eruption mechanism as inferred from geomagnetic changes with special attention to the 1989 1990 activity of aso volcano abstract geomagnetic changes associated with the volcanic activity of aso volcano were detected with a dense network of continuously recording proton precession magnetometers during the period from june 1989 to june 1990 magnetic date clearly indicate that changes in the magnetization within the volcano are most probably caused by temperature changes this activity can be divided into five stages which are characterized by magnetization and demagnetization of the volcano these magnetic changes with durations of a few months are definitely correlated with some typical volcanic events at the crater as well as the volcanic tremor activity the demagnetization stage appears when the vent is covered by a water pool or the volcanic activity is enhanced the magnetization stage follows the opening of a vent and several large explosions which make the vent permeable the source of magnetic changes lies at a depth of about 200 m below the crater rim in the southwestern part of the active crater magnetic moments responsible for observed magnetic changes at stages 1 2 and 4 are 3 4 5 2 and 2 2 wbm respectively the corresponding source volume is estimated as a single sphere of radius 40 50 m or a spherical shell of 100 m or so an effective mechanism of rapid heating cooling exists which is ascribed to the interaction of groundwater and superheated vapor i e a shallow hydrothermal system this hydrothermal system driven by the surface cap of the vent controls every feature of the eruptions at the final outlet of aso volcano

the 1982 83 warm episode in the california current the warm episode el nino of 1982 83 has produced elevated steric height geopotential anomaly along the coast of california and baja california fifty percent of the stations observed during a survey in february and march had the greatest steric height observed for this season for the entire 33 years of california cooperative oceanic fisheries investigations calcofi observations where it occurred onshore along central california in early february this anomalous height was balanced by a strong countercurrent along baja california in late march the greatest steric height was offshore and hence produced a strong equatorward flow these conditions may not have been synoptic an offshore shift in the subsurface thermal anomaly between january and may suggests a reversal of the flow within this time frame

possible electrokinetic origin of large magnetic variations at la fournaise volcano abnormal time variations of the geomagnetic field related to volcanic activity have been reported for several decades1 10 two main candidates have been considered for the source mechanism of these volcanomagnetic variations piezomagnetism and electro kinetic effects we considered both of these mechanisms in our attempts to interpret the most spectacular volcanomagnetic variations observed on piton de la fournaise volcano reunion island 11 but now new analysis of the latest data which covers a time span of more than three years leads us to think that water circulation is the main agent of the strong magnetic signals observed on the volcano in addition to the signals that we correlated with the volcano activity11 12 longer period components also exist as shown here with amplitudes and characteristics that have not been reported before we propose that these magnetic variations are generated by electrokinetic effects in which case the water circulation system into this massif would be a sensor for detecting stress changes linked to the volcano activity

satellite observations of the 1982 1983 el nino along the u s pacific coast satellite infrared temperature images illustrate several effects of the 1982 1983 el nino warm sea surface temperatures with the greatest anomalies near the coast weakened coastal upwelling and changes in surface circulation patterns phytoplankton pigment images from the coastal zone color scanner indicate reduced productivity during el nino apparently related to the weakened coastal upwelling the satellite images provide direct evidence of mesoscale changes associated with the oceanwide el nino event

volcanomagnetic effects observed on piton de la fournaise volcano reunion island 1985 1987 a permanent network of four to six telemetered magnetic stations has been installed on piton de la fournaise volcano in october 1985 and 1986 eight eruptive sequences have occurred since then some of which affected only the summit whereas others affected the whole massif volcanomagnetic variations are observed with each of these volcanic events the geomagnetic field intensity is measured simultaneously every minute at each station with a precision of 0 25 nt nanotesla the main results are the following volcanomagnetic variations observed with eruptions have amplitudes of several nanoteslas to more than 10 nt with characteristic time durations ranging from l min or less to several months a good correlation between the magnetic variations recorded at the different stations is observed spatial and temporal properties of the volcanomagnetic field appear to be controlled by the features of the eruptions several days before the beginning of the december 1985 march july november december 1986 and january 1987 eruptions changes in the intensity differences are observed with amplitudes of a few nanoteslas up to 5 nt at stations located close to the active part of the rift zone variations are also observed in the most remote stations for larger eruptions in march 1986 november december 1986 and january 1987 correlations between magnetic variations ground deformations and seismic activity have been observed for the december 1985 march 1986 november december 1986 and january 1987 events three main mechanisms could account for the observed volcanomagnetic variations piezomagnetic effects electrokinetic effects and electrical resistivity changes since variations in the stress field in the surroundings can modify the induced and natural magnetizations of magnetized rocks the circulation of water through the interconnected pore network microcracks faults aquifers and also the electrical resistivity of geological structures through the modification of the properties of the pore network

