Thermal structure of intense convective clouds derived from GPS radio occultations

Biondi, Riccardo; Randel, William J.; Ho, Shu‐Peng; Neubert, Torsten; Syndergaard, Stig

doi:10.5194/acp-12-5309-2012

Cited by 68 publications

(74 citation statements)

References 27 publications

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“…There is a considerable amount of observational evidence of local cooling of the lower stratosphere over land convective systems, ranging from 2 K to 10 K (e.g. Johnson and Kriete, 1982;Danielsen, 1993;Sherwood and Dessler, 2003;Pommereau and Held, 2007;Cairo et al, 2010;Biondi et al, 2012). However the contributions of various processes to the TTL thermal structure are still unclear.…”

Section: S M Khaykin Et Al: Impact Of Land Convection On Temperatumentioning

confidence: 99%

Impact of land convection on temperature diurnal variation in the tropical lower stratosphere inferred from COSMIC GPS radio occultations

2013

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Following recent studies evidencing the influence of deep convection on the chemical composition and thermal structure of the tropical lower stratosphere, we explore its impact on the temperature diurnal variation in the upper troposphere and lower stratosphere using the high-resolution COSMIC GPS radio-occultation temperature measurements spanning from 2006 through 2011. The temperature in the lowermost stratosphere over land during summer displays a marked diurnal cycle characterized by an afternoon cooling. This diurnal cycle is shown collocated with most intense land convective areas observed by the Tropical Rainfall Measurement Mission (TRMM) precipitation radar and in phase with the maximum overshooting occurrence frequency in late afternoon. Two processes potentially responsible for that are identified: (i) non-migrating tides, whose physical nature is internal gravity waves, and (ii) local cross-tropopause mass transport of adiabatically cooled air by overshooting turrets. Although both processes can contribute, only the lofting of adiabatically cooled air is well captured by models, making it difficult to characterize the contribution of non-migrating tides. The impact of deep convection on the temperature diurnal cycle is found larger in the southern tropics, suggesting more vigorous convection over clean rain forest continents than desert areas and polluted continents in the northern tropics

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Section: S M Khaykin Et Al: Impact Of Land Convection On Temperatumentioning

confidence: 99%

Impact of land convection on temperature diurnal variation in the tropical lower stratosphere inferred from COSMIC GPS radio occultations

2013

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“…Part of the equatorial wave spectrum in the TTL is known to be coupled with convection, a small part of which reaches the tropopause (Wheeler and Kiladis, 1999;Fueglistaler et al, 2009), and the occurrence of cirrus clouds is also related to equatorial waves (Virts and Wallace, 2010). Case studies using GPS-RO data have investigated the temperature inversion generally found at cloud tops for convective clouds (Biondi et al, 2012) and nonconvective cirrus clouds (Taylor et al, 2011). The signal from any cloud coupled with an equatorial wave would be captured by its corresponding wavenumber-frequency domain filter, since the cloud signal would travel together with the wave in the same domain.…”

Section: Average Effect On the Seasonal Zonal-mean Profilementioning

confidence: 99%

The tropical tropopause inversion layer: variability and modulation by equatorial waves

2016

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Abstract. The tropical tropopause layer (TTL) acts as a transition layer between the troposphere and the stratosphere over several kilometers, where air has both tropospheric and stratospheric properties. Within this region, a fine-scale feature is located: the tropopause inversion layer (TIL), which consists of a sharp temperature inversion at the tropopause and the corresponding high static stability values right above, which theoretically affect the dispersion relations of atmospheric waves like Rossby or inertia-gravity waves and hamper stratosphere-troposphere exchange (STE). Therefore, the TIL receives increasing attention from the scientific community, mainly in the extratropics so far. Our goal is to give a detailed picture of the properties, variability and forcings of the tropical TIL, with special emphasis on small-scale equatorial waves and the quasi-biennial oscillation (QBO).We use high-resolution temperature profiles from the COSMIC satellite mission, i.e., ∼ 2000 measurements per day globally, between 2007 and 2013, to derive TIL properties and to study the fine-scale structures of static stability in the tropics. The situation at near tropopause level is described by the 100 hPa horizontal wind divergence fields, and the vertical structure of the QBO is provided by the equatorial winds at all levels, both from the ERA-Interim reanalysis.We describe a new feature of the equatorial static stability profile: a secondary stability maximum below the zero wind line within the easterly QBO wind regime at about 20-25 km altitude, which is forced by the descending westerly QBO phase and gives a double-TIL-like structure. In the lowermost stratosphere, the TIL is stronger with westerly winds. We provide the first evidence of a relationship between the tropical TIL strength and near-tropopause divergence, with stronger (weaker) TIL with near-tropopause divergent (convergent) flow, a relationship analogous to that of TIL strength with relative vorticity in the extratropics.To elucidate possible enhancing mechanisms of the tropical TIL, we quantify the signature of the different equatorial waves on the vertical structure of static stability in the tropics. All waves show, on average, maximum cold anomalies at the thermal tropopause, warm anomalies above and a net TIL enhancement close to the tropopause. The main drivers are Kelvin, inertia-gravity and Rossby waves. We suggest that a similar wave modulation will exist at mid-and polar latitudes from the extratropical wave modes.

