scholarly journals Temporal–Spatial Distribution of Thin Moist Layers in the Midtroposphere over the Tropical Eastern Pacific

2009 ◽  
Vol 22 (19) ◽  
pp. 5102-5114
Author(s):  
Shigenori Otsuka ◽  
Shigeo Yoden
Keyword(s):  
Spatial Distribution ◽  
Annual Variation ◽  
Intertropical Convergence Zone ◽  
Eastern Pacific ◽  
Boreal Summer ◽  
Boreal Winter ◽  
Tropical Eastern Pacific ◽  
Local Maxima ◽  
The North ◽  
The Vertical Distribution

Abstract The temporal–spatial distribution of thin moist layers in the midtroposphere over the tropical eastern Pacific is studied by data analyses of radiosonde soundings and downscaling numerical experiments with a regional model. Radiosonde soundings at San Cristóbal, Galápagos, show frequent existence of thin moist layers between 2 and 10 km in altitude, with a local minimum at 7–8 km. The downscaling experiments with global objective analyses are completed for 2005–06, September and December of 1999–2004, and March of 2000–04. The vertical distribution of thin moist layers has three local maxima at 5, 10, and 16 km, where bimodality of the frequency distribution of water vapor is evident. Between 4 and 7 km, an annual variation is dominant in the occurrence ratio of thin moist layers, which tend to appear in nonconvective regions. In boreal winter, the layers appear to the north of the intertropical convergence zone (ITCZ), whereas in boreal summer the layers appear in the equator-side of the ITCZ. Interannual variations of the appearance of thin moist layers are also studied in 1999–2006, based on the experiments for particular months (March, September, and December). The occurrence ratio is generally high in December and March and low in September. In La Niña years, the annual variation is smaller than that in El Niño years; the occurrence ratio is higher in boreal summer to the south of the ITCZ.

scholarly journals Estimate of the Predictability of Boreal Summer and Winter Intraseasonal Oscillations from Observations

2011 ◽  
Vol 139 (8) ◽  
pp. 2421-2438 ◽  
Author(s):  
Ruiqiang Ding ◽  
Jianping Li ◽  
Kyong-Hwan Seo
Keyword(s):  
Spatial Distribution ◽  
Intraseasonal Variability ◽  
Intraseasonal Oscillation ◽  
Longwave Radiation ◽  
Boreal Summer ◽  
Boreal Winter ◽  
Potential Predictability ◽  
The North ◽  
Intraseasonal Oscillations ◽  
The North Pacific

AbstractTropical intraseasonal variability (TISV) shows two dominant modes: the boreal winter Madden–Julian oscillation (MJO) and the boreal summer intraseasonal oscillation (BSISO). The two modes differ in intensity, frequency, and movement, thereby presumably indicating different predictabilities. This paper investigates differences in the predictability limits of the BSISO and the boreal winter MJO based on observational data. The results show that the potential predictability limit of the BSISO obtained from bandpass-filtered (30–80 days) outgoing longwave radiation (OLR), 850-hPa winds, and 200-hPa velocity potential is close to 5 weeks, comparable to that of the boreal winter MJO. Despite the similarity between the potential predictability limits of the BSISO and MJO, the spatial distribution of the potential predictability limit of the TISV during summer is very different from that during winter. During summer, the limit is relatively low over regions where the TISV is most active, whereas it is relatively high over the North Pacific, North Atlantic, southern Africa, and South America. The spatial distribution of the limit during winter is approximately the opposite of that during summer. For strong phases of ISO convection, the initial error of the BSISO shows a more rapid growth than that of the MJO. The error growth is rapid when the BSISO and MJO enter the decaying phase (when ISO signals are weak), whereas it is slow when convection anomalies of the BSISO and MJO are located in upstream regions (when ISO signals are strong).

scholarly journals Accounting for the surface temperature persistence by using signal energy

