HY-2A Satellite Altimetric data Evaluation in the Arctic Ocean

Yongcun ChengOle Baltazar Andersen

2 IGARSS 2014 07/18/2014

Outline

1.Introduction Status of altimetric data in the Arctic Ocean (>66ºN) HY-2A (Data from NSOAS, IGDR) SARAL/AltiKa CryoSat-2

2. HY-2A altimetric data in the Arctic Ocean Applied range and geophysical corrections Comparision with RADS Altika and CryoSat-2 data DUACS NRT HY-2A data 20+ years of sea level timeries in the Arctic Ocean

3. Summary

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Data StatusFeb. Mar.

1

Jul.

Data availability in along-track RADS (ERS-1/2-Envisat), reprocessed (ERS-1/2-Envisat) and DUACS gridded weekly sea level products.

Envisat was dead in April 2012. HY-2, CryoSat-2 and Altika available in the Arctic Ocean.

0

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HY-2A overview

o HY-2A (‘HaiYang’ denotes Ocean) from the National Satellite Ocean Application Service has been designed for the monitoring the Ocean dynamics.

o HY-2A was launched in August 2011.o HY-2A payloads: Radar altimeter (Ku and C

bands), orbit altitude of 965 km, sun-synchronous with 99º inclination.

o Repeat cycle: 14 days (for three years) and 168 days.

o Data available from NSOAS.

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SARAL/AltiKa overview

o Operator: ISRO/CNES, enable better observation of ice, rain, coastal zones, land masses (forests, etc.), and wave heights.

o SARAL was launched in Feb, 2013.o SARAL payloads: Radar altimeter (Ka

band), orbit altitude of 800 km, sun-synchronous with 98.55º inclination.

o Repeat cycle: 35 days (the same ground-track as Envisat)

o Data available from RADS.

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CryoSat-2 overview

The SAR mode (green) operated over ice-covered regions and the coastal zone. The SAR Interferometric (SARIn) and Low Resolution Mode (LRM) modes are in purple and red, respectively (https://earth.esa.int).Data available from RADS.

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Range and Geophysical corrections

Andersen and Scharroo, 2011

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Range and Geophysical corrections

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RADS (AltiKa and CryoSat-2):

Dry tropospheric correction ： ECMWF modelWet tropospheric correction ： radiometer measurements (AltiKa)/ECMWF model (CryoSat-2)Ionosphere correction ： NIC09Sea State Correction ： hybrid modelOcean tide ： GOT4.8Inverted Barometer ： MOG2DMSS: DTU10

Range and Geophysical corrections

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Sea level anomaly (in meters) maps for the same period between 20130803 and 20130817 (HY-2A cycle049)

|SLA|<1m

Summer

HY-2A

AltiKa CryoSat-2

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HY-2A Globally data

HY-2A+10cm AltiKa

CryoSat-2 Jason-2Sea level anomaly (in m): Time period 20130808 to 20130817.

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All corrections (50ºS-50ºN)

Time period: 201305 (independent process by Yalong Liu)

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Sea level anomaly (in meters) maps for the same period between 20140104 and 20140118 (HY-2A cycle060)

HY-2A

AltiKa CryoSat-2

Winter

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HY-2/Jason-2 crossover dif.

Crossover sea surface height differences between Jason-2 and HY-2 satellite altimetric data in December 2013

Time period: 201312 (independent process by Yalong Liu)

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DUACS NRT HY-2A data

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DUACS NRT HY-2A data (Available from 20140514)

SLA map for the time period 20140514-20140601

CryoSat-2(RADS)

HY-2A(DUACS)

AltiKa(RADS)

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Sea level timeseries in the Arctic Ocean

DTU reprocessed ERS-1/2-Envisat (black)RADS CryoSat-2 (blue)RADS AltiKa (red)

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Sea level timeseries in the Arctic Ocean(HY-2A)

SLA cycle averaged Number of data

m

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Summary

1. HY-2A satellite altimetry provides valuable data in the Arctic Ocean.

2. More alternative range and geophysical corrections are required in the released HY-2A data sets for comparison.

3. The bias among the satellite altimetry missions needs further investigation to improve the long term sea level time series in the Arctic Ocean.

4. SLA ‘drops’ in 2013 needs further investigation.

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Thanks for your attention