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“…Studies include the thermal and dynamical structure of UTLS during TC (Koteswaram, 1967), horizontal and vertical structure of temperature in the cyclone (Waco, 1970), temperature and ozone variations in a hurricane (Penn, 1965), troposphere-stratosphere transport and dehydration in cyclones (Danielsen, 1993), UTLS structure during TCs using AIRS and MLS measurements (Ray and Rosenlof, 2007), RO bending angle anomalies during tropical cyclones (Biondi et al, 2011), thermal structure of intense convective clouds derived from GPS RO (Biondi et al, 2012), estimating the TC cloud top height and vertical temperature structure using GPS RO measurements (Biondi et al, 2013), and observations of temperature in the UTLS of tropical weather disturbances (Davis et al, 2014). Note that the above list is only indicative, not exhaustive.…”

Section: Published By Copernicus Publications On Behalf Of the Europementioning

confidence: 99%

Effect of tropical cyclones on the tropical tropopause parameters observed using COSMIC GPS RO data

Babu

Ratnam

Basha³

et al. 2015

Atmos. Chem. Phys.

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Abstract. Tropical cyclones (TCs) are deep convective synoptic-scale systems that play an important role in modifying the thermal structure, tropical tropopause parameters and hence also modify stratosphere-troposphere exchange (STE) processes. In the present study, high vertical resolution and high accuracy measurements from COSMIC Global Positioning System (GPS) radio occultation (RO) measurements are used to investigate and quantify the effect of tropical cyclones that occurred over Bay of Bengal and Arabian Sea in the last decade on the tropical tropopause parameters. The tropopause parameters include cold-point tropopause altitude (CPH) and temperature (CPT), lapse-rate tropopause altitude (LRH) and temperature (LRT) and the thickness of the tropical tropopause layer (TTL), that is defined as the layer between convective outflow level (COH) and CPH, obtained from GPS RO data. From all the TC events, we generate the mean cyclone-centred composite structure for the tropopause parameters and removed it from the climatological mean obtained from averaging the GPS RO data from 2002 to 2013. Since the TCs include eye, eye walls and deep convective bands, we obtained the tropopause parameters based on radial distance from the cyclone eye. In general, decrease in the CPH in the eye is noticed as expected. However, as the distance from the cyclone eye increases by 300, 400, and 500 km, an enhancement in CPH (CPT) and LRH (LRT) is observed. Lowering of CPH (0.6 km) and LRH (0.4 km) values with coldest CPT and LRT (2-3 K) within a 500 km radius of the TC centre is noticed. Higher (2 km) COH leading to the lowering of TTL thickness (2-3 km) is clearly observed. There are multiple tropopause structures in the profiles of temperature obtained within 100 km from the centre of the TC. These changes in the tropopause parameters are expected to influence the water vapour transport from the troposphere to the lower stratosphere, and ozone from the lower stratosphere to the upper troposphere, hence influencing STE processes.

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Thermal structure of intense convective clouds derived from GPS radio occultations

Cited by 68 publications

References 27 publications

Impact of land convection on temperature diurnal variation in the tropical lower stratosphere inferred from COSMIC GPS radio occultations

Impact of land convection on temperature diurnal variation in the tropical lower stratosphere inferred from COSMIC GPS radio occultations

The tropical tropopause inversion layer: variability and modulation by equatorial waves

Effect of tropical cyclones on the tropical tropopause parameters observed using COSMIC GPS RO data

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