Diurnal variability of the global tropical tropopause: results inferred from COSMIC observations

Suneeth, K. V.; Das, Siddarth Shankar; Das, Subrata Kumar

doi:10.1007/s00382-016-3512-x

Cited by 17 publications

(11 citation statements)

References 42 publications

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“…Thus, the convective growing stage is quicker over land (7 h) than over ocean (10 h). These results are consistent with a previous study by Takahashi and Luo (2014), showing that the lifetime of the mature stage of the deep convection is between 6 and 12 h after the onset of the deep convection considering the Northern and Southern Hemisphere over the tropics. Furthermore, while the estimated means of IWC UT min over land and ocean are very close (1.34 and 1.36 mg m −3 , respectively), the means of the land and ocean IWC UT show great differences (2.73 and 0.60 mg m −3 , respectively).…”

Section: Amount Of Ice Injected Into the Austral Convective Utsupporting

confidence: 93%

Ice injected into the tropopause by deep convection – Part 1: In the austral convective tropics

et al. 2019

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Abstract. The contribution of deep convection to the amount of water vapour and ice in the tropical tropopause layer (TTL) from the tropical upper troposphere (UT; around 146 hPa) to the tropopause level (TL; around 100 hPa) is investigated. Ice water content (IWC) and water vapour (WV) measured in the UT and the TL by the Microwave Limb Sounder (MLS; Version 4.2) are compared to the precipitation (Prec) measured by the Tropical Rainfall Measurement Mission (TRMM; Version 007). The two datasets, gridded within 2∘ × 2∘ horizontal bins, have been analysed during the austral convective season, December, January, and February (DJF), from 2004 to 2017. MLS observations are performed at 01:30 and 13:30 local solar time, whilst the Prec dataset is constructed with a time resolution of 1 h. The new contribution of this study is to provide a much more detailed picture of the diurnal variation of ice than is provided by the very limited (two per day) MLS observations. Firstly, we show that IWC represents 70 % and 50 % of the total water in the tropical UT and TL, respectively, and that Prec is spatially highly correlated with IWC in the UT (Pearson's linear coefficient R=0.7). We propose a method that uses Prec as a proxy for deep convection bringing ice up to the UT and TL during the growing stage of convection, in order to estimate the amount of ice injected into the UT and the TL, respectively. We validate the method using ice measurements from the Superconducting Submillimeter-Wave Limb-Emission Sounder (SMILES) during the period DJF 2009–2010. Next, the diurnal cycle of injection of IWC into the UT and the TL by deep convection is calculated by the difference between the maximum and the minimum in the estimated diurnal cycle of IWC in these layers and over selected convective zones. Six tropical highly convective zones have been chosen: South America, South Africa, Pacific Ocean, Indian Ocean, and the Maritime Continent region, split into land (MariCont-L) and ocean (MariCont-O). IWC injection is found to be 2.73 and 0.41 mg m−3 over tropical land in the UT and TL, respectively, and 0.60 and 0.13 mg m−3 over tropical ocean in the UT and TL, respectively. The MariCont-L region has the greatest ice injection in both the UT and TL (3.34 and 0.42–0.56 mg m−3, respectively). The MariCont-O region has less ice injection than MariCont-L (0.91 mg m−3 in the UT and 0.16–0.34 mg m−3 in TL) but has the highest diurnal minimum value of IWC in the TL (0.34–0.37 mg m−3) among all oceanic zones.

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Section: Amount Of Ice Injected Into the Austral Convective Utsupporting

confidence: 93%

Ice injected into the tropopause by deep convection – Part 1: In the austral convective tropics

et al. 2019

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“…Details of uncertainty, precision, and accuracy of radiosonde/ozonesonde can be found in Akhil Raj et al (2018) and Das et al (2019). The cold-point and convective tropopause (COT) are derived from the radiosonde-measured temperature profile as described in Mehta et al (2008) and Suneeth et al (2017).…”

Section: Radiosonde/ozonesondementioning

confidence: 99%

“…Radio Science temperature inversion layer, and thus, it is highly stable (Mehta et al, 2008;Suneeth et al, 2017;Sunilkumar et al, 2015). The tropospheric air is highly humid, especially during the ISM, whereas the stratospheric air is dry and ozone rich in all the seasons.…”

Section: 1029/2019rs006969mentioning

confidence: 99%

“…In this context, we have plotted the monthly mean tropopause altitude and temperature (averaged of 2006-2015) in Figure 7. A mechanism for the role of tropopause oscillation in exchange of air masses between the stratosphere and the troposphere is explained in Suneeth et al, (2017). The authors proposed a hypothesis that the oscillating tropopause altitude from the higher-to-lower-to-higher altitude leads to the intrusion of ozone-rich stratospheric air downward into the troposphere as the stratospheric air is highly…”

