Boundary-Layer Meteorology

, Volume 160, Issue 2, pp 299–317 | Cite as

Comparison Between Radar and Automatic Weather Station Refractivity Variability

  • Ruben HallaliEmail author
  • Francis Dalaudier
  • Jacques Parent du Chatelet
Research Article


Weather radars measure changes in the refractive index of air in the atmospheric boundary layer. The technique uses the phase of signals from ground targets located around the radar to provide information on atmospheric refractivity related to meteorological quantities such as temperature, pressure and humidity. The approach has been successfully implemented during several field campaigns using operational S-band radars in Canada, UK, USA and France. In order to better characterize the origins of errors, a recent study has simulated temporal variations of refractivity based on Automatic Weather Station (AWS) measurements. This reveals a stronger variability of the refractivity during the summer and in the afternoon when the refractivity is the most sensitive to humidity, probably because of turbulence close to the ground. This raises the possibility of retrieving information on the turbulent state of the atmosphere from the variability in radar refractivity. An analysis based on a 1-year dataset from the operational C-band radar at Trappes (near Paris, France) and AWS refractivity variability measurements was used to measure those temporal and spatial variabilities. Particularly during summer, a negative bias increasing with range is observed between radar and AWS estimations, and is well explained by a model based on Taylor’s hypotheses. The results demonstrate the possibility of establishing, depending on season, a quantitative and qualitative link between radar and AWS refractivity variability that reflects low-level coherent turbulent structures.


