Report from CNSA 16th GSICS Executive Panel, Boulder, 15-16 May 2015 Peng Zhang, Jun Gao

Report from CNSA

16th GