scholarly journals Vertically Propagating Kelvin Waves and Tropical Tropopause Variability

2008 ◽  
Vol 65 (6) ◽  
pp. 1817-1837 ◽  
Author(s):  
Jung-Hee Ryu ◽  
Sukyoung Lee ◽  
Seok-Woo Son
Keyword(s):  
Tropical Pacific ◽  
Wave Action ◽  
Kelvin Waves ◽  
Western Pacific ◽  
Tropopause Height ◽  
Kelvin Wave ◽  
Western Tropical Pacific ◽  
Tropical Tropopause ◽  
Vertically Propagating ◽  
The Western Pacific

Abstract The relationship between local convection, vertically propagating Kelvin waves, and tropical tropopause height variability is examined. This study utilizes both simulations of a global primitive-equation model and global observational datasets. Regression analysis with the data shows that convection over the western tropical Pacific is followed by warming in the upper troposphere (UT) and cooling in lower stratosphere (LS) over most longitudes, which results in a lifting of the tropical tropopause. The model results reveal that these UT–LS temperature anomalies are closely associated with vertically propagating Kelvin waves, indicating that these Kelvin waves drive tropical tropopause undulations at intraseasonal time scales. The model simulations further show that regardless of the longitudinal position of the imposed heating, the UT–LS Kelvin wave reaches its maximum amplitude over the western Pacific. This result, together with an analysis based on wave action conservation, is used to contend that the Kelvin wave amplification over the western Pacific should be attributed to the zonal variation of background zonal wind field, rather than to the proximity of the heating. The wave action conservation law is also used to offer an explanation as to why the vertically propagating Kelvin waves play the central role in driving tropical tropopause height undulations. The zonal and vertical modulation of the Kelvin waves by the background flow may help explain the origin of the very cold air over the western tropical Pacific, which is known to cause freeze-drying of tropospheric air en route to the stratosphere.

First Record of the Ceratioid Anglerfish Species Gigantactis microdontis (Teleostei: Lophiiformes: Gigantactinidae) in the Western Pacific Ocean

Zootaxa ◽  
2019 ◽  
Vol 4664 (3) ◽  
pp. 441-444 ◽  
Author(s):  
ARTEM M. PROKOFIEV ◽  
THEODORE W. PIETSCH
Keyword(s):  
Pacific Ocean ◽  
Hawaiian Islands ◽  
First Record ◽  
Tropical Pacific ◽  
Western Pacific ◽  
Eastern Pacific ◽  
Western Pacific Ocean ◽  
Western Tropical Pacific ◽  
Caroline Islands ◽  
The Western Pacific

The rare ceratioid anglerfish Gigantactis microdontis was formerly known from 12 specimens collected in the Eastern Pacific from 158° W eastward: off Hawaiian Islands, Oregon, California and Peru. Thirteenth specimen reported herein extends the known distribution of this species some 7630 km westward into the western tropical Pacific (off Caroline Islands). The newly reported specimen shows no principal differences in morphology from the previously known individuals. 

Recent Changes in ENSO Teleconnection over the Western Pacific Impacts the Eastern China Precipitation Dipole

2016 ◽  
Vol 29 (21) ◽  
pp. 7587-7598 ◽  
Author(s):  
Dachao Jin ◽  
Saji N. Hameed ◽  
Liwei Huo
Keyword(s):  
Eastern China ◽  
Tropical Pacific ◽  
The Other ◽  
Western Pacific ◽  
Asia Pacific ◽  
Boreal Summer ◽  
Central Pacific ◽  
Western Tropical Pacific ◽  
Enso Teleconnections ◽  
The Western Pacific

