The climatology and interannual variability of landfalling tropical cyclones and their impacts on precipitation in the continental United States and Mexico are examined. The analysis is based on ...National Hurricane Center 6-hourly tropical cyclone track data for the Atlantic and eastern Pacific basins and gridded daily U.S. precipitation data for the period August–October 1950–98. Geographic maps of total tropical cyclone strike days, and the mean and maximum percentage of precipitation due to tropical cyclones, are examined by month. To make the procedures objective, it is assumed that precipitation is symmetric about the storm’s center. While this introduces some uncertainty in the analysis, sensitivity tests show that this assumption is reasonable for precipitation within 5° of the circulation center.
The relationship between landfalling tropical cyclones and two leading patterns of interannual climate variability—El Niño–Southern Oscillation (ENSO) and the Arctic Oscillation (AO)—are then examined. Relationships between tropical cyclone frequency and intensity and composites of 200-hPa geopotential height and wind shear anomalies are also examined as a function of ENSO phase and AO phase using classifications devised at the Climate Prediction Center.
The data show that tropical cyclone activity in the Atlantic basin is modulated on both seasonal and intraseasonal time scales by the AO and ENSO and that impact of the two modes of climate variability is greater together than apart. This suggests that, during La Niña conditions, atmospheric circulation is more conducive to activity in the main development region during AO-positive conditions than during AO-negative ones and that, during El Niño conditions, atmospheric circulation appears even less conducive to tropical cyclone development during the negative phase of the AO than during the positive phase.
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BFBNIB, DOBA, IZUM, KILJ, NUK, PILJ, PNG, SAZU, SIK, UILJ, UKNU, UL, UM, UPUK
Storage of hydrogen in activated carbon at liquid nitrogen temperature is considerably enhanced in terms of compression and adsorption on activated carbon. To reach the capacity of
4.1
kg
per
100
l
...of storage vessel, it needs to compress the gas to as high a pressure as
75
MPa
at
298
K
, but only to
15
MPa
if compressed at
77
K
. The pressure is reduced to
6
MPa
if the container is filled with pellets of activated carbon AX-21. Liquid nitrogen is cheap in cost and widely available. Therefore, storing hydrogen on activated carbon cooled by liquid nitrogen seems feasible for the hydrogen vehicle programs.
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GEOZS, IJS, IMTLJ, KILJ, KISLJ, NUK, OILJ, PNG, SAZU, SBCE, SBJE, UL, UM, UPCLJ, UPUK
Adsorption isotherms of hydrogen on activated carbon and multiwalled carbon nanotubes (MWNT) were collected using volumetric method for the range of 233–
298
K
and pressures up to
11
Mpa
. The same ...shape of isotherms revealed a common mechanism of adsorption. However, the amount of H
2 adsorbed on MWNT is 3–5 times less than on activated carbon, but the surface concentration of H
2 on MWNT is 4–6 times higher than on activated carbon. Temperature exerts much less effect on the adsorption of H
2 on MWNT than on the adsorption of H
2 on activated carbon. Isosteric heat of adsorption was evaluated from a set of isotherms basing on the Clausius–Clapeyron equation, and
−1.7
kJ/mol
was obtained for MWNT,
−6.4
kJ/mol
was obtained for activated carbon. Considering the much less quantity adsorbed, the much less heat of adsorption and the much smaller surface area, carbon nanotubes seem not to be a promising carrier of hydrogen for practical applications.
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GEOZS, IJS, IMTLJ, KILJ, KISLJ, NUK, OILJ, PNG, SAZU, SBCE, SBJE, UL, UM, UPCLJ, UPUK
Nanostructure carbons are the most important physisorption-based hydrogen carriers. The mechanism of hydrogen uptake was studied based on the adsorption isotherms collected for a wide range of ...temperature and pressure. It was concluded that the hydrogen adsorbed is arranged on carbon surface monolayerly; therefore, the storage capacity depends only on the specific surface area of the carbon. This rule applies also for other organic/inorganic materials if the interaction between hydrogen and the solid surface remains the Van der Waals force. Carbon nanotubes cannot be good carriers of hydrogen due to the small surface area, but superactivated carbon is of great potential and a storage capacity over 10 wt% was proven for the condition of 77
K and 6
MPa.