satellite data empirical orthogonal functions and the 1997 1998 el nino off california abstract the features of the 1997 1998 el nino event were analyzed by empirical orthogonal functions eof statistical methods applied to the remotely sensed sea surface temperature anomalies ssta measured by avhrr radiometers anomalies of water circulation derived from sea surface height anomalies ssha measured by topex poseidon radar altimeter and meteorological information air temperature upwelling index and wind stress curl eof statistics demonstrated the features of an el nino event during the second half of 1997 and the first half of 1998 with sea level elevated along the coast and with ssha gradients indicating a retarding of both the equatorward california current and the alongshore poleward southern california countercurrent the positive sst anomaly developed first in the southern california bight and then in the zone of upwelling to the north of point conception the anomalies of upwelling index and the wind stress curl pattern also changed during the el nino event but these changes occurred later than hydrographic variations and were too weak to explain the observed changes in ssta and ssha we conclude that off central and southern california oceanic teleconnection i e the consequences of propagation northward of coastally trapped downwelling waves was responsible for the 1997 1998 el nino event

el nino induced onshore transport in the california current during 1982 1983 persistent 9 month large scale positive temperature 3 4 c negative salinity 0 1 0 3 and positive dissolved oxygen 0 5 1 ml l subsurface anomalies characterize the el nino induced onshore transport in the california current during 1982 83 these anomalies characteristic diagrams and sign reversals in the salinity and oxygen anomalies are consistent only with enhanced onshore transport of subarctic water from the offshore california current onshore transport excludes poleward propagating kelvin waves as a generation mechanism for the 1982 83 californian el nino the data however support the conclusion simpson 1983 that an anomalous basinwide atmospheric circulation produced the californian el nino

evolution of oceanographic conditions off baja california 1997 1999 abstract this paper examines the oceanic response off baja california mexico to the 1997 1998 el nino and the transition to la nina conditions the data presented were gathered during seven cruises over a grid based on the calcofi station plan from lines 100 130 out to station 80 t s diagrams with data obtained during the peak phase of el nino demonstrate that warmer and saltier spicier than normal conditions prevailed in the upper 600 m over this region temperature and salinity anomalies calculated for calcofi line 120 revealed waters near the coast at 50 m depth to be up to 8 7 c warmer and s 0 8 saltier than the climatology during october 1997 these large anomalies persisted through january 1998 with some slight diminution in the magnitudes near the surface this study suggests that anomalously warm and salty waters were fed from a source of spicy water to the southwest identified as subtropical surface water stsw and that low salinity tropical surface waters tsw were blocked to the southeast in the vicinity of the tip of the peninsula subsurface waters associated with the california undercurrent cu fed from the eastern tropical pacific etp were also warmer and saltier than normal and indicate a significant expansion in volume of the cu presumably a result of intensification of poleward flow at depth we postulate that the well defined near surface and deep poleward flows in the study area reflect anomalous large scale cyclonic circulation affecting the flow in the southeastern region of the north pacific subtropical gyre east of 125 w following the el nino event warm and salty upper waters retreated to latitudes south of punta eugenia with the return to normal and cooler conditions equatorward flow over the sampling grid predominated with an increased meandering and mesoscale activity transition to la nina conditions would have been associated with re establishment of normal anticyclonic flow in the southeastern quadrant of the pacific subtropical gyre

a search for the volcano magnetic effect at ruapehu and ngauruhoe new zealand abstract a differential magnetometer network has been operating in the tongariro national park north island new zealand near the active volcanoes ruapehu and ngauruhoe from 1973 to the present day to monitor local magnetic field changes that might be associated with volcanic activity although several large eruptions of ruapehu and ngauruhoe have occurred while the network has been operating no magnetic field changes related to volcanic activity have been detected above the background noise

