6,726 research outputs found
Observations of enhanced nonlinear instability in the surface reflection of internal tides
Enhanced vertically standing waves formed by the superposition of two upward and downward going near-diurnal (D1) waves are observed during one semidiurnal (D2) spring tide in an approximately 75day long velocity record from the northeastern South China Sea. Bicoherence estimates suggest that the enhanced D1 waves are likely due to nonlinear parametric subharmonic instability of D2 internal tides. The timescale for energy growth by an order of magnitude is about 2.5days for these waves. In addition to subharmonics, higher harmonics D4 (=D2+D2) and a mean flow are generated by a different nonlinear interaction during the same D2 spring tide. The separation of coherent from incoherent internal tidal signals and a rotary spectral decomposition in the vertical direction reveal that D2 waves with opposite vertical propagation directions in the region of internal tide reflection from the surface may be responsible for the pronounced nonlinear instability
SU(3) and Nonet Breaking Effects in Induced by due to Anomaly
In this paper we study the effects of on in the Standard Model. We find that this interaction can induce
new sizeable SU(3) and U(3) nonet breaking effects in
transitions and therefore in due to large matrix elements
of from QCD
anomaly. These new effects play an important role in explaining the observed
value. We also study the effects of this interaction on the contribution to
.Comment: RevTex, 12 Pages, no figures. Version to be published in PR
The statistical properties of spread F observed at Hainan station during the declining period of the 23rd solar cycle
The temporal variations of the low latitude nighttime
spread F (SF) observed by DPS-4 digisonde at low latitude Hainan
station (geog. 19.5° N, 109.1° E, dip lat. 9.5° N) during the
declining solar cycle 23 from March 2002 to February 2008 are
studied. The spread F measured by the digisonde were classified into
four types, i.e., frequency SF (FSF), range SF (RSF), mixed SF
(MSF), and strong range SF (SSF). The statistical results show that
MSF and SSF are the outstanding irregularities in Hainan, MSF mainly
occurs during summer and low solar activity years, whereas SSF
mainly occurs during equinoxes and high solar activity years. The
SSF has a diurnal peak before midnight and usually appears during
20:00–02:00 LT, whereas MSF peaks nearly or after midnight and occurs
during 22:00–06:00 LT. The time of maximum occurrence of SSF is later
in summer than in equinoxes and this time delay can be caused by the
later reversal time of the <I><B>E</B></I>×<I><B>B</B></I> drift in
summer. The SunSpot Number (SSN) dependence of each type SF is different during
different season. The FSF is independent of SSN during each season;
RSF with SSN is positive relation during equinoxes and summer and is
no relationship during the winter; MSF is significant dependence on
SSN during the summer and winter, and does not relate to SSN during
the equinoxes; SSF is clearly increasing with SSN during equinoxes
and summer, while it is independent of SSN during the winter. The
occurrence numbers of each type SF and total SF have the same trend,
i.e., increasing as Kp increases from 0 to 1, and then decreasing as
increasing Kp. The correlation with Kp is negative for RSF, MSF, SSF
and total SF, but is vague for the FSF
Mapping growing stock volume and biomass carbon storage of larch plantations in Northeast China with L-band ALOS PALSAR backscatter mosaics
Reliable spatial information on growing stock volume (GSV) and biomass is critical for creating management strategies for plantation forests. This study developed empirical models to map the GSV and biomass of larch plantations (LPs) in Northeast China (1.25 million km(2) total area) by integrating L-band synthetic aperture radar (SAR) data with ground-based survey data. The best correlation model was used to map the GSVs and biomasses of LPs. The total GSV and biomass carbon storage were estimated at 224.3 +/- 59.0 million m(3) and 113.0 +/- 29.7 x 10(12) g C with average densities of 85.1 m(3) ha(-1) and 42.9 10(6) g x C ha(-1), respectively, over a total area of 2.64 million ha. The saturation effect of SAR was determined beyond 260 m(3) ha(-1), which was expected to influence the estimations for a small proportion of the study area. The accuracy of the estimations has limitations mainly due to the uncertainties in the GSV inventories, discrimination of natural larch and the SAR dataset. Based on the mapping results of the GSVs of LPs, a planning strategy for multipurpose management was tentatively proposed. This study can inform policies and management practices to assure broader and sustainable benefits from plantation forests in the future.ArticleINTERNATIONAL JOURNAL OF REMOTE SENSING.39(22):7978-7997(2018)journal articl
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