The role of ocean dynamics in producing decadal climate variability in the North Pacific     

D. W. Pierce  T. P. Barnett  N. Schneider  R. Saravanan  D. Dommenget  M. Latif 《Climate Dynamics》2001,18(1-2):51-70

 Decadal time scale climate variability in the North Pacific has implications for climate both locally and over North America. A crucial question is the degree to which this variability arises from coupled ocean/atmosphere interactions over the North Pacific that involve ocean dynamics, as opposed to either purely thermodynamic effects of the oceanic mixed layer integrating in situ the stochastic atmospheric forcing, or the teleconnected response to tropical variability. The part of the variability that is coming from local coupled ocean/atmosphere interactions involving ocean dynamics is potentially predictable by an ocean/atmosphere general circulation model (O/A GCM), and such predictions could (depending on the achievable lead time) have distinct societal benefits. This question is examined using the results of fully coupled O/A GCMs, as well as targeted numerical experiments with stand-alone ocean and atmosphere models individually. It is found that coupled ocean/atmosphere interactions that involve ocean dynamics are important to determining the strength and frequency of a decadal-time scale peak in the spectra of several oceanic variables in the Kuroshio extension region off Japan. Local stochastic atmospheric heat flux forcing, integrated by the oceanic mixed layer into a red spectrum, provides a noise background from which the signal must be extracted. Although teleconnected ENSO responses influence the North Pacific in the 2–7 years/cycle frequency band, it is shown that some decadal-time scale processes in the North Pacific proceed without ENSO. Likewise, although the effects of stochastic atmospheric forcing on ocean dynamics are discernible, a feedback path from the ocean to the atmosphere is suggested by the results. Received: 23 January 2000 / Accepted: 10 January 2001  相似文献   

Uranium-Series Ages of Travertines and Timing of the Last Glaciation in the Northern Yellowstone Area, Wyoming-Montana     

Neil C. Sturchio  Kenneth L. Pierce  Michael T. Murrell  Michael L. Sorey 《Quaternary Research》1994,41(3)

Uranium-series age determinations by mass spectrometric methods were done for travertines and associated carbonate veins related to clastic deposits of the last glaciation (Pinedale) in the northern Yellowstone area. Dramatic variations in the hydrologic head are inferred from variations in the elevation of travertine deposition with time and are consistent with the expected hydrologic effects of glaciation. We determine the following chronology of the Pinedale Glaciation, with the key assumption that travertine deposits (and associated carbonate veins) perched high above present thermal springs were deposited when glaciers filled the valley below these perched deposits: (1) the early Pinedale outlet glacier advanced well downvalley between 47,000 and 34,000 yr B.P.; (2) the outlet glacier receded to an interstadial position between 34,000 and 30,000 yr B.P.; (3) an extensive Pinedale ice advance occurred between 30,000 and 22,500 yr B.P.; (4) a major recession occurred between 22,500 and 19,500 yr B.P.; (5) a minor readvance (Deckard Flats) culminated after 19,500 yr B.P.; and (6) recession from the Deckard Flats position was completed before 15,500 yr B.P. This chronology is consistent with the general trend of climatic changes in the northern hemisphere as revealed by recent high-resolution ice-core records from the Greenland ice sheet.  相似文献   

Towards the Reconstruction of Agriculture: Paths of Change and Adjustment*     

John T. Pierce 《The Professional geographer》1994,46(2):178-190

This paper provides both retrospective and prospective insights into the processes of agricultural change. It begins with an analysis of structural change in Canadian agriculture and goes on to interpret these changes within the context of a number of contemporary theories and models of agricultural development and restructuring. It is clear from this discussion that there is no unified pattern of change or response to uncertainty. Instead there is a multiplicity of strategies which are formulated on the basis of complex farm-based and external factors. Since agricultural policy has played such a significant role in shaping much of the sector today, it is argued that society has the potential to create new opportunities and development paths which fulfill many of the criteria for sustainable food and rural systems.  相似文献   

