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1.
Masaru Tsujiura 《Pure and Applied Geophysics》1983,121(4):573-600
Through the analyses of waveform and spectrum for two swarm sequences in the Kanto District, including the results from 15
earthquake swarsm obtained previously, the mechanism of the faulting process in earthquake swarms is clarified in more detail.
Earthquakes occurring in short time intervals consist mainly of events with similar waveforms andS-P times. These are called “earthquake families,” and many families are observed during a swarm sequence (70–80 percent); for
example, 15 families were observed in the 1983 Izu Peninsula earthquake swarm. The source spectra of earthquake families share
the same corner frequency, even though their low-frequency levels may differ by a factor as great as 1000, and the value of
the corner frequency depends on the size of the largest event in the family. Local variations of corner frequencies within
a factor of 25 are found among the earthquake swarms in the Kanto District. These observations suggest the existence of a
characteristic fault length depending on the swarm area, and its length may be responsible for the size of the largest event
in the family. The characteristic fault length is about 100 m for Ashio, about 400 m for the Izu Peninsula and about 2.5 km
for areas off the Chiba Prefecture, and the magnitudes of the largest events expected from these fault lengths are about 2.5,
4, and 6, respectively. 相似文献
2.
The sources for thirteen deep focus earthquakes ofm
b≥5.5 andh>400 km in Northwest Pacific region were studied using waveform fitting and shear fracture source model. The source parameters
were obtained as follows: focal depth, faulting plane, slip direction, rupture velocity, rupture length, rupture direction
and scalar moment tensor. It was found that all these earthquake sources can be interpreted as shear faulting and have simple
source time functions. The strike direction of faulting plane for most deep focus earthquakes coincides with that of the subduction
zone, especially in the deep part of the subduction zone, it results in the tendency of reducing the dip angle of the subduction
zone. The multiple point source model was also used to study the source process. The waveform fitting is better than the shear
fracture model, but the general rupture direction which coincides with that from unilateral shear source model can not be
obtained from the multiple point source model.
This study is supported by the National Science Foundation of China and the Chinese Joint Seismological Science Foundation. 相似文献
3.
In summer 2003, a Chaparral Model 2 microphone was deployed at Shishaldin Volcano, Aleutian Islands, Alaska. The pressure
sensor was co-located with a short-period seismometer on the volcano’s north flank at a distance of 6.62 km from the active
summit vent. The seismo-acoustic data exhibit a correlation between impulsive acoustic signals (1–2 Pa) and long-period (LP,
1–2 Hz) earthquakes. Since it last erupted in 1999, Shishaldin has been characterized by sustained seismicity consisting of
many hundreds to two thousand LP events per day. The activity is accompanied by up to ∼200 m high discrete gas puffs exiting
the small summit vent, but no significant eruptive activity has been confirmed. The acoustic waveforms possess similarity
throughout the data set (July 2003–November 2004) indicating a repetitive source mechanism. The simplicity of the acoustic
waveforms, the impulsive onsets with relatively short (∼10–20 s) gradually decaying codas and the waveform similarities suggest
that the acoustic pulses are generated at the fluid–air interface within an open-vent system. SO2 measurements have revealed a low SO2 flux, suggesting a hydrothermal system with magmatic gases leaking through. This hypothesis is supported by the steady-state
nature of Shishaldin’s volcanic system since 1999. Time delays between the seismic LP and infrasound onsets were acquired
from a representative day of seismo-acoustic data. A simple model was used to estimate source depths. The short seismo-acoustic
delay times have revealed that the seismic and acoustic sources are co-located at a depth of 240±200 m below the crater rim.
This shallow depth is confirmed by resonance of the upper portion of the open conduit, which produces standing waves with
f=0.3 Hz in the acoustic waveform codas. The infrasound data has allowed us to relate Shishaldin’s LP earthquakes to degassing
explosions, created by gas volume ruptures from a fluid–air interface. 相似文献
4.
