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HY-2A Satellite Altimetric data Evaluation in the Arctic Ocean. Yongcun Cheng Ole Baltazar Andersen. Outline. 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
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HY-2A Satellite Altimetric data Evaluation in the Arctic Ocean Yongcun Cheng Ole Baltazar Andersen
Outline • 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
Data Status Feb. Mar. 1 Jul. 0 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.
HY-2Aoverview • HY-2A (‘HaiYang’ denotes Ocean) from the National Satellite Ocean Application Service has been designed for the monitoring the Ocean dynamics. • HY-2A was launched in August 2011. • HY-2A payloads: Radar altimeter (Ku and C bands), orbit altitude of 965 km, sun-synchronous with 99º inclination. • Repeat cycle: 14 days (for three years) and 168 days. • Data available from NSOAS.
SARAL/AltiKa overview • Operator: ISRO/CNES, enable better observation of ice, rain, coastal zones, land masses (forests, etc.), and wave heights. • SARAL was launched in Feb, 2013. • SARAL payloads: Radar altimeter (Ka band), orbit altitude of 800 km, sun-synchronous with 98.55º inclination. • Repeat cycle: 35 days (the same ground-track as Envisat) • Data available from RADS.
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.
Range and Geophysical corrections Andersen and Scharroo, 2011
RADS (AltiKa and CryoSat-2): Range and Geophysical corrections Dry tropospheric correction:ECMWF model Wet tropospheric correction:radiometer measurements (AltiKa)/ECMWF model (CryoSat-2) Ionosphere correction:NIC09 Sea State Correction: hybrid model Ocean tide:GOT4.8Inverted Barometer:MOG2D MSS: DTU10
Summer CryoSat-2 AltiKa Sea level anomaly (in meters) maps for the same period between 20130803 and 20130817 (HY-2A cycle049) |SLA|<1m HY-2A
HY-2A Globally data HY-2A+10cm AltiKa CryoSat-2 Jason-2 Sea level anomaly (in m): Time period 20130808 to 20130817. CryoSat-2 Jason-2
All corrections (50ºS-50ºN) Time period: 201305 (independent process by Yalong Liu)
Winter AltiKa CryoSat-2 Sea level anomaly (in meters) maps for the same period between 20140104 and 20140118 (HY-2A cycle060) HY-2A
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)
(Available from 20140514) DUACS NRT HY-2A data AltiKa (RADS) CryoSat-2 (RADS) SLA map for the time period 20140514-20140601 HY-2A (DUACS)
DTU reprocessed ERS-1/2-Envisat (black)RADS CryoSat-2 (blue)RADS AltiKa (red) Sea level timeseries in the Arctic Ocean
Sea level timeseries in the Arctic Ocean (HY-2A) m SLA cycle averaged Number of data
Summary • HY-2A satellite altimetry provides valuable data in the Arctic Ocean. • More alternative range and geophysical corrections are required in the released HY-2A data sets for comparison. • The bias among the satellite altimetry missions needs further investigation to improve the long term sea level time series in the Arctic Ocean. • SLA ‘drops’ in 2013 needs further investigation.