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Radiative forcing and climate metrics for ozone precursor emissions: the impact of multi-model averaging
Multi-model ensembles are frequently used to assess understanding of the response of ozone and methane lifetime to changes in emissions of ozone precursors such as NOx, VOCs (volatile organic compounds) and CO. When these ozone changes are used to calculate radiative forcing (RF) (and climate metrics such as the global warming potential (GWP) and global temperature-change potential (GTP)) there is a methodological choice, determined partly by the available computing resources, as to whether the mean ozone (and methane) concentration changes are input to the radiation code, or whether each model's ozone and methane changes are used as input, with the average RF computed from the individual model RFs. We use data from the Task Force on Hemispheric Transport of Air Pollution source–receptor global chemical transport model ensemble to assess the impact of this choice for emission changes in four regions (East Asia, Europe, North America and South Asia).
We conclude that using the multi-model mean ozone and methane responses is accurate for calculating the mean RF, with differences up to 0.6% for CO, 0.7% for VOCs and 2% for NOx. Differences of up to 60% for NOx 7% for VOCs and 3% for CO are introduced into the 20 year GWP. The differences for the 20 year GTP are smaller than for the GWP for NOx, and similar for the other species.
However, estimates of the standard deviation calculated from the ensemble-mean input fields (where the standard deviation at each point on the model grid is added to or subtracted from the mean field) are almost always substantially larger in RF, GWP and GTP metrics than the true standard deviation, and can be larger than the model range for short-lived ozone RF, and for the 20 and 100 year GWP and 100 year GTP. The order of averaging has most impact on the metrics for NOx, as the net values for these quantities is the residual of the sum of terms of opposing signs. For example, the standard deviation for the 20 year GWP is 2–3 times larger using the ensemble-mean fields than using the individual models to calculate the RF. The source of this effect is largely due to the construction of the input ozone fields, which overestimate the true ensemble spread.
Hence, while the average of multi-model fields are normally appropriate for calculating mean RF, GWP and GTP, they are not a reliable method for calculating the uncertainty in these fields, and in general overestimate the uncertainty
Dynamics of the Quiet Solar Chromosphere
The solar chromosphere has never been static although it
was often modeled so.Even the quiet-sun internetwork chromosphere
has become thoroughly dynamic with the acoustic shock interpretation
of the Ca II K 2V grains. We concentrate on the latter in this brief review.
Recent analysis of ASP data confirms that their excitation is more likely
set acoustically than magnetically.TRACE imagery permits seeing-free
studies of their occurrence patterns
Aramco and Tapline in international oil
Thesis (B.S.) Massachusetts Institute of Technology. Dept. of Economics and Engineering, 1953.MIT copy bound with: The law of picketing / Harry Thain Allan. 1953.Bibliography: leaves 81-82.by John B. Shine.B.S
Formation Process of a Light Bridge Revealed with the Hinode Solar Optical Telescope
The Solar Optical Telescope (SOT) aboard HINODE successfully and continuously
observed a formation process of a light bridge in a matured sunspot of the NOAA
active region 10923 for several days with high spatial resolution. During its
formation, many umbral dots were observed emerging from the leading edges of
penumbral filaments, and intruding into the umbra rapidly. The precursor of the
light bridge formation was also identified as the relatively slow inward motion
of the umbral dots which emerged not near the penumbra, but inside the umbra.
The spectro-polarimeter on SOT provided physical conditions in the photosphere
around the umbral dots and the light bridges. We found the light bridges and
the umbral dots had significantly weaker magnetic fields associated with
upflows relative to the core of the umbra, which implies that there was hot gas
with weak field strength penetrating from subphotosphere to near the visible
surface inside those structures. There needs to be a mechanism to drive the
inward motion of the hot gas along the light bridges. We suggest that the
emergence and the inward motion are triggered by a buoyant penumbral flux tube
as well as the subphotospheric flow crossing the sunspot.Comment: 8 pages, 6 figures, accepted in the PASJ Hinode special issu
Observations of Sunspot Oscillations in G band and Ca II H line with Solar Optical Telescope on Hinode
Exploiting high-resolution observations made by the Solar Optical Telescope
onboard Hinode, we investigate the spatial distribution of power spectral
density of oscillatory signal in and around NOAA active region 10935. The
G-band data show that in the umbra the oscillatory power is suppressed in all
frequency ranges. On the other hand, in Ca II H intensity maps oscillations in
the umbra, so-called umbral flashes, are clearly seen with the power peaking
around 5.5 mHz. The Ca II H power distribution shows the enhanced elements with
the spatial scale of the umbral flashes over most of the umbra but there is a
region with suppressed power at the center of the umbra. The origin and
property of this node-like feature remain unexplained.Comment: 7 pages, 8 figures, accepted for publication in PASJ (Hinode Special
Issue
Polar ozone
The observation and interpretation of a large, unexpected ozone depletion over Antarctica has changed the international scientific view of stratospheric chemistry. The observations which show the veracity, seasonal nature, and vertical structure of the Antarctic ozone hole are presented. Evidence for Arctic and midlatitude ozone loss is also discussed. The chemical theory for Antarctic ozone depletion centers around the occurrence of polar stratospheric clouds (PSCs) in Antarctic winter and spring; the climatology and radiative properties of these clouds are presented. Lab studies of the physical properties of PSCs and the chemical processes that subsequently influence ozone depletion are discussed. Observations and interpretation of the chemical composition of the Antarctic stratosphere are described. It is shown that the observed, greatly enhanced abundances of chlorine monoxide in the lower stratosphere are sufficient to explain much if not all of the ozone decrease. The dynamic meteorology of both polar regions is given, interannual and interhemispheric variations in dynamical processes are outlined, and their likely roles in ozone loss are discussed
Flare Ribbons Observed with G-band and FeI 6302A Filters of the Solar Optical Telescope on Board Hinode
The Solar Optical Telescope (SOT) on board Hinode satellite observed an X3.4
class flare on 2006 December 13. Typical two-ribbon structure was observed, not
only in the chromospheric CaII H line but also in G-band and FeI 6302A line.
The high-resolution, seeing-free images achieved by SOT revealed, for the first
time, the sub-arcsec fine structures of the "white light" flare. The G-band
flare ribbons on sunspot umbrae showed a sharp leading edge followed by a
diffuse inside, as well as previously known core-halo structure. The underlying
structures such as umbral dots, penumbral filaments and granules were visible
in the flare ribbons. Assuming that the sharp leading edge was directly heated
by particle beam and the diffuse parts were heated by radiative back-warming,
we estimate the depth of the diffuse flare emission using the intensity profile
of the flare ribbon. We found that the depth of the diffuse emission is about
100 km or less from the height of the source of radiative back-warming. The
flare ribbons were also visible in the Stokes-V images of FeI 6302A, as a
transient polarity reversal. This is probably related to "magnetic transient"
reported in the literature. The intensity increase in Stokes-I images indicates
that the FeI 6302A line was significantly deformed by the flare, which may
cause such a magnetic transient.Comment: 14 pages, 7 figures, PASJ in pres
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