Atmospheric variability modes and trends in the UTLS from the RO recordA. K. Steiner1, B. Scherllin-Pirscher1, F. Ladstädter1,

R. Biondi1, L. Brunner1, G. Kirchengast1,2, and the ARSCliSys group

1 Wegener Center for Climate and Global Change (WEGC) and 2 IGAM/Inst. of Physics, University of Graz, Austria

andi.steiner@uni-graz.at

.SPARC Temperature Trends Workshop, Victoria, BC, Canada, April 9-10, 2015

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Courtesy: T. Rieckh

Global Positioning System (GPS) radio signals at 2 frequencies1575.42 MHz (~19 cm)1227.60 MHz (~24 cm)

Receiver on LEO satellite

Occultation geometry

Atmospheric refraction of signals

Measurements of phase pathbased on precise atomic clocks

Retrieval of key atmospheric/ climate parameters e.g., refractivity N, pressure p,geopotential height Z,temperature T, humidity q

GPS–LEO satellite constellations

GPS Radio Occultation

GPS RO Data Availability and Products

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Bending angle

Refractivity

Pressure

Geopotential height

Temperature

Humidity

Tropopause parameters

Geostrophic/gradient wind

Number of Observations over Time

(Fig. courtesy: R. Biondi/WEGC)

(Fig. courtesy: U. Foelsche/WEGC)

Summary of RO Data Characteristics

Global coverage

All weather capability

Best data quality in upper troposphere–lower stratosphere (UTLS)

Vertical resolution ~0.3 km to ~1.5 km in the UTLS

Horizontal resolutionabout 100 km to 300 km in the UTLS, synoptic scales, climate

Long-term stabilitymeasurements based on accurate&precise clocks (SI-traceable to time)

No need of inter-satellite calibration

Error characterization of profiles and climatological fields

Structural uncertainty estimates

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RO Data Consistency

Consistency of different satellitesOne processing center WEGC

meeting GCOS climate monitoring targets in UTLS long-term stable within ~0.1 K/decade

(not for horizontal target resolution <100km, and not yet globally)

Temperature

different processing centersStructural uncertainty CHAMP

[Ho et al. JGR 2009, 2012; Foelsche et al. TAO 2009, AMT 2011; Steiner et al. RS 2009, ACP 2013]

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Cal/Val – Comparison with other Observations (1)

Envisat MIPAS and GOMOS (here global 10/20km–30km)ESA project MMValRO Multi-Mission Validation against RORO is a valuable reference record over Envisat period 2002–2012MIPASv6.0 was ‘test-reprocessing’; the slight bias from Q4/2006 is from

stronger bias < 17 km; official re-processing on-going to ~May 2015

MIPAS – v6.0 GOMOS – v6.01

[Schwaerz et al. OPAC-IROWG 2013; TR ESA-ESRIN 2013]

http://validate.globclim.org

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Cal/Val – Comparison with other Observations (2)

Radiosonde Data Vaisala 90/92 vs RO

[Ladstädter et al. AMT 2015]

RAOBs V90/92 and GRUAN vs RO for day and nightAnnual-mean temp differences (global, 10hPa–30hPa, day/night)

[Ladstädter et al. AMT 2015] 8

Cal/Val – Comparison with other Observations (3)

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Atmospheric Variability – Volcanoes (1)

Thermal structure before and after volcanic eruptions Detection of volcanic cloud top height: Nabro volcano eruption

before (1-11 June 2011) after (12-14 June 2011)

[Biondi et al., A novel technique including GPS RO for detecting and monitoring volcanic clouds, GRL 2015, in revision]

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Atmospheric Variability – Volcanoes (2)

[Biondi et al., A novel technique including GPS RO for detecting and monitoring volcanic clouds, GRL 2015, in revision]

Thermal structure after volcanic eruptions Temporal evolution of volcanic cloud top & thermal structure from RO

Nabro, Eritrea (13.37°N, 41.70°E), 12 Jun 2011, mainly SO2 cloud)

Puyehue Chile (40.35°S, 72.07°W), 5 Jun 2011, mainly ash cloudand

Ejafjöll Iceland (63.63°N, 19.60°W), March and April 2010, ash and SO2 cloud

○Caliop data

Monitoring Climate Variability with RO

RO Temperature anomalies 05/2001-12/2013 in UTLS (SE subtracted)

QBO signal above the tropical tropopauseENSO signal below the tropical tropopause

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Principal Component Analysis – QBO

Principal component analysis in LS (20km-30km): PC1, PC2 → QBO

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Regression Results (1)

Regression Results Tropical LS: altitude levels 25 km and 20 km

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Regression Results (2)