Abstract The eastern China precipitation dipole (ECPD) features an out-of-phase relationship between boreal summer precipitation over the middle and lower reaches of the Yangtze River and the Hetao region to its northwest. The precipitation dipole is strongly influenced by ENSO teleconnections over the western tropical Pacific. Here it is shown that a pronounced weakening of both the rainfall variability over eastern China as well as the precipitation dipole structure occurred around the mid-1990s. The changes have been analyzed by considering two epochs: one during 1979–95 and the other during 1996–2009. The characteristic feature of the circulation anomaly during the first epoch is the well-known East Asia–Pacific/Pacific–Japan (EAP/PJ) pattern, a quasi-meridional teleconnection pattern emanating from the western tropical Pacific. On the other hand, during the latter epoch eastern China precipitation variability occurs as an integral part of the circulation anomalies over the western Pacific. In contrast to the more meridionally restricted anomalies during canonical ENSO episodes, the western Pacific circulation has a significantly larger meridional scale. Intriguingly correlation of the precipitation dipole with Pacific sea surface temperature flips in sign during the second epoch, with enhanced precipitation over southeastern China associated with La Niña–like variability, in contrast to the co-occurrence of enhanced precipitation over this region with El Niño during the first epoch. The results suggest that the dominance of Modoki or central Pacific El Niños, and the altered structure of ENSO teleconnections associated with these, may play a role in the weakened ECPD structure during the latter epoch.

scholarly journals A Shift in Western Tropical Pacific Sea Level Trends during the 1990s

2011 ◽  
Vol 24 (15) ◽  
pp. 4126-4138 ◽  
Author(s):  
Mark A. Merrifield
Keyword(s):  
Sea Level ◽  
Tide Gauge ◽  
Tropical Pacific ◽  
Western Pacific ◽  
Sea Surface ◽  
Eastern Pacific ◽  
Tide Gauge Records ◽  
Western Tropical Pacific ◽  
The Western Pacific ◽  
The Tropical Pacific

Abstract Pacific Ocean sea surface height trends from satellite altimeter observations for 1993–2009 are examined in the context of longer tide gauge records and wind stress patterns. The dominant regional trends are high rates in the western tropical Pacific and minimal to negative rates in the eastern Pacific, particularly off North America. Interannual sea level variations associated with El Niño–Southern Oscillation events do not account for these trends. In the western tropical Pacific, tide gauge records indicate that the recent high rates represent a significant trend increase in the early 1990s relative to the preceding 40 years. This sea level trend shift in the western Pacific corresponds to an intensification of the easterly trade winds across the tropical Pacific. The wind change appears to be distinct from climate variations centered in the North Pacific, such as the Pacific decadal oscillation. In the eastern Pacific, tide gauge records exhibit higher-amplitude decadal fluctuations than in the western tropical Pacific, and the recent negative sea level trends are indistinguishable from these fluctuations. The shifts in trade wind strength and western Pacific sea level rate resemble changes in dominant global modes of outgoing longwave radiation and sea surface temperature. It is speculated that the western Pacific sea level response indicates a general strengthening of the atmospheric circulation over the tropical Pacific since the early 1990s that has developed in concert with recent warming trends.

scholarly journals Long-term behavior of the Kelvin waves revealed by CHAMP/GPS RO measurements and their effects on the tropopause structure

2006 ◽  
Vol 24 (5) ◽  
pp. 1355-1366 ◽  
Author(s):  
M. Venkat Ratnam ◽  
T. Tsuda ◽  
T. Kozu ◽  
S. Mori
Keyword(s):  
Wave Activity ◽  
Kelvin Waves ◽  
Tropopause Height ◽  
Kelvin Wave ◽  
Quasi Biennial Oscillation ◽  
Tropical Tropopause ◽  
Hemisphere Winter ◽  
Biennial Oscillation ◽  
Northern Hemisphere Winter

