Characterization of cyclones and volcanic clouds with GPS ... · Case study – Puyehue 2011 (ash...
Transcript of Characterization of cyclones and volcanic clouds with GPS ... · Case study – Puyehue 2011 (ash...
3rd International Conference on GPS Radio Occultation ICGPSRO 2016, Taipei, Taiwan 9–11 March 2016
Characterization of cyclones and volcanic clouds with GPS
radio occultation
A. K. Steiner1, R. Biondi2,1, G. Kirchengast1, and T. Rieckh3,1
1 Wegener Center for Climate and Global Change (WEGC), University of Graz, Austria 2 Istituto di Scienze dell´Atmosfera e del Clima (ISAC), Lecce, Italy
3 COSMIC Project Office, UCAR, Boulder, Colorado, USA
GPS RO data
Year
# oc
culta
tions
PROS • High vertical resolution • Global coverage • High accuracy • Long term stability • Cheap technology • Independent of weather conditions • Independent of sensor • Independent of processing scheme
CONS • Relatively low horizontal resolution • Moist air ambiguity (low-mid tropo)
background info for T, p, e
FUTURE • COSMIC-2 will increase the
number of daily occultations with better coverage of the tropical area
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Method – RO reference climatology
Interpolation: of RO profiles to a common vertical grid of 100 m
Averaging: profiles collected in the period 2001 to 2012 were binned at 5 x 5 degree resolution and averaged to monthly means
Sampling: the final RO reference climatology was sampled at 1 x 1 degree resolution in latitude and longitude
July RO distribution Full archive RO distribution
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Method – cloud top detection
Anomaly computation: difference profiles with respect to climatology for bending angle BA and temperature T
Convective system structure: inversion below cloud top, cooling (T min) corresponding to cloud top
Cloud top height detection: BA max anomaly (>3% within 2km), T min anomaly
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Method – demonstration
Cloud top detection of convective clouds and tropical cyclones Confirmation with CALIPSO (lidar) data
High correlation btw cloud top heights from RO and CALIPSO
Biondi et al., Thermal structure of intense convective clouds derived from GPS radio occultations, Atmos. Chem. Phys., 12, 2012.
Biondi et al., Tropical cyclone cloud-top height and vertical temperature structure detection using GPS radio occultation measurements, J. Geophys. Res., 118, 2013.
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Cyclones cloud top detection with RO – data set
Co-location of tropical cyclones (TC) best tracks and GPS RO
Period: 2001–2012 within <6 hours and <600 km
Number of selected cases: 20732
~500 ROs co-located within 10 minutes/100 km from the TC track
RO classification by ocean basin and storm intensity
Sub-selection of tropical and extra-tropical cyclones
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Cyclones – thermal structure
West Pacific Ocean South Pacific Ocean
Cloud top height & temperature
Different characteristics over different ocean basins
Warmer troposphere, cold cloud top during TC
NH (W.Pacific) warming above cloud top vs SH
Coldest anomalies & highest cloud tops over South Pacific and Indian ocean
Colder and higher cloud tops of storms in the SH than in NH
Double tropopause, convection uplift 7
Possible overshooting into the stratosphere Cloud top height > MM tropopause height High percentage in SH ocean basins 40-50% Western Pacific for high intensity storms 30-50% WP storms: Apr-Dec at 0-30°, Aug-Oct at 30°-40° Overshootings in green and magenta
Cyclones – overshooting
Hcoldest_std > Hmm_trop + Hmstd_trop Hcoldest_std+1 > Hmm_trop + Hmstd_trop + 1 km *
West Pacific Ocean
0-20°
20°-30°
30°-40°
*
Biondi, R., A. K. Steiner, G. Kirchengast, and T. Rieckh, Characterization of thermal structure and conditions for overshooting of tropical and extratropical cyclones with GPS radio occultation, Atmos. Chem. Phys., 15, 5181–5193, doi:10.5194/acp-15-5181-2015, 2015
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Volcanic cloud top detection – method
OMI SO2 data AIRS/IASI ash index
Volcanic cloud type, discriminate against water clouds
SO2 observations (UV-Vis) from OMI instrument
Ash observations from IR sounders AIRS/IASI
Select RO observations in volcanic cloud area
Cloud top detection in BA and T anomaly profiles
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Volcanic cloud top detection – case study
Case study – Nabro 2011 & Puyehue 2011
Nabro, Eritrea (13.37°N, 41.70°E) 12 Jun 2011 mainly SO2 cloud 214 RO profiles to 20 days after eruption Puyehue Chile (40.35°S, 72.07°W) 5 Jun 2011 mainly ash cloud 1022 RO profiles and
Volcano area – climatological conditions
Climatological normal conditions in volcano areas Monthly mean T and BA anomaly profiles averaged over 2007–2013
Puyehue May/June Nabro May/June
mean May stDev May mean June stDev June
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Dust cloud May to Sep, pre-monsoon activity
Convection
Volcanic cloud – thermal structure
RO profile in volcanic cloud Temperature and bending angle anomalies Puyehue June 2011
Cloud (IASI/AIRS) GPS RO CALIPSO track
-10 -8 -6 -4 -2 0 2 4 6 8 100
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Anomaly [Temp in K & Bending Angle in %]
Altit
ude
abov
e m
sl [k
m]
Bending angleTemperature
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CALIPSO
Case study – Puyehue 2011 (ash eruption)
Thermal structure before and after volcanic eruption Detection of volcanic cloud top height for Puyehue cooling in mid-upper troposphere (~11 km)
before (May 2011) after (5-30 June 2011)
Biondi, R., A. K. Steiner, G. Kirchengast, H. Brenot, and T. Rieckh A novel technique including GPS radio occultation for detecting and monitoring volcanic clouds, Atmos. Chem. Phys. Discuss., 1–26, doi:10.5194/acp-2015-974, in review, 2016
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Case study – Nabro 2011 (SO2 eruption)
Thermal structure before and after volcanic eruptions Detection of volcanic cloud top height for Nabro warming in lower stratosphere (16.3 km) before (1-11 June 2011) after (12-14 June 2011)
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Thermal structure after Nabro eruption stratospheric warming months after the eruption (hydrated sulfate aerosols)
before eruption
after eruption
Case study – Nabro 2011 (SO2 eruption)
Conclusions
GPS RO is well suited for
Cloud top height detection
Tropopause height determination
Detection of possible overshooting conditions
Characterization of thermal vertical structure
Improving the detection and monitoring of cyclones
and volcanic clouds, and supporting warning systems.
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The research leading to these results has received funding from the People Programme (Marie Curie Actions) of the European Union's Seventh Framework Programme (FP7/2007-2013) under REA grant agreement n°328233.
Thank you
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