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NASA NTRS2019

Editorial: North Pacific Environment and Paleoclimate from the Late Pleistocene to Present

The vast area of the North Pacific, spanning ~55° longitude, represents a challenge for documenting and understanding the geologic history of ocean, atmosphere, and terrestrial environmental change. This special issue highlights site-specific analyses to address various questions and provides clues that arise in response to continued North Pacific warming today in a rapidly changing climate (Figure 1). The emergence of new methods and novel application of existing methods serve to enhance our fundamental understanding of natural modes of climate variability driven by ocean and atmospheric circulation patterns, including the role of external (e.g., insolation) vs. internal forcing [e.g., El Niño Southern Oscillation (ENSO) and the Pacific Decadal Oscillation (PDO)]. Included in this volume are geographically diverse studies that present new and traditional methods for the interpretation of climate records drawn from pollen, macrofossils, tree rings, diatoms, grain size, and glacial studies. Many provide new geographic comparisons, such as Kamchatka and Hawaii, or emerge from novel geologic archives and environments, such as the marine shelf, a thermokarst lake, and a fossil forest.

Jones, Miriam C.↗

NASA NTRS2022

Mid-Pliocene El Niño/Southern Oscillation Suppressed By Pacific Intertropical Convergence Zone Shift

The El Niño/Southern Oscillation (ENSO), the dominant driver of year-to-year climate variability in the equatorial Pacific Ocean, impacts climate pattern across the globe. However, the response of the ENSO system to past and potential future temperature increases is not fully understood. Here we investigate ENSO variability in the warmer climate of the mid-Pliocene (~3.0–3.3 Ma), when surface temperatures were ~2–3 °C above modern values, in a large ensemble of climate models—the Pliocene Model Intercomparison Project. We show that the ensemble consistently suggests a weakening of ENSO variability, with a mean reduction of 25% (±16%). We further show that shifts in the equatorial Pacific mean state cannot fully explain these changes. Instead, ENSO was suppressed by a series of off-equatorial processes triggered by a northward displacement of the Pacific intertropical convergence zone: weakened convective feedback and intensified Southern Hemisphere circulation, which inhibit various processes that initiate ENSO. The connection between the climatological intertropical convergence zone position and ENSO we find in the past is expected to operate in our warming world with important ramifications for ENSO variability.

Atmospheric dynamics↗

NASA NTRSDate not supplied

Impact of Pacific Ocean Heatwaves on Phytoplankton Community Composition

Since 2013, marine heatwaves have become recurrent throughout the equatorial and northeastern Pacific Ocean and are expected to increase in intensity relative to historic norms. Among the ecological ramifications associated with these high temperature anomalies are increased mortality of higher trophic organisms such as marine mammals and seabirds, which are likely triggered by changes in the composition of phytoplankton, the base of the marine trophic food web. Here, we assimilated satellite ocean color data into an ocean biogeochemical model to describe changes in the abundance of phytoplankton functional types (PFTs) during the last decade’s (2010s) warm anomalies in the equatorial and northeastern Pacific Ocean. We find important changes associated with the “Blob” warm anomaly in the Gulf of Alaska, where reduced silica supply led to a switch in community composition from diatoms to dinoflagellates, resulting in an increase in surface ocean chlorophyll during the Summer–Fall of 2014. A more dramatic change was observed in the equatorial Pacific, where the extreme warm conditions of the 2016 El Niño resulted in a major decline of about 40% in surface chlorophyll, which was associated with a nearly total collapse in diatoms.

Lionel A Quintero↗

NASA NTRSDate not supplied

Impact of Pacific Ocean Heatwaves on Phytoplankton Community Composition

Since 2013, marine heatwaves have become recurrent throughout the equatorial and northeastern Pacific Ocean and are expected to increase in intensity relative to historic norms. Among the ecological ramifications associated with these high temperature anoma- lies are increased mortality of higher trophic organisms such as marine mammals and sea- birds, which are likely triggered by changes in the composition of phytoplankton, the base of the marine trophic food web. Here, we assimilated satellite ocean color data into an ocean biogeochemical model to describe changes in the abundance of phytoplankton functional types (PFTs) during the last decade’s (2010s) warm anomalies in the equatorial and northeastern Pacific Ocean. We find important changes associated with the “Blob” warm anomaly in the Gulf of Alaska, where reduced silica supply led to a switch in community composition from diatoms to dinoflagellates, resulting in an increase in surface ocean chlorophyll during the Summer–Fall of 2014. A more dramatic change was observed in the equatorial Pacific, where the extreme warm conditions of the 2016 El Niño resulted in a major decline of about 40% in surface chlorophyll, which was associated with a nearly total collapse in diatoms.