Abstract. The vertical and temporal variations of Kelvin waves and the associated effects on the tropical tropopause were studied using long-term (from May 2001 to October 2005) CHAMP/GPS (CHAllenging Mini satellite Payload/Global Positioning System) radio occultation (RO) measurements. The periods of these waves were found to be varying in between 10 and 15 days, with vertical wavelengths 5–8 km. These variations clearly show eastward phase propagation in the time-longitude section and eastward phase tilts with height in altitude-longitude, displaying the characteristics of Kelvin waves. The peak variance in the temperature is found over the Indian Ocean and into the western Pacific within the broad region of the equator. Kelvin wave amplitudes were found significantly enhanced in the eastward shear of the quasi-biennial oscillation (QBO) and are confined in and around the tropopause during westward phase of QBO, where it extends between 17 and 25 km during the eastward phase of QBO and is damped away above, consistent with earlier reported results. The amplitudes are increasing during the months of Northern Hemisphere winter and sometimes they are highly sporadic in nature. Seasonal and inter-annual variations in the Kelvin wave amplitudes near the tropical tropopause coincide exactly with the tropopause height and temperature, with a sharp tropopause during maximum Kelvin wave activity. A clear annual oscillation, along with a month-to-month coincidence is evident most of the time in both the tropopause height and Kelvin wave activity, with maximum and minimum Kelvin wave amplitudes during the Northern Hemisphere winter and summer, respectively. In addition, a signature of quasi-biennial oscillation (QBO) in the tropopause structure is also seen in long-term tropopause variations, although the amplitudes are less when compared to the annual oscillation. In the westward phase of QBO (during strong Kelvin wave activity) at 20km (in 2001–2002 winter and 2003–2004 winter), the tropopause height was slightly larger with a sharp tropopause and low temperature. The process behind these observed features has been discussed.

scholarly journals Tropical temperature variability and Kelvin-wave activity in the UTLS from GPS RO measurements

2017 ◽  
Vol 17 (2) ◽  
pp. 793-806 ◽  
Author(s):  
Barbara Scherllin-Pirscher ◽  
William J. Randel ◽  
Joowan Kim
Keyword(s):  
Large Scale ◽  
Deep Convection ◽  
Wave Activity ◽  
Kelvin Waves ◽  
Temperature Variability ◽  
Stationary Waves ◽  
Kelvin Wave ◽  
Quasi Biennial Oscillation ◽  
Tropical Tropopause ◽  
Tropopause Region

Abstract. Tropical temperature variability over 10–30 km and associated Kelvin-wave activity are investigated using GPS radio occultation (RO) data from January 2002 to December 2014. RO data are a powerful tool for quantifying tropical temperature oscillations with short vertical wavelengths due to their high vertical resolution and high accuracy and precision. Gridded temperatures from GPS RO show the strongest variability in the tropical tropopause region (on average 3 K2). Large-scale zonal variability is dominated by transient sub-seasonal waves (2 K2), and about half of sub-seasonal variance is explained by eastward-traveling Kelvin waves with periods of 4 to 30 days (1 K2). Quasi-stationary waves associated with the annual cycle and interannual variability contribute about a third (1 K2) to total resolved zonal variance. Sub-seasonal waves, including Kelvin waves, are highly transient in time. Above 20 km, Kelvin waves are strongly modulated by the quasi-biennial oscillation (QBO) in stratospheric zonal winds, with enhanced wave activity during the westerly shear phase of the QBO. In the tropical tropopause region, however, peaks of Kelvin-wave activity are irregularly distributed in time. Several peaks coincide with maxima of zonal variance in tropospheric deep convection, but other episodes are not evidently related. Further investigations of convective forcing and atmospheric background conditions are needed to better understand variability near the tropopause.

scholarly journals Impacts of the Tropical Pacific–Indian Ocean Associated Mode on Madden–Julian Oscillation over the Maritime Continent in Boreal Winter

Atmosphere ◽  
2020 ◽  
Vol 11 (10) ◽  
pp. 1049
Author(s):  
Xin Li ◽  
Ming Yin ◽  
Xiong Chen ◽  
Minghao Yang ◽  
Fei Xia ◽  
...  
Keyword(s):  
Indian Ocean ◽  
Kinetic Energy ◽  
Tropical Pacific ◽  
Western Pacific ◽  
Boreal Summer ◽  
Boreal Winter ◽  
Madden Julian Oscillation ◽  
Maritime Continent ◽  
The Western Pacific ◽  
The Tropical Pacific