2021 ◽  
Vol 144 (1-2) ◽  
pp. 363-377
Author(s):  
Jiangnan Li ◽  
Zhian Sun ◽  
Feng Zhang
Keyword(s):  
Surface Temperature ◽  
Critical Exponent ◽  
Random Noise ◽  
Boreal Summer ◽  
Boreal Winter ◽  
Signal Energy ◽  
The North ◽  
Power Rule ◽  
Short Period ◽  
Temporal Intervals

AbstractThe autocorrelation function (ACF) and its finite Fourier transform, referred to as signal energy, have been investigated using the ECMWF daily surface temperature data. ACF itself provides a measure of the influence of leading fluctuation between two different time points. Considering the decay of ACF, it is found that the scaling power-rule of ACF is only valid in a very short period, as the decay of ACF exists before it reaches a random noise state. Therefore, the method of the critical exponent of ACF is limited in the short length of the temporal interval. On the other hand, the distributions of the signal energy always show nice patterns, indicating the degree of persistence change. It is found, for a short period, that the distributions of the signal energy and the critical exponent are very similar, with a correlation coefficient over 0.97. For a longer period, though the critical exponent of ACF becomes invalid, the signal energy can always provide an effective method to investigate climate persistence in different lengths of time. In a 5-day period of boreal winter, the southern part of North America has a larger value of signal energy compared to the northern part; thus, the surface temperature is more stable in the north part. The result becomes opposite in the boreal summer. The method of signal energy can also be applied to a particular interval of time. In different temporal intervals, the signal energy presents very different results, especially over the El Nino regions

scholarly journals Shallow-Water Foraminifera and Other Microscopic Biota of Clipperton Island, Tropical Eastern Pacific

2019 ◽  
Author(s):  
Mary L McGann ◽  
Robert W. Schmieder ◽  
Louis-Philippe Loncke
Keyword(s):  
Shallow Water ◽  
Geographic Location ◽  
Oceanic Islands ◽  
Tropical Pacific ◽  
Eastern Pacific ◽  
North Equatorial Current ◽  
Tropical Eastern Pacific ◽  
Foraminiferal Assemblage ◽  
Island Endemic ◽  
The North

<p></p><p>The recent foraminiferal fauna and associated microbiota of Clipperton Island (10.2833°N, 109.2167°W) were investigated at 20 sites collected in the intertidal zone around the perimeter of the island and from the edge of the inner brackish-water lagoon. Due to the island’s geographic location in a low productivity zone, a lack of variable habitats on and surrounding the island, and heavy surf that pounds the exposed land, a depauperate fauna was recovered although mixed biogeographic affinities are represented. The shallow-water foraminiferal assemblage has no endemics but primarily tropical Indo-Pacific and eastern Pacific (Panamic) affinities, as well as one species of Caribbean affinity. The most abundant taxa are <i>Sorites</i> spp. and <i>Quinqueloculina</i> spp. Noticeably absent are any species of <i>Amphistegina, </i>despite the fact that they are considered ubiquitous in the tropical Pacific. The molluscan fauna has Clipperton Island endemics, a tropical Pacific/Inter-Island endemic, and tropical eastern Pacific oceanic islands/Panamic Molluscan affinities. The ostracods included endemics found restricted to Clipperton Island lagoon, as well as Indo-Pacific and Panamic Province species. The foraminifera, mollusks, and ostracods are thought to disperse to Clipperton Island by way of the North Equatorial Countercurrent and North Equatorial Current, suggesting that the island is indeed a stepping stone for migration both east and west across the Eastern Pacific Barrier.</p><br><p></p>

ENSO Drove 2500-Year Collapse of Eastern Pacific Coral Reefs

Science ◽  
2012 ◽  
Vol 337 (6090) ◽  
pp. 81-84 ◽  
Author(s):  
Lauren T. Toth ◽  
Richard B. Aronson ◽  
Steven V. Vollmer ◽  
Jennifer W. Hobbs ◽  
Dunia H. Urrego ◽  
...  
Keyword(s):  
Climate Change ◽  
Coral Reef ◽  
Global Climate Change ◽  
Southern Oscillation ◽  
Global Climate ◽  
Intertropical Convergence Zone ◽  
Eastern Pacific ◽  
Convergence Zone ◽  
Reef Growth ◽  
Tropical Eastern Pacific

