Tropospheric water-vapour and ozone cross-sections in a zonal plane over the central equatorial Pacific Ocean

Kley, D.; SMIT, HGJ; Vömel, H.; Graßl, Hartmut; Ramanathan, V.; Crutzen, P. J.; Williams, S. F.; Meywerk, J.; OLTMANS, SJ

doi:10.1256/smsqj.54311

Cited by 17 publications

(23 citation statements)

References 0 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…Kley et al . 12 likewise hypothesize a mlUT origin for HOLW features near 700 hPa measured by ozonesondes in the equatorial western Pacific during the CEPEX and TOGA-COARE campaigns conducted during fall 1992. Finally, Ridder et al .…”

mentioning

confidence: 79%

“…Large increases in O 3 relative to these low background values have frequently been observed in the TWP mid-troposphere 12 14 18 19 20 21 22 23 24 25 . Many of these studies note that water vapour tends to be depressed, with respect to the local background, for these high O 3 air parcels 12 14 18 19 20 21 22 24 , often attributing the HOLW structures to sources outside the tropical troposphere. Stoller et al .…”

mentioning

confidence: 93%

“…or lower 10 11 . Local convection can transmit this low O 3 air throughout the tropospheric column 12 , resulting at times in O 3 profiles that have mixing ratios of ∼20 p.p.b.v. over an extended altitude range 13 14 .…”

mentioning

confidence: 99%

See 2 more Smart Citations

A pervasive role for biomass burning in tropical high ozone/low water structures

et al. 2016

View full text Add to dashboard Cite

Air parcels with mixing ratios of high O3 and low H2O (HOLW) are common features in the tropical western Pacific (TWP) mid-troposphere (300–700 hPa). Here, using data collected during aircraft sampling of the TWP in winter 2014, we find strong, positive correlations of O3 with multiple biomass burning tracers in these HOLW structures. Ozone levels in these structures are about a factor of three larger than background. Models, satellite data and aircraft observations are used to show fires in tropical Africa and Southeast Asia are the dominant source of high O3 and that low H2O results from large-scale descent within the tropical troposphere. Previous explanations that attribute HOLW structures to transport from the stratosphere or mid-latitude troposphere are inconsistent with our observations. This study suggest a larger role for biomass burning in the radiative forcing of climate in the remote TWP than is commonly appreciated.

show abstract

mentioning

confidence: 79%

mentioning

confidence: 93%

See 1 more Smart Citation

A pervasive role for biomass burning in tropical high ozone/low water structures

et al. 2016

View full text Add to dashboard Cite

show abstract

“…The balloon borne NOAA-FPH has been used in Boulder, Colorado since 1980 (Vömel et al, 1995), producing the longest stratospheric water vapor record in existence (Hurst et al, 2011a). It has also been flown from Lauder, New Zealand since 2004 and has been part of a number of tropical, mid-latitude and polar measurement campaigns (Kley et al, 1997). The measurement uncertainty for this instrument is largely determined by the stability of the frost layer and under optimal performance is around 0.5 K in frost-point temperature.…”

Section: Frost-point Hygrometersmentioning

confidence: 99%

Measurements of Humidity in the Atmosphere and Validation Experiments (MOHAVE)-2009: overview of campaign operations and results

Leblanc¹,

Walsh²,

McDermid³

et al. 2011

Preprint

View full text Add to dashboard Cite

The Measurements of Humidity in the Atmosphere and Validation Experiment (MOHAVE) 2009 campaign took place on 11–27 October 2009 at the JPL Table Mountain Facility in California (TMF). The main objectives of the campaign were to (1) validate the water vapor measurements of several instruments, including, three Raman lidars, two microwave radiometers, two Fourier-Transform spectrometers, and two GPS receivers (column water), (2) cover water vapor measurements from the ground to the mesopause without gaps, and (3) study upper tropospheric humidity variability at timescales varying from a few minutes to several days. A total of 58 radiosondes and 20 Frost-Point hygrometer sondes were launched. Two types of radiosondes were used during the campaign. Non negligible differences in the readings between the two radiosonde types used (Vaisala RS92 and InterMet iMet-1) made a small, but measurable impact on the derivation of water vapor mixing ratio by the Frost-Point hygrometers. As observed in previous campaigns, the RS92 humidity measurements remained within 5 % of the Frost-point in the lower and mid-troposphere, but were too dry in the upper troposphere. Over 270 h of water vapor measurements from three Raman lidars (JPL and GSFC) were compared to RS92, CFH, and NOAA-FPH. The JPL lidar profiles reached 20 km when integrated all night, and 15 km when integrated for 1 h. Excellent agreement between this lidar and the frost-point hygrometers was found throughout the measurement range, with only a 3 % (0.3 ppmv) mean wet bias for the lidar in the upper troposphere and lower stratosphere (UTLS). The other two lidars provided satisfactory results in the lower and mid-troposphere (2–5 % wet bias over the range 3–10 km), but suffered from contamination by fluorescence (wet bias ranging from 5 to 50 % between 10 km and 15 km), preventing their use as an independent measurement in the UTLS. The comparison between all available stratospheric sounders allowed to identify only the largest biases, in particular a 10 % dry bias of the Water Vapor Millimeter-wave Spectrometer compared to the Aura-Microwave Limb Sounder. No other large, or at least statistically significant, biases could be observed. Total Precipitable Water (TPW) measurements from six different co-located instruments were available. Several retrieval groups provided their own TPW retrievals, resulting in the comparison of 10 different datasets. Agreement within 7 % (0.7 mm) was found between all datasets. Such good agreement illustrates the maturity of these measurements and raises confidence levels for their use as an alternate or complementary source of calibration for the Raman lidars. Tropospheric and stratospheric ozone and temperature measurements were also available during the campaign. The water vapor and ozone lidar measurements, together with the advected potential vorticity results from the high-resolution transport model MIMOSA, allowed the identificat...

show abstract

“…This dataset (92 soundings) can be considered as a random sample with respect to weather events, in an area deliberately chosen because sharp gradients in cloud and water vapour were anticipated (Kley et al 1997). …”

Section: Datamentioning

confidence: 99%

Untitled

2003

Quart J Royal Meteoro Soc

View full text Add to dashboard Cite

SUMMARYProbability distribution functions of tropospheric water vapour in the tropics are shown to be commonly bimodal. This bimodality implies sharp gradients between dry and moist regimes in space and time. A method of testing for and quantifying bimodality is introduced. Using this method, the bimodality of water vapour is surveyed in satellite and in situ observations, as well as in global model re-analysis data and simulations. The bimodality suggests that the radiative drying time after an injection of moisture by convection is short (1-2 days) compared to a homogenizing time, whether physical (mixing) or mathematical (averaging). It is shown that the local bimodality found in cloud-model simulations and in situ point measurements disappears with modest time averaging (18 h and 200 km), but then reappears on the global-scale, where dry and moist regions are separated so widely that synoptic-and large-scale mixing times exceed the drying time-scale. Large discrepancies exist in the ability to reproduce the global-scale bimodality by global model re-analysis and simulations.

show abstract

Tropospheric water-vapour and ozone cross-sections in a zonal plane over the central equatorial Pacific Ocean

Cited by 17 publications

References 0 publications

A pervasive role for biomass burning in tropical high ozone/low water structures

A pervasive role for biomass burning in tropical high ozone/low water structures

Measurements of Humidity in the Atmosphere and Validation Experiments (MOHAVE)-2009: overview of campaign operations and results

Untitled

Contact Info

Product

Resources

About