Global comparisons of barotropic and internal tides generated in an eddy‐resolving ocean circulation model are made with tidal estimates obtained from altimetric sea surface heights and an ...altimetry‐constrained tide model. As far as we know, our Hybrid Coordinate Ocean Model (HYCOM) simulations shown here and in an earlier paper are the only published high‐resolution global simulations to contain barotropic tides, internal tides, the general circulation, and mesoscale eddies concurrently. Comparing the model barotropic tide with a global data‐assimilative shallow water tide model shows that the global tidal elevation differences are approximately evenly split between discrepancies in tidal amplitude and phase. Both the model and observations show strong generation of internal tides at a limited number of “hot spot” regions with propagation of beams of energy for thousands of kilometers away from the sources. The model internal tidal amplitudes compare well with observations near these energetic tidal regions. Averaged over these regions, the model and observation internal tide amplitude estimates agree to approximately 15% for the four largest semidiurnal constituents and 23% for the four largest diurnal constituents. Away from the hot spots, the comparison between the model and altimetric amplitude is not as good due, in part, to two problems, errors in the model barotropic tides and overestimation of the altimetric tides in regions of strong mesoscale eddy activity. Examining the general energy distribution of the simulated internal tide is an important first step in the evaluation of internal tides in HYCOM.
Key Points
Model and observations show generation of internal tides in limited regions
Our global model is able to generate internal waves consistent with observations
Barotropic phase errors are a major source of errors in the model internal tide
•We tune several linear (modified) wave drag schemes in a tidal barotropic model.•We compare with TPXO elevation and dissipation rates, horizontally and with depth.•A scalarized tensor wave drag ...performs as well or better than the tensor equivalent.•Reducing the wave drag strength at supercritical slopes improves the solution.•The inclusion of artificial abyssal hill roughness yields a modest improvement.
A global tuning experiment for the semidiurnal tide is performed with a barotropic model. The model is forced with the M2 equilibrium tide and accounts for the self-attraction and loading (SAL) term. In addition to a quadratic drag, various linear internal wave drag terms adjusted by a scale factor of O(1) are applied. The drag terms include the original Nycander (2005) tensor scheme, the Nycander tensor scheme reduced at supercritical slopes, and their scalar sisters, a Nycander scalar scheme computed for additional abyssal hill roughness, and the Jayne and St. Laurent (2001) scalar scheme. The Nycander scheme does not have a tunable parameter, but to obtain the best tidal solutions, it is demonstrated that some tuning is unavoidable. It is shown that the scalar Nycander schemes yield slightly lower root-mean square (RMS) elevation errors vs. the data-assimilative TPXO tide model than the tensor schemes. Although the simulation with the optimally tuned original Nycander scalar yields dissipation rates close to TPXO, the RMS error is among the highest. The RMS error is lowered for the reduced schemes, which place relatively more dissipation in deeper water. The inclusion of abyssal hill roughness improves the regional agreement with TPXO dissipation rates, without changing the RMS errors. It is difficult to have each ocean basin optimally tuned with the application of a constant scale factor. The relatively high RMS error in the Atlantic Ocean is reduced with a spatially varying scale factor with a larger value in the Atlantic. Our best global mean RMS error of 4.4cm for areas deeper than 1000m and equatorward of 66° is among the lowest obtained in a forward barotropic tide model.
Global maps of the mesoscale eddy available potential energy (EAPE) field at a depth of 500 m are created using potential density anomalies in a high‐resolution 1/12.5° global ocean model. Maps made ...from both a free‐running simulation and a data‐assimilative reanalysis of the HYbrid Coordinate Ocean Model (HYCOM) are compared with maps made by other researchers from density anomalies in Argo profiles. The HYCOM and Argo maps display similar features, especially in the dominance of western boundary currents. The reanalysis maps match the Argo maps more closely, demonstrating the added value of data assimilation. Global averages of the simulation, reanalysis, and Argo EAPE all agree to within about 10%. The model and Argo EAPE fields are compared to EAPE computed from temperature anomalies in a data set of “moored historical observations” (MHO) in conjunction with buoyancy frequencies computed from a global climatology. The MHO data set allows for an estimate of the EAPE in high‐frequency motions that is aliased into the Argo EAPE values. At MHO locations, 15–32% of the EAPE in the Argo estimates is due to aliased motions having periods of 10 days or less. Spatial averages of EAPE in HYCOM, Argo, and MHO data agree to within 50% at MHO locations, with both model estimates lying within error bars observations. Analysis of the EAPE field in an idealized model, in conjunction with published theory, suggests that much of the scatter seen in comparisons of different EAPE estimates is to be expected given the chaotic, unpredictable nature of mesoscale eddies.