Cores of coral reef frameworks along an upwelling gradient in Panamá show that reef ecosystems in the tropical eastern Pacific collapsed for 2500 years, representing as much as 40% of their history, beginning about 4000 years ago. The principal cause of this millennial-scale hiatus in reef growth was increased variability of the El Niño–Southern Oscillation (ENSO) and its coupling with the Intertropical Convergence Zone. The hiatus was a Pacific-wide phenomenon with an underlying climatology similar to probable scenarios for the next century. Global climate change is probably driving eastern Pacific reefs toward another regional collapse.

scholarly journals Water Vapor Fluxes over the Intra-Americas Sea: Seasonal and Interannual Variability and Associations with Rainfall

2007 ◽  
Vol 20 (9) ◽  
pp. 1910-1922 ◽  
Author(s):  
Alberto M. Mestas-Nuñez ◽  
David B. Enfield ◽  
Chidong Zhang
Keyword(s):  
United States ◽  
Gulf Of Mexico ◽  
Interannual Variability ◽  
Boreal Summer ◽  
Boreal Winter ◽  
The North ◽  
The Pacific ◽  
Central United States ◽  
Low Level Jet ◽  
The Caribbean

Abstract The seasonal and interannual variability of moisture transports over the Intra-Americas Sea (including the Gulf of Mexico and the Caribbean Sea) is evaluated using the NCEP–NCAR global reanalysis. The seasonal variability of these moisture transports is consistent with previous studies and shows distinctive winter and summer regimes. Boreal winter moisture is mainly delivered to the central United States from the Pacific with some contribution from the Gulf of Mexico. It is during the boreal summer that the moisture flow over the Intra-Americas Sea is most effective in supplying the water vapor to the central United States via the northern branch of the Caribbean low-level jet. The increase of intensity of this jet during July is associated with an increase in evaporation over the Intra-Americas Sea, consistent with midsummer drought conditions over this region. During both summer and winter, the interannual variability of the inflow of moisture from the Intra-Americas Sea into central United States is associated with Caribbean low-level jet variability. The source of the varying moisture is mainly the Gulf of Mexico and the North Atlantic area just east of the Bahamas Islands and the sink is precipitation over east-central United States. The main teleconnection pattern for these interannual variations appears to be the Pacific–North American, although in boreal winter ENSO and possibly the North Atlantic Oscillation may also play a role. During boreal summer, associations with ENSO mainly involve the zonal moisture exchange between the Intra-Americas Sea/tropical Atlantic and the tropical Pacific.

Association of Convection with the 5-Day Rossby–Haurwitz Wave

2015 ◽  
Vol 72 (9) ◽  
pp. 3309-3321 ◽  
Author(s):  
Malcolm J. King ◽  
Matthew C. Wheeler ◽  
Todd P. Lane
Keyword(s):  
Large Scale ◽  
Southern Oscillation ◽  
Tropical Convection ◽  
Marshall Islands ◽  
Eastern Pacific ◽  
Boreal Summer ◽  
Boreal Winter ◽  
Tropical Andes ◽  
Quasi Biennial Oscillation ◽  
Frequency Spectra

Abstract The seasonality, regionality, and nature of the association between tropical convection and the 5-day wavenumber-1 Rossby–Haurwitz wave are examined. Spectral coherences between daily outgoing longwave radiation (OLR), a proxy for convection, and 850-hPa zonal wind over the period January 1979–February 2013 are compared for different seasons and for phases of El Niño–Southern Oscillation (ENSO) and the quasi-biennial oscillation (QBO). Increased coherence, indicating a stronger association, occurs in boreal spring and autumn, with slightly reduced coherence in boreal summer and significantly reduced coherence in boreal winter. The regionality of the association is examined using lagged-regression techniques. Significant local signals in tropical convection are found over West Africa, the tropical Andes, the eastern Pacific Ocean, and the Marshall Islands. The relative phasing between the 5-day wave wind and OLR signals is in quadrature in Africa and the Marshall Islands, in phase with easterlies over the Andes, and out of phase with easterlies over the eastern Pacific. Frequency spectra of precipitation averaged over the identified local regions reveal spectral peaks in the 4–6-day range. The phasing between the large-scale wind and local convection signals suggests that the 5-day wave is actively modulating the convection around the Americas.

