scholarly journals VARIASI TRACE GASES SELAMA 10 TAHUN DAN PENCAMPURAN DI SEKITAR LAPISAN TROPOPAUSE DI INDONESIA BERBASIS SATELIT (TRACE GASES VARIATION FOR 10 YEARS AND MIXING AROUND THE TROPOPAUSE LAYERS IN INDONESIA BASED ON SATELLITE)

2018 ◽  
Vol 14 (2) ◽  
pp. 83
Author(s):  
Novita Ambarsari ◽  
Ninong Komala ◽  
Fanny Aditya Putri
Keyword(s):  
Time Series ◽  
Cross Section ◽  
Lower Stratosphere ◽  
Trace Gases ◽  
Radiation Budget ◽  
Vertical Profiles ◽  
Upper Troposphere ◽  
Tropical Tropopause Layer ◽  
Tropical Tropopause ◽  
Budget Analysis

Measurement of trace gases (CO, O3, CH3Cl, HCl, H2O, and HNO3) and temperatures around upper troposphere/lower stratosphere (UT/LS) or rather around Tropical Tropopause Layer (TTL) in Indonesia by using Microwave Limb Sounder (MLS) instrument board on Satellite AURA for 2005-2014 period to make variations of these gases over the 10 years around TTL allows to be studied more deeply. TTL becomes the main route entry of chemical compounds and aerosols originating in the troposphere into the stratosphere. The composition of minor gases in the TTL is very important because it affects the global radiation budget. Analysis of vertical profiles of these gases in the TTL was done to determine the suitability of the concept of TTL which starts from the upper troposphere to the lower stratosphere. Other method are the time series diagram of the altitude (height versus time series cross section) which shows the annual and interannual variations in vertical profiles of these gases in the TTL and the possible influence of the dynamics of the atmosphere. The results showed correlation of these gases with ozone showed most of the air in the stratosphere is experiencing mixing in the TTL. In addition, changes in concentration and temperature values in the TTL have been calculated using the trends of each parameter and it is known that the parameters of HCl, CH3Cl, and temperature show respective decreases of -0.036 ppmv, -0.024 ppmv, and -0.456 K. As for other parameters such as ozone, CO, H2O, and HNO3 showed an increase of respectively 0.0036 ppmv, 0.0096 ppmv, 0.108 ppmv, and 0.06 ppmv. AbstrakPengukuran trace gases (CO, O3, CH3Cl, HCl, H2O, HNO3) dan temperatur di sekitar lapisan troposfer atas/stratosfer bawah (UT/LS) atau tepatnya di sekitar Tropical Tropopause Layer (TTL) di Indonesia menggunakan instrumen Microwave Limb Sounder (MLS) pada Satelit AURA periode 2005-2014 menjadikan variasi gas-gas tersebut selama 10 tahun di sekitar TTL memungkinkan untuk dikaji lebih dalam. TTL menjadi jalur utama masuknya senyawa-senyawa kimia dan aerosol yang bersumber di troposfer ke stratosfer. Komposisi gas-gas minor di TTL sangat penting karena mempengaruhi budget radiasi global. Analisis profil vertikal gas-gas tersebut di TTL dilakukan untuk mengetahui kesesuaian konsep TTL yang dimulai dari lapisan troposfer atas hingga ke stratosfer bawah. Metode lainnya adalah dengan diagram time series terhadap ketinggian (time series versus height cross section) yang menunjukkan variasi tahunan maupun antar tahunan profil vertikal gas-gas tersebut di TTL serta kemungkinan adanya pengaruh dari proses dinamika atmosfer. Hasil penelitian menunjukkan korelasi gas-gas tersebut dengan ozon menunjukkan adanya sebagian udara di stratosfer yang mengalami pencampuran di wilayah TTL. Selain itu, perubahan nilai konsentrasi dan temperatur di TTL telah dihitung menggunakan trend masing-masing parameter dan diketahui bahwa parameter HCl, CH3Cl, dan temperatur menunjukkan penurunan masing-masing sebesar  -0,036 ppmv, -0,024 ppmv, dan -0,456 K. Adapun parameter lain seperti ozon, CO, H2O, dan HNO3 menunjukkan adanya peningkatan masing-masing sebesar 0,0036 ppmv, 0,0096 ppmv, 0,108 ppmv, dan 0,06 ppmv.  

scholarly journals The impact of overshooting deep convection on local transport and mixing in the tropical upper troposphere/lower stratosphere (UTLS)

2015 ◽  
Vol 15 (11) ◽  
pp. 6467-6486 ◽  
Author(s):  
W. Frey ◽  
R. Schofield ◽  
P. Hoor ◽  
D. Kunkel ◽  
F. Ravegnani ◽  
...  
Keyword(s):  
Lower Stratosphere ◽  
Deep Convection ◽  
Horizontal Resolution ◽  
Transport Processes ◽  
Convective System ◽  
Upper Troposphere ◽  
Tropical Tropopause Layer ◽  
Tropical Tropopause ◽  
Transport And Mixing ◽  
The Impact

Abstract. In this study we examine the simulated downward transport and mixing of stratospheric air into the upper tropical troposphere as observed on a research flight during the SCOUT-O3 campaign in connection with a deep convective system. We use the Advanced Research Weather and Research Forecasting (WRF-ARW) model with a horizontal resolution of 333 m to examine this downward transport. The simulation reproduces the deep convective system, its timing and overshooting altitudes reasonably well compared to radar and aircraft observations. Passive tracers initialised at pre-storm times indicate the downward transport of air from the stratosphere to the upper troposphere as well as upward transport from the boundary layer into the cloud anvils and overshooting tops. For example, a passive ozone tracer (i.e. a tracer not undergoing chemical processing) shows an enhancement in the upper troposphere of up to about 30 ppbv locally in the cloud, while the in situ measurements show an increase of 50 ppbv. However, the passive carbon monoxide tracer exhibits an increase, while the observations show a decrease of about 10 ppbv, indicative of an erroneous model representation of the transport processes in the tropical tropopause layer. Furthermore, it could point to insufficient entrainment and detrainment in the model. The simulation shows a general moistening of air in the lower stratosphere, but it also exhibits local dehydration features. Here we use the model to explain the processes causing the transport and also expose areas of inconsistencies between the model and observations.

scholarly journals Evidence of horizontal and vertical transport of water in the Southern Hemisphere tropical tropopause layer (TTL) from high-resolution balloon observations

2016 ◽  
Vol 16 (18) ◽  
pp. 12273-12286 ◽  
Author(s):  
Sergey M. Khaykin ◽  
Jean-Pierre Pommereau ◽  
Emmanuel D. Riviere ◽  
Gerhard Held ◽  
Felix Ploeger ◽  
...  
Keyword(s):  
High Resolution ◽  
Water Vapour ◽  
Southern Hemisphere ◽  
Water Budget ◽  
Lower Stratosphere ◽  
Vertical Profiles ◽  
Tropical Tropopause Layer ◽  
Horizontal Transport ◽  
Tropical Tropopause

Abstract. High-resolution in situ balloon measurements of water vapour, aerosol, methane and temperature in the upper tropical tropopause layer (TTL) and lower stratosphere are used to evaluate the processes affecting the stratospheric water budget: horizontal transport (in-mixing) and hydration by cross-tropopause overshooting updrafts. The obtained in situ evidence of these phenomena are analysed using satellite observations by Aura MLS (Microwave Limb Sounder) and CALIPSO (Cloud-Aerosol Lidar and Infrared Pathfinder Satellite Observation) together with trajectory and transport modelling performed using CLaMS (Chemical Lagrangian Model of the Stratosphere) and HYSPLIT (Hybrid Single-Particle Lagrangian Integrated Trajectory) model. Balloon soundings were conducted during March 2012 in Bauru, Brazil (22.3° S) in the frame of the TRO-Pico campaign for studying the impact of convective overshooting on the stratospheric water budget. The balloon payloads included two stratospheric hygrometers: FLASH-B (Fluorescence Lyman-Alpha Stratospheric Hygrometer for Balloon) and Pico-SDLA instrument as well as COBALD (Compact Optical Backscatter Aerosol Detector) sondes, complemented by Vaisala RS92 radiosondes. Water vapour vertical profiles obtained independently by the two stratospheric hygrometers are in excellent agreement, ensuring credibility of the vertical structures observed. A signature of in-mixing is inferred from a series of vertical profiles, showing coincident enhancements in water vapour (of up to 0.5 ppmv) and aerosol at the 425 K (18.5 km) level. Trajectory analysis unambiguously links these features to intrusions from the Southern Hemisphere extratropical stratosphere, containing more water and aerosol, as demonstrated by MLS and CALIPSO global observations. The in-mixing is successfully reproduced by CLaMS simulations, showing a relatively moist filament extending to 20° S. A signature of local cross-tropopause transport of water is observed in a particular sounding, performed on a convective day and revealing water vapour enhancements of up to 0.6 ppmv as high as the 404 K (17.8 km) level. These are shown to originate from convective overshoots upwind detected by an S-band weather radar operating locally in Bauru. The accurate in situ observations uncover two independent moisture pathways into the tropical lower stratosphere, which are hardly detectable by space-borne sounders. We argue that the moistening by horizontal transport is limited by the weak meridional gradients of water, whereas the fast convective cross-tropopause transport, largely missed by global models, can have a substantial effect, at least at a regional scale.

