page 1 envisat validation workshop, acvt-gbmcd, mipas p&t&h20 12/12/2002 envisat validation...

Envisat Validation Workshop, ACVT-GBMCD, MIPAS p&T&H20 12/12/2002

Envisat Validation Workshop

Atmospheric Chemistry Validation Team

Ground-Based Measurements and Campaign Database Subgroup

Comparison with MIPAS Pressure, Temperature and Water vapour

ProfilesHenk Schets, Royal Meteorological Institute of Belgium, [email protected]


Validation Team

Projects participating in this presentation :

AOID 222 PI : K. H. Fricke AOID 9083 PI : V. Cuomo AOID 300 PI : D. De Muer


Overview• Comparison of MIPAS temperature profiles with radiosounding data from Uccle (RMI Belgium), AOID 300Influence of following parameters has been investigated :

•distance•temperature•time difference•height (as pressure level)

• Comparison of MIPAS p,T and water vapour profiles with data from IMAA-CNS, Italy, AOID 9083• Comparison of MIPAS temperature and pressure profiles with a statistical modelled atmosphere (University of Bonn), AOID 222


Intercomparison of Temperature Profiles with data from radiosoundings (PTU) launched at Uccle

•MIPAS L2 data from 24/10/2002 to 26/11/2002 (43 profiles) •radiosoundings are launched 2/day from Uccle (50.8N, 4.35E) -> time difference between the measurements is very short•only temperature has been validated•all profiles have been analyzed versus pressure


Intercomparison of Temperature Profiles with data from Uccle radiosoundings (PTU)

INDIVIDUAL PROFILES

Example of a very good agreement between MIPAS and radiosounding :

LEFT In black : the sounding temperature profileIn blue : the sounding profile rebinned to the same resolution as the MIPAS profileIn red : the MIPAS profile

RIGHTthe relative difference (MIPAS - PTU)/PTU for each MIPAS level



INDIVIDUAL PROFILES (2)

Probing different airmasses


Intercomparison of Temperature Profiles with data from Uccle radiosoundings (PTU

Influence of different parameters

• The influence of the time delay, the distance of the scan from Uccle and the temperature on the difference between the sounding and the MIPAS scan has been investigated for different height levels

• The statistical significance of this analysis is rather limited because of the small dataset available



Distance

• no discrimination in height level•the largest differences show up from about 500 km distance•indication of an overestimation by MIPAS ?



Time difference

• the largest difference in time is about 3 hours• no indication of a large dependency



Temperature



Distribution (1)



Distribution (2) (preliminary from July to November)


Intercomparison of Temperature Profiles with data from Uccle radiosoundings (PTU)Height, all profiles



Height, morning profiles (32)



Height, evening profiles (11)



Height, profiles closer than 500km (10)


Intercomparison of Pressure andTemperature Profiles with data from IMAA-CNR radiosoundings (PTU)

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28 October 2002

MIPAS (20:57 UTC) RADIOSONDE (20:56 UTC)

Lidar Station 40.60N 15.73E - 820 m a.s.l.MIPAS 39.76-42.65N 18.79-19.05E

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28 October 2002Lidar Station 40.60N 15.73E - 820 m a.s.l.MIPAS 39.76-42.65N 18.79-19.05E

MIPAS (20:57 UTC) RADIOSONDE (20:56 UTC)

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Intercomparison of Temperature Profiles with a falling sphere model above northern Scandinavia

(AOID 222)• preliminary report describing the validation of MIPAS temperature and density profiles• for each MIPAS data point, the model prediction was computed• altitude range from 35 to 93 km• MIPAS data from July and August 2002


Intercomparison of Density and Temperature Profiles with a falling sphere model above northern Scandinavia (AOID 222)

Temperature deviation histogram



Density deviation histogram



• Inspection of the profile data indicates a systematic deviation with altitude -> related to the wrong tangent heights in MIPAS data before auxiliary data update (LOS) on 13/11 ?

• Comparison with Esrange lidar data is planned


Intercomparison of Water Vapour profiles with Raman Lidar and radiosonde measurements at IMAA-CNR

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MIPAS 20:14 UTC Lidar 20:27-20:36 UTC Lidar 20:02-21:01 UTC Radiosonde launched at 20:32

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MIPAS 21:20 UTC Lidar 20:12-20:21 UTC Lidar 20:02-21:01 UTC Radiosonde launched at 21:17 UTC

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Water Vapour Mixing Ratio (g/kg)

Lidar station 40.60N 15.73EMIPAS 39.76 – 42.65N 29.57-29.80E18/9/2002

Lidar station 40.60N 15.73EMIPAS 29.13 – 30.03N 12.39-12.80E28/11/2002


Conclusions and outlook

• Agreement between radiosounding and MIPAS temperature profiles is good• Deviation with altitude detected for July and August profiles• Indications of a dependency of the differences between MIPAS and radiosounding temperature profiles on day/night time• More data is needed to assess whether or not these indications are significant• Indication of a deviation of the lowermost MIPAS water vapour measurement from lidar measurement

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