Space Weather Observations by GNSS Radio Occultation: From FORMOSAT‐3/COSMIC to FORMOSAT‐7/COSMIC‐2

Yue, Xinan; Schreiner, William S.; Pedatella, N. M.; Anthes, Richard A.; Mannucci, A. J.; Straus, P. R.; Liu, Jann Yenq

doi:10.1002/2014sw001133

Cited by 103 publications

(84 citation statements)

References 13 publications

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“…The slight underestimation of blocking frequencies in RO compared to three different reanalyses, ERA-Interim, JRA-55, and MERRA-2, is most probably due to a too-sparse measurement density. Future RO missions, like the FORMOSAT-7/COSMIC-2 constellation, and the exploitation of signals from more Global Navigation Satellite System (GNSS) constellations, like the European Galileo, the Russian GLONASS, and the Chinese BeiDou, are expected to significantly increase the number of RO events, promising to overcome this undersampling and allowing an even better performance of RO data in blocking representation (Yue et al, 2014).…”

Section: Summary Conclusion and Outlookmentioning

confidence: 99%

A global perspective on atmospheric blocking using GPS radio occultation – one decade of observations

Brunner

Steiner

2017

Atmos. Meas. Tech.

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Abstract. Atmospheric blocking represents a weather pattern where a stationary high-pressure system weakens or reverses the climatological westerly flow at mid-latitudes for up to several weeks. It is closely connected to strong anomalies in key atmospheric variables such as geopotential height, temperature, and humidity. Here we provide, for the first time, a comprehensive, global perspective on atmospheric blocking and related impacts by using an observation-based data set from Global Positioning System (GPS) radio occultation (RO) from 2006 to 2016. The main blocking regions in both hemispheres and seasonal variations are found to be represented well in RO data. The effect of blocking on vertically resolved temperature and humidity anomalies in the troposphere and lower stratosphere is investigated for blocking regions in the Northern and Southern hemispheres, respectively. We find a statistically significant correlation of blocking with positive temperature anomalies, exceeding 3 K in the troposphere, and a reversal above the tropopause with negative temperature anomalies below −3 K in the lower stratosphere. Specific humidity is positively correlated with temperature throughout the troposphere with larger anomalies revealed in the Southern Hemisphere. At the eastern and equatorward side of the investigated blocking regions, a band of tropospheric cold anomalies reveals advection of cold air by anticyclonic motion around blocking highs, which is less distinct in the Southern Hemisphere due to stronger zonal flow. We find GPS RO to be a promising new data set for blocking research that gives insight into the vertical atmospheric structure, especially in light of the expected increase in data coverage that future missions will provide.

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Section: Summary Conclusion and Outlookmentioning

confidence: 99%

A global perspective on atmospheric blocking using GPS radio occultation – one decade of observations

Brunner

Steiner

2017

Atmos. Meas. Tech.

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“…COSMIC uses the technique of Global Positioning System (GPS) radio occultation (RO) to profile the neutral atmosphere (troposphere and stratosphere) and ionosphere [Anthes et al, 2008;Yue et al, 2014]. COSMIC consists of six microsatellites that are in ∼800 km and 72 ∘ inclination orbits.…”

Section: Cosmicmentioning

confidence: 99%

Short‐term nonmigrating tide variability in the mesosphere, thermosphere, and ionosphere