scholarly journals Evidence of horizontal and vertical transport of water in the Southern Hemisphere Tropical Tropopause Layer (TTL) from high-resolution balloon observations

2016 ◽  
pp. 1-15
Author(s):  
Sergey M. Khaykin ◽  
Jean-Pierre Pommereau ◽  
Emmanuel D. Riviere ◽  
Gerhard Held ◽  
Felix Ploeger ◽  
...  
Keyword(s):  
High Resolution ◽  
Water Vapour ◽  
Southern Hemisphere ◽  
Water Budget ◽  
Lower Stratosphere ◽  
Vertical Profiles ◽  
Tropical Tropopause Layer ◽  
Horizontal Transport ◽  
Tropical Tropopause

High-resolution in situ balloon measurements of water vapour, aerosol, methane and temperature in the upper Tropical Tropopause Layer (TTL) and lower stratosphere are used to evaluate the processes controlling the stratospheric water budget: horizontal transport (inmixing) and hydration by cross-tropopause overshooting updrafts. The obtained in situ evidences of these phenomena are analyzed using satellite observations by Aura MLS (Microwave Limb Sounder) and CALIPSO (Cloud-Aerosol Lidar and Infrared Pathfinder Satellite Observation) together with trajectory and transport modeling performed using CLaMS (Chemical Lagrangian Model of the Stratosphere) and HYSPLIT (HYbrid Single-Particle Lagrangian Integrated Trajectory) model. <br><br> Balloon soundings were conducted during March 2012 in Bauru, Brazil (22.3°&thinsp;S) in the frame of the TRO-Pico campaign for studying the impact of convective overshooting on the stratospheric water budget. The balloon payloads included two stratospheric hygrometers: FLASH-B (Fluorescence Lyman-Alpha Stratospheric Hygrometer for Balloon) and Pico-SDLA instrument as well as COBALD (Compact Optical Backscatter Aerosol Detector) sondes, complemented by Vaisala RS-92 radiosondes. Water vapour vertical profiles obtained independently by the two stratospheric hygrometers are in excellent agreement, ensuring credibility of the vertical structures observed. <br><br> A signature of in-mixing is inferred from a series of vertical profiles, showing coincident enhancements in water vapour and aerosol at the 425&thinsp;K (18.5&thinsp;km) level. Trajectory analysis unambiguously links these features to intrusions from the Southern Hemisphere extra-tropical stratosphere, containing more water and aerosol, as demonstrated by MLS and CALIPSO global observations. The in-mixing is successfully reproduced by CLaMS simulations, showing a relatively moist filament extending to 20&thinsp;S°. A signature of local cross-tropopause transport of water is observed in a particular sounding, performed on a convective day and revealing water vapour enhancements of up to 0.6&thinsp;ppmv as high as the 404&thinsp;K (17.8&thinsp;km) level. These are shown to originate from convective overshoots upwind detected by an S-band weather radar operating locally in Bauru. <br><br> The accurate in situ observations uncover two independent moisture pathways into the tropical lower stratosphere, whose manifestations are hardly detectable by space-borne sounders. We argue that the moistening by horizontal transport is limited by the weak meridional gradients of water, whereas the fast convective cross-tropopause transport, largely missed by global models, can have a substantial effect, at least at a regional scale.

scholarly journals The governing processes and timescales of stratosphere-to-troposphere transport and its contribution to ozone in the Arctic troposphere

2009 ◽  
Vol 9 (9) ◽  
pp. 3011-3025 ◽  
Author(s):  
Q. Liang ◽  
A. R. Douglass ◽  
B. N. Duncan ◽  
R. S. Stolarski ◽  
J. C. Witte
Keyword(s):  
Lower Stratosphere ◽  
Trace Gases ◽  
Lower Troposphere ◽  
Threshold Level ◽  
The Arctic ◽  
Trace Gas ◽  
Seasonal Cycles ◽  
Upper Troposphere ◽  
Budget Analysis ◽  
Wet Removal

Abstract. We used the seasonality of a combination of atmospheric trace gases and idealized tracers to examine stratosphere-to-troposphere transport and its influence on tropospheric composition in the Arctic. Maximum stratosphere-to-troposphere transport of CFCs and O3 occurs in April as driven by the Brewer-Dobson circulation. Stratosphere-troposphere exchange (STE) occurs predominantly between 40° N to 80° N with stratospheric influx in the mid-latitudes (30–70° N) accounting for 67–81% of the air of stratospheric origin in the Northern Hemisphere extratropical troposphere. Transport from the lower stratosphere to the lower troposphere (LT) takes three months on average, one month to cross the tropopause, the second month to travel from the upper troposphere (UT) to the middle troposphere (MT), and the third month to reach the LT. During downward transport, the seasonality of a trace gas can be greatly impacted by wet removal and chemistry. A comparison of idealized tracers with varying lifetimes suggests that when initialized with the same concentrations and seasonal cycles at the tropopause, trace gases that have shorter lifetimes display lower concentrations, smaller amplitudes, and earlier seasonal maxima during transport to the LT. STE contributes to O3 in the Arctic troposphere directly from the transport of O3 and indirectly from the transport of NOy. Direct transport of O3 from the stratosphere accounts for 78% of O3 in the Arctic UT with maximum contributions occurring from March to May. The stratospheric contribution decreases significantly in the MT/LT (20–25% of total O3) and shows a very weak March–April maximum. Our NOx budget analysis in the Arctic UT shows that during spring and summer, the stratospheric injection of NOy-rich air increases NOx concentrations above the 20 pptv threshold level, thereby shifting the Arctic UT from a regime of net photochemical ozone loss to one of net production with rates as high as +16 ppbv/month.

scholarly journals The impact of overshooting deep convection on local transport and mixing in the tropical upper troposphere/lower stratosphere (UTLS)

2015 ◽  
Vol 15 (1) ◽  
pp. 1041-1091 ◽  
Author(s):  
W. Frey ◽  
R. Schofield ◽  
P. Hoor ◽  
D. Kunkel ◽  
F. Ravegnani ◽  
...  
Keyword(s):  
Lower Stratosphere ◽  
Deep Convection ◽  
Horizontal Resolution ◽  
Transport Processes ◽  
Convective System ◽  
Upper Troposphere ◽  
Tropical Tropopause Layer ◽  
Tropical Tropopause ◽  
Transport And Mixing ◽  
The Impact

Abstract. In this study we examine the simulated downward transport and mixing of stratospheric air into the upper tropical troposphere as observed on a research flight during the SCOUT-O3 campaign in connection to a deep convective system. We use the Advanced Research Weather and Research Forecasting (WRF-ARW) model with a horizontal resolution of 333 m to examine this downward transport. The simulation reproduces the deep convective system, its timing and overshooting altitudes reasonably well compared to radar and aircraft observations. Passive tracers initialised at pre-storm times indicate the downward transport of air from the stratosphere to the upper troposphere as well as upward transport from the boundary layer into the cloud anvils and overshooting tops. For example, a passive ozone tracer (i.e. a tracer not undergoing chemical processing) shows an enhancement in the upper troposphere of up to about 30 ppbv locally in the cloud, while the in situ measurements show an increase of 50 ppbv. However, the passive carbon monoxide tracer exhibits an increase, while the observations show a decrease of about 10 ppbv, indicative of an erroneous model representation of the transport processes in the tropical tropopause layer. Furthermore, it could point to insufficient entrainment and detrainment in the model. The simulation shows a general moistening of air in the lower stratosphere but it also exhibits local dehydration features. Here we use the model to explain the processes causing the transport and also expose areas of inconsistencies between the model and observations.

scholarly journals Overshooting of clean tropospheric air in the tropical lower stratosphere as seen by the CALIPSO lidar