magnetic measurements on la soufriere volcano guadeloupe lesser antilles 1976 1984 a re examination of the volcanomagnetic effects observed during the volcanic crisis of 1976 1977 abstract during the seismovolcanic crisis of 1976 1977 at la soufriere on guadeloupe a magnetic network of 12 reference markers was set up measurements of the intensity of the earth s magnetic field carried out up to once a day at each marker showed volcano magnetic variations of several nanoteslas nt the variations at certain markers were more or less concealed by transient magnetic variations due to anomalies in conductivity as early as 1978 measurements were resumed and a telemetering network was coupled with the network of reference markers to which 4 new markers were added a detailed study of conductivity anomalies was carried out on the entire volcano contrasts in conductivity linked to the existence of a superficial conducting surface on a ssw nne axis located south of the volcano caused a great lack of homogeneity in the field variations measured at the surface variations greater than about 10 nt appeared in the difference in intensity of the earth s magnetic field between two stations no long term magnetic variation was observed between 1978 and 1984 on the network of markers the accuracy of measurements of volcanic effects was at best 2 nt measurements carried out on the telemetering network during the night refined these results since their accuracy was 1 nt the only significant volcanic crisis between 1978 and 1984 5 7 january 1981 seems to be observed by telemetering stations all the measurements carried out in periods of volcanic inactivity make it possible to re examine the crisis of 1976 1977 though volcanomagnetic effects over short periods cannot be accurately determined variations with a time constant of several weeks were present over the entire volcano these variations were as high as 7 8 nt in remote stations and they can be linked to the three major phases of eruptive activity at la soufriere during the crisis of 1976 1977

hydrochemical borehole logs characterizing fluoride contamination in a crystalline aquifer maheshwaram india summary hydrochemical borehole loggings with a submersible idronaut ocean seven 302 multiparameter probe equipped of f and no 3 ion selective electrodes in combination with ec ph and dissolved oxygen were applied for characterizing fluoride f contamination in a crystalline hard rock aquifer of a small indian agricultural watershed where groundwater is intensively abstracted for rice irrigation a high accuracy of f concentrations determined in situ shown by comparing with laboratory analyses was obtained through using conductivity logs for ionic strength consideration large variations in chemical composition and particularly of f concentration were observed inside boreholes though restricted to the weathered fractured layer down to 30 35 m depth this conforms to the hydrogeological model of a crystalline aquifer where most groundwater flow occurs in the shallow part of the fractured zone the general trend of increasing f content with depth results from f accumulation through water rock interaction but the shape of the f profile depends on the connectivity of the fracture network close to the borehole the concentrations seen within the water table fluctuation zone locally suggest f input from fertilizers in groundwater in addition to the earlier demonstrated role of evaporation from irrigation return flow it is also likely that locally the deepening of boreholes has contributed to increasing the population s vulnerability by tapping f enriched groundwater at depth

large scale thermal anomalies in the california current during the 1982 1983 el nino the large scale thermal structure of the california current during 1982 83 shows several anomalous conditions warm sea surface temperature anomalies 1 2 c depression of the thermocline by 50 m or more and pronounced subsurface warming 3 4 c relative to the 30 year mean the subsurface anomaly is much greater than the surface anomaly these persistent 6 months structures coupled with unusually high sea levels along the north american coast show that a major californian el nino occurred during 1982 83 the data support the conclusion that the expansion and intensification of the aleutian low and the decrease in strength of the pacific high produced an anomalous basin wide atmospheric circulation which coupled directly to the large scale oceanic wind driven circulation to produce the californian el nino the enhanced transport from the west offshore california and south baja california which such a circulation would produce is consistent with the observed water properties the equatorial 1982 83 el nino is probably related to the californian el nino through an atmospheric teleconnection between equatorial sea surface temperature and the atmospheric hadley circulations

possible tectonomagnetic effect observed from mid 1989 to mid 1990 in long valley caldera california precise measurements of local magnetic fields have been obtained with a differentially connected array of three proton magnetometers in the long valley caldera region since 1984 two magnetometers are located inside the caldera with a third reference magnetometer located 26km southeast of the caldera after correction for secular variation it is apparent that an anomalous 2 nt decrease in the magnetic field occurred from mid 1989 to mid 1990 at the magnetometer located closest to the center of the resurgent dome inside the caldera during this period a significant increase in geodetic strain rate of 8 5 ppm a was observed on the two color geodimeter network within the caldera from october 1989 to mid 1990 and a dramatic increase in seismic activity occurred from december 1989 to july 1990 a simple dilatational point source model with pressure increasing by 52 mpa from october 1989 to august 1990 at a depth of about 7km beneath the center of the resurgent dome can be fit to the strain data if this same model is used to calculate piezomagnetic fields in the caldera the results obtained agree with the observed local magnetic field data provided the curie point isotherm is at a depth of 5km taken together these magnetic seismic and geodetic data suggest that an episode of active magmatic intrusion occurred from late 1989 to mid 1990 at a depth of about 7 8km beneath the resurgent dome within the long valley caldera other indications of this intrusion should be evident in measurements of leveling local gravity and seismic imaging data

