scholarly journals Measurements of the upper troposphere and lower stratosphere during tropical cyclones using the GPS radio occultation technique

2011 ◽  
Vol 47 (2) ◽  
pp. 348-355 ◽  
Author(s):  
Riccardo Biondi ◽  
Torsten Neubert ◽  
Stig Syndergaard ◽  
Johannes Nielsen
Keyword(s):  
Tropical Cyclones ◽  
Radio Occultation ◽  
Lower Stratosphere ◽  
Upper Troposphere ◽  
Gps Radio Occultation

scholarly journals Evaluation of CMIP5 upper troposphere and lower stratosphere geopotential height with GPS radio occultation observations

2015 ◽  
Vol 120 (5) ◽  
pp. 1678-1689 ◽  
Author(s):  
Chi O. Ao ◽  
Jonathan H. Jiang ◽  
Anthony J. Mannucci ◽  
Hui Su ◽  
Olga Verkhoglyadova ◽  
...  
Keyword(s):  
Geopotential Height ◽  
Radio Occultation ◽  
Lower Stratosphere ◽  
Upper Troposphere ◽  
Gps Radio Occultation

scholarly journals Radio occultation bending angle anomalies during tropical cyclones

2011 ◽  
Vol 4 (6) ◽  
pp. 1053-1060 ◽  
Author(s):  
R. Biondi ◽  
T. Neubert ◽  
S. Syndergaard ◽  
J. K. Nielsen
Keyword(s):  
Radio Occultation ◽  
Lower Stratosphere ◽  
Time Window ◽  
Deep Convection ◽  
Atomic Clock ◽  
Space Station ◽  
Radiation Balance ◽  
Bending Angle ◽  
Upper Troposphere ◽  
Gps Radio Occultation

Abstract. The tropical deep convection affects the radiation balance of the atmosphere changing the water vapor mixing ratio and the temperature of the upper troposphere lower stratosphere. The aim of this work is to better understand these processes and to investigate if severe storms leave a significant signature in radio occultation profiles in the tropical tropopause layer. Using tropical cyclone best track database and data from different GPS radio occultation missions (COSMIC, GRACE, CHAMP, SACC and GPSMET), we selected 1194 profiles in a time window of 3 h and a space window of 300 km from the eye of the cyclone. We show that the bending angle anomaly of a GPS radio occultation signal is typically larger than the climatology in the upper troposphere and lower stratosphere and that a double tropopause during deep convection can easily be detected using this technique. Comparisons with co-located radiosondes, climatology of tropopause altitudes and GOES analyses are also shown to support the hypothesis that the bending angle anomaly can be used as an indicator of convective towers. The results are discussed in connection to the GPS radio occultation receiver which will be part of the Atomic Clock Ensemble in Space (ACES) payload on the International Space Station.

scholarly journals Radio occultation bending angle anomalies during tropical cyclones

2011 ◽  
Vol 4 (1) ◽  
pp. 1371-1395 ◽  
Author(s):  
R. Biondi ◽  
T. Neubert ◽  
S. Syndergaard ◽  
J. Nielsen
Keyword(s):  
Radio Occultation ◽  
Lower Stratosphere ◽  
Time Window ◽  
Deep Convection ◽  
Atomic Clock ◽  
Space Station ◽  
Radiation Balance ◽  
Bending Angle ◽  
Upper Troposphere ◽  
Gps Radio Occultation

Abstract. The tropical deep convection affects the radiation balance of the atmosphere changing the water vapor mixing ratio and the temperature of the upper troposphere lower stratosphere. The aim of this work is to better understand these processes and to investigate if severe storms leave a significant signature in radio occultation profiles in the tropical tropopause layer. Using tropical cyclone best track database and data from different GPS radio occultation missions (COSMIC, GRACE, CHAMP, SACC and GPSMET), we selected 1194 profiles in a time window of 3 h and a space window of 300 km from the eye of the cyclone. We show that the bending angle anomaly of a GPS radio occultation signal is typically larger than the climatology in the upper troposphere and lower stratosphere and that a double tropopause during deep convection can easily be detected using this technique. Comparisons with co-located radiosondes, climatology of tropopause altitudes and GOES analyses are also shown to support the hypothesis that the bending angle anomaly can be used as an indicator of convective towers. The results are discussed in connection to the GPS radio occultation receiver which will be part of the Atomic Clock Ensemble in Space (ACES) payload on the International Space Station.