Lionel A. Arteaga↗

NASA NTRS2012

Simulation of the Intraseasonal Variability over the Eastern Pacific ITCZ in Climate Models

During boreal summer, convective activity over the eastern Pacific (EPAC) inter-tropical convergence zone (ITCZ) exhibits vigorous intraseasonal variability (ISV). Previous observational studies identified two dominant ISV modes over the EPAC, i.e., a 40-day mode and a quasi-biweekly mode (QBM). The 40-day ISV mode is generally considered a local expression of the Madden-Julian Oscillation. However, in addition to the eastward propagation, northward propagation of the 40-day mode is also evident. The QBM mode bears a smaller spatial scale than the 40-day mode, and is largely characterized by northward propagation. While the ISV over the EPAC exerts significant influences on regional climate/weather systems, investigation of contemporary model capabilities in representing these ISV modes over the EPAC is limited. In this study, the model fidelity in representing these two dominant ISV modes over the EPAC is assessed by analyzing six atmospheric and three coupled general circulation models (GCMs), including one super-parameterized GCM (SPCAM) and one recently developed high-resolution GCM (GFDL HIRAM) with horizontal resolution of about 50 km. While it remains challenging for GCMs to faithfully represent these two ISV modes including their amplitude, evolution patterns, and periodicities, encouraging simulations are also noted. In general, SPCAM and HIRAM exhibit relatively superior skill in representing the two ISV modes over the EPAC. While the advantage of SPCAM is achieved through explicit representation of the cumulus process by the embedded 2-D cloud resolving models, the improved representation in HIRAM could be ascribed to the employment of a strongly entraining plume cumulus scheme, which inhibits the deep convection, and thus effectively enhances the stratiform rainfall. The sensitivity tests based on HIRAM also suggest that fine horizontal resolution could also be conducive to realistically capture the ISV over the EPAC, particularly for the QBM mode. Further analysis illustrates that the observed 40-day ISV mode over the EPAC is closely linked to the eastward propagating ISV signals from the Indian Ocean/Western Pacific, which is in agreement with the general impression that the 40-day ISV mode over the EPAC could be a local expression of the global Madden-Julian Oscillation (MJO). In contrast, the convective signals associated with the 40-day mode over the EPAC in most of the GCM simulations tend to originate between 150degE and 150degW, suggesting the 40-day ISV mode over the EPAC might be sustained without the forcing by the eastward propagating MJO. Further investigation is warranted towards improved understanding of the origin of the ISV over the EPAC.

Intraseasonal Variability↗

NASA NTRSDate not supplied

Large Eddy Simulations of Upper-Ocean Turbulence Across the Equatorial Pacific Cold Tongue

Turbulence in the equatorial Pacific cold tongue plays multiple roles in the sea-surface temperature budget. However, observations of turbulence are limited to a handful of field experiments lasting from a few days to one month at 0 N , 140 W, and the key turbulent fluxes can only be inferred. Although explicit simulations of turbulence resolve these fluxes, the required large eddy simulations (LES) are costly and thus also limited to a few weeks. A two-fold hypothesis motivates this contribution to the PUMP pre-field modelling experiments in support of TPOS: 1) that there exist useful relationships between the surface wind, wave, and buoyancy forcing, oceanic shear and stratification, and turbulent mixing, but 2) these relationships differ between regions of equatorial dynamics (f~0) and higher latitudes, such that the state space is insufficiently sampled to understand these relationships and represent them in ocean general circulation models (OGCM). To address the lack of observations, we simulated 35 continuous days of upper ocean turbulence using LES during October-November 1985 at sites in two regions (70 days in total) of the cold tongue: 0 N, 140 W and 3 N, 140 W. The model reproduces many features of the observed turbulence at 0,140W, including the “deep-cycle” observed by Gregg et al. (1985) Nature and the turbulent pulses every few hours during the night and in the early morning. Furthermore, the results at 3 N support the hypothesis advanced by Cherian et al. (2021) JPO that strong, but intermittent deep-cycle turbulence is observed to the north of the equator in the presence of strong shear associated with Tropical Instability Waves. Comparisons with the K-profile parameterization (KPP) scheme show that additional tuning of the KPP parameters can reduce differences between the turbulent fluxes produced by KPP and LES at both sites. The results will suggest modifications to OGCMs and already emphasize the need for a more extensive measurements of vertical profiles of shear, stratification and turbulent mixing to reveal the spatio-temporal structure of turbulence and how it relates to forcing, shear and stratification across the equatorial Pacific Cold tongue.

Large Eddy Simulations↗

NASA NTRS1976

Formation of ferrobasalt at east Pacific midocean spreading centers

A numerical modeling using a least squares petrologic mixing program demonstrates that ridge ferrobasalts from three east Pacific regions are generated from normal midocean ridge balsalt by crystal fractionation of plagioclase, clinopyroxene, and minor olivine at shallow mantle depths. Clinopyroxene is an important fractionating phase in this model in contrast to most previously proposed fractionation models. Calculations demonstrate that the ferrobasalts represent a much smaller percentage of residual liquid than has previously been proposed. Implications of extensive shallow crystal fractionation for the determination of depths of magma generation are discussed. The different fields on an anorthite-olivine-hypersthene ternary diagram for basalts from east Pacific fast and moderate spreading ridges can be explained by variable degrees of shallow crystal fractionation rather than by different depths of magma generation as suggested by Bass (1971) and Scheidegger (1973).

Clague, D. A.↗

NASA NTRS1979

Application of Nimbus-6 microwave data to problems in precipitation prediction for the Pacific west coast

The preliminary results of a research study that emphasizes the analysis and interpretation of data related to total precipitable water and nonprecipitating cloud liquid water obtained from NIMBUS-6 SCAMS are reported. Sixteen cyclonic storm situations in the northeastern Pacific Ocean that resulted in significant rainfall along the west coast of the United States during the winter season October 1975 through February 1976 are analyzed in terms of their distributions and amounts of total water vapor and liquid water, as obtained from SCAMS data. The water-substance analyses for each storm case are related to the distribution and amount of coastal precipitation observed during the subsequent time period when the storm system crosses the coastline. Concomitant precipitation predictions from the LFM are also incorporated. Techniques by which satellite microwave data over the ocean can be used to improve precipitation prediction for the Pacific West Coast are emphasized.

Viezee, W.↗

NASA NTRS1979

Estimation of mean sea surfaces in the north Atlantic, the Pacific and the Indian Ocean using GEOS-3 altimeter data

The mean surfaces of several regions of the world's oceans were estimated using GEOS-3 altimeter data. The northwest Atlantic, the northeast Pacific off the coast of California, the Indian Ocean, the southwest Pacific, and the Phillipine Sea are included. These surfaces have been oriented with respect to a common earth center-of-mass system by constraining the separate solutions to conform to precisely determined laser reference control orbits. The same reference orbits were used for all regions assuring continuity of the separate solutions. Radial accuracies of the control orbits were in the order of one meter. The altimeter measured sea surface height crossover differences were minimized by the adjustment of tilt and bias parameters for each pass with the exception of laser reference control passes. The tilt and bias adjustments removed long wavelength errors which were primarily due to orbit error. Ocean tides were evaluated. The resolution of the estimated sea surfaces varied from 0.25 degrees off the east coast of the United States to about 2 degrees in part of the Indian Ocean near Australia. The rms crossover discrepancy after adjustment varied from 30 cm to 70 cm depending upon geographic location. Comparisons of the altimeter derived mean sea surface in the North Atlantic with the 5 feet x 5 feet GEM-8 detailed gravimetric geoid indicated a relative consistency of better than a meter.

Marsh, J. G.↗

NASA NTRS1977

Economic Analysis in the Pacific Northwest Land Resources Project: Theoretical Considerations and Preliminary Results

The Pacific Northwest Land Resources Inventory Demonstration Project i s an a ttempt to combine a whole spectrum of heterogeneous geographic, institutional and applications elements in a synergistic approach to the evaluation of remote sensing techniques. This diversity is the prime motivating factor behind a theoretical investigation of alternative economic analysis procedures. For a multitude of reasons--simplicity, ease of understanding, financial constraints and credibility, among others--cost-effectiveness emerges as the most practical tool for conducting such evaluation determinatIons in the Pacific Northwest. Preliminary findings in two water resource application areas suggest, in conformity with most published studies, that Lands at-aided data collection methods enjoy substantial cost advantages over alternative techniques. The pntential for sensitivity analysis based on cost/accuracy tradeoffs is considered on a theoretical plane in the absence of current accuracy figures concerning the Landsat-aided approach.

Morse, D. R. A.↗

NASA NTRS1980

A quantitative analysis of inter-island telephony traffic in the Pacific Basin Region (PBR)

As part of NASA's continuing assessment of future communication satellite requirements, a study was conducted to quantitatively scope current and future telecommunication traffic demand in the South Pacific Archipelagos. This demand was then converted to equivalent satellite transponder capacities. Only inter-island telephony traffic for the Pacific Basin Region was included. The results show that if all this traffic were carried by a satellite system, one-third of a satellite transponder would be needed to satisfy the base-year (1976-1977) requirement and about two-thirds of a satellite transponder would be needed to satisfy the forecasted 1985 requirement.

