Homogenization (instrumental correction) of water vapour data from Vaisala radiosondes and older (MARZ, RKZ) used in Polish aerological service. Barbara BrzÃ³ska. Goal.
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Homogenization(instrumental correction)of water vapour data from Vaisala radiosondes and older (MARZ, RKZ) used in Polish aerological service
The water vapour content in the atmosphere has crucial role for the ozone chemistry and photochemical processes of its destruction. Thus the research on its variability are of crucial importance, particularly in the levels of upper troposphere and lower stratosphere (UTLS).
The most reliable source of information on the relative humidity (RH) are the radiosonde measurements.
Unfortunately, the numerous changes of radiosonde types influence the homogeneity of the RH series.
The simple humidity sensors (MARZ, RKZ) was used in Polish aerological service till the 90-ties. Since 1992 Vaisala radiondes are used. However, the change of the radiosonde type in June 1999 (RS-80A to RS-90) and in June 2006 (RS-90 to RS-92) caused the break of homogeneity of the series.
In the first step of homogenisation, data fromVaisala radiosondes was smoothed using a 12-month moving average.
SPARC Assessment of Upper Tropospheric and Stratospheric Water Vapour, 2000:
Hcorr = (-2∙10-5∙t3 - 0.0021∙t2 - 0.089∙t - 0.3) ∙H(‘Vaisala’)
Miloshevich, L. M. et al., 2000: “Characterization and correction of relative humidity measurements from Vaisala RS80-A radiosondes at cold temperatures”:
Hcorr =H* G(t) (‘Miloshevich’)
G(t) = (3.9407∙10-8) ∙t4 + (1.8179∙10-6) ∙t3 + (1.5783∙10-4) ∙t2 + (-5.9662∙10-3) ∙t + 0.9278
Wang et al., 2002: “Corrections of humidity measurement errors from the Vaisala RS80 radiosonde - Application to TOGA COARE Data”
Leiterer, U., et al.,2002:"Method for correction of RS80 A – Humicap
For homogenisation of humidity data from Vaisala radiosondes (RS-80A, RS-90 and RS-92) four correction methods have been chosen for correction data from RS-80A radiosounds.
Two methods (‘Wang’ and ‘Leiterer’) were submitted for further studies.
Analyses of humidity trends on different goepotential surfaces show dominance of ‘Leirerer’ correction over ‘Wang’ one.
greater RS-90’s sensitivity and/or sensorheating mechanism?