In order to clarify the time relation of the expansion of a gas pocket and failure of its overlying plug of lava during Vulcanian
eruptions, infrasound records and video images of the Vulcanian eruption that occurred at Sakurajima volcano on January 2,
2007 were analyzed with respect to their origin times. Weak (≤3 Pa) and slowly increasing air pressure preceded the impulsive
compression phase by 0.25–0.32 s, and a longer-period rarefaction phase of infrasound waves was recognized at all microphone
stations. The velocity of the compression phase was assumed to be supersonic (ca. 400 m/s) up to 850 m above the crater bottom
from other recent explosions. On the other hand, the propagation velocity of the preceding weak signal was regarded to be
similar to the air sound velocity because the lack of impulsiveness is unlikely to be related to the main compression phase.
Therefore, the estimated origin time of the main compression phase was delayed by 0.5–0.7 s from the preceding phase. The
origin time of the preceding phase coincided with the onset of the isotropic expansion process of the pressurized gas pocket,
which was obtained by the waveform inversion of the explosion earthquake. In contrast, the origin time of the main impulsive
phase coincided with the time when the expansion rate reached its peak. This observation suggests that the volumetric increase
of the gas pocket caused swelling of the surface of the crater bottom and its subsequent failure. When the expansion velocity
exceeded a threshold level, the main impulsive compression phase radiated with a high velocity by the sudden releases of the
pressurized gases. The volumetric change at the source was estimated to be 280–560 m3 from the preceding phase of the infrasound. This volume change indicates that the vertical displacement of the swelling ground
was on the order of 1.0 m, assuming the radius of the lava plug was ca. 10 m. 相似文献
5.
Matthew Robert Palmer 《Ocean Dynamics》2010,60(2):219-226
Understanding the fate of freshwater runoff and corresponding nutrient and pollution loads is of critical importance for the
development of accurate predictive models and coastal management tools. A key element of such studies is the identification
and understanding of the interaction between stratification and current structure. This paper presents a new series of measurements
made in the Liverpool Bay region of freshwater influence (ROFI) during spring 2004 where freshwater-maintained horizontal
density gradients and strong tidal currents interact to produce strain-induced periodic stratification (SIPS). During stratification,
tidal current profiles are significantly modified such that the tidal flow deviates from the otherwise rectilinear E–W axis
generating counter rotating upper and lower mixed layers. This feature has often been reported for the Rhine ROFI but not
previously identified in Liverpool Bay despite previous investigation at this site. Investigation of an ongoing long-term
dataset collected nearby reveals this process to be a common feature throughout the year. Liverpool Bay is shown to maintain
three different regimes, long term mixed, long term stratified, and a transitional state when SIPS occurs. The phase of SIPS
relative to the tide results in a residual flow away from the Welsh coastline in the upper water column of 2.3–3.6 cm s−1 with a counterflow in the lower layer of 2.8–3.1 cm s−1 towards the coast. 相似文献
6.
Based on Generalized Seismic Ray Theory (Helmberger, 1968), a new quickly linear inversion method from the data of seismic
waveform to seismic moment tensor and source mechanism for domestic earthquake is studied in this paper. Six moderately strong
earthquakes which occurred in Chinese mainland in the past few years are studied. The seismic source parameters of these earthquakes,
seismic moment tensors, scalar seismic moments, fault plane solutions and source time functionsetc, are obtained.
The Chinese version of this paper appeared in the Chinese edition ofActa Seismologica Sinica,15, 261–268, 1993. 相似文献
7.