Key Points
Global maps of the mesoscale eddy available potential energy are made from a HYCOM simulation and reanalysis
Modeled eddy available potential energy compares well to Argo observations globally, and to moored instruments locally
Model‐data comparisons of eddy available potential energy exhibit intrinsic scatter
Physical, geochemical and biological observations across the Tasman Front off southeast Australia provide the first detailed view of the relationship between physical forcing and biological ...properties within the frontal system. At the beginning of the austral spring of 2004, high resolution measurements were taken using a CTD and a towed undulating vehicle along transects perpendicular to the Tasman Front at
152
∘
00
′
E
,
153
∘
00
′
E
and
153
∘
30
′
E
. The front was characterised by a sharp surface gradient in physical and biological properties and a sub-surface intrusion of low-salinity water. In general the surface temperature changes across the front from
19
∘
C
in the Coral Sea waters to the north to
17
∘
C
in the Tasman Sea waters over
∼
10
km
. Over the same distance we observed (1) an increase of the mixed layer depth from
∼
40
to
∼
100
m
; (2) a 3–8-fold increase in the depth-integrated chlorophyll; (3) an order of magnitude increase in biovolume of particulate matter in the size range of 357–
2223
μ
m
; (4) a 2-fold increase in filtered particulate organic matter; (5) a
3
‰
increase in
δ
13
C
POM
; and (6) a
4
‰
increase in
δ
15
N
POM
. The particulate matter in the warmer Coral Sea waters is well approximated by a linear fit of the normalised biomass size spectrum (NBSS) with a slope of between
-
0.95
and
-
0.99
, while the Tasman Sea waters have a more non-linear and less negative (
-
0.59
to
-
0.8
) spectrum. The low-salinity intrusion that penetrates to within 40
m of the surface between the Coral Sea and Tasman Sea waters is biologically unproductive, with low oxygen, fluorescence and particulate matter counts. The unproductive low salinity intrusion of the Tasman Front contrasts with the highly productive intrusion observed at the Gulf Stream Front off Cape Hatteras, USA. Observations are consistent with Coral Sea and Tasman Sea waters being found in close proximity with steep gradients in biological properties across the front suggesting minimal cross-front mixing. North of the front, the stratified, oligotrophic Coral Sea waters are relatively unproductive, while the vertically well-mixed waters south of the front exhibit strong biological activity.
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•SCW hydrolysis was used to obtain sugars and char formation from sugarcane straw.•The highest yield of TRS 32.1% and glucose 2.1% were obtained at 200°C, 10MPa.•Subcritical water ...hydrolysis temperature of 200°C minimized char formation.•Pressure had no significant effect on the solid residue composition.•TGA and FT-IR analysis provided additional information about char formation.
Subcritical water has potential as an environmentally friendly solvent for applications including hydrolysis, liquefaction, extraction, and carbonization. Here, we report hydrolysis of sugarcane straw, an abundant byproduct of sugar production, in a semi-continuous reactor at reaction temperatures ranging from 190 to 260°C and at operating pressures of 9 and 16MPa. The target hydrolysis products were total reducing sugars. The main products of sugarcane straw hydrolysis were glucose, xylose, arabinose, and galactose in addition to 5- hydroxymethylfurfural and furfural as minor byproducts. Fourier transform infrared spectroscopy and thermogravimetric analysis provided additional information on the surface and bulk composition of the residual biomass. Char was present on samples treated at temperatures equal to and greater than 190°C. Samples treated at 260°C contained approximately 20wt% char, yet retained substantial hemicellulose and cellulose content. Hydrolysis temperature of 200°C provided the greatest TRS yield while minimizing char formation.