What Maintains the SST Front North of the Eastern Pacific Equatorial Cold Tongue?*

2007 ◽  
Vol 20 (11) ◽  
pp. 2500-2514 ◽  
Author(s):  
Simon P. de Szoeke ◽  
Shang-Ping Xie ◽  
Toru Miyama ◽  
Kelvin J. Richards ◽  
R. Justin O. Small
Keyword(s):  
Mixed Layer ◽  
Radiative Forcing ◽  
Cold Water ◽  
Eastern Pacific ◽  
Boreal Summer ◽  
Cold Tongue ◽  
Surface Cooling ◽  
Sst Front ◽  
The North ◽  
Atmospheric Feedback

Abstract A coupled ocean–atmosphere regional model suggests a mechanism for formation of a sharp sea surface temperature (SST) front north of the equator in the eastern Pacific Ocean in boreal summer and fall. Meridional convergence of Ekman transport at 5°N is forced by eastward turning of the southeasterly cross-equatorial wind, but the SST front forms considerably south of the maximum Ekman convergence. Geostrophic equatorward flow at 3°N in the lower half of the isothermally mixed layer enhances mixed layer convergence. Cold water is upwelled on or south of the equator and is advected poleward by mean mixed layer flow and by eddies. The mixed layer current convergence in the north confines the cold advection, so the SST front stays close to the equator. Warm advection from the north and cold advection from the south strengthen the front. In the Southern Hemisphere, a continuous southwestward current advects cold water far from the upwelling core. The cold tongue is warmed by the net surface flux, which is dominated by solar radiation. Evaporation and net surface cooling are at a maximum just north of the SST front where relatively cool dry air is advected northward over warm SST. The surface heat flux is decomposed into a response to SST alone, and an atmospheric feedback. The atmospheric feedback enhances cooling on the north side of the front by 178 W m−2, about half of which is due to enhanced evaporation from cold dry advection, while the other half is due to cloud radiative forcing.

Revisiting the diversity and distribution of the ophiuroids (Echinodermata: Ophiuroidea) from Peru

Zootaxa ◽  
2020 ◽  
Vol 4766 (4) ◽  
pp. 539-556
Author(s):  
REBECA GRANJA FERNÁNDEZ ◽  
YURI HOOKER
Keyword(s):  
Spatial Distribution ◽  
New Records ◽  
Transitional Zone ◽  
Eastern Pacific ◽  
Distribution Analysis ◽  
Deep Zone ◽  
Tropical Eastern Pacific ◽  
Southeastern Pacific ◽  
Warm Temperate ◽  
Pacific Area

While the Ophiuroidea of Peruvian waters have long been studied, there exists inconsistencies regarding taxonomy and spatial distribution records. Based on literature review and museum records, we provide an updated checklist of the ophiuroids accompanied by the first geographical distribution analysis. Peruvian waters host 36 species of Ophiuroidea (three doubtful), yet 15 previous records of species are considered invalid for the area. We recorded five new records of species for Peru: Amphiodia oerstedi, Diopederma daniana, Ophiocomella alexandri, Ophiolepis crassa, and Ophiophthalmus normani. Peruvian maritime area is divided into four areas: The Tropical Eastern Pacific area where 16 species of ophiuroids occur, the Transition Zone with 13 species, the Warm Temperate Southeastern Pacific with nine species, and the Deep Zone with 14 species. We found significant differences in species composition among areas (except among the Eastern Pacific and the Transitional Zone), and each of them is represented by particular species. According to the rarefaction curve, the inventory of ophiuroids for the country is not yet complete; therefore, we suggest performing more expeditions along the Peruvian waters focusing mainly on the deep zones which remain relatively unexplored to date. 

Sign in / Sign up

Export Citation Format

Share Document