The North Pacific Experiment (NORPEX-98): Targeted Observations for Improved North American Weather Forecasts

1999 ◽  
Vol 80 (7) ◽  
pp. 1363-1384 ◽  
Author(s):  
R. H. Langland ◽  
Z. Toth ◽  
R. Gelaro ◽  
I. Szunyogh ◽  
M. A. Shapiro ◽  
...  
Keyword(s):  
North American ◽  
North Pacific ◽  
Weather Forecasts ◽  
The North ◽  
Targeted Observations ◽  
The North Pacific

scholarly journals Contrastive Influence of ENSO and PNA on Variability and Predictability of North American Winter Precipitation

2019 ◽  
Vol 32 (19) ◽  
pp. 6271-6284 ◽  
Author(s):  
Xiaofan Li ◽  
Zeng-Zhen Hu ◽  
Ping Liang ◽  
Jieshun Zhu
Keyword(s):  
North America ◽  
Surface Temperature ◽  
Sea Surface Temperature ◽  
North American ◽  
North Pacific ◽  
Winter Precipitation ◽  
Sea Surface ◽  
The North ◽  
Remote Forcing ◽  
The North Pacific

Abstract In this work, the roles of El Niño–Southern Oscillation (ENSO) in the variability and predictability of the Pacific–North American (PNA) pattern and precipitation in North America in winter are examined. It is noted that statistically about 29% of the variance of PNA is linearly linked to ENSO, while the remaining 71% of the variance of PNA might be explained by other processes, including atmospheric internal dynamics and sea surface temperature variations in the North Pacific. The ENSO impact is mainly meridional from the tropics to the mid–high latitudes, while a major fraction of the non-ENSO variability associated with PNA is confined in the zonal direction from the North Pacific to the North American continent. Such interferential connection on PNA as well as on North American climate variability may reflect a competition between local internal dynamical processes (unpredictable fraction) and remote forcing (predictable fraction). Model responses to observed sea surface temperature and model forecasts confirm that the remote forcing is mainly associated with ENSO and it is the major source of predictability of PNA and winter precipitation in North America.

scholarly journals A Multifaceted Climatology of Atmospheric Blocking and Its Recent Linear Trend

2007 ◽  
Vol 20 (4) ◽  
pp. 633-649 ◽  
Author(s):  
M. Croci-Maspoli ◽  
C. Schwierz ◽  
H. C. Davies
Keyword(s):  
North Pacific ◽  
Linear Trend ◽  
Age Distribution ◽  
Atmospheric Blocking ◽  
Weather Forecasts ◽  
The North ◽  
Four Seasons ◽  
Medium Range ◽  
The Mean ◽  
The North Pacific

Abstract A dynamically based climatology is derived for Northern Hemisphere atmospheric blocking events. Blocks are viewed as large amplitude, long-lasting, and negative potential vorticity (PV) anomalies located beneath the dynamical tropopause. The derived climatology [based on the 40-yr European Centre for Medium-Range Weather Forecasts (ECMWF) Re-Analysis (ERA-40)] provides a concise, coherent, and illuminating description of the main physical characteristics of blocks and the accompanying linear trends. The latitude–longitude distribution of blocking frequency captures the standard bimodal geographical distribution with major peaks over the North Atlantic and eastern North Pacific in all four seasons. The accompanying pattern for the age distribution, the genesis–lysis regions, and the track of blocks reveals that 1) younger blocks (1–4 days) are more prevalent at lower latitudes whereas significantly older blocks (up to 12 days) are located at higher latitudes; 2) genesis is confined predominantly to the two major ocean basins and in a zonal band between 40° and 50°N latitude, whereas lysis is more dispersed but with clear preference to higher latitudes; and 3) the general northeastward–west-northwest movement of blocks in the genesis–lysis phase also exhibits subtle seasonal and intra- and interbasin differences. Examination of the intensity and spatial-scale changes during the blocking life cycle suggests that in the mean a block’s evolution is independent of the genesis region and its eventual duration. A novel analysis of blocking trends reveals significant negative trends in winter over Greenland and in spring over the North Pacific. It is shown that the changes over Greenland are linked to the number of blocking episodes, whereas a neighboring trend signal to the south is linked to higher-frequency anticyclonic systems. Furthermore, evidence is adduced that changes in blocking frequency contribute seminally to tropopause height trends.

Key Role of the North Pacific Oscillation–West Pacific Pattern in Generating the Extreme 2013/14 North American Winter

2015 ◽  
Vol 28 (20) ◽  
pp. 8109-8117 ◽  
Author(s):  
Stephen Baxter ◽  
Sumant Nigam
Keyword(s):  
North America ◽  
North American ◽  
North Pacific ◽  
Eastern North America ◽  
North Pacific Oscillation ◽  
Winter Climate ◽  
West Pacific ◽  
The North ◽  
The Tropics ◽  
The North Pacific

Abstract The 2013/14 boreal winter (December 2013–February 2014) brought extended periods of anomalously cold weather to central and eastern North America. The authors show that a leading pattern of extratropical variability, whose sea level pressure footprint is the North Pacific Oscillation (NPO) and circulation footprint the West Pacific (WP) teleconnection—together, the NPO–WP—exhibited extreme and persistent amplitude in this winter. Reconstruction of the 850-hPa temperature, 200-hPa geopotential height, and precipitation reveals that the NPO–WP was the leading contributor to the winter climate anomaly over large swaths of North America. This analysis, furthermore, indicates that NPO–WP variability explains the most variance of monthly winter temperature over central-eastern North America since, at least, 1979. Analysis of the NPO–WP related thermal advection provides physical insight on the generation of the cold temperature anomalies over North America. Although NPO–WP’s origin and development remain to be elucidated, its concurrent links to tropical SSTs are tenuous. These findings suggest that notable winter climate anomalies in the Pacific–North American sector need not originate, directly, from the tropics. More broadly, the attribution of the severe 2013/14 winter to the flexing of an extratropical variability pattern is cautionary given the propensity to implicate the tropics, following several decades of focus on El Niño–Southern Oscillation and its regional and far-field impacts.

