Impact of GPS radio occultation measurements in the ECMWF system using adjoint‐based diagnostics

Cardinali, Carla; Healy, S. B.

doi:10.1002/qj.2300

Cited by 74 publications

(60 citation statements)

References 36 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…In addition to the role radiosondes have in forecasting (e.g., Cardinali and Healy, 2014) and climatological studies (e.g., Seidel et al, 2012), recently observed anomalous evolution of the QBO (Newman et al, 2016) further bears out the need for continued radiosonde observations. Additional observations in this region will allow for more robust attribution of wave sources -whether Kelvin, Rossby, or gravity waves -to changes in zonal wind structure in the tropical stratosphere.…”

Section: Discussionmentioning

confidence: 99%

Intraseasonal to interannual variability of Kelvin wave momentum fluxes as derived from high-resolution radiosonde data

2017

View full text Add to dashboard Cite

Abstract. Observational estimates of Kelvin wave momentum fluxes in the tropical lower stratosphere remain challenging. Here we extend a method based on linear wave theory to estimate daily time series of these momentum fluxes from high-resolution radiosonde data. Daily time series are produced for sounding sites operated by the US Department of Energy (DOE) and from the recent Dynamics of the MaddenJulian Oscillation (DYNAMO) field campaign. Our momentum flux estimates are found to be robust to different data sources and processing and in quantitative agreement with estimates from prior studies. Testing the sensitivity to vertical resolution, our estimated momentum fluxes are found to be most sensitive to vertical resolution greater than 1 km, largely due to overestimation of the vertical wavelength. Climatological analysis is performed over a selected 11-year span of data from DOE Atmospheric Radiation Measurement (ARM) radiosonde sites. Analyses of this 11-year span of data reveal the expected seasonal cycle of momentum flux maxima in boreal winter and minima in boreal summer, and variability associated with the quasi-biennial oscillation of maxima during easterly phase and minima during westerly phase. Comparison between periods with active convection that is either strongly or weakly associated with the MaddenJulian Oscillation (MJO) suggests that the MJO provides a nontrivial increase in the lowermost stratospheric momentum fluxes.

show abstract

Section: Discussionmentioning

confidence: 99%

Intraseasonal to interannual variability of Kelvin wave momentum fluxes as derived from high-resolution radiosonde data

2017

View full text Add to dashboard Cite

show abstract

“…Several studies within the past decade have demonstrated the positive impact that results when RO is assimilated into numerical weather prediction models by operational forecast agencies (e.g. Cardinali and Healy, 2014).…”

Section: Introductionmentioning

confidence: 99%

Probability of intense precipitation from polarimetric GNSS radio occultation observations

Cardellach

Padullés

Tomás

et al. 2017

Quart J Royal Meteoro Soc

View full text Add to dashboard Cite

There is currently a gap in satellite observations of the moisture structure during heavy precipitation conditions, since infrared and microwave sounders cannot sense water-vapour structure near the surface in the presence of intense precipitation. Conversely, Global Navigation Satellite System (GNSS) radio occultations (RO) can profile the moisture structure with high precision and vertical resolution, but cannot indicate the presence of precipitation directly. Polarimetric RO (PRO) measurements have been proposed as a method to characterize heavy rain in GNSS RO, by measuring the polarimetric differential phase delay induced by large size hydrometeors. Previous studies have shown that the PRO polarimetric phase shift is sensitive to the path-integrated rain rate under intense precipitation scenarios, but there is no current method to invert PRO measurements into quantitative estimates of the path-averaged rain rate. In this manuscript, a probabilistic inversion approach to the GNSS PRO observables is proposed, where the GPM precipitation products are used for the construction of an a priori look-up table (LUT) database. The performance of the LUTs is assessed for use in the inversion of satellite-based GNSS PRO observations, based on synthetically generated PRO data of actual events, which correspond to co-locations between GNSS RO profiles and the TRMM observations. The synthetic data include end-to-end propagation effects of the polarimetric observables and a simple separation algorithm to isolate the hydrometeor component of the observation. The assessment results in agreement better than ±1 mm h −1 between the reference LUT and the actual rain statistics of the synthetic data, proving the suitability of the GPMbased probabilistic inversion tool. These findings indicate that the GNSS PRO products are capable of extending the current GNSS RO ones by associating indications of rainrate probabilities at different altitudes, at ∼250 m vertical resolution and under intense precipitation scenarios with the standard vertical thermodynamic profiles.

show abstract

“…It has the advantage of all-weather capability, high vertical resolution, and global coverage. RO data have significantly reduced systematic errors in global weather analysis (e.g., Healy and Thépaut, 2006;Cardinali and Healy, 2014) and are very useful for climate monitoring (e.g., Foelsche et al, 2009).…”

Section: Introductionmentioning

confidence: 99%

A simulation study with a new residual ionospheric error model for GPS radio occultation climatologies

2015

View full text Add to dashboard Cite

Abstract. In this study, a new model was explored which corrects for higher order ionospheric residuals in Global Positioning System (GPS) radio occultation (RO) data. Recently, the theoretical basis of this new "residual ionospheric error model" has been outlined (Healy and Culverwell, 2015). The method was tested in simulations with a one-dimensional model ionosphere.The proposed new model for computing the residual ionospheric error is the product of two factors, one of which expresses its variation from profile to profile and from time to time in terms of measurable quantities (the L1 and L2 bending angles), while the other describes the weak variation with altitude. A simple integral expression for the residual error (Vorob'ev and Krasil'nikova, 1994) has been shown to be in excellent numerical agreement with the exact value, for a simple Chapman layer ionosphere. In this case, the "altitudinal" element of the residual error varies (decreases) by no more than about 25 % between ∼ 10 and ∼ 100 km for physically reasonable Chapman layer parameters. For other simple model ionospheres the integral can be evaluated exactly, and results are in reasonable agreement with those of an equivalent Chapman layer.In this follow-up study the overall objective was to explore the validity of the new residual ionospheric error model for more detailed simulations, based on modeling through a complex three-dimensional ionosphere.The simulation study was set up, simulating day and night GPS RO profiles for the period of a solar cycle with and without an ionosphere. The residual ionospheric error was studied, the new error model was tested, and temporal and spatial variations of the model were investigated. The model performed well in the simulation study, capturing the temporal variability of the ionospheric residual. Although it was not possible, due to high noise of the simulated bending-angle profiles at mid-to high latitudes, to perform a thorough latitudinal investigation of the performance of the model, first positive and encouraging results were found at low latitudes. Furthermore, first application tests of the model on the data showed a reduction in temperature level of the ionospheric residual at 40 km from about −2.2 to −0.2 K.

show abstract

Impact of GPS radio occultation measurements in the ECMWF system using adjoint‐based diagnostics

Cited by 74 publications

References 36 publications

Intraseasonal to interannual variability of Kelvin wave momentum fluxes as derived from high-resolution radiosonde data

Intraseasonal to interannual variability of Kelvin wave momentum fluxes as derived from high-resolution radiosonde data

Probability of intense precipitation from polarimetric GNSS radio occultation observations

A simulation study with a new residual ionospheric error model for GPS radio occultation climatologies

Contact Info

Product

Resources

About