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•The subcritical water hydrolysis of two coffee residues in subcritical water were studied.•The operational conditions were different temperatures, two supercritical pressures at ...water flow rate.•Higher yields of reducing sugars and phenolic compounds recovered from residues coffee in subcritical water.•The concentrations of sugars were identified (arabinose, cellobiose, glucose and xylose), 5-hydroxy-methyl-furfural (5-HMF) and furfural in the hydrolysates.•The residual solid was analyzed by scanning electron microscopy.
Two abundant coffee waste residues (powder and defatted cake) were treated using subcritical water (SubCW) for hydrolysis and extraction of reducing sugars (RS), total reducing sugars (TRS), and total phenolic compounds (TPC) under semi-continuous flow conditions. The flow-through process was carried out at 150, 175, 200 and 250°C, with a water flow of 10mL/min and reaction pressures of either 22.5 or 30MPa. For treated coffee powder, the maximum observed sugar recovery was 6.3% for RS (150°C and 30MPa) and 9.0% for TRS (150°C and 30MPa). The maximum TPC recovery was 26.64mg GAE (Gallic Acid Equivalent)/g powder coffee, observed at 200°C and 22.5MPa. For the defatted coffee cake, the maximum sugar yields were 8.79% and 17.23% for RS and TRS; both observed at a treatment temperature of 175°C. The highest TPC yield was 55.31mg TPC GAE/g defatted coffee cake, also at 175°C. HPLC was used to quantify specific carbohydrates (arabinose, cellobiose, glucose, and xylose), 5-hydroxy-methyl-furfural (5-HMF) and furfural in both coffee waste hydrolyzates, providing evidence of thermal degradation of the coffee carbohydrates. Scanning electron microscopy of the treated samples revealed particles deposited on the surface and other signs of physical degradation of the biomass structure. Fourier Transform Infrared Spectroscopy of the residues revealed that the density of surface bound acid groups increased with increasing treatment temperature. The results presented here provide a basis for the use of subcritical water to obtain reducing sugars and phenolic compounds from coffee residue.
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•Hydrothermal fractionation of brewer´s spent grains in a semi-continuous reactor.•Temperature influenced production of compounds solubilized in subcritical water.•The flow rate of 20 ...mL/min with an S/F: 64, maximize production of sugars.•The maximum RS yield was 5.89% and the maximum TRS yield was 35.11%.•Maximum yield of C5 was approximately 3.35%.
The objective of this work was to produce C-5 sugars from the hydrolysis of the spent grains of the brewery. The total sugar recovery and formation of by-products were evaluated as a function of the reaction temperature (140, 160, 180 and 210 °C), flow rate (10 and 20 mL min–1) and the solvent/feed ratio (S/F: 64, 80 and 112). The total carbohydrate yields were dependent on the hydrolysis temperature. Arabinose was the main product, followed by xylose and the arabinose yield increased with increasing the S/F ratio and the flow rate. Yields of furfural were sensitive to flow rate. The hemicellulose content of the residual solids was reduced by approximately 90% after hydrolysis, with the parallel formation of carbonyl and carbonized species. The effects of flow rate on the efficiency of converting hemicellulose into simple sugars were complex, suggesting roles for the formation of autocatalytic acids.
The origin of novel traits is recognized as an important process underlying many major evolutionary radiations. We studied the genetic basis for the evolution of haustoria, the novel feeding organs ...of parasitic flowering plants, using comparative transcriptome sequencing in three species of Orobanchaceae. Around 180 genes are upregulated during haustorial development following host attachment in at least two species, and these are enriched in proteases, cell wall modifying enzymes, and extracellular secretion proteins. Additionally, about 100 shared genes are upregulated in response to haustorium inducing factors prior to host attachment. Collectively, we refer to these newly identified genes as putative "parasitism genes." Most of these parasitism genes are derived from gene duplications in a common ancestor of Orobanchaceae and Mimulus guttatus, a related nonparasitic plant. Additionally, the signature of relaxed purifying selection and/or adaptive evolution at specific sites was detected in many haustorial genes, and may play an important role in parasite evolution. Comparative analysis of gene expression patterns in parasitic and nonparasitic angiosperms suggests that parasitism genes are derived primarily from root and floral tissues, but with some genes co-opted from other tissues. Gene duplication, often taking place in a nonparasitic ancestor of Orobanchaceae, followed by regulatory neofunctionalization, was an important process in the origin of parasitic haustoria.