magnetic monitoring at merapi volcano indonesia abstract merapi volcano located 30 km north of the heavily populated city of yogjakarta java is one of the most active of the 129 volcanoes in indonesia about every 2 years a new phase of activity is observed depending on the past activity the unrest gives rise either to an endogenous dome which partly collapses in the southwest direction or to pyroclastic flows which travel as far as 15 km the 1990 1997 period has involved a plume emission on 30 august 1990 an extrusion on 20 january 1992 and a pyroclastic eruption on 22 november 1994 the intensity of the earth magnetic field has been measured simultaneously and digitally recorded at four stations since 1990 two overhauser magnetometers with resolution of 0 01 nt have been installed in the summit area to strengthen the volcano monitoring outstanding magnetic changes appear to correlate with volcanic activity three types of volcanomagnetic signals can be identified long term trends up to 15 nt with period 10 years medium term cyclic variations at most 3 nt in amplitude and with 1 2 years period and small events reaching 1 5 nt lasting a few months and associated with any remarkable volcanic activity merapi volcano began a new cycle of activity in 1995 leading to a dome growth in july 1996 and accompanied by 27 nuees ardentes in august the comparison between magnetic data seismicity and surface phenomena suggests that some long term trends of decade periods could be of thermomagnetic origin while mid term volcanomagnetic variations associated with the cycles of merapi activity could be of piezomagnetic origin short term variations of a few weeks duration less than 1 5 nt are well correlated with the 1995 1996 seismic activity

underwater gliders reveal rapid arrival of el nino effects off california s coast 1 the 2009 2010 el nino marked the first occurrence of this climate phenomenon since the initiation of sustained autonomous glider surveillance in the california current system ccs spray glider observations reveal the subsurface effects of el nino in the ccs with spatial and temporal resolutions that could not have been obtained practically with any other observational method glider observations show that upper ocean waters in the ccs were unusually warm and isopycnals were abnormally deep during the el nino event but indicate no anomalous water masses in the region observed oceanic anomalies in the ccs are nearly in phase with an equatorial el nino index and local anomalies of atmospheric forcing these observations point toward an atmospheric teleconnection as an important mechanism for the 2009 2010 el nino s remote effect on the midlatitude ccs

altimeter derived surface circulation in the large scale ne pacific gyres part 2 1997 1998 el nino anomalies abstract changes in the sea surface heights ssh and geostrophic transports in the ne pacific are examined during the 1997 1998 el nino using altimeter data sea level pressure slp fields proxy winds and satellite sea surface temperature sst most of the signal occurs along the boundaries of the basin from panama to the alaska peninsula changes in the ssh and alongshore transports along the boundaries are caused both by propagation of signals from the south stronger between the equator and the gulf of california and by local and basin scale winds stronger between the pacific northwest and the alaska peninsula two periods of high ssh occur at the equator may july 1997 and october 1997 january 1998 the first coastal ssh signal moved quickly polewards to approximately 24 n in early june then stalled and moved farther north during transient events in july september large scale wind forcing combined with the equatorial signals during the second period of high equatorial ssh fall 1997 to move the high ssh and poleward transports quickly around the alaska gyre a connection between the boundary currents and the interior north pacific developed as part of the large scale response to the basin scale winds after changes in the boundaries decreases in anomalies of ssh and poleward transports began in january 1998 south of 40 n and in february 1998 farther north

nutrient variability during el nino 1997 98 in the california current system off central california abstract nutrient conditions off central california during the 1997 98 el nino are described data were collected on 11 cruises from march 1997 to january 1999 along a hydrographic section off central california as well as every two weeks at a coastal station in monterey bay perturbations associated with el nino are shown as anomalies of thermohaline and nutrient distributions along this section the anomalies were obtained by subtracting seasonal averages for the period from april 1988 to april 1991 from the 1997 98 observations the first indications of el nino conditions high sea levels were observed at monterey between late may and early june 1997 but the coastal nutricline did not begin to deepen until august 1997 it reached maximum depth of 130 dbar in january 1998 at the time that maximum sea level anomalies were observed during this period 1 the highest subsurface temperature anomalies coincided with subsurface nutrient anomaly minima at the depth of the pycnocline 2 southern saline and nutrient poor waters occupied the upper 80 dbar of the water column along the entire section and 3 nitrate levels were close to zero in the euphotic zone collapsing the potential new primary production in the coastal domain at the end of february 1998 the nutricline shoaled to 40 dbar at the coast although it remained anomalously deep offshore higher temperatures and lower nutrient levels were observed for the entire section through august 1998 although in contrast with the previous winter there was a strong freshening mainly due to an onshore movement of subarctic waters