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GEOZS, IJS, IMTLJ, KILJ, KISLJ, NUK, OILJ, PNG, SAZU, SBCE, SBJE, UL, UM, UPCLJ, UPUK
The Dark‐target (DT) aerosol algorithm retrieves spectral Aerosol Optical Depth (AOD) and other aerosol properties from Moderate‐resolution Imaging Spectrometer (MODIS) reflectance observations. Over ...the ocean, the DT algorithm is known to contain scattering‐angle‐dependent biases in its retrievals of AOD, Angstrom Exponent (AE), and Fine Mode Fraction (FMF) for dust aerosols. Following a two‐step strategy to improve the DT retrieval of dust over ocean, for which the first step is to identify dusty pixels (reported in “Part 1”), in this “Part 2,” we report on construction of a new dust model lookup table (LUT) and the strategy for applying it within the existing DT algorithm. In particular, we evaluate different characterizations of dust optical properties from a variety of frameworks and databases, and compare them with the current DT retrieval assumptions. Substituting the standard operational LUT with a spheroid dust model with identified dusty pixels shows significant improvement when compared with collocated AERONET‐identified dusty pixels. Specifically, the application of the new dust model to dusty pixels reduces their AOD bias from 0.06 to 0.02 while improving the fraction of retrievals within expected error from 64% to 82%. At the same time, the overall bias in AE is reduced from 0.13 to 0.06, and the scattering‐angle‐dependent AE bias is largely eliminated. In testing on two full months of data (April and July), the new retrieval will reduce the monthly mean AOD by up to 0.1 and 0.2 in the north Atlantic and Arabian seas, respectively. The average AE and FMF are also reduced in these dust heavy regions.
Key Points
MODIS Dark Target Ocean aerosol retrieval algorithm has a long‐standing retrieval bias for dust aerosol
This study implements a nonspherical dust aerosol model to better represent dust optical properties
The new algorithm reduces biases in AOD, AE, and FMF in dusty pixels and causes an overall reduction in AOD in major dust regions over ocean
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FZAB, GIS, IJS, KILJ, NLZOH, NUK, OILJ, SBCE, SBMB, UL, UM, UPUK
Jasmonic acid (JA) is regarded as an endogenous regulator which plays an important role in regulating plant growth, development and stress response. Using the seedlings of A. thaliana ecotype Col-0 ...(wild-type, WT), phospholipase Dδ (PLDδ) deficient mutant (pldδ), the G protein α subunit (GPA1) deficient mutant (gpa1-4), 9-Lipoxygenase (9-LOX) deficient mutants (lox1 and lox5) as materials, the effects of JA responding to osmotic stress and the functions of G protein and PLDδ in this response were investigated. The results showed that GPA1 involved in the regulation of JA to PLDδ under osmotic stress. Both GPA1 and PLDδ participated in the regulation of JA on the seed germination and osmotic tolerance. Exogenous MeJA reduced the EL and MDA in WT, but increased the EL and MDA in gpa1-4 and pldδ, indicating that GPA1 and PLDδ were involved in the protection of JA on the membrane. The genes expression levels, and the activities of PLDδ and LOX1 were significantly induced by osmotic stress. The LOX activity and JA content in pldδ seedings were lower obviously than those in WT, but were markedly increased and were higher than WT after applying phosphatidic acid (PA). These results demonstrated that JA responded to osmotic stress by regulating G protein and PLDδ in A. thaliana. PLDδ was located upstream of 9-LOX and involved in the JA biosynthesis.
•The endogenous JA content, G protein activity, PLD activity and LOX activity were increased under osmotic stress.•Both GPA1 and PLDδ participated in the seed germination and drought tolerance regulated by JA.•JA regulated G protein and PLDδ to respond to osmotic stress.•PLDδ/PA is located upstream of 9-LOX and involved in the JA biosynthesis.
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GEOZS, IJS, IMTLJ, KILJ, KISLJ, NLZOH, NUK, OILJ, PNG, SAZU, SBCE, SBJE, UILJ, UL, UM, UPCLJ, UPUK, ZAGLJ, ZRSKP
A series of high surface area graphitic carbon materials （HSGCs） were prepared by ball-milling method. Effect of the graphitic degree of HSGCs on the catalytic performance of Ba-Ru-K/HSGC-x （x is the ...ball-milling time in hour） catalysts was studied using ammonia synthesis as a probe reaction. The graphitic degree and pore structure of HSGC-x supports could be successfully tuned via the variation of ball-milling time. Ru nanoparticles of different Ba-Ru-K/HSGC-x catalysts are homogeneously distributed on the supports with the particle sizes ranging from 1.6 to 2.0 nm. The graphitic degree of the support is closely related to its facile electron transfer capability and so plays an important role in improving the intrinsic catalytic performance of Ba-Ru-K/HSGC-x catalyst.
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GEOZS, IJS, IMTLJ, KILJ, KISLJ, NUK, OILJ, PNG, SAZU, SBCE, SBJE, UL, UM, UPCLJ, UPUK
The dynamic behavior of charging/discharging methane onto/from water-preloaded activated carbon was studied at different conditions. It was shown that methane hydrate could form quickly in the porous ...space of carbon at the condition of 275
K and pressures beginning with 4.12
MPa. The stored methane could be continuously released at a constant flowrate for the whole discharging process. The packing density of 0.6
g
cm
−3 seemed optimal for the wet carbon tested, which yielded 152
V/V of released methane at charging pressure of 8
MPa. The thermal effect observed on the charging/discharging process was low and did not affect the effective storage capacity.
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GEOZS, IJS, IMTLJ, KILJ, KISLJ, NUK, OILJ, PNG, SAZU, SBCE, SBJE, UL, UM, UPCLJ, UPUK
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