Evans, D. D.↗

NASA NTRS1984

Geoid anomalies and fracture zones in the Pacific Ocean

The high degree and order geoid field in the Pacific is a superposition of fracture zone anomalies and hot-spot swell anomalies. A two-dimensional spectral analysis of this field reveals a very strong north-south wavenumber contribution with a dominant wavelength of about 2000 km, a much smaller contribution from east-west wavenumbers, and negligible contributions from other directions. One dimensional profiles were taken in order to appreciate the magnitudes of the north-south and east-west components. A calculated geoid anomaly using an idealized fracture zone model contains just about the same amount of power in the 2350 km band wavelength as does the north-south profile of the SEASAT geoid field. In an attempt to correlate plate age with geoid anomalies, a digitized age map of the Pacific was used to generate a synthetic geoid, which was subtracted from SEASAT. This procedure produces a residual geoid in which the fracture zone anomalies appear to be diminished, if not removed.

Source record↗

NASA NTRS1981

Pacific Basin Communications Study, Volume 1

The Pacific Basin Communications Study describes and assesses extent telecommunications systems in the Pacific Islands region. The study examines user needs in terms of the development of social services and commercial activities. Alternative technological solutions to communications problems are proposed and described. Recommendations include the augmentation and improvement of existing systems allowing for increased communications capacity. Regional cooperation will be required to accommodate the specific, unique requirements of individual nations. Questions of financing, implementation, management, costs and benefits of a regional telecommunications system are discussed.

Young, E. L.↗

NASA NTRS1984

The variability of the surface wind field in the equatorial Pacific Ocean: Criteria for satellite measurements

The natural variability of the equatorial Pacific surface wind field is described from long period surface wind measurements made at three sites along the equator (95 deg W, 109 deg 30 W, 152 deg 30 W). The data were obtained from surface buoys moored in the deep ocean far from islands or land, and provide criteria to adequately sample the tropical Pacific winds from satellites.

Halpern, D.↗

NASA NTRS1984

Determination of rainfall and condensational heating in the South Pacific convergence zone during FGGE SOP-1

The role of cloud related diabatic processes in maintaining the structure of the South Pacific Convergence Zone is discussed. The method chosen to evaluate the condensational heating is a diagnostic cumulus mass flux technique which uses GOES digital IR data to characterize the cloud population. This method requires as input an estimate of time/area mean rainfall rate over the area in question. Since direct observation of rainfall in the South Pacific is not feasible, a technique using GOES IR data is being developed to estimate rainfall amounts for a 2.5 degree grid at 12h intervals.

Robertson, F. R.↗

NASA NTRS1984

Intermediate-wavelength magnetic anomalies over the central Pacific

A technique to extract the intermediate wavelength anomaly field from random ship tracks has been developed and is applied to extract the field from marine survey data of the central Pacific in the band pass of 4000-400 km. The technique minimizes the effects of external field sources, secular variation, and strike aliasing. The derived data field is compared to the equivalent MAGSAT data set, and it is shown that anomalies observed in both fields are correlatable to geologic features within the oceanic lithosphere but differ in amplitude by a factor of two. Likely sources for this discrepancy are identified. It is also shown that remanent magnetization of the central Pacific seamounts produces negative magnetic anomalies which are observed at satellite altitude.

Labrecque, J. L.↗

NASA NTRS1985

Cyclone development in the South Pacific convergence zone during FGGE, 10-17 January 1979

An analysis is presented of the life cycles of three different South Pacific cyclones. Emphasis is given to two of the cyclones which propagate south-eastward along the western edge of the South Pacific convergence zone (SPCZ) and reach middle latitudes before decaying. The analysis is based on imagery from the GOES-West Satellite and on data from the European Center for Medium Range Weather Forecasts (EMWF). A comparison between estimates of the mean sea level pressure in the vicinity of the cyclones taken at observation stations and from ECMWF predictions shows good agreement when the cyclone disturbances are above grid-scale. The propagation characteristics of the cyclones are discussed in detail.

Vincent, D. G.↗

NASA NTRS1984

NASA/NOAA/USAID implementation of the South Pacific severe storm detection and warning system project

Implementation by NASA of the South Pacific severe storm detection and warning system project for the Fiji Meteorological Service (FMS) in Nadi, Fiji, is discussed. A description of the need and use of the system by the FMS, of data reception, of interactive computer techniques, of training, and of the benefits to be derived from implementation of the system is given. The project allows precise tracking of all South Pacific tropical cyclones with frequent high-resolution reception of both the Japanese GMS and the U.S. GOES-West visible and IR cloud images.

Dodge, J.↗