Estimation of refractivity uncertainties and vertical error correlations in collocated radio occultations, radiosondes, and model forecasts

Autor: J. K. Nielsen, H. Gleisner, S. Syndergaard, K. B. Lauritsen
Jazyk: angličtina
Rok vydání: 2022
Předmět:
Zdroj: Atmospheric Measurement Techniques, Vol 15, Pp 6243-6256 (2022)
Druh dokumentu: article
ISSN: 1867-1381
1867-8548
DOI: 10.5194/amt-15-6243-2022
Popis: Random uncertainties and vertical error correlations are estimated for three independent data sets. The three collocated data sets are (1) refractivity profiles of radio occultation measurements retrieved from the Metop-A and B and COSMIC-1 missions, (2) refractivity derived from GRUAN-processed RS92 sondes, and (3) refractivity profiles derived from ERA5 forecast fields. The analysis is performed using a generalization of the so-called three-cornered hat method to include off-diagonal elements such that full error covariance matrices can be calculated. The impacts from various sources of representativeness error on the uncertainty estimates are analysed. The estimated refractivity uncertainties of radio occultations, radiosondes, and model data are stated with reference to the vertical representation of refractivity in these data sets. The existing theoretical estimates of radio occultation uncertainty are confirmed in the middle and upper troposphere and lower stratosphere, and only little dependence on latitude is found in that region. In the lower troposphere, refractivity uncertainty decreases with latitude. These findings have implications for both retrieval of tropospheric humidity from radio occultations and for assimilation of radio occultation data in numerical weather prediction models and reanalyses.
Databáze: Directory of Open Access Journals
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