In the English Channel, extreme surge heights did not occur at the time of extreme high tides during the last decades and
maximum recorded heights usually do not exceed the maximum astronomical tide by more than a few decimetres. To understand
whether this lack of coincidence may be due to specific phenomena or only to chance, we have studied hourly tide records lasting
a few decades from nine English and nine French stations as well as air pressure and wind data from nearby meteorological
observatories. Among the case studies of moderate flooding at several coastal stations occurring during spring tide, we have
selected those of 24–25/10/1980 and of 30/01/1983 to 02/02/1983 as representative of a normal situation without any special
chance. The third case study 26–28/02/1990 was potentially more dangerous because of the storm intensity and duration; however,
by chance, surge peaks occurred near the low tide. Finally, the propagation of the surge peak of 15–16/10/1987, which reached
the maximum height recorded during all the instrumental period at several stations, has been followed all along the English
Channel, using the hourly records of 12 tide-gauge stations and of 16 meteorological stations. The surge peak of this great
storm, probably the strongest in the last two centuries, occurred everywhere at high tide and spread with the same velocity
of the tidal wave. Fortunately, no major flooding occurred because it was the day after a neap tide. In conclusion, some good
fortune has saved the low coastal areas of the English Channel from major floods during the last decades. However, the occurrence
of the peak of a strong storm surge arriving near the western entrance of the Channel at the time of a great astronomical
high tide is a possible event that could be devastating along both sides of the Channel coasts.
Main parts of this paper have been presented orally in June 2005 at the joint INQUA–IGCP 495 Meeting “Dunkerque 2005” and
in February 2006 at the ASLO-TOS-AGU “Ocean Sciences Meeting” (Honolulu, HI). 相似文献
8.
Lupei Zhu Ying Tan Donald V. Helmberger Chandan K. Saikia 《Pure and Applied Geophysics》2006,163(7):1193-1213
We use the recordings from 51 earthquakes produced by a PASSCAL deployment in Tibet to develop a two-layer crustal model for
the region. Starting with their ISC locations, we iteratively fit the P-arrival times to relocate the earthquakes and estimate mantle and crustal seismic parameters. An average crustal P velocity of 6.2–6.3 km/s is obtained for a crustal thickness of 65 km while the P velocity of the uppermost mantle is 8.1 km/s. The upper layer of the model is further fine-tuned by obtaining the best synthetic
SH waveform match to an observed waveform for a well-located event. Green's functions from this model are then used to estimate
the source parameters for those events using a grid search procedure. Average event relocation relative to the ISC locations,
excluding two poorly located earthquakes, is 16 km. All but one earthquake are determined by the waveform inversion to be
at depths between 5 and 15 km. This is 15 km shallower, on average, than depths reported by the ISC. The shallow seismicity
cut-off depth and low crustal velocities suggest high temperatures in the lower crust. Thrust faulting source mechanisms dominate
at the margins of the plateau. Within the plateau, at locations with surface elevations less than 5 km, source mechanisms
are a mixture of strike-slip and thrust. Most events occurring in the high plateau where elevations are above 5 km show normal
faulting. This indicates that a large portion of the plateau is under EW extension. 相似文献
9.
Mehmet Simav Hasan Yildiz Ali Türkezer Onur Lenk Emin ?zsoy 《Studia Geophysica et Geodaetica》2012,56(1):215-230
Sea level trends and interannual variability at Antalya and Menteş tide gauges are investigated during the 1985–2001 period,
quantifying the roles of atmospheric, steric and local land motion contributions. Tide gauge sea level measurements, temperature/salinity
climatologies and GPS data are used in the analyses and the results are compared with the output of a barotropic model forced
by atmospheric pressure and wind. The overall sea level trends at two tide gauges collocated with GPS are in the range of
5.5 to 7.9 mm/yr during the study period, but showing different behaviour in the sub-periods 1985–1993 and 1993–2001 due to
variations in the contributing factors both in space and time. After the removal of the atmospheric forcing and steric contribution
from sea level records, the resulting trends vary between 1.9 to 4.5 mm/yr in Antalya and −1.2 to −11.6 mm/yr in Menteş depending
on the period considered. Vertical land movement estimated from GPS data seems to explain the high positive residual trend
in Antalya during the whole period. On the other hand, the source of the highly negative sea level trend of about −14 mm/yr
in Menteş during 1985–1993 could not be resolved with the available datasets. Interannual variability of wind and atmospheric
pressure appear to dominate the sea level at both tide gauges during the study period. Atmospheric and steric contributions
together account for ∼50% of the total sea level variance at interannual time scales. Mass induced sea level variations which
were not considered in this study may help to close the sea level trend budgets as well as to better explain the interannual
sea level variance. 相似文献
10.