Section: Climatology Of Ozone and Water Vapormentioning

confidence: 99%

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Long‐Term Observations of Stratosphere‐Troposphere Exchange Using MST Radar and Aura MLS Measurements Over a Tropical Station Gadanki

et al. 2020

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This paper presents the climatology of stratospheric intrusion into the troposphere during the Indian Summer Monsoon (ISM) observed using the mesosphere-stratosphere-troposphere (MST) radar located at Gadanki (13.5°N, 79.2°E). The most significant and new observation is the presence of enhanced signal-to-noise ratio (SNR) of 3 dB and half-power full spectral width of >0.2 m s −1 in the vicinity of tropopause during the ISM. Downdrafts (updrafts) are dominated in the vicinity of tropopause from April to June (July to March). The result of stratospheric air intrusion is also supported with 10 years of ozone measurements obtained from Aura-Microwave Limb Sounder (MLS) and 5 years of in situ ozonesonde observations. Detailed analysis shows that the horizontal advection along with turbulence in the vicinity of tropopause caused by the tropical easterly jet and tropopause altitude variability is the prime candidate for stratosphere to troposphere transport of ozone. In contrast, the tropical tropopause temperature plays a significant role in the troposphere to stratosphere transport of water vapor during the ISM. The significance of the present study is to qualitatively constitute the climatology of these exchange processes over Gadanki using Indian MST radar.

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“…Based on these studies and with data from the space-borne Microwave Limb Sounder (MLS) instrument, Carminati et al (2014) studied the diurnal cycle of WV and ice in the TL over Africa and South America and have shown the presence of a strong diurnal signal over the two continents. Suneeth et al (2017) have shown the differences in the diurnal cycles of CPT altitudes and CPT temperatures over tropical land and ocean.…”

mentioning

confidence: 99%

Ice injected up to the Tropopause by Deep Convection: 1) in the Austral Convective Tropics

Dion¹,

Ricaud²,

Haynes³

et al. 2018

Preprint

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The impact of deep convection on the water budget (water vapor and ice) from the tropical Upper Troposphere (UT, around 146 hPa) to the Tropopause Level (TL, around 100 hPa) is investigated. Ice water content (IWC) and water vapour (WV) measured in the UT and the TL by the Microwave Limb Sounder (MLS, Version 4.2) are compared to the precipitation (Prec) measured by the Tropical Rainfall Measurement Mission (TRMM, Version 007). The two datasets, gridded within 2°×2° horizontal bins, have been analyzed during the austral convective season: December, January and February (DJF) from 2004 to 2017. MLS observations are performed at 01:30 and 13:30 Local Solar Time whilst the Prec dataset is constructed with a time resolution of 1 hour.The new contribution of this study is to provide a much more detailed picture of the diurnal variation of ice than is provided by the very limited (2 per day) MLS observations. Firstly, we show that IWC represents 70 and 50% of the total water in the tropical UT and TL, respectively and that Prec is spatially highly correlated with IWC in the UT (Pearson linear coefficient R=0.7). We propose a method using Prec as a proxy of deep convection bringing ice up into the TL, during the growing stage of the convection. We validate the method using ice measurements from the Superconducting Submillimeter-Wave Limb-Emission Sounder (SMILES) during the period DJF 2009-2010. Next, the diurnal amount of IWC injected into the UT and the TL by deep convection is calculated by the difference between the maximum and the minimum in the estimated diurnal cycle of IWC in these layers and over selected convective zones. Six tropical highly convective zones have been chosen: South America, South Africa, Pacific Ocean, Indian Ocean, and the Maritime Continent region, split into land (MariCont-L) and ocean (MariCont-O). IWC injection is found to be 2.73 and 0.41 mg m −3 over tropical land in the UT and TL, respectively, and 0.60 and 0.13 mg m −3 over tropical ocean in the UT and TL, respectively. The MariCont-L region has the greatest ice injection in both UT and TL (3.34 and 0.42-0.56 mg m −3 , respectively). The MariCont-O region has less ice injection than MariCont-L (0.91 mg m −3 in the UT and 0.16-0.34 mg m −3 in TL), but has the highest diurnal minimum value of IWC in the TL (0.34-0.37 mg m −3 ) among all oceanic zones.

show abstract

Diurnal variability of the global tropical tropopause: results inferred from COSMIC observations

Cited by 17 publications

References 42 publications

Ice injected into the tropopause by deep convection – Part 1: In the austral convective tropics

Ice injected into the tropopause by deep convection – Part 1: In the austral convective tropics

Long‐Term Observations of Stratosphere‐Troposphere Exchange Using MST Radar and Aura MLS Measurements Over a Tropical Station Gadanki

Ice injected up to the Tropopause by Deep Convection: 1) in the Austral Convective Tropics

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