et al. 2016

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The intraseasonal variability of the eastward propagating nonmigrating diurnal tide with zonal wave number 3 (DE3) during 2007 in the mesosphere, ionosphere, and thermosphere is investigated using a whole atmosphere model reanalysis and satellite observations. The atmospheric reanalysis is based on implementation of data assimilation in the Whole Atmosphere Community Climate Model (WACCM) using the Data Assimilation Research Testbed (DART) ensemble Kalman filter. The tidal variability in the WACCM+DART reanalysis is compared to the observed variability in the mesosphere and lower thermosphere (MLT) based on the Thermosphere Ionosphere Mesosphere Energetics Dynamics satellite Sounding of the Atmosphere using Broadband Emission Radiometry (TIMED/SABER) observations, in the ionosphere based on Constellation Observing System for Meteorology, Ionosphere, and Climate (COSMIC) observations, and in the upper thermosphere (∼475 km) based on Gravity Recovery and Climate Experiment (GRACE) neutral density observations. To obtain the short‐term DE3 variability in the MLT and upper thermosphere, we apply the method of tidal deconvolution to the TIMED/SABER observations and consider the difference in the ascending and descending longitudinal wave number 4 structure in the GRACE observations. The results reveal that tidal amplitude changes of 5–10 K regularly occur on short timescales (∼10–20 days) in the MLT. Similar variability occurs in the WACCM+DART reanalysis and TIMED/SABER observations, demonstrating that the short‐term variability can be captured in whole atmosphere models that employ data assimilation and in observations by the technique of tidal deconvolution. The impact of the short‐term DE3 variability in the MLT on the ionosphere and thermosphere is also clearly evident in the COSMIC and GRACE observations. Analysis of the troposphere forcing in WACCM+DART and simulations of the Global Scale Wave Model (GSWM) show that the short‐term DE3 variability in the MLT is not related to a single source; rather, it is due to a combination of changes in troposphere forcing, zonal mean atmosphere, and wave‐wave interactions.

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“…Hajj and Romans, 1998) has been employed to invert the electron density from the RO TEC. With the success of F3/C, the United States and Taiwan are moving forward with a follow-on RO mission named FORMOSAT-7/COSMIC-2 (F7/C2), which will ultimately place 12 satellites in orbit with two launches with 24-28.5 • inclination and 520-550 km altitude in 2016 and with 72 • inclination and 720-750 km altitude in 2018 (Lee et al, 2013;Yue et al, 2014;Yen, 2015). Scientists find that the local spherical symmetry assumption in the standard (Abel) RO inversion processes results in systemic biases, especially the EIA (equatorial ionization anomaly) at low latitudes, where the horizontal gradient is most significant (cf.…”

Section: Introductionmentioning

confidence: 99%

Electron density profiles probed by radio occultation of FORMOSAT-7/COSMIC-2 at 520 and 800 km altitude

2015

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Abstract. The FORMOSAT-7/COSMIC-2 (F7/C2) will ultimately place 12 satellites in orbit with two launches with 24-28.5 • inclination and 520-550 km altitude in 2016 and with 72 • inclination and 720-750 km altitude in 2018. It would be very useful for the community to construct the global three-dimensional electron density structure by simultaneously combining the two launch observations for studying ionospheric structure and dynamics. However, to properly construct the global electron density structure, it is essential to know and evaluate differences between the ionospheric electron densities probed by the two launches. To mimic the F7/C2 observations, we examine the electron density probed at the two satellite altitudes 500 and 800 km by means of FORMOSAT-3/COSMIC (F3/C) observations at the parking orbit 500 km altitude and mission orbit 800 km altitude, as well as a corresponding observing system simulation experiment (OSSE). Observation and OSSE results show that the sounding geometries by satellite orbiting at 500 and 800 km altitudes can cause the overall differences in the electron density, the F2 peak electron density, and the F2 peak height of about 18-24, 12-28 %, and 7-19 km, respectively. Results confirm that the discrepancies mainly result from the sounding geometry and the grid (contour) bias of the electron density.

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Space Weather Observations by GNSS Radio Occultation: From FORMOSAT‐3/COSMIC to FORMOSAT‐7/COSMIC‐2

Cited by 103 publications

References 13 publications

A global perspective on atmospheric blocking using GPS radio occultation – one decade of observations

A global perspective on atmospheric blocking using GPS radio occultation – one decade of observations

Short‐term nonmigrating tide variability in the mesosphere, thermosphere, and ionosphere

Electron density profiles probed by radio occultation of FORMOSAT-7/COSMIC-2 at 520 and 800 km altitude

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