Based on the observation and reanalysis data, the relationship between the Madden–Julian Oscillation (MJO) over the Maritime Continent (MC) and the tropical Pacific–Indian Ocean associated mode was analyzed. The results showed that the MJO over the MC region (95°–150° E, 10° S–10° N) (referred to as the MC–MJO) possesses prominent interannual and interdecadal variations and seasonally “phase-locked” features. MC–MJO is strongest in the boreal winter and weakest in the boreal summer. Winter MC–MJO kinetic energy variation has significant relationships with the El Niño–Southern Oscillation (ENSO) in winter and the Indian Ocean Dipole (IOD) in autumn, but it correlates better with the tropical Pacific–Indian Ocean associated mode (PIOAM). The correlation coefficient between the winter MC–MJO kinetic energy index and the autumn PIOAM index is as high as −0.5. This means that when the positive (negative) autumn PIOAM anomaly strengthens, the MJO kinetic energy over the winter MC region weakens (strengthens). However, the correlation between the MC–MJO convection and PIOAM in winter is significantly weaker. The propagation of MJO over the Maritime Continent differs significantly in the contrast phases of PIOAM. During the positive phase of the PIOAM, the eastward propagation of the winter MJO kinetic energy always fails to move across the MC region and cannot enter the western Pacific. However, during the negative phase of the PIOAM, the anomalies of MJO kinetic energy over the MC is not significantly weakened, and MJO can propagate farther eastward and enter the western Pacific. It should be noted that MJO convection is more likely to extend to the western Pacific in the positive phases of PIOAM than in the negative phases. This is significant different with the propagation of the MJO kinetic energy.

scholarly journals Deriving an atmospheric budget of total organic bromine using airborne in situ measurements from the western Pacific area during SHIVA

2014 ◽  
Vol 14 (13) ◽  
pp. 6903-6923 ◽  
Author(s):  
S. Sala ◽  
H. Bönisch ◽  
T. Keber ◽  
D. E. Oram ◽  
G. Mills ◽  
...  
Keyword(s):  
Stratospheric Ozone ◽  
Radiative Heating ◽  
Western Pacific ◽  
Data Set ◽  
Tropical Regions ◽  
Upper Troposphere ◽  
Tropical Tropopause ◽  
Vertical Range ◽  
The Western Pacific

Abstract. During the recent SHIVA (Stratospheric Ozone: Halogen Impacts in a Varying Atmosphere) project an extensive data set of all halogen species relevant for the atmospheric budget of total organic bromine was collected in the western Pacific region using the Falcon aircraft operated by the German Aerospace agency DLR (Deutsches Zentrum für Luft- und Raumfahrt) covering a vertical range from the planetary boundary layer up to the ceiling altitude of the aircraft of 13 km. In total, more than 700 measurements were performed with the newly developed fully automated in situ instrument GHOST-MS (Gas chromatograph for the Observation of Tracers – coupled with a Mass Spectrometer) by the Goethe University of Frankfurt (GUF) and with the onboard whole-air sampler WASP with subsequent ground-based state-of-the-art GC / MS analysis by the University of East Anglia (UEA). Both instruments yield good agreement for all major (CHBr3 and CH2Br2) and minor (CH2BrCl, CHBrCl2 and CHBr2Cl) VSLS (very short-lived substances), at least at the level of their 2σ measurement uncertainties. In contrast to the suggestion that the western Pacific could be a region of strongly increased atmospheric VSLS abundance (Pyle et al., 2011), we found only in the upper troposphere a slightly enhanced amount of total organic bromine from VSLS relative to the levels reported in Montzka and Reimann et al. (2011) for other tropical regions. From the SHIVA observations in the upper troposphere, a budget for total organic bromine, including four halons (H-1301, H-1211, H-1202, H-2402), CH3Br and the VSLS, is derived for the level of zero radiative heating (LZRH), the input region for the tropical tropopause layer (TTL) and thus also for the stratosphere. With the exception of the two minor VSLS CHBrCl2 and CHBr2Cl, excellent agreement with the values reported in Montzka and Reimann et al. (2011) is found, while being slightly higher than previous studies from our group based on balloon-borne measurements.

