Global multiple tropopause features derived from COSMIC radio occultation data during 2007 to 2012

Xinwen, Xu; Gao, Pan; Zhang, Xiaohong

doi:10.1002/2014jd021620

Cited by 8 publications

(5 citation statements)

References 77 publications

(155 reference statements)

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“…The main characteristics of the global DT distribution can be deduced from Figure 1. The figure reaffirms previous studies (e.g., Peevey et al., 2012, 2014; Randel et al., 2007; Schmidt et al., 2006; Wang & Polvani, 2011; Xu et al., 2014) and shows that the features are consistently revealed in the multiyear RO record. The seasonal features have been described in greater detail in Peevey et al.…”

Section: Resultssupporting

confidence: 91%

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Double Tropopauses and the Tropical Belt Connected to ENSO

Wilhelmsen

Ladstädter

Schmidt

et al. 2020

Geophysical Research Letters

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A detailed analysis of double tropopause (DT) occurrences requires vertically well resolved, accurate, and globally distributed information on the troposphere‐stratosphere transition zone. Here, we use radio occultation observations from 2001 to 2018 with such properties. We establish a connection between El Niño‐Southern Oscillation (ENSO) phases and the distribution of DTs by analyzing the global and seasonal DT characteristics. The seasonal distribution of DTs reveals several hotspot locations, such as near the subtropical jet stream and over high mountain ranges, where DTs occur particularly often. In this study, we detect a higher number of DTs during the cold La Niña state while warmer El Niño events result in lower DT rates, affecting the structure of the tropopause region. Close to the Niño 3 region, this relates to a much lower first lapse rate tropopause altitude during La Niña and corresponds to an apparent narrowing of the tropical belt there.

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Section: Resultssupporting

confidence: 91%

“…Some studies have used a subset of available RO data to study DTs (e.g. Lakkis & Canziani, 2009; Randel et al., 2007; Schmidt et al., 2006; Xu et al., 2014).…”

Section: Introductionmentioning

confidence: 99%

Double Tropopauses and the Tropical Belt Connected to ENSO

Wilhelmsen

Ladstädter

Schmidt

et al. 2020

Geophysical Research Letters

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“…The long-term GPS-RO data indicate climate change signals from warming in the upper troposphere and cooling in the lower stratosphere . Many recent studies have utilized GPS-RO data to investigate the variability in the upper troposphere and the lower stratosphere (UTLS) such as fluctuation details of the coldpoint tropopause (CPT) (Kim and Son 2012), and the occurrence of the multiple lapse rate tropopause (LRT) (Xu et al 2014).…”

Section: Introductionmentioning

confidence: 99%

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

Noersomadi

Tsuda

2017

Earth Planets Space

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Combining geometrical optics (GO) and wave optics (WO), the COSMIC data analysis and archive center (CDAAC) retrieved two sets of dry atmosphere temperatures (T) from COSMIC GPS radio occultation (GPS-RO), which are called atmPrf2010 and atmPrf2013. In atmPrf2010, the sewing height between WO and GO varies between 10 and 20 km, but is fixed at 20 km for atmPrf2013. The height resolution of the atmPrf2010 depends on the sewing height, while the T profiles by atmPrf2013 are smoothed over 500 m. We also derived T by applying WO throughout the troposphere and the stratosphere up to a 30-km altitude, which is called rishfsi2013. The three retrievals have different characteristics in the height resolution around the tropopause. Therefore, we aim to examine a possible discrepancy in the statistical results of the cold-point tropopause (CPT) and the lapse rate tropopause (LRT) among the three datasets, conducting their inter-comparisons as well as the comparison between GPS-RO and the simultaneous radiosonde dataset. We investigate the T variations in the upper troposphere and lower stratosphere (UTLS) over the tropics from October 1, 2011, to March 31, 2012, when radiosonde soundings were conducted as the CINDY-DYNAMO 2011 campaign. The mean T profiles are consistent between atmPrf2010 and atmPrf2013, but rishfsi2013 results are colder (warmer) than the CDAAC retrievals below (above) the tropopause. The mean T difference between atmPrf2013 and atmPrf2010 is 0.17 K at the cold-point tropopause (CPT) and −0.38 K at the lapse rate tropopause (LRT). On the other hand, rishfsi2013 shows a colder T at CPT by −0.77 and −0.59 K relative to atmPrf2013 and atmPrf2010, respectively, and the warmer T by 0.60 and 0.20 Kd at LRT. During CINDY-DYNAMO, we found 134 radiosonde soundings that coincide with GPS-RO within ±3 h and are collocated within 200 km from GPS-RO. The mean T difference at CPT from the radiosondes is 0.32, 0.49 and −0.24 K for atmPrf2010, atmPrf2013 and rishfsi2013, respectively. Both atmPrf2013 and atmPrf2010 have a positive bias at CPT, while rishfsi2013 has a negative one. Similar comparisons at LRT are −0.45, −0.69 and −0.41 K, respectively, showing a negative bias for all GPS-RO retrievals. The results show that rishfsi2013 is consistent with the retrievals at CDAAC and the radiosondes. Due to its good height resolution, rishfsi2013 is useful for studies on mesoscale T perturbations in the UTLS.

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“…In the past decade, FY-3C products have been evaluated via comparisons with other ROs' profiles. For example, FY-3C refractivity products from the near surface to the altitude of 30 km are as good as COSMIC refractivity products [33,34]. Over a long-term perspective, the latitudinal and seasonal variations of refractivity, temperature and specific humidity data produced by FY-3C were fully investigated and showed slight differences from ERA-Interim data [35].…”

Section: Introductionmentioning

confidence: 93%

Preliminary Validation of Surface Reflections from Fengyun-3C Radio Occultation Data

Chen

Xiong

et al. 2021

Remote Sensing

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Fengyun-3C (FY-3C) is a Global Navigation Satellite Systems (GNSS) Radio Occultation (RO) mission founded which was by China on 23 September 2013. In this study, under a specific temporal and spatial domain, we systematically compare FY-3C refractivity profiles with Constellation Observing System for Meteorology Ionosphere and Climate (COSMIC) refractivity profiles for the year 2015. The COSMIC profiles used in this study contain reflections, as identified in the Radio Occultation Meteorology Satellite Application Facility (ROM SAF) flag database. From 0 to 25 km altitude, the mean biases and relative standard deviations of the comparisons between FY-3C and COSMIC are less than 1% and 2% when COSMIC profiles present reflected signals. Radio holographic analysis is used to visualize and identify the spectra of FY-3C-reflected signals in the time-frequency domain. It is confirmed that the reflected signals in the lower troposphere and near the surface can be tracked by an FY-3C receiver. Further, most of the FY-3C events that matched with COSMIC reflected events show reflection patterns at a lower height, especially above the ocean’s surface. Under Bouguer’s rule and spherical symmetry assumptions, we reconstructed the reflected bending angle models by Abel transformation, which are valuable for reducing N-bias in the ducting layer. Three examples of FY-3C events show that the reflected bending branch is near the surface. Overall, the reflected signal of FY-3C could be used as a supplementary data portion for FY-3C atmospheric products.

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Global multiple tropopause features derived from COSMIC radio occultation data during 2007 to 2012

Cited by 8 publications

References 77 publications

Double Tropopauses and the Tropical Belt Connected to ENSO

Double Tropopauses and the Tropical Belt Connected to ENSO

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

Preliminary Validation of Surface Reflections from Fengyun-3C Radio Occultation Data

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