Regression Results Tropical UT: altitude levels 15 km and 10 km

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QBO and ENSO Variability

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QBO & ENSO Residual Variance

Deseasonalized Temp. Anomalies Kelvin Waves

[Scherllin-Pirscher et al. EGU 2015]

RO Temperature Trends in Tropical UTLS

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Trend in Tropics Variance

Trend not significant, residual variance large near TP, above 28 km

Ozone and Temperature Evolution

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Ozone observations – vertically resolved:HARMOZ: Harmonized dataset of ozone profile occultation and limb sounders: GOMOS, MIPAS, OSIRIS, ACE-FTS [Sofieva et al. ESSD 2013]

GOZCARDS: Global ozone and related trace gas records for the stratosphereMerged SAGE, HALOE, MLS, ACE-FTS [Froidevaux et al. AMT 2013]

SBUV: Solar Backscatter UltraViolet instruments (nadir) [Bhartia et al. AMT 2013]

ERA-Interim: ECMWF reanalysis-Interim

Temperature data: RO and ERA-Interim

[L. Brunner, MSc Thesis, WEGC Rep. 2014]

HARMOZ ozone anomalies GOSZCARDS ozone anomalies

Ozone and Temperature Regression Results

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Multiple Standard Linear Regression: QBO winds, ENSO SST indices

[L. Brunner, MSc Thesis, WEGC Rep. 2014]

HARMOZ QBO coeff. SBUV QBO coeff.

RO QBO coeff. RO ENSO coeff.

Ozone and Temperature Trends 2002–2012

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GOZCARDS Ozone SBUV Ozone ERA-Interim Ozone

Agreement RO and ERA-Int, temperature trends not significant, large nat. variability O3 increase in mid- and upper stratosphere at mid- and high latitudes

O3 decline in tropics near 30 km to 35 km, consistent with literature

Anti-correlation of O3 and temperature above ~30 km, points to indirect effects/feedbacks

RO Temperature ERA-Interim Temperature HARMOZ Ozone

[L. Brunner, MSc Thesis, WEGC Rep. 2014]

Conclusions

GPS RO – a unique resource:

high accuracy and vertical resolution, consistency, long-term stability

reference standard in the troposphere/stratosphere- for validating and calibrating data from other observing systems- as absolute reference within assimilation system- for climate model evaluation

for monitoring climate variability and climate change

meeting GCOS climate monitoring targets in the UTLSGPS RO long-term stable within ~0.1 K/decade (not for horizontal target resolution <100 km, and not yet globally)

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Outlook

Reference records with integrated uncertainty estimation(SI-traceable)

Structural uncertainty assessment (RO Trends Working Group)

Improving the maturity of RO climate records (SCOPE-CM* project RO-CLIM)

Contribution to the WMO Integrated Global Observing System (WIGOS)

Scientific applications in support of WCRP grand challenges

Essential: continuous global observations “Ensure the continuity of the constellation of GNSS RO satellites.” (Action A21 [A20 IP-04], GCOS-138, 2010)

*SCOPE-CM (Sustained and coordinated processing of Environmental Satellite data for Climate Monitoring)

[GCOS-154, 2011]

www.atmos-meas-tech.net/special_issue68.htmlwww.atmos-meas-tech-discuss.net/special_issue48.html

Activities – AMT Special Issue – Results OPAC 2013

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Activities – IROWG-4 Workshop Upcoming

The IROWG was established as a permanent Working Group of the Coordination Group for Meteorological Satellites (CGMS) at the 37th meeting in October 2009 (Jeju Island, South Korea). The IROWG is co-sponsored by CGMS and the World Meteorological Organization (WMO). The IROWG serves as a forum for operational and research users of radio occultation data.

• UPCOMING next week:IROWG-4 WorkshopApril 16–22, 2015 Melbourne, Australiahttp://cawcr.gov.au/events/IROWG-4/

www.irowg.org

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Announcement OPAC-IROWG 2016 Workshop

(www.uni-graz.at/opacirowg2013)

Joint OPAC-6 & IROWG-5

8–14 September 2016

2016 6

THANK YOU !

Thanks for funds to

Note: WEGC publications available at www.wegcenter.at/en/arsclisys-publ

RAOBs V90/92 and GRUAN vs RO CHAMP, GRACE, COSMICAnnual-mean temp differences (global, altitude range 100hPa–30hPa)

[Ladstädter et al. AMT 2015] 26

Cal/Val – Comparison with other Observations (3)

[Biondi et al. 2010, 2011, 2014]

Thermal structure of strong convective systems – Cyclones Detection of cloud top height using RO bending angle and temperature

Atmospheric Variability – Convective Clouds

West Pacific Ocean South Pacific Ocean27