Reflections on the surface energy imbalance problem

Abstract Waveform inversion of Vertical Seismic Profiling (VSP) data, including upgoing and downgoing wavefields, is a challenging technique for building an accurate model. During the inversion process, upgoing and downgoing wavefields have different contributions to the objective function due to an energy imbalance between them that may cause the upgoing field to not be used effectively. Therefore, we propose a method of joint waveform inversion with the separated upgoing and downgoing wavefields of VSP data based on the establishment of a multiobjective function without introducing weight coefficients. The separating step with direct simulation of upgoing and downgoing wavefields of VSP data by the reflectivity method simplifies the complexity of separating wavefields. Specially, the zero-offset VSP data can be obtained in the τ−p domain to reduce computational cost greatly. Establishment of a multiobjective function of the difference between upgoing and downgoing wavefields can overcome the energy imbalance problem for them. The joint inversion step with a multiobjective optimization method avoids insufficient or incomplete information from just using an upgoing or downgoing wavefield alone. Numerical tests applied on synthetic models indicate that this method has the potential to increase the accuracy of estimating the velocity and density.

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Dew Formation, Eddy-Correlation Latent Heat Fluxes, and the Surface Energy Imbalance at Cabauw During Stable Conditions

Boundary-Layer Meteorology ◽

10.1007/s10546-010-9476-1 ◽

2010 ◽

Vol 135 (3) ◽

pp. 369-383 ◽

Cited By ~ 19

Author(s):

Stephan R. de Roode ◽

Fred C. Bosveld ◽

Petra S. Kroon

Keyword(s):

Surface Energy ◽

Latent Heat ◽

Heat Fluxes ◽

Eddy Correlation ◽

Energy Imbalance ◽

Dew Formation ◽

Stable Conditions

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THE IMPACT OF THE SURFACE HETEROGENEITY ON THE ENERGY IMBALANCE PROBLEM USING LES

PROCEEDINGS OF HYDRAULIC ENGINEERING ◽

10.2208/prohe.49.343 ◽

2005 ◽

Vol 49 ◽

pp. 343-348

Author(s):

Atsushi Inagaki ◽

Manabu Kanda ◽

Oliver Letzel Marcus ◽

Raasch Siegfried

Keyword(s):

Surface Heterogeneity ◽

Energy Imbalance ◽

Imbalance Problem ◽

The Impact

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LES STUDY ON THE ENERGY IMBALANCE PROBLEM FOR HETEROGENEOUS SURFACE

PROCEEDINGS OF HYDRAULIC ENGINEERING ◽

10.2208/prohe.47.37 ◽

2003 ◽

Vol 47 ◽

pp. 37-42

Author(s):

Atsushi Inagaki ◽

Manabu Kanda ◽

Marcus Oliver Letzel ◽

Siegfried Raasch

Keyword(s):

Heterogeneous Surface ◽

Energy Imbalance ◽

Imbalance Problem

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Energy-Efficient Cluster Management Using a Mobile Charger for Solar-Powered Wireless Sensor Networks

Sensors ◽

10.3390/s20133668 ◽

2020 ◽

Vol 20 (13) ◽

pp. 3668 ◽

Cited By ~ 1

Author(s):

Youngjae Son ◽

Minjae Kang ◽

Younghyun Kim ◽

Ikjune Yoon ◽

Dong Kun Noh

Keyword(s):

Wireless Sensor Networks ◽

Sensor Networks ◽

Mobile Sink ◽

Sensor Nodes ◽

Wireless Sensor ◽

Sink Node ◽

Energy Imbalance ◽

Cluster Heads ◽

Imbalance Problem ◽

Solar Powered

In solar-powered wireless sensor networks (SP-WSNs), sensor nodes can continuously harvest energy to relieve the energy constraint problem in battery-powered WSNs. With the advent of wireless power transmission (WPT) technology, the nodes can be charged remotely if the energy harvested is insufficient. However, even in SP-WSNs with WPT, an energy imbalance problem is observed, in which the energy consumption of the nodes around a sink node increases abnormally if the sink node is stationary. To solve this problem, recent studies have been conducted using a mobile sink node instead of a stationary one. Generally, a clustering scheme is used for the efficient utilization of a mobile sink. However, even in the case of mobile sinks, it is still necessary to minimize the energy burden of the cluster heads and their surrounding nodes. In this study, we propose a scheme that mitigates the energy imbalance problem of SP-WSNs by using a WPT-capable mobile sink and an efficient clustering scheme. In the proposed scheme, the energy imbalance is minimized by electing the cluster heads effectively after considering the energy state of the nodes, and by enabling the sink node to charge the energy of the cluster heads while collecting data from them. Consequently, this scheme allows the sink node to collect more data with fewer blackouts of the sensor nodes.

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Impact of Climate Change and Surface Energy (Im) Balance on North-East India Monsoonal Rainfall

Journal of Climate Change ◽

10.3233/jcc210010 ◽

2021 ◽

Vol 7 (2) ◽

pp. 35-47

Author(s):

Pramod Kumar

Keyword(s):

Climate Change ◽

Surface Energy ◽

Thermal Radiation ◽

Sensible Heat ◽

Study Region ◽

Near Surface ◽

Energy Imbalance ◽

North East India ◽

North East ◽

Monsoonal Precipitation

In recent decades, climate change and its impact on the ecosystem has remained a concern from global to regional to local scale. Many studies performed over India have highlighted the change in precipitation associated with the Indian summer monsoon (ISM) and its linkage with changed land surface processes. Over North-East India (NEI), changed surface and atmospheric energy imbalance due to increase in wasteland, deforestation and over cultivation have made the soil barren. In addition, soil moisture of barren land has decreased, latent (sensible) heat decreased (increased) with stimulating ground heat increment. This led to lower evapotranspiration and convection leading to precipitation decrement. To analyse this in detail, the present study shows a lower increase in the near surface temperature during 1956-1985 (period I), but a higher increasing trend has been seen during 1986-2015 (period II). In the case of precipitation trends, an increase during period I and a decrease at a 95% significant level during period II are seen. The average air temperature warming rate increase of 0.09 °C/year is observed. The monsoonal precipitation has decreased significantly in recent years (1986-2015) than that in the past (1956-1985). In addition, a decrease in monsoonal precipitation at 0.35 mm/year rate during period II is seen over NEI. A prominent increment of 0.12 W/m2 is observed in surface sensible heat flux over NEI. Land use land cover change (LULCC) is continuously altering the local rate of change of thermal radiation, evapotranspiration and convection, and has also played a critical role in defining monsoonal precipitation over NEI. However, the surface net solar and thermal radiation change are in equilibrium with the surface sensible and latent heat for sustaining the surface energy budget. Hence, a small change in surface net radiation causes an imbalance of surface energetics. It is one of the most prominent causes for the precipitation pattern changes over NEI. The LULCCs and earth’ surface energy imbalance reinforce climate variability and climate change over the study region.

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