scholarly journals Correlation between equatorial Kelvin waves and the occurrence of extremely thin ice clouds at the tropical tropopause

2008 ◽  
Vol 8 (14) ◽  
pp. 4019-4026 ◽  
Author(s):  
F. Immler ◽  
K. Krüger ◽  
M. Fujiwara ◽  
G. Verver ◽  
M. Rex ◽  
...  
Keyword(s):  
Kelvin Waves ◽  
Clear Correlation ◽  
Temperature Structure ◽  
Kelvin Wave ◽  
Ice Clouds ◽  
Tropical Tropopause Layer ◽  
Tropical Tropopause ◽  
Water Vapour Concentration ◽  
Vapour Concentration ◽  
The Tropics

Abstract. A number of field-campaigns in the tropics have been conducted in recent years with two different LIDAR systems at Paramaribo (5.8° N, 55.2° W), Suriname. The lidars detect particles in the atmosphere with high vertical and temporal resolution and are capable of detecting extremely thin cloud layers which frequently occur in the tropical tropopause layer (TTL). Radiosonde as well as operational ECMWF analysis showed that equatorial Kelvin waves propagated in the TTL and greatly modulated its temperature structure. We found a clear correlation between the temperature anomalies introduced by these waves and the occurrence of thin cirrus in the TTL. In particular we found that extremely thin ice clouds form regularly where cold anomalies shift the tropopause to high altitudes. These findings suggest an influence of Kelvin wave activity on the dehydration in the TTL and thus on the global stratospheric water vapour concentration.

scholarly journals Dehydration in the tropical tropopause layer estimated from the water vapor match

2013 ◽  
Vol 13 (1) ◽  
pp. 633-688 ◽  
Author(s):  
Y. Inai ◽  
F. Hasebe ◽  
M. Fujiwara ◽  
M. Shiotani ◽  
N. Nishi ◽  
...  
Keyword(s):  
Relaxation Time ◽  
Water Vapor ◽  
Relative Humidity ◽  
Western Pacific ◽  
Dehydration Process ◽  
Saturation State ◽  
Air Mass ◽  
Tropical Tropopause Layer ◽  
Tropical Tropopause ◽  
The Western Pacific

Abstract. Variation in stratospheric water vapor is controlled mainly by the dehydration process in the tropical tropopause layer (TTL) over the western Pacific; however, this process is poorly understood. To address this shortcoming, in this study the match method is applied to quantify the dehydration process in the TTL over the western Pacific. The match pairs are sought from the Soundings of Ozone and Water in the Equatorial Region (SOWER) campaign network observations using isentropic trajectories. For the pairs identified, extensive screening procedures are performed to verify the representativeness of the air parcel and the validity of the isentropic treatment, and to check for possible water injection by deep convection, consistency between the sonde data and analysis field, and conservation of the ozone content. Among the pairs that passed the screening test, we found some cases corresponding to the first quantitative value of dehydration associated with horizontal advection in the TTL. The statistical features of dehydration for the air parcels advected in the lower TTL are derived from the match pairs. Match analysis indicates that ice nucleation starts before the relative humidity with respect to ice (RHice) reaches 207 ± 81% (1σ) and that the air mass is dehydrated until RHice reaches 83 ± 30% (1σ). The efficiency of dehydration is estimated as the relaxation time required for the relative humidity of the supersaturated air parcel to approach the saturation state. This is empirically estimated from the match pairs as the quantity that reproduces the second water vapor observation, given the first observed water vapor amount and the history of the saturation mixing ratio of the match air mass exposed during the advection. The relaxation time is found to range from 2 to 3 h, which is consistent with previous studies.

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