947 research outputs found
The contribution of transport policies to the mitigation potential and cost of 2 °C and 1.5 °C goals
The transport sector contributes around a quarter of global CO2 emissions; thus, low-carbon transport policies are required to achieve the 2â°C and 1.5â°C targets. In this paper, representative transport policy scenarios are structured with the aim of achieving a better understanding of the interaction between the transport sector and the macroeconomy. To accomplish this, the AsiaâPacific Integrated Model/Transport (AIM/Transport) model, coupled with a computable general equilibrium model (AIM/CGE), is used to simulate the potential for different transport policy interventions to reduce emissions and cost over the period 2005â2100. The results show that deep decarbonization in the transport sector can be achieved by implementing transport policies such as energy efficiency improvements, vehicle technology innovations particularly the deployment of electric vehicles, public transport developments, and increasing the car occupancy rate. Technological transformations such as vehicle technological innovations and energy efficiency improvements provide the most significant reduction potential. The key finding is that low-carbon transport policies can reduce the carbon price, gross domestic product loss rate, and welfare loss rate generated by climate mitigation policies to limit global warming to 2â°C and 1.5â°C. Interestingly, the contribution of transport policies is more effective for stringent climate change targets in the 1.5â°C scenario, which implies that the stronger the mitigation intensity, the more transport specific policy is required. The transport sector requires attention to achieve the goal of stringent climate change mitigation
On the Weakening of Chromospheric Magnetic Field in Active Regions
Simultaneous measurement of line-of-sight (LOS) magnetic and velocity fields
at the photosphere and chromosphere are presented. Fe I line at
and at are used respectively for deriving the
physical parameters at photospheric and chromospheric heights. The LOS magnetic
field obtained through the center-of-gravity method show a linear relation
between photospheric and chromospheric field for field strengths less than 700
G. But in strong field regions, the LOS magnetic field values derived from
are much weaker than what one gets from the linear relationship
and also from those expected from the extrapolation of the photospheric
magnetic field. We discuss in detail the properties of magnetic field observed
in from the point of view of observed velocity gradients. The
bisector analysis of Stokes profiles show larger velocity
gradients in those places where strong photospheric magnetic fields are
observed. These observations may support the view that the stronger fields
diverge faster with height compared to weaker fields.Comment: accepted for publication in Ap
Contribution of the transport sector to climate change mitigation: Insights from a global passenger transport model coupled with a computable general equilibrium model
A passenger transport model, Asia-pacific Integrated Model (AIM)/Transport, incorporating travelersâ mode of choice and transport technological details was developed in this study. This AIM/Transport was coupled with the AIM/Computable General Equilibrium (AIM/CGE) to capture interactive mechanisms between the transport sector, energy consumption, greenhouse gas (GHG) emissions, and the macro-economy. This paper presents the model structure and mathematical formulation of AIM/Transport, and explains how it was integrated with the CGE model by an iterative algorithm, taking into consideration the feedback between AIM/Transport and AIM/CGE. A numerical simulation proved that the integration of AIM/CGE and AIM/Transport can achieve a convergence after 13 iterations. A business-as-usual (BaU) scenario and a mitigation scenario were created to test the robustness of the model integration and how the mitigation potential and cost would be modified by coupling AIM/Transport. The key finding was that the carbon price and mitigation cost were modified with the coupled CGE-Transport model
Tuning of magnetic quantum criticality in artificial Kondo superlattice CeRhIn5/YbRhIn5
The effects of reduced dimensions and the interfaces on antiferromagnetic
quantum criticality are studied in epitaxial Kondo superlattices, with
alternating layers of heavy-fermion antiferromagnet CeRhIn and 7 layers
of normal metal YbRhIn. As is reduced, the Kondo coherence temperature
is suppressed due to the reduction of effective Kondo screening. The N\'{e}el
temperature is gradually suppressed as decreases and the quasiparticle mass
is strongly enhanced, implying dimensional control toward quantum criticality.