satellite derived sea surface temperature variability off california during the upwelling season abstract an empirical orthogonal function analysis of an advanced very high resolution radiometer sea surface temperature data set encompassing the spring summer period during 1991 1993 was used to examine patterns of temperature variability off northern and central california this analysis decomposed the spatial variability of remotely sensed sea surface temperature in 124 images that covered an offshore distance of 200 km and an alongshore distance of 500 km the first mode empirical orthogonal function described 65 of the spatial variability in the data set the spatial amplitude pattern of the first mode which closely resembled the mean of all the images revealed a strong cross shore gradient with much cooler water nearshore and warmer water offshore these areas of cool waters were associated with known upwelling locales and the large scale temperature structure compared favorably to that derived from historical california cooperative oceanographic fisheries investigation calcofi climatology the mode 1 temporal amplitude function representing the temporal modulation of this spatial pattern was coupled with changes in the alongshore component of the coastal wind field interannual variations in the timing of the spring transition were reflected in this temporal amplitude time series the second mode empirical orthogonal function described 11 of the variability in the data set the spatial pattern revealed a north south structure that appeared to be related to regional spatial variations in the strength of upwelling favorable wind the third empirical orthogonal function described only 3 of the data variability and the spatial structure suggested a meandering of the coastal surface flow the results of this investigation indicate that the empirical orthogonal function method was effective at characterizing from the satellite data the dominant nearshore surface properties of the california current system related to upwelling and wind and by extension suggest that it is a suitable approach for remotely investigating other less well known eastern boundary current systems

radiolarian assemblages from santa barbara basin sediments recent interdecadal variability santa barbara basin contains a sedimentary record ideal for high resolution paleoclimate studies because of the annual varves and regional to global scale climate signals preserved in the sediments lange et al 1990 kennett and ingram 1995 even though it does not lie directly in the path of the california current a nearly 100 year annual time series 1909 1991 of polycystine radiolarian assemblages from santa barbara basin sbb sediments was analyzed to the species level counts on a replicate sbb core dated 1870 1987 indicate that results are reproducible and the flux of a few representative species can be extrapolated to estimate fluxes of environmentally sensitive groups the frequency of species occurrences resembles a lognormal curve and year by year comparisons of species fluxes revealed only modest changes in the assemblages from 1909 1991 indicating that the assemblages represent a single oceanic province for paleoceanographic analysis of the radiolarian record species were combined into groups according to the water mass in which they occur to test this method temperature sensitive species were identified using t tests this generated warm and cool classes exhibiting trends in relative flux similar to those of the water mass groups both total flux and relative fluxes of water mass groups relate to low frequency decadal scale temperature fluctuations but not strongly to el nino southern oscillation events generally fluxes of species from different water masses covary suggesting changing carrying capacities and productivity through time while the consistent inverse relationship in relative fluxes indicate variability in climate the subtle decadal scale changes in assemblages diversity and increase in percent warm water fauna are consistent with a spin down of the california current system suggested by other records

the 1982 1983 el nino signal off northern california the major el nino event of 1982 1983 affected the entire california current system the anomalous conditions along the west coast of north america were related to the equatorial anomalies and also to the anomalous atmospheric circulation in the northeast pacific where the aleutian low was east of its usual position and the associated 700 mbar height reached its lowest value on record in february march 1983 positive temperature and negative salinity anomalies in the upper ocean extending from the coast to at least 200 km offshore were reported from san diego to vancouver island in data acquired in domains centered approximately 180 km off northern california by the ocean prediction through observation modeling and analysis program anomalies in both temperature and salinity were most pronounced subsurface spatially and monthly averaged temperatures were about 3 c warmer than normal at 80 to 100 m in april and again in december 1983 at 100 to 120 m salinity was about 0 4 parts per thousand lower than normal in july 1983 and july 1984 several months later than the temperature anomaly maxima the temperature anomalies may be related to the poleward propagation of the equatorial el nino perturbation by coastally trapped waves with offshore propagation by planetary rossby waves possibly playing some role in the relaxation of the perturbed eastern boundary current circulation anomalous onshore advection associated with the perturbed atmospheric circulation deeper than normal mixed layers or depression of the thermocline and halocline by the passage of rossby waves could each account for coincident positive temperature and negative salinity anomalies