Orobanchaceae is the only plant family with members representing the full range of parasitic lifestyles plus a free-living lineage sister to all parasitic lineages, Lindenbergia. A generalist member ...of this family, and an important parasitic plant model, Triphysaria versicolor regularly feeds upon a wide range of host plants. Here, we compare de novo assembled transcriptomes generated from laser micro-dissected tissues at the host-parasite interface to uncover details of the largely uncharacterized interaction between parasitic plants and their hosts.
The interaction of Triphysaria with the distantly related hosts Zea mays and Medicago truncatula reveals dramatic host-specific gene expression patterns. Relative to above ground tissues, gene families are disproportionally represented at the interface including enrichment for transcription factors and genes of unknown function. Quantitative Real-Time PCR of a T. versicolor β-expansin shows strong differential (120x) upregulation in response to the monocot host Z. mays; a result that is concordant with our read count estimates. Pathogenesis-related proteins, other cell wall modifying enzymes, and orthologs of genes with unknown function (annotated as such in sequenced plant genomes) are among the parasite genes highly expressed by T. versicolor at the parasite-host interface.
Laser capture microdissection makes it possible to sample the small region of cells at the epicenter of parasite host interactions. The results of our analysis suggest that T. versicolor's generalist strategy involves a reliance on overlapping but distinct gene sets, depending upon the host plant it is parasitizing. The massive upregulation of a T. versicolor β-expansin is suggestive of a mechanism for parasite success on grass hosts. In this preliminary study of the interface transcriptomes, we have shown that T. versicolor, and the Orobanchaceae in general, provide excellent opportunities for the characterization of plant genes with unknown functions.
Celotno besedilo
Dostopno za:
DOBA, IZUM, KILJ, NUK, PILJ, PNG, SAZU, SIK, UILJ, UKNU, UL, UM, UPUK
This study sought to identify new sources of resistance to cowpea aphids (CPA) using molecular and phenotypic approaches and the inheritance pattern. Sixty cowpea genotypes were phenotyped for ...resistance to CPA using insect proof cages and further confirmed using markers linked to aphid resistance. Result revealed that among the cowpea genotypes, TVu 2897 and TVNu 1158 supported lowest number of aphids and plant damage scores. The seedlings of these genotypes also had high level of survival rates and were completely healthy with normal growth. This indicates that these genotypes are resistant to aphid attacks. However, the resistance in TVNu 1158 did not seem strong compared to the genotype TV
U
2897 that was confirmed to be resistant to multiple aphid biotypes. The mechanism of resistance in TVu 2897 and TVNu 1158 were expressed as a hypersensitive response at the site of infestation on the leaves. The other genotypes especially Aloka local and keffi local supported the highest number of aphids, damage score and low level of survival rate, suggesting that they are susceptible to aphid attack. The cowpea genotype IT84S-224-6 previously reported to be resistant to aphids supported high number of aphids and was marked by stunted growth and high mortality rate. Molecular and phenotypic screening revealed that TVu-2876 has a strong resistance to cowpea aphid and should be a good source of resistance gene that can be used in breeding to develop new aphid resistant cowpea cultivars. Although, the results of phenotypic tests and molecular marker detection agreed in most cases, molecular markers detection was found more reliable in identifying genotypes for resistance to CPA. The segregation in F
2
and BC1 populations derived from the cross between TVNu 2876 and Keffi local indicated that resistance to cowpea aphids in TVu-2876 is controlled by a single dominant gene. Allelism test revealed that resistance gene in TVNu 2876 is non-allelic with the gene that confers resistance in SARC 1-57-2 and TVNu 1158.
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