Magnetotransport measurements reveal that a quantum critical point is reached
for superlattice by applying small magnetic fields. Remarkably, the
anisotropy of the quantum critical field is opposite to the expectations from
the magnetic susceptibility in bulk CeRhIn, suggesting that the Rashba
spin-orbit interaction arising from the inversion symmetry breaking at the
interface plays a key role for tuning the quantum criticality in the
two-dimensional Kondo lattice.Comment: Main text: 5 pages, 4 figures; Supplemental material:6 pages, 3
figures. Accepted for publication in Physical Review Letter
H-Alpha and Hard X-Ray Observations of a Two-Ribbon Flare Associated with a Filament Eruption
We perform a multi-wavelength study of a two-ribbon flare on 2002 September
29 and its associated filament eruption, observed simultaneously in the H-alpha
line by a ground-based imaging spectrograph and in hard X-rays by RHESSI. The
flare ribbons contain several H-alpha bright kernels that show different
evolutional behaviors. In particular, we find two kernels that may be the
footpoints of a loop. A single hard X-ray source appears to cover these two
kernels and to move across the magnetic neutral line. We explain this as a
result of the merging of two footpoint sources that show gradually asymmetric
emission owing to an asymmetric magnetic topology of the newly reconnected
loops. In one of the H-alpha kernels, we detect a continuum enhancement at the
visible wavelength. By checking its spatial and temporal relationship with the
hard X-ray emission, we ascribe it as being caused by electron beam
precipitation. In addition, we derive the line-of-sight velocity of the
filament plasma based on the Doppler shift of the filament-caused absorption in
the H-alpha blue wing. The filament shows rapid acceleration during the
impulsive phase. These observational features are in principal consistent with
the general scenario of the canonical two-ribbon flare model.Comment: 15 pages, 5 figures, accepted for publication in Ap
Self-Consistent MHD Modeling of a Coronal Mass Ejection, Coronal Dimming, and a Giant Cusp-Shaped Arcade Formation
We performed magnetohydrodynamic simulation of coronal mass ejections (CMEs)
and associated giant arcade formations, and the results suggested new
interpretations of observations of CMEs. We performed two cases of the
simulation: with and without heat conduction. Comparing between the results of
the two cases, we found that reconnection rate in the conductive case is a
little higher than that in the adiabatic case and the temperature of the loop
top is consistent with the theoretical value predicted by the Yokoyama-Shibata
scaling law. The dynamical properties such as velocity and magnetic fields are
similar in the two cases, whereas thermal properties such as temperature and
density are very different.In both cases, slow shocks associated with magnetic
reconnectionpropagate from the reconnection region along the magnetic field
lines around the flux rope, and the shock fronts form spiral patterns. Just
outside the slow shocks, the plasma density decreased a great deal. The soft
X-ray images synthesized from the numerical results are compared with the soft
X-ray images of a giant arcade observed with the Soft X-ray Telescope aboard
{\it Yohkoh}, it is confirmed that the effect of heat conduction is significant
for the detailed comparison between simulation and observation. The comparison
between synthesized and observed soft X-ray images provides new interpretations
of various features associated with CMEs and giant arcades.Comment: 39 pages, 18 figures. Accepted for publication in the Astrophysical
Journal. The PDF file with high resplution figures can be downloaded from
http://www.kwasan.kyoto-u.ac.jp/~shiota/study/ApJ62426.preprint.pdf
Discovery of possible molecular counterparts to the infrared Double Helix Nebula in the Galactic center
We have discovered two molecular features at radial velocities of -35 km/s
and 0 km/s toward the infrared Double Helix Nebula (DHN) in the Galactic center
with NANTEN2. The two features show good spatial correspondence with the DHN.
We have also found two elongated molecular ridges at these two velocities
distributed vertically to the Galactic plane over 0.8 degree. The two ridges
are linked by broad features in velocity and are likely connected physically
with each other. The ratio between the 12CO J=2-1 and J=1-0 transitions is 0.8
in the ridges which is larger than the average value 0.5 in the foreground gas,
suggesting the two ridges are in the Galactic center. An examination of the K
band extinction reveals a good coincidence with the CO 0 km/s ridge and is
consistent with a distance of 8 +/-2 kpc. We discuss the possibility that the
DHN was created by a magnetic phenomenon incorporating torsional Alfv\'en waves
launched from the circumnuclear disk (Morris, Uchida & Do 2006) and present a
first estimate of the mass and energy involved in the DHN.Comment: 32 pages, 23 figures, Accepted by Ap
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