The joint probability method (JPM) to estimate the probability of extreme sea levels (Pugh and Vassie, Extreme sea-levels from tide and surge probability. Proc. 16th Coastal Engineering Conference, 1978, Hamburg, American Society of Civil Engineers, New York, pp 911–930, 1979) has been applied to the hourly records of 13 tide-gauge stations of the tidally dominated Atlantic coast of France (including
Brest, since 1860) and to three stations in the southwest of the UK (including Newlyn, since 1916). The cumulative total length
of the available records (more than 426 years) is variable from 1 to 130 years when individual stations are considered. It
appears that heights estimated with the JPM are almost systematically greater than the extreme heights recorded. Statistical
analysis shows that this could be due: (1) to surge–tide interaction (that may tend to damp surge values that occur at the
time of the highest tide levels), and (2) to the fact that major surges often occur in seasonal periods that may not correspond
to those of extreme astronomical tides. We have determined at each station empirical ad hoc correction coefficients that take
into account the above two factors separately, or together, and estimated return periods for extreme water levels also at
stations where only short records are available. For seven long records, for which estimations with other computing methods
(e.g. generalized extreme value [GEV] distribution and Gumbel) can be attempted, average estimations of extreme values appear
slightly overestimated in relation to the actual maximum records by the uncorrected JPM (+16.7 ± 7.2 cm), and by the Gumbel
method alone (+10.3 ± 6.3 cm), but appear closer to the reality with the GEV distribution (−2.0 ± 5.3 cm) and with the best-fitting
correction to the JPM (+2.9 ± 4.4 cm). Because the GEV analysis can hardly be extended to short records, it is proposed to
apply at each station, especially for short records, the JPM and the site-dependent ad hoc technique of correction that is
able to give the closest estimation to the maximum height actually recorded. Extreme levels with estimated return times of
10, 50 and 100 years, respectively, are finally proposed at all stations. Because astronomical tide and surges have been computed
(or corrected) in relation to the yearly mean sea level, possible changes in the relative sea level of the past, or foreseeable
in the future, can be considered separately and easily added to (or deduced from) the extremes obtained. Changes in climate,
on the other hand, may modify surge and tide distribution and hence return times of extreme sea levels, and should be considered
separately.
Parts of this paper have been presented orally at the session “Geophysical extremes: scaling aspects and modern statistical
approaches” of the EGU General Assembly, Vienna, 2–6 April 2006. 相似文献
11.
We report on an experimental study conducted to investigate the influence of small-scale wind waves on the airflow structure
in the immediate vicinity of the air–water interface. PIV technique was used to measure the two-dimensional velocity fields
at wind speeds of 3.7 and 4.4 m s−1 and at a fetch of 2.1 m. The flow structure was analyzed as a function of wave phase. In the near-surface region, significant
variations were observed in the flow structure over the waveform. The phase-averaged profiles of velocity, vorticity, and
Reynolds stress showed different behavior on the windward and leeward sides of the wave in the near-surface region. The influence
of wave-induced velocity was restricted within a distance of three significant wave heights from the surface, which also showed
opposite trends on the windward and leeward sides of the crest. The results also show that the turbulent Reynolds stress mainly
supports downward momentum transfer whereas the wave-induced Reynolds stress is responsible for the upward momentum transfer
from wave to wind. In the immediate vicinity of the air–water interface, the momentum is transferred from waves to wind along
the windward side, whereas, the momentum transfer is from wind to waves along the leeward side. 相似文献
12.
An early detection of the presence of rupture directivity plays a major role in the correct estimation of ground motions and
risks associated to the earthquake occurrence. We present here a simple method for a fast detection of rupture directivity,
which may be additionally used to discriminate fault and auxiliary planes and have first estimations of important kinematic
source parameters, such as rupture length and rupture time. Our method is based on the inversion of amplitude spectra from
P-wave seismograms to derive the apparent duration at each station and on the successive modelling of its azimuthal behaviour.