Assessing the adequacy of North American agricultural land resources     

John T. Pierce  Owen J. Furuseth 《Geoforum》1983,14(4):413-425

This paper provides a prospective analysis of supply/demand conditions for agricultural land in Canada and the U.S.A. according to various growth scenarios and an assessment of the economic and environmental costs associated with expanding and intensifying the cropland base. Future cropland expansion is estimated on the basis of the interrelationship between growth in demand and the productivity of cereal output. The adequacy of the land resource base is assessed by comparing individual projections with expected reserves of cropland adjusted for non-agricultural demands for land. Within the context of these findings the paper proceeds with a general discussion of the man-made, resource and environmental constraints to expanding production and the resulting economic and environmental costs to society.  相似文献   

Chemical contaminant exposure and effects in four fish species from Tampa Bay,Florida     

Bruce B. McCain  Donald W. Brown  Tom Hom  Mark S. Myers  Susan M. Pierce  Tracy K. Collier  John E. Stein  Sin-Lam Chan  Usha Varanasi 《Estuaries and Coasts》1996,19(1):86-104

Concentrations of selected anthropogenic chemical contaminants and levels of pollution-related biological effects were measured during three consecutive years (1990–1992) in hardhead catfish (Arius felis), Gulf killifish (Fundulus grandis), longnose killifish (F. majalis), and red drum (Scieaenops ocellatus) from 12 subtidal and intertidal sites in Tampa Bay and nearby Sarasota Bay. Each species was collected from at least four sites. Compared to nonindustrialized sites, concentrations of PCBs, DDTs, and alpha-chlordane in liver, and of fluorescent aromatic compounds in bile, were highest in fish from sites in or near Hillsborough Bay, the most industrialized portion of Tampa Bay. The results of analyses for two biochemical markers of contaminant-induced effects in fish, hepatic cytochrome P4501A activities and levels of hepatic DNA adducts, also showed the highest levels to be in all four fish species from sites in the vicinity of Hillsborough Bay. Liver lesions, considered to be pollution-associated in several other bottom-feeding fish species, were found in hardhead catfish and longnose killifish, exclusively from sites in Hillsborough Bay. Overall, concentrations of selected contaminants and their derivatives in the four target fish species generally reflected concentrations of these contaminants found in sediment. The biochemical and histopathological responses demonstrated that chemical contaminant concentrations in the vicinity of Hillsborough Bay are sufficiently high to cause adverse effects in indigenous fish species. The results, collectively, showed that the extent of contaminant exposure and biological effects in fish from sites in Tampa Bay were low to moderate compared to more urbanized coastal sites of the United States. *** DIRECT SUPPORT *** A01BY073 00009  相似文献   

Coal Waste,Socioeconomic Change,and Environmental Inequality in Appalachia: Implications for a Just Transition in Coal Country     

Pierce Greenberg 《社会与自然资源》2018,31(9):995-1011

Resource-dependent communities are subject to both unstable economic patterns and environmental degradation associated with extractive industries. However, few studies have empirically analyzed these dynamics in tandem and over time. This paper explores whether Appalachian neighborhoods closer to coal waste impoundments experienced steeper poverty changes from 1990 to 2000. Impoundment failures have resulted in some of the largest environmental disasters in U.S. history and scientists have expressed concerns over their growing heights and risks. Spatial regression models show that neighborhoods closer to impoundments have higher poverty increases on average, even after controlling for mining employment and other variables. These findings highlight the need for a deeper consideration of the environmental inequalities associated with the continued downturn of coal production and employment in the United States. Further, discussions about just transitions must recognize the legacy hazards and externalities associated with extractive industries – and their impacts on communities.  相似文献   

Interannual modulation of subtropical Atlantic boreal summer dust variability by ENSO   总被引：1，自引：0，他引：1  

Michael J. DeFlorio  Ian D. Goodwin  Daniel R. Cayan  Arthur J. Miller  Steven J. Ghan  David W. Pierce  Lynn M. Russell  Balwinder Singh 《Climate Dynamics》2016,46(1-2):585-599