cooling rate and thermal structure determined from progressive magnetization of the dacite dome at mount st helens washington our study of a magnetic anomaly associated with the recently active dacite dome at mount st helens suggests that the dome consists of a hot nonmagnetized core surrounded by a cool magnetized carapace and flanking talus the talus does not contribute to the anomaly because its constituent blocks are randomly oriented temporal changes in the magnetic anomaly indicate that the magnetized carapace thickened at an average rate of 0 03 0 01 m d from 1984 to 1986 petrographic and rock magnetic properties of dome samples indicate that the dominant process responsible for these changes is magnetization of extensively oxidized rock at progressively deeper levels within the dome as the rock cools through its blocking temperature rather than subsequent changes in magnetization caused by further oxidation newly extruded material cools rapidly for a short period as heat is conducted outward in response to convective heat loss from its surface the cooling rate gradually declines for several weeks and thereafter the material cools at a relatively constant rate by convective heat loss from its interior along fractures that propagate inward the rate of internal convective heat loss through fractures varies with rainfall snowmelt and large scale fracturing during subsequent eruptive episodes in accordance with a model for solidification of the 1959 lava lake at kilauea iki hawaii we picture the dome s magnetized carapace as being a two phase porous convective zone separated from the nonmagnetized core of the dome by a thin single phase conductive zone as a consequence of the heat balance between the conductive and convective zones the blocking temperature isotherm migrates inward at a relatively constant rate if the dome remains inactive the time scale for its complete magnetization is estimated to be 18 36 years a forecast which can be refined by shallow drilling into the dome and by continuing studies of its growing magnetic anomaly

el nino in santa barbara basin diatom radiolarian and foraminiferan responses to the 1983 el nino event abstract santa barbara basin box cores collected in august of 1985 were sub sampled and processed in search of microfossil evidence of the 1983 el nino microplankton and microbenthos indicate the presence of that el nino bounded by non el nino conditions specifically the event is recognized by an increase in diatom diversity and the presence of several warm water taxa e g coscinodiscus plicatoides hemidiscus cuneiformis nitzschia kolaczekii pseudoeunotia doliolus thalassiosira lineata thalassiosira nodulolineata an increase in polycystine radiolarian flux and the presence of the eastern tropical pacific species spongaster pentas an increase in the diversity of planktonic foraminifera and the occurrence of the warm water species globoturborotalita rubescens there is also evidence for an oxygenation of the basin during the 1983 el nino as suggested by the increase in the abundance of the benthic foraminifera bolivina vaughani and by the decrease in the preservation of phaeodarian radiolarian spines which are best preserved under anoxic conditions a new onboard procedure for sampling of box cores and freezing of subcores is described

atmospheric forcing of interannual variability in the northeast pacific ocean connections with el nino the nature and causes of the observed interannual variability of oceanic conditions in the northeast pacific were investigated using a variety of meteorological and oceanographic data sets an examination of a long series of seasonal mean atmospheric sea level pressure slp charts showed that when the winter average slp pattern in the north pacific varies significantly from climatology it tends to do this in one of two characteristic ways in particular in some winters there is an anomalously strong circulation which differs from climatology mainly in having an intensified aleutian low in other winters there is an anomalously weak atmospheric circulation this is almost invariably associated with the westward displacement of the aleutian low and the production of a separate but much weaker low in the gulf of alaska the north pacific winter slp appears to have some relation to the southern oscillation so and oceanic temperatures in the tropics in particular el nino southern oscillation enso episodes are generally coincident with strong north pacific slp patterns and often follow winters with weak slp patterns however this relationship is far from being perfectly regular and predictable interannual variations in the intensity of the north pacific atmospheric surface circulation were found to be strongly correlated with the anomalies of both sea surface temperature sst and sea level height slh at stations along the british columbia coast an intense aleutian low is invariably associated with warm coastal waters and high coastal sea levels by comparing a large number of pacific slp and sst maps it was possible to verify that the relation between north pacific slp and oceanic surface temperature actually applies to the sst over much of the northeast pacific at least as far west as 150 w the relationship of north pacific slp with the so together with the relationship between north pacific slp and oceanic conditions in the northeast pacific can account for the observed general tendency for sst and slh along the west coast of north america to be anomalously high during tropical enso episodes on the other hand the lack of a truly predictable relation between the southern oscillation and north pacific slp explains the fact that not all enso events are associated with wanning of the northeast pacific