Synthetic waveforms are built assuming a spatial point source approximation, and the finite apparent duration of the spatial
point source is interpreted in terms of rupture directivity. Since synthetic seismograms for a point source are calculated
very quickly, the presence of directivity may be detected within few seconds, once a focal mechanism has been derived. The
method is here first tested using synthetic datasets, both for linear and planar sources, and then successfully applied to
recent Mw 6.2–6.8 shallow earthquakes in Peloponnese, Greece. The method is suitable for automated application and may be
used to improve kinematic waveform modelling approaches. 相似文献
13.
Shun-Liang Chi 《地震学报(英文版)》1993,6(3):731-737
The analysis results of observations data indicate that this shallow-borehole (21 m – 52 m) strainmeter can record accurate
crustal movements. Its records of earthquake and solid tide can be analysed. To use long period frequency data, null drift
must be considered. To extend its application, the technique of installation and anti-lightning stroke should be improved.
The Chinese version of this paper appeared in the Chinese edition ofActa Seismologica Sinica,15, 224–231, 1993.
This project is supported by the Earth-quake Monitoring Department of the State Seismological Bureau. 相似文献
14.
L. M. Balakina 《Izvestiya Physics of the Solid Earth》2011,47(9):835-846
The paper addresses the interpretation of the location, type, and size of the source for the earth-quake of March 11, 2011.
The source—a subvertical reverse fault trending in the azimuth of ∼25° along the island arc—is located in the middle part
of the Pacific slope of Honshu Island, between 38°–38.5°N and 35.5°N. The length of the source, about 350 km, approximately
corresponds to a magnitude ∼8.7 earthquake. In the north, the source is bounded by a sublatitudinal reverse fault, which generated
an earthquake with magnitude 7.2–7.5 in 1978. On this segment of the Pacific slope of Honshu Island, there are probably another
one or a few other large seismic sources, which are still latent. They are longitudinal reverse faults, which are comparable
in scale with the source of the March, 2011 earthquake. The recurrence period of the maximal earthquakes in such sources is
more than 1000 years. 相似文献
15.
Effiom Antia 《Ocean Dynamics》1996,48(1):97-107
Summary Asymmetry in spring-neap, flood-ebb, and acceleration-deceleration near-bottom tidal current parameters is assessed on the
basis of fair-weather measurements at nineteen locations off Spiekeroog Island, German Bight. The study is aimed at a better
understanding of flow-substrate interactions and, by implication, the development of shoreface-conneeted ridges which occur
in 8–18 m water depth off the East Frisian coast. The ridges are spaced 1–1.5 km apart, have a relief of 3–5 m, widths of
1–2 km, and flank steepnesses of < 1‡. Flood-current peak-velocity asymmetry on each ridge was found to increase from the
trough across the crest towards the seaward flank at both spring and neap tide. Tidal excursion was flood asymmetric at spring
tide, but the asymmetry diminished with offshore distance. Flood and ebb accelerating currents had higher mean velocities
than the decelerating counterparts at spring tide. The mean velocity of decelerating currents tended to be flood-asymmetric
at neap tide. Asymmetry was also noted between flood and ebb current directions, on the one hand, and between spring tide
and neap tide cross-ridge flow angle (0–44‡) of these currents, on the other. The observed asymmetries in tidal flow parameters
are considered critical to ridge growth and maintenance, and most probably result from a combination of overtides as well
as geometric and inertial effects due to the ridge topography.