Dust variability in the climate system has been studied for several decades, yet there remains an incomplete understanding of the dynamical mechanisms controlling interannual and decadal variations in dust transport. The sparseness of multi-year observational datasets has limited our understanding of the relationship between climate variations and atmospheric dust. We use available in situ and satellite observations of dust and a century-length fully coupled Community Earth System Model (CESM) simulation to show that the El Niño-Southern Oscillation (ENSO) exerts a control on North African dust transport during boreal summer. In CESM, this relationship is stronger over the dusty tropical North Atlantic than near Barbados, one of the few sites having a multi-decadal observed record. During strong La Niña summers in CESM, a statistically significant increase in lower tropospheric easterly wind is associated with an increase in North African dust transport over the Atlantic. Barbados dust and Pacific SST variability are only weakly correlated in both observations and CESM, suggesting that other processes are controlling the cross-basin variability of dust. We also use our CESM simulation to show that the relationship between downstream North African dust transport and ENSO fluctuates on multidecadal timescales and is associated with a phase shift in the North Atlantic Oscillation. Our findings indicate that existing observations of dust over the tropical North Atlantic are not extensive enough to completely describe the variability of dust and dust transport, and demonstrate the importance of global models to supplement and interpret observational records.  相似文献   

The observed limb effect in Fraunhofer lines,II     

A. Keith Pierce 《Solar physics》1992,139(1):1-12

In this paper the absolute limb effect for a number of Fraunhofer lines observed at the McMath Solar Observatory is given. Results, uncorrected for scattered light, are given for the following lines: Fei 37334.9, 3735.3, 5123.7, 5250.2, 5434.5, 6678.0, and 8886.6. Additional lines observed are five lines of CN 3876.3–3880.0, two lines of Cai 6161.3 and 6162.2, one line of Nai, 6160.7, and one CN line (7957.0) of the red system.Operated by the Association of Universities for Research in Astronomy, Inc. (AURA) under cooperative agreement with the National Science Foundation.  相似文献   

Does the North Atlantic current affect spatial distribution of whiting? Testing environmental hypotheses using statistical and GIS techniques     

Zheng  X.; Pierce  G. J.; Reid  D. G.; Jolliffe  I. T. 《ICES Journal of Marine Science》2002,59(2):239-253

  相似文献   

Brevetoxin abundance and composition during ECOHAB-Florida field monitoring cruises in the Gulf of Mexico     

Richard Pierce  Michael Henry  Patricia Blum 《Continental Shelf Research》2008

This project was undertaken to provide information about the composition and fate of brevetoxins in concert with the multidisciplinary study, ECOHAB-FL, of Karenia brevis blooms in the Gulf of Mexico. Brevetoxin composition was provided for water samples collected during and in the absence of K. brevis blooms from November 1998, through September 2002. The identity and concentration of the most abundant brevetoxins were determined using high performance liquid chromatography with ultraviolet diode array detection (HPLC-DAD). The analytical methods changed in 2002 to the use of a mass spectrometer for brevetoxin identification and quantitation. The most abundant brevetoxins observed during blooms were PbTx-1, -2 and -3. PbTx-2 was the most abundant toxin observed in viable bloom situations with an abundance of K. brevis cells. Starting with the 2000 cruises, a distinction was made between intra-cellular toxins (inside viable K. brevis cells) and extra-cellular brevetoxins (dissolved brevetoxins outside of the cell). An important observation was the change in composition of the major brevetoxins from intra-cellular to extra-cellular toxins. The most abundant intra-cellular toxin was PbTx-2, whereas the most abundant brevetoxin recovered from the extra-cellular (dissolved) fraction in the water was PbTx-3. The abundance of PbTx-3 relative to PbTx-2 generally increased as a bloom aged, indicating the conversion of PbTx-2 to -3 as cells lysed, and the persistence of PbTx-3 in the water after cell death.  相似文献