Evaluating Tropical Tropospheric Ozone and Water Vapor in MERRA-2, ERA-Interim, and CAM-Chem Using Aircraft Observations From the Western Pacific

<p>We analyzed the variability of global positioning system (GPS) water vapor during the 2011 La Niña events over the western Pacific Ocean. The precipitable water vapor (PWV) derived from the UMSK (Malaysia) GPS station was investigated and compared with four other selected GPS stations: NTUS (Singapore), PIMO (Philippines), BAKO (Indonesia) and TOW2 (Australia). Analysis of the correlation between PWV and the sea-surface temperature anomaly (SSTa) on a weekly basis for the three La Niña cases of January–February–March, August–September–October, and October–November–December was used as an indicator of the influence of the El Niño Southern Oscillation. A good relationship between GPS PWV and SSTa for the Niño 4 region, with correlation coefficients between -0.91 and -0.94, was observed for the August–September–October and October–November–December cases. During the 2011 La Niña events, the water vapor was seen to increase to about 8.39 mm for the October–November–December case, with decreases of about 4.20 mm for the remaining months, compared to the mean 2011 value. This implies that during these events, the precipitation in the western Pacific is increased, due to stronger easterly trade winds blowing along the eastern Pacific Ocean than along the western Pacific, and a mass of warm water moving westwards, thereby increasing the evaporation.</p>

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Erratum to “The composition of aerosol particles in the middle troposphere over the western Pacific Ocean: Aircraft observations from Australia to Japan, January 1994”

Atmospheric Environment ◽

10.1016/j.atmosenv.2005.11.040 ◽

2006 ◽

Vol 40 (4) ◽

pp. 793

Author(s):

Miwako Ikegami ◽

Kikuo Okada ◽

Yuji Zaizen ◽

Yukitomo Tsutsumi ◽

Yukio Makino ◽

...

Keyword(s):

Pacific Ocean ◽

Aerosol Particles ◽

Western Pacific ◽

Western Pacific Ocean ◽

Middle Troposphere ◽

Aircraft Observations ◽

The Western Pacific

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Processes Governing Water Vapor Isotope Composition in the Indo-Pacific Region: Convection and Water Vapor Transport

Journal of Climate ◽

10.1175/jcli-d-16-0297.1 ◽

2016 ◽

Vol 29 (23) ◽

pp. 8535-8546 ◽

Cited By ~ 15

Author(s):

Zhongyin Cai ◽

Lide Tian

Keyword(s):

Water Vapor ◽

El Nino ◽

Isotope Composition ◽

Vapor Transport ◽

Western Pacific ◽

Water Vapor Transport ◽

Pacific Region ◽

Convective Activity ◽

La Nina ◽

The Western Pacific

Abstract In an effort to understand the mechanisms controlling water vapor isotope composition in the Indo-Pacific region, encompassing southeastern Asia, this study investigates the spatial and interannual patterns in summer [June–September (JJAS)] water vapor isotopologues retrieved from the Tropospheric Emission Spectrometer (TES), especially those patterns associated with convection and water vapor transport. Both precipitation and water vapor isotope values exhibit a V-shaped longitudinal pattern in their spatial variations, reflecting the gradual rainout and increase in convective intensity along water vapor transport routes. On the temporal scale, compared with the 2006–10 JJAS mean conditions, TES water vapor δD over the eastern Indian Ocean and southeastern Asia (R_W120; 10°S–30°N, 80°–120°E) is higher in the 2009 JJAS El Niño event when convective activity is reduced and lower in the 2010 JJAS La Niña event when convective activity is enhanced. This is consistent with the direct response of water vapor δD to deep convection. In contrast, TES water vapor δD over the western Pacific (R_WP; 10°S–30°N, 120°–140°E) is higher in the La Niña year than in the El Niño year, although convective activity in R_WP varies in the same manner as in R_W120. A comparison of water vapor δD values with convection and water vapor transport suggests that the westward transport of water vapor–isotopic anomalies and changes in the flux of water vapor transported from the central to the western Pacific lead to such an opposite response in the R_WP. These findings help interpret what causes the interannual variations recorded by Indo-Pacific water isotopologues.

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Aircraft measurements of tropospheric ozone over the Western Pacific Ocean

Atmospheric Environment ◽

10.1016/1352-2310(95)00378-9 ◽

1996 ◽

Vol 30 (10-11) ◽

pp. 1763-1772 ◽

Cited By ~ 9

Author(s):

Yukitomo Tsutsumi ◽

Yukio Making ◽

Jørgen Jensen

Keyword(s):

Pacific Ocean ◽

Tropospheric Ozone ◽

Western Pacific ◽

Western Pacific Ocean ◽

Aircraft Measurements ◽

The Western Pacific

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Comparison of TC Temperature and Water Vapor Climatologies between the Atlantic and Pacific Oceans from GPS RO Observations

Journal of Climate ◽

10.1175/jcli-d-18-0074.1 ◽

2018 ◽

Vol 31 (20) ◽

pp. 8557-8571 ◽

Cited By ~ 2

Author(s):

S. Yang ◽

X. Zou ◽

P. S. Ray

Keyword(s):

Water Vapor ◽

Pacific Ocean ◽

Atlantic Ocean ◽

Inner Core ◽

Temperature Anomaly ◽

Water Vapor Pressure ◽

Western Pacific ◽

Western Pacific Ocean ◽

Warm Core ◽

The Western Pacific

Tropical cyclone (TC) temperature and water vapor structures are essential atmospheric variables. In this study, global positioning system (GPS) radio occultation (RO) observations from the GPS RO mission named the Constellation Observing System for Meteorology, Ionosphere, and Climate and the Global Navigation Satellite System (GNSS) Receiver for Atmospheric Sounding on board both MetOp-A and MetOp-B satellites over the 9-yr period from 2007 to 2015 are used to generate a set of composite structures of temperature and water vapor fields within tropical depressions (TDs), tropical storms (TSs), and hurricanes (HUs) over the Atlantic Ocean and TDs, TSs, and typhoons (TYs) over the western Pacific Ocean. The composite TC structures are different over the two oceanic regions, reflecting different climatological environments. The warm cores for TCs over the western Pacific Ocean have higher altitudes and larger sizes than do those over the Atlantic Ocean for all storm categories. A radial variation of the warm-core temperature anomaly with descending altitude is seen, probably resulting from spiral cloud and rainband features. The large TC water vapor pressure anomalies, which are often more difficult to obtain than temperature anomalies, are located below the maximum warm-core temperature anomaly centers. Thus, the maximum values of the fractional water vapor pressure anomaly, defined as the anomaly divided by the environmental value, for TSs and HUs over the Atlantic Ocean (1.4% for TSs and 2.2% for HUs) are higher than those for TSs and TYs over the western Pacific Ocean (1.2% for TSs and 1.4% for TYs). These TC structures are obtained only after a quality control procedure is implemented, which consists of a range check that removes negative refractivity values and unrealistic temperature values, as well as a biweight check that removes data that deviate from the biweight mean by more than 3 times the biweight standard deviation. A limitation of the present study is an inability to resolve the TC inner-core structures because of a lack of sufficient RO profiles that collocate with TCs in their inner-core regions and the relatively coarse along-track resolutions of GPS RO data.

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

Atmospheric Chemistry and Physics Discussions ◽

10.5194/acpd-13-633-2013 ◽

2013 ◽

Vol 13 (1) ◽

pp. 633-688 ◽

Cited By ~ 1

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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