Tidestromasymmetrien der Zungenrifftopographie vor Spiekeroog
Zusammenfassung Basierend auf Daten von 19 Me\stationen vor Spiekeroog wurden die Asymmetrien bodennaher Tidestromparameter bei Spring-und Nipptide, Ebbe und Flut sowie Tidebeschleunigung/-verz?gerung bei ruhigem Wetter untersucht. Ziel der Studie ist ein besseres Verst?ndnis der Wechselwirkung zwischen Str?mung und Boden und somit der Entwicklung der Zungenriffe vor der ostfriesischen Küste in 8 bis 18 m Tiefe. Die 1–1,5 km auseinanderliegenden Riffe sind 3–5 m hoch, 1–2 km breit und haben eine Neigung von < 1‡. Bei maximalem Flutstrom nahm die Asymmetrie auf den Zungenriffen von der Mulde über den Scheitel zum seew?rtigen Riffhang hin zu, und zwar bei Spring-und bei Nipptide. Die Gezeitenauslenkung war bei Springtide asymmetrisch, jedoch nahm die Asymmetrie mit zunehmender Entfernung von der Küste ab. Die Flut-und Ebbstr?me hatten bei Springtide h?here mittlere Geschwindigkeiten als die Str?me bei Nipptide. Die mittlere Geschwindigkeit der Str?me bei Nipptide war eher flutasymmetrisch. Asymmetrie wurde auch zwischen den Richtungen bei Flut-und Ebbstrom einerseits und dem Str?mungswinkel (0–44‡) über die Riffzunge bei Nipp-und Springtide andererseits beobachtet. Die Asymmetrien der Tidestrompara-meter sind offenbar für Wachstum und Erhalt der Riffzungen von Bedeutung. Sie sind wahrscheinlich auf Obertiden sowie geometrie-und inertialbedingte Effekte der Riffzungentopographie zurückzuführen.相似文献
16.
A. G. Camacho J. Fernández M. Charco K. F. Tiampo G. Jentzsch 《Pure and Applied Geophysics》2007,164(4):733-749
Significant gravity changes observed around the Mayon Volcano (Philippines) between 1992 and 1994 at 26 stations are interpreted
in terms of an increase of mass and pressure changes at several point sources modelled using a fast inversion process. This
inversion approach attempts to fit gravity and elevation changes by combining a random search for the positions of the sources
and a linear least-squares fit for the incremental mass, pressure and possible common regional values for gravity or elevation
changes. Some stabilizer terms are included in the misfit function. Models with one and two sources were tested against the
observed changes at Mayon. Models with only one-source give a best fit for a shallow source with a positive mass increment,
horizontally displaced far from the summit. The study using two sources gives a best fit that is similar to the one-source
model, but in addition indicates anomalous behavior at stations in the SW. Neglecting the stations located southward from
a local fracture, the best-fitting model suggests one central positive mass change source, which is likely to be an intrusion
of about 0.5 MU with a depth of about 5 km beneath the volcano. Standard deviation for the residuals ranges from 7–8 μGal
for one-source models to 6–7 μGal for models with two sources. Both of the cases are below the error value of 9.4 μGal estimated
for the gravity data, so that it is not possible to discriminate between both possible interpretations without additional
information. 相似文献
17.
The tidal dynamics in a pristine, mesotidal (>2 m range), marsh-dominated estuary are examined using moored and moving vessel field observations. Analysis focuses on the structure of the M
2 tide that accounts for approximately 80% of the observed tidal energy, and indicates a transition in character from a near standing wave on the continental shelf to a more progressive wave within the estuary. A slight maximum in water level (WL) occurs in the estuary 10–20 km from the mouth. M
2 WL amplitude decreases at 0.015 m/km landward of this point, implying head of tide approximately 75 km from the mouth. In contrast, tidal currents in the main channel 25 km inland are twice those at the estuary mouth. Analysis suggests the tidal character is consistent with a strongly convergent estuarine geometry controlling the tidal response in the estuary. First harmonic (M
4) current amplitude follows the M
2 WL distribution, peaking at mid-estuary, whereas M
4 WL is greatest farther inland. The major axis current amplitude is strongly influenced by local bathymetry and topography. On most bends a momentum core shifts from the inside to outside of the bend moving seaward, similar to that seen in unidirectional river flow but with point bars shifted seaward of the bends. Dissipation rate estimates, based on changes in energy flux, are 0.18–1.65 W m−2 or 40–175 μW kg–1. A strong (0.1 m/s), depth-averaged residual flow is produced at the bends, which resembles flow around headlands, forming counter-rotating eddies that meet at the apex of the bends. A large sub-basin in the estuary exhibits remarkably different tidal characteristics and may be resonant at a harmonic of the M
2 tide. 相似文献
18.