Atmospheric humidity Radar Refractivity Turbulence 


  1. Bean BR, Dutton EJ (1968) Radio Meteorology no. 92 monograph. National Bureau of Standards, Washington DCGoogle Scholar
  2. Besson L, Boudjabi C, Caumont O, Parent du Châtelet J (2012) Links between weather phenomena and characteristics of refractivity measured by precipitation radar. Boundary-Layer Meteorol 143:77–95CrossRefGoogle Scholar
  3. Besson L, Parent du Chatelet J (2013) Solutions for improving the radar refractivity measurement by taking operational constraints into account. J Atmos Ocean Technol 30:1730–1742CrossRefGoogle Scholar
  4. Bodine D, Heinselman PL, Cheong BL, Palmer RD, Michaud D (2010) A case study on the impact of moisture variability on convection initiation using radar refractivity retrievals. J Appl Meteorol Climatol 49:1766–1778CrossRefGoogle Scholar
  5. Boudjabi C (2011) Validation de la mesure de réfractivité avec un radar en bande C équipé d’un émetteur à magnétron. Ph-D letter Université Paul Sabatier, Toulouse FranceGoogle Scholar
  6. Boudjabi C, Parent du Chatelet J (2009) Evaluation of phase ambiguity problem due to sampling time when measuring refractivity with precipitation radar. In: 34th international conference on radar meteorology, American Meteorological Society, WilliamsburgGoogle Scholar
  7. Caumont O, Foray A, Besson L, Parent du Chatelet J (2013) An observation operator for radar refractivity change: comparison of observations and convective-scale simulations. Boundary-Layer Meteorol 148:379–397CrossRefGoogle Scholar
  8. Crook NA (1996) Sensitivity of moist convection forced by boundary layer processes to low-level thermodynamic fields. Mon Weather Rev 124:1767–1785CrossRefGoogle Scholar
  9. Dabberdt WF, Schlatter TW (1996) Research opportunities from emerging atmospheric observing and modelling capabilities. Bull Am Meteorol Soc 77:305–323CrossRefGoogle Scholar
  10. Ducrocq V, Braud I, Davolio S, Ferretti R, Flamant C, Jansa A, Kalthoff N, Richard E, Taupier-Letage I, Ayral P-A, Belamari S, Berne A, Borga M, Boudevillain B, Bock O, Boichard J-L, Bouin M-N, Bousquet O, Bouvier C, Chiggiato J, Cimini D, Corsmeier U, Coppola L, Cocquerez P, Defer E, Delanoë J, Di Girolamo P, Doerenbecher A, Drobinski P, Dufournet Y, Fourrié N, Gourley JJ, Labatut L, Lambert D, Le Coz J, Marzano FS, Molini G, Montani A, Nord G, Nuret M, Ramage K, Rison B, Roussot O, Saïd F, Schwarzenboeck A, Testor P, van Baelen J, Vincendon B, Aran M, Tamayo J (2014) HyMeX-SOP1, the field campaign dedicated to heavy precipitation and flash flooding in the northwestern Mediterranean. Bull Am Meteorol Soc 95:1083–1100CrossRefGoogle Scholar
  11. Emanuel K, Raymond D, Betts A, Bosart L, Bretherton C, Droegemeier K, Farrell B, Fritsch JM, Houze R, Le Mone M, Lilly D, Rotunno R, Shapiro M, Smith R, Thorpe A (1995) Report of the first prospectus development team of the U.S. Weather Research Program to NOAA and the NSF. Bull Am Meteorol Soc 76:1194–1208Google Scholar
  12. Fabry F, Frush C, Zawadzki I, Kilambi A (1997) On the extraction of near-surface index of refraction using radar phase measurements from ground targets. J Atmos Ocean Technol 14:978–987CrossRefGoogle Scholar
  13. Fabry F (2004) Meteorological value of ground target measurements by radar. J Atmos Ocean Technol 21:560–573CrossRefGoogle Scholar
  14. Gasperoni NA, Xue M, Palmer RD, Gao J, Cheong BL, Michaud DS (2009) Low-level moisture analysis from refractivity data derived from a network of S-band and X-band radars using ARPS 3DVAR. In: 34th conference on radar meteorology, American Meteorological Society, Ed WilliamsburgGoogle Scholar
  15. Gasperoni NA, Xue M, Palmer RD, Gao J (2012) Sensitivity of convective initiation prediction to near-surface moisture when assimilating radar refractivity: Impact tests using OSSEs. J Atmos Ocean Technol 30:2281–2302CrossRefGoogle Scholar
  16. Koch SE, Aksakal A, McQueen JT (1997) The influence of mesoscale humidity and evapotranspiration fields on a model forecast of a cold-frontal squall line. Mon Weather Rev 125:384–409CrossRefGoogle Scholar
  17. Mahfouf JF, Brasnett B, Gagnon S (2007) A Canadian precipitation analysis (CaPA) project: description and preliminary results. Atmos-Ocean 45(1):1–17CrossRefGoogle Scholar
  18. Miao Q, Geerts B, Lemone MA (2006) Vertical velocity and buoyancy characteristics of coherent echo plumes in the convective boundary layer detected by a profiling airborne lidar. J Appl Meteorol Clim 45:838–855CrossRefGoogle Scholar
  19. Montmerle T, Caya A, Zawadzki I (2002) Short-term numerical forecasting of a shallow storms complex using bistatic and single-doppler radar data. Weather Forecast 17:1211–1225CrossRefGoogle Scholar
  20. Nicol J, Illingworth A, Bartholomew K (2014) The potential of 1h refractivity changes from an operational C-band magnetron-based radar for numerical weather prediction validation and data assimilation. Q J R Meteorol Soc 140(681):1209–1218CrossRefGoogle Scholar
  21. Ottersten H (1969) Radar backscattering from the turbulent clear atmosphere. Radio Sci 4:1251–1255CrossRefGoogle Scholar
  22. Parent du Chatelet J, Boudjabi C, Besson L, Caumont O (2012) Errors caused by long-term drifts of magnetron frequencies for refractivity measurement with a radar: Theoretical formulation and initial validation. J Atmos Oceanic Technol 29:1428–1434CrossRefGoogle Scholar
  23. Roberts RD, Nelson E, Wilson JW, Rehak N, Sun J, Ellis S, Weckwerth T, Fabry F, Kennedy PC, Fritz J, Chandrasekar V, Reising S, Padmanabhan S, Braun J, Crum T, Mooney L, Palmer R (2008) REFRACTT 2006. Bull Am Meteorol Soc 89:1535–1548CrossRefGoogle Scholar
  24. Smith EK, Weintraub S (1953) The constants in the equation for atmospheric refractive index at radio frequencies. Proc Inst Radio Eng 41:1035–1037Google Scholar
  25. Stull RB (1988) An Introduction to boundary-layer meteorology. Kluwer Academic, DordrechtCrossRefGoogle Scholar
  26. Sun J (2005) Convective-scale assimilation of radar data: progress and challenges. Q J R Meteorol Soc 131:3439–3463CrossRefGoogle Scholar
  27. Taylor GI (1938) The spectrum of turbulence. Proc R Soc 164:476–490CrossRefGoogle Scholar
  28. Wakimoto RM, Murphey HV (2009) Analysis of a dryline during IHOP: implications for convection initiation. Mon Weather Rev 137:912–936CrossRefGoogle Scholar
  29. Weckwerth TM, Parsons DB, Koch SE, Moore JA, LeMone MA, Demoz BB, Flamant C, Geerts B, Wang J, Feltz WM (2004) An overview of the International H\(_2\)O Project (IHOP_2002) and some preliminary highlights. Bull Am Meteorol Soc 85:253–277CrossRefGoogle Scholar
  30. Weckwerth TM, Pettet CR, Fabry F, Park S, Lemone MA, Wilson JW (2005) Radar refractivity retrieval: validation and application to short-term forecasting. J Appl Meteorol 44:285–300CrossRefGoogle Scholar
  31. Wesely ML (1976) The combined effect of temperature and humidity fluctuation on refractive index. J Appl Meteorol 15:43–49CrossRefGoogle Scholar

Copyright information

© Springer Science+Business Media Dordrecht 2016

Authors and Affiliations

  • Ruben Hallali
    • 1
    • 2
    Email author
  • Francis Dalaudier
    • 1
  • Jacques Parent du Chatelet
    • 2
  1. 1.LATMOS/IPSL, UVSQ Université Paris-Saclay, UPMC Univ. Paris 06, CNRSGuyancourtFrance
  2. 2.CNRM, UMR 3589, Météo-France/CNRSToulouseFrance

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