

2007 ◽  
Vol 24 (8) ◽  
pp. 1425-1438 ◽  
Author(s):  
Darren L. Jackson ◽  
Brian J. Soden
Keyword(s):  
Climate Model ◽  
Sampling Bias ◽  
Observation Time ◽  
Geophysical Fluid Dynamics Laboratory ◽  
Tropospheric Temperature ◽  
Brightness Temperatures ◽  
Channel Surface ◽  
Local Observation ◽  
Radiance Data ◽  
Climate Studies

Abstract Diurnal sampling biases arise in the High-Resolution Infrared Radiation Sounder (HIRS) satellite observations because some of the NOAA polar-orbiting satellites drift significantly from their original local observation time. Such bias adversely affects interpretation of these data for climate studies. Twenty-six years of HIRS/2 radiance satellite data (1979–2004) were examined by creating monthly mean gridded data that categorize the observations by local observing time through averaging ascending and descending orbits separately. Corresponding HIRS/2 simulated radiance data from the Geophysical Fluid Dynamics Laboratory (GFDL) climate model were constructed using HIRS/2 satellite sampling and were found to accurately represent the diurnal sampling bias. Correction of the HIRS/2 observations from the observed diurnal sampling bias was using the model simulations of HIRS brightness temperatures to adjust the observed brightness temperatures to the model daily mean. The diurnal bias was found to vary with channel, surface type, latitude, satellite, and cloud cover, but showed little dependence on satellite scan angle. Diurnal bias is most pronounced for ascending orbit observations of the afternoon [1400 local solar time (LST)] satellites with 60°N to 60°S domain averaged brightness temperatures variations up to 0.78 K yr−1. Lower tropospheric temperature and water vapor channels contained the largest bias, and biases over land were more than twice as large as those over the ocean. Brightness temperature adjustments of up to 10 K were needed in the most extreme situations.

scholarly journals Incorporation of the C-GOLDSTEIN efficient climate model into the GENIE framework: "eb_go_gs" configurations of GENIE

2011 ◽  
Vol 4 (4) ◽  
pp. 957-992 ◽  
Author(s):  
R. Marsh ◽  
S. A. Müller ◽  
A. Yool ◽  
N. R. Edwards
Keyword(s):  
Sea Ice ◽  
Climate Model ◽  
Horizontal Resolution ◽  
Wind Forcing ◽  
The Arctic ◽  
System Modelling ◽  
State Variables ◽  
Time Step ◽  
Transport Pathways ◽  
Ocean Atmosphere

Abstract. A computationally efficient, intermediate complexity ocean-atmosphere-sea ice model (C-GOLDSTEIN) has been incorporated into the Grid ENabled Integrated Earth system modelling (GENIE) framework. This involved decoupling of the three component modules that were re-coupled in a modular way, to allow replacement with alternatives and coupling of further components within the framework. The climate model described here (referred to as "eb_go_gs" for short) is the most basic version of GENIE in which atmosphere, ocean and sea ice all play an active role. Among improvements on the original C-GOLDSTEIN model, latitudinal grid resolution is generalized to allow a wider range of surface grids to be used. The ocean, atmosphere and sea-ice components of the "eb_go_gs" configuration of GENIE are individually described, along with details of their coupling. The setup and results from simulations using four different meshes are presented. The four alternative meshes comprise the widely-used 36 × 36 equal-area-partitioning of the Earth surface with 16 depth layers in the ocean, a version in which horizontal and vertical resolution are doubled, a setup matching the horizontal resolution of the dynamic atmospheric component available in the GENIE framework, and a setup with enhanced resolution in high-latitude areas. Results are presented for a spin-up experiment with a baseline parameter set and wind forcing typically used for current studies in which "eb_go_gs" is coupled with the ocean biogeochemistry module of GENIE, as well as for an experiment with a modified parameter set, revised wind forcing, and additional cross-basin transport pathways (Indonesian and Bering Strait throughflows). The latter experiment is repeated with the four mesh variants, with common parameter settings throughout, except for time-step length. Selected state variables and diagnostics are compared in two regards: (i) between simulations at lowest resolution that are obtained with the baseline and modified configurations, predominantly in order to evaluate the revision of the wind forcing, the modification of some key parameters, and the effect of additional transport pathways across the Arctic Ocean and the Indonesian Archipelago; (ii) between simulations with the four meshes, in order to explore various effects of mesh choice.

Sign in / Sign up

Export Citation Format

Share Document