19.
The source parameters of the M
W
= 7.6 Olyutorskii earthquake were estimated using the moments of the slip rate function with degrees 1 and 2. The moments
were estimated from broadband P-wave records at 52 stations of the worldwide network. The first step was to find a function S(t) for each station; this function is an apparent source time function, i.e., the P-wave slip as radiated by the source toward a station under consideration. The method of empirical Green’s functions was used
to estimate S(t). The next step was to calculate the moments of S(t) of degrees 1 and 2 over time and to set up relevant equations to be solved by least squares for the unknown source moments.
The horizontal linear source was used as a nonparametric model for calculating the source moments. Haskell’s parametric model
was used for further interpretation of the source moments. The resulting estimates are as follows: the source centroid was
13–25 km southwest of the epicenter, the source was 105–120 km long, the source strike was 222°–228°, the rupture velocity
was 2.7–3.0 km/s, and the total radiation duration was 24–27 s. These estimates indicate a bilateral rupture dominated by
a southwestward sense of rupture propagation. The source characteristics are consistent with the aftershock area geometry
and with the focal mechanism, as well as with surface breakage as observed by geologists in the field. 相似文献
20.
Dynamic characteristics of monthly rainfall in the Korean Peninsula under climate change 总被引：3，自引：1，他引：2
Min Soo Kyoung Hung Soo Kim Bellie Sivakumar Vijay P. Singh Kyung Soo Ahn 《Stochastic Environmental Research and Risk Assessment (SERRA)》2011,25(4):613-625
Global climate change is one of the most serious issues we are facing today. While its exact impacts on our water resources
are hard to predict, there is a general consensus among scientists that it will result in more frequent and more severe hydrologic
extremes (e.g. floods, droughts). Since rainfall is the primary input for hydrologic and water resource studies, assessment
of the effects of climate change on rainfall is essential for devising proper short-term emergency measures as well as long-term
management strategies. This is particularly the case for a region like the Korean Peninsula, which is susceptible to both
floods (because of its mountainous terrain and frequent intense rainfalls during the short rainy season) and droughts (because
of its smaller area, long non-rainy season, and lack of storage facilities). In view of this, an attempt is made in the present
study to investigate the potential impacts of climate change on rainfall in the Korean Peninsula. More specifically, the dynamics
of ‘present rainfall’ and ‘future rainfall’ at the Seoul meteorological station in the Han River basin are examined and compared;
monthly scale is considered in both cases. As for ‘present rainfall,’ two different data sets are used: (1) observed rainfall
for the period 1971–1999; and (2) rainfall for the period 1951–1999 obtained through downscaling of coarse-scale climate outputs
produced by the Bjerknes Center for Climate Research-Bergen Climate Model Version 2 (BCCR-BCM2.0) climate model with the Intergovernmental
Panel on Climate Change Special Report on Emission Scenarios (IPCC SRES) 20th Century Climate in Coupled Models (20C3M) scenario.
The ‘future rainfall’ (2000–2099) is obtained through downscaling of climate outputs projected by the BCCR-BCM2.0 with the
A2 emission scenario. For downscaling of coarse-scale climate outputs to basin-scale rainfall, a K-nearest neighbor (K-NN) technique is used. Examination of the nature of rainfall dynamics is made through application of four methods: autocorrelation
function, phase space reconstruction, correlation dimension, and close returns plot. The results are somewhat mixed, depending
upon the method, as to whether the rainfall dynamics are chaotic or stochastic; however, the dynamics of the future rainfall
seem more on the chaotic side than on the stochastic side, and more so when compared to that of the present rainfall. 相似文献