2011 ◽  
Vol 11 (18) ◽  
pp. 9683-9696 ◽  
Author(s):  
J.-P. Vernier ◽  
J.-P. Pommereau ◽  
L. W. Thomason ◽  
J. Pelon ◽  
A. Garnier ◽  
...  
Keyword(s):  
Biomass Burning ◽  
Lower Stratosphere ◽  
Thermal Structure ◽  
Radiative Heating ◽  
Major Contributor ◽  
Upper Troposphere ◽  
Tropical Tropopause Layer ◽  
Volcanic Plumes ◽  
Tropical Tropopause ◽  
Organic Particles

Abstract. The evolution of aerosols in the tropical upper troposphere/lower stratosphere between June 2006 and October 2009 is examined using the observations of the space borne CALIOP lidar aboard the CALIPSO satellite. Superimposed on several volcanic plumes and soot from an extreme biomass-burning event in 2009, the measurements reveal the existence of fast-cleansing episodes in the lower stratosphere to altitudes as high as 20 km. The cleansing of the layer, which extends from 14 to 20 km, takes place within 1 to 4 months during the southern tropics convective season that transports aerosol-poor tropospheric air into the lower stratosphere. In contrast, the convective season of the Northern Hemisphere summer shows an increase in the particle load at the tropopause consistent with a lofting of air rich with aerosols. These aerosols can consist of surface-derived material such as mineral dust and soot as well as liquid sulfate and organic particles. The flux of tropospheric air during the Southern Hemisphere convective season derived from CALIOP observations is shown to be 5 times at 16 km and 20 times at 19 km larger, respectively, than that associated with flux caused by slow ascent through radiative heating. These results suggest that convective overshooting is a major contributor to troposphere-to-stratosphere transport with concomitant implications for the Tropical Tropopause Layer top height, the humidity, the photochemistry and the thermal structure of the layer.

scholarly journals Overshooting of clean tropospheric air in the tropical lower stratosphere as seen by the CALIPSO lidar

2011 ◽  
Vol 11 (1) ◽  
pp. 163-192 ◽  
Author(s):  
J. P. Vernier ◽  
J. P. Pommereau ◽  
L. W. Thomason ◽  
J. Pelon ◽  
A. Garnier ◽  
...  
Keyword(s):  
Transport Process ◽  
Lower Stratosphere ◽  
Thermal Structure ◽  
Radiative Heating ◽  
Convective Activity ◽  
Upper Troposphere ◽  
Tropical Tropopause Layer ◽  
Volcanic Plumes ◽  
Tropical Tropopause ◽  
Hemisphere Winter

Abstract. The evolution of aerosols in the tropical upper troposphere/lower stratosphere between June 2006 and October 2009 is examined using the observations of the space borne CALIOP lidar aboard the CALIPSO satellite. Superimposed on several volcanic plumes and soot from an extreme biomass-burning event in 2009, the measurements reveal the existence of fast cleansing episodes of the lower stratosphere to altitudes as high as 20 km. The cleansing of the full 14–20 km layer takes place within 1–4 months. Its coincidence with the maximum of convective activity in the southern tropics, suggests that the cleansing is the result of a large number of overshooting towers, injecting aerosol-poor tropospheric air into the lower stratosphere. The enhancements of aerosols at the tropopause level during the NH summer may be due to the same transport process but associated with intense sources of aerosols at the surface. Since, the tropospheric air flux derived from CALIOP observations during North Hemisphere winter is 5–20 times larger than the slow ascent by radiative heating usually assumed, the observations suggest that convective overshooting is a major contributor to troposphere-to-stratosphere transport with concommitant implications to the Tropical Tropopause Layer top height, chemistry and thermal structure.

scholarly journals The governing processes and timescales of stratosphere-to-troposphere transport and its contribution to ozone in the Arctic troposphere

2008 ◽  
Vol 8 (6) ◽  
pp. 19377-19414
Author(s):  
Q. Liang ◽  
A. R. Douglass ◽  
B. N. Duncan ◽  
R. S. Stolarski ◽  
J. C. Witte
Keyword(s):  
Lower Stratosphere ◽  
Trace Gases ◽  
Lower Troposphere ◽  
Threshold Level ◽  
The Arctic ◽  
Trace Gas ◽  
Seasonal Cycles ◽  
Upper Troposphere ◽  
Budget Analysis ◽  
Wet Removal

Abstract. We used the seasonality of a combination of atmospheric trace gases and idealized tracers to examine stratosphere-to-troposphere transport and its influence on tropospheric composition in the Arctic. Maximum stratosphere-to-troposphere transport of CFCs and O3 occurs in April as driven by the Brewer-Dobson circulation. Stratosphere-troposphere exchange (STE) occurs predominantly between 40° N to 80° N with stratospheric influx in the mid-latitudes (30–70° N) accounting for 67–81% of the air of stratospheric origin in the Northern Hemisphere extratropical troposphere. Transport from the lower stratosphere to the lower troposphere (LT) takes three months on average, one month to cross the tropopause, the second month to travel from the upper troposphere (UT) to the middle troposphere (MT), and the third month to reach the LT. During downward transport, the seasonality of a trace gas can be greatly impacted by wet removal and chemistry. A comparison of idealized tracers with varying lifetimes suggests that when initialized with the same concentrations and seasonal cycles at the tropopause, trace gases that have shorter lifetimes display lower concentrations, smaller amplitudes, and earlier seasonal maxima during transport to the LT. STE contributes to O3 in the Arctic troposphere directly from the transport of O3 and indirectly from the transport of NOy. Direct transport of O3 from the stratosphere accounts for 78% of O3 in the Arctic UT with maximum contributions occurring from March to May. The stratospheric contribution decreases significantly in the MT/LT (20–25% of total O3) and shows a very weak March–April maximum. Our NOx budget analysis in the Arctic UT shows that during spring and summer, the stratospheric injection of NOy-rich air increases NOx concentrations above the 20 pptv threshold level, thereby shifting the Arctic UT from a regime of net photochemical ozone loss to one of net production with rates as high as +16 ppbv/month.

scholarly journals Modeling upper tropospheric and lower stratospheric water vapor anomalies

2013 ◽  
Vol 13 (4) ◽  
pp. 9653-9679 ◽  
Author(s):  
M. R. Schoeberl ◽  
A. E. Dessler ◽  
T. Wang
Keyword(s):  
Water Vapor ◽  
Lower Stratosphere ◽  
Calculation Model ◽  
Vapor Concentration ◽  
Cold Temperatures ◽  
Tropical Tropopause Layer ◽  
Stratospheric Water Vapor ◽  
Tropical Tropopause ◽  
Minimum Displacement ◽  
Asian Monsoons

Abstract. The domain-filling, forward trajectory calculation model developed by Schoeberl and Dessler (2011) is used to further investigate processes that produce upper tropospheric and lower stratospheric water vapor anomalies. We examine the pathways parcels take from the base of the tropical tropopause layer (TTL) to the lower stratosphere. Most parcels found in the lower stratosphere arise from East Asia, the Tropical West Pacific (TWP) and the Central/South America. The belt of TTL parcel origins is very wide compared to the final dehydration zones near the top of the TTL. This is due to the convergence of rising air as a result of the stronger diabatic heating near the tropopause relative to levels above and below. The observed water vapor anomalies – both wet and dry – correspond to regions where parcels have minimal displacement from their initialization. These minimum displacement regions include the winter TWP and the Asian and American monsoons. To better understand the stratospheric water vapor concentration we introduce the water vapor spectrum and investigate the source of the wettest and driest components of the spectrum. We find that the driest air parcels that originate below the TWP, moving upward to dehydrate in the TWP cold upper troposphere. The wettest air parcels originate at the edges of the TWP as well as the summer American and Asian monsoons. The wet air parcels are important since they skew the mean stratospheric water vapor distribution toward higher values. Both TWP cold temperatures that produce dry parcels as well as extra-TWP processes that control the wet parcels determine stratospheric water vapor.

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

2015 ◽  
Vol 15 (18) ◽  
pp. 10239-10249 ◽  
Author(s):  
S. Ravindra Babu ◽  
M. Venkat Ratnam ◽  
G. Basha ◽  
B. V. Krishnamurthy ◽  
B. Venkateswararao
Keyword(s):  
Tropical Cyclones ◽  
Lower Stratosphere ◽  
Thermal Structure ◽  
Radial Distance ◽  
Lapse Rate ◽  
Tropical Tropopause Layer ◽  
Water Vapour Transport ◽  
Tropical Tropopause ◽  
High Vertical Resolution ◽  
Cold Point

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.

Sign in / Sign up

Export Citation Format

Share Document