Intraseasonal temperature variability in the upper troposphere and lower stratosphere from the GPS radio occultation measurements

2012 ◽  
Vol 117 (D15) ◽  
pp. n/a-n/a ◽  
Author(s):  
Baijun Tian ◽  
Chi O. Ao ◽  
Duane E. Waliser ◽  
Eric J. Fetzer ◽  
Anthony J. Mannucci ◽  
...  
Keyword(s):  
Radio Occultation ◽  
Lower Stratosphere ◽  
Temperature Variability ◽  
Upper Troposphere ◽  
Gps Radio Occultation

scholarly journals GPS radio occultation with TerraSAR-X and TanDEM-X: sensitivity of lower troposphere sounding to the Open-Loop Doppler model

2014 ◽  
Vol 7 (12) ◽  
pp. 12719-12733 ◽  
Author(s):  
F. Zus ◽  
G. Beyerle ◽  
S. Heise ◽  
T. Schmidt ◽  
J. Wickert
Keyword(s):  
Radio Occultation ◽  
Weather Prediction ◽  
Lower Troposphere ◽  
Systematic Difference ◽  
Open Loop ◽  
Negative Bias ◽  
Upper Troposphere ◽  
Gps Radio Occultation ◽  
Global Positioning ◽  
Data Source

Abstract. The Global Positioning System (GPS) radio occultation (RO) technique provides valuable input for numerical weather prediction and is considered as a data source for climate related research. Numerous studies outline the high precision and accuracy of RO atmospheric soundings in the upper troposphere and lower stratosphere. In this altitude region (8–25 km) RO atmospheric soundings are considered to be free of any systematic error. In the tropical (30° S–30° N) Lower (<8 km) Troposphere (LT), this is not the case; systematic differences with respect to independent data sources exist and are still not completely understood. To date only little attention has been paid to the Open Loop (OL) Doppler model. Here we report on a RO experiment carried out on-board of the twin satellite configuration TerraSAR-X and TanDEM-X which possibly explains to some extent biases in the tropical LT. In two sessions we altered the OL Doppler model aboard TanDEM-X by not more than ±5 Hz with respect to TerraSAR-X and compare collocated atmospheric refractivity profiles. We find a systematic difference in the retrieved refractivity. The bias mainly stems from the tropical LT; there the bias reaches up to ±1%. Hence, we conclude that the negative bias (several Hz) of the OL Doppler model aboard TerraSAR-X introduces a negative bias (in addition to the negative bias which is primarily caused by critical refraction) in our retrieved refractivity in the tropical LT.

scholarly journals Effect of tropical cyclones on the Stratosphere-Troposphere Exchange observed using satellite observations over north Indian Ocean

2016 ◽  
Author(s):  
M. Venkat Ratnam ◽  
S. Ravindra Babu ◽  
S. S. Das ◽  
Ghouse Basha ◽  
B. V. Krishnamurthy ◽  
...  
Keyword(s):  
Water Vapor ◽  
Indian Ocean ◽  
Tropical Cyclones ◽  
Lower Stratosphere ◽  
North Indian Ocean ◽  
Satellite Observations ◽  
Upper Troposphere ◽  
North West ◽  
The North ◽  
The Impact

Abstract. Tropical cyclones play an important role in modifying the tropopause structure and dynamics as well as stratosphere-troposphere exchange (STE) process in the Upper Troposphere and Lower Stratosphere (UTLS) region. In the present study, the impact of cyclones that occurred over the North Indian Ocean during 2007–2013 on the STE process is quantified using satellite observations. Tropopause characteristics during cyclones are obtained from the Global Positioning System (GPS) Radio Occultation (RO) measurements and ozone and water vapor concentrations in UTLS region are obtained from Aura-Microwave Limb Sounder (MLS) satellite observations. The effect of cyclones on the tropopause parameters is observed to be more prominent within 500 km from the centre of cyclone. In our earlier study we have observed decrease (increase) in the tropopause altitude (temperature) up to 0.6 km (3 K) and the convective outflow level increased up to 2 km. This change leads to a total increase in the tropical tropopause layer (TTL) thickness of 3 km within the 500 km from the centre of cyclone. Interestingly, an enhancement in the ozone mixing ratio in the upper troposphere is clearly noticed within 500 km from cyclone centre whereas the enhancement in the water vapor in the lower stratosphere is more significant on south-east side extending from 500–1000 km away from the cyclone centre. We estimated the cross-tropopause mass flux for different intensities of cyclones and found that the mean flux from stratosphere to troposphere for cyclonic stroms is 0.05 ± 0.29 × 10−3 kg m−2 and for very severe cyclonic stroms it is 0.5 ± 1.07 × 10−3 kg m−2. More downward flux is noticed in the north-west and south-west side of the cyclone centre. These results indicate that the cyclones have significant impact in effecting the tropopause structure, ozone and water vapour budget and consequentially the STE in the UTLS region.

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