scholarly journals Combined Influences on North American Winter Air Temperature Variability from North Pacific Blocking and the North Atlantic Oscillation: Subseasonal and Interannual Time Scales

2020 ◽  
Vol 33 (16) ◽  
pp. 7101-7123 ◽  
Author(s):  
Binhe Luo ◽  
Dehai Luo ◽  
Aiguo Dai ◽  
I. Simmonds ◽  
Lixin Wu
Keyword(s):  
North America ◽  
Air Temperature ◽  
North Atlantic ◽  
North American ◽  
North Pacific ◽  
Eastern North America ◽  
The North ◽  
The North Atlantic ◽  
The North Atlantic Oscillation ◽  
The North Pacific

AbstractWinter surface air temperature (SAT) over North America exhibits pronounced variability on subseasonal, interannual, decadal, and interdecadal time scales. Here, reanalysis data from 1950–2017 are analyzed to investigate the atmospheric and surface ocean conditions associated with its subseasonal to interannual variability. Detrended daily SAT data reveal a known warm west/cold east (WWCE) dipole over midlatitude North America and a cold north/warm south (CNWS) dipole over eastern North America. It is found that while the North Pacific blocking (PB) is important for the WWCE and CNWS dipoles, they also depend on the phase of the North Atlantic Oscillation (NAO). When a negative-phase NAO (NAO−) coincides with PB, the WWCE dipole is enhanced (compared with the PB alone case) and it also leads to a warm north/cold south dipole anomaly in eastern North America; but when PB occurs with a positive-phase NAO (NAO+), the WWCE dipole weakens and the CNWS dipole is enhanced. The PB events concurrent with the NAO− (NAO+) and SAT WWCE (CNWS) dipole are favored by the Pacific El Niño–like (La Niña–like) sea surface temperature mode and the positive (negative) North Pacific mode. The PB-NAO+ has a larger component projecting onto the SAT WWCE dipole during the La Niña winter than during the El Niño winter because a more zonal wave train is formed. Strong North American SAT WWCE dipoles and enhanced projections of PB-NAO+ events onto the SAT WWCE dipole component are also readily seen for the positive North Pacific mode. The North Pacific mode seems to play a bigger role in the North American SAT variability than ENSO.

THE IDENTITY OF THE SPECIES OF LEPEOPHTHEIRUS (COPEPODA) PARASITIC ON PACIFIC SALMON (GENUS ONCORHYNCHUS) AND ATLANTIC SALMON (SALMO SALAR)

1958 ◽  
Vol 36 (6) ◽  
pp. 889-892 ◽  
Author(s):  
L. Margolis
Keyword(s):  
Atlantic Salmon ◽  
Salmo Salar ◽  
North American ◽  
North Pacific ◽  
Pacific Salmon ◽  
Distinct Species ◽  
Atlantic Salmon Salmo Salar ◽  
The North ◽  
Wide Range ◽  
The North Pacific

A review of existing descriptions of Lepeophtheirus from salmonids, based on specimens collected mainly from Salmo salar in the European and North American Atlantic and from Oncorhynchus spp. in the Asiatic and North American Pacific, coupled with observations by the author on material from S. salar from England and from Oncorhynchus spp. from a wide range of localities in the North Pacific, suggest that L. salmonis (Krøyer, 1838) is the only species found on salmonids from both oceans. The differentiation of L. uenoi Yamaguti, 1939 as a distinct species on Pacific salmon seems to be the result of incorrect or inadequate early descriptions of L. salmonis.

scholarly journals Which MJO Events Affect North American Temperatures?

2013 ◽  
Vol 141 (11) ◽  
pp. 3840-3850 ◽  
Author(s):  
Carl J. Schreck ◽  
Jason M. Cordeira ◽  
David Margolin
Keyword(s):  
North America ◽  
North American ◽  
North Pacific ◽  
Wave Breaking ◽  
La Niña ◽  
Teleconnection Patterns ◽  
The North ◽  
La Nina ◽  
The Pacific ◽  
The North Pacific

Abstract Tropical convection from the Madden–Julian oscillation (MJO) excites and amplifies extratropical Rossby waves around the globe. This forcing is reflected in teleconnection patterns like the Pacific–North American (PNA) pattern, and it can ultimately result in temperature anomalies over North America. Previous studies have not explored whether the extratropical response might vary from one MJO event to another. This study proposes a new index, the multivariate PNA (MVP), to identify variations in the extratropical waveguide over the North Pacific and North America that might affect the response to the MJO. The MVP is the first combined EOF of 20–100-day OLR, 850-hPa streamfunction, and 200-hPa streamfunction over the North Pacific and North America. The North American temperature patterns that follow each phase of the MJO change with the sign of the MVP. For example, real-time multivariate MJO (RMM) phase 5 usually leads to warm anomalies over eastern North America. This relationship was only found when the MVP was negative, and it was not associated with El Niño or La Niña. RMM phase 8, on the other hand, usually leads to cold anomalies. Those anomalies only occur if the MVP is positive, which happens somewhat more frequently during La Niña years. Composite analyses based on combinations of the MJO and the MVP show that variability in the Pacific jet and its associated wave breaking play a key role in determining whether and how the MJO affects North American temperatures.

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