The vertical and spatial structure of ENSO in the upper troposphere and lower stratosphere from GPS radio occultation measurements

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.

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Radio occultation bending angle anomalies during tropical cyclones

Atmospheric Measurement Techniques Discussions ◽

10.5194/amtd-4-1371-2011 ◽

2011 ◽

Vol 4 (1) ◽

pp. 1371-1395 ◽

Cited By ~ 3

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.

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

Journal of Geophysical Research Atmospheres ◽

10.1029/2012jd017715 ◽

2012 ◽

Vol 117 (D15) ◽

pp. n/a-n/a ◽

Cited By ~ 11

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

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Comparison of three retrievals of COSMIC GPS radio occultation results in the tropical upper troposphere and lower stratosphere

Earth Planets and Space ◽

10.1186/s40623-017-0710-7 ◽

2017 ◽

Vol 69 (1) ◽

Cited By ~ 8

Author(s):

Noersomadi ◽

Toshitaka Tsuda

Keyword(s):

Radio Occultation ◽

Lower Stratosphere ◽

Upper Troposphere ◽

Gps Radio Occultation ◽

Tropical Upper Troposphere

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Variability of the upper troposphere and lower stratosphere observed with GPS radio occultation bending angles and temperatures

Advances in Space Research ◽

10.1016/j.asr.2010.01.021 ◽

2010 ◽

Vol 46 (2) ◽

pp. 150-161 ◽

Cited By ~ 58

Author(s):

Torsten Schmidt ◽

Jens Wickert ◽

Antonia Haser

Keyword(s):

Radio Occultation ◽

Lower Stratosphere ◽

Upper Troposphere ◽

Gps Radio Occultation ◽

Bending Angles

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

Atmospheric Measurement Techniques Discussions ◽

10.5194/amtd-7-12719-2014 ◽

2014 ◽

Vol 7 (12) ◽

pp. 12719-12733 ◽

Cited By ~ 1

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.

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A global analysis of wave potential energy in the lower stratosphere derived from 5 years of GPS radio occultation data with CHAMP

Geophysical Research Letters ◽

10.1029/2006gl027696 ◽

2006 ◽

Vol 33 (24) ◽

Cited By ~ 59

Author(s):

A. de la Torre ◽

T. Schmidt ◽

J. Wickert

Keyword(s):

Potential Energy ◽

Radio Occultation ◽

Lower Stratosphere ◽

Global Analysis ◽

Gps Radio Occultation ◽

Wave Potential ◽

Occultation Data ◽

Radio Occultation Data

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Where to see climate change best in radio occultation variables – study using GCMs and ECMWF reanalyses

Annales Geophysicae ◽

10.5194/angeo-29-2147-2011 ◽

2011 ◽

Vol 29 (11) ◽

pp. 2147-2167 ◽

Cited By ~ 2

Author(s):

B. C. Lackner ◽

A. K. Steiner ◽

G. Kirchengast

Keyword(s):

Climate Change ◽

Large Scale ◽

Radio Occultation ◽

Lower Stratosphere ◽

Circulation Model ◽

Vertical Resolution ◽

Proxy Data ◽

Intergovernmental Panel ◽

Climate Signal ◽

Upper Troposphere

Abstract. Radio occultation (RO) is a new technique to observe the upper troposphere and lower stratosphere (UTLS), a region that reacts particularly sensitive to climate change. Featuring characteristics such as long-term stability, SI traceability, all-weather capability, global coverage, and high accuracy and vertical resolution, RO data fulfill the requirements for climate monitoring in the UTLS. However, while a range of studies has shown the climate utility of RO it has not yet been explored sytematically where to see climate change best in RO variables. Therefore we perform here a systematic trend study for the RO variables refractivity, pressure, and temperature (bending angle, not depending on height but impact parameter, is left for separate study). The trends, given at geopotential height levels and for layer gradients, are explored to determine seasons, geographic regions, and height domains, which show a significant trend signal. Because continuous RO data are available since 2001 only, reanalyses (ERA-40 and ERA-Interim) and global circulation model simulations of the Intergovernmental Panel on Climate Change Assessment Report 4 (CCSM3, ECHAM5, HadCM3) are used as proxy data for RO. It is shown that RO data are sensitive at different height ranges and that thus several indicators of climate change can be retrieved. Refractivity emerges as indicator in the lower stratosphere (LS) and tropopause region at about 14 km to 24 km, pressure over the whole UTLS, and both in all large-scale regions except the polar caps. Temperature qualifies as indicator in the upper troposphere below about 16 km and in the LS above about 21 km. Overall, refractivity and pressure alone are adequate indicators for the UTLS, but temperature as commonly used variable facilitates easy interpretation of results. Layer gradients were found to be further sensitive indicators providing additional information. Besides large-scale global and hemispheric means the tropics and the mid-latitudes appear as regions suitable to track climate change with RO data. The results also point to the value of utilizing in addition to annual means specific seasons, such as northern hemispheric fall and summer, for early climate signal detection. Since RO data feature much better vertical resolution than the proxy data of this study, more detailed insights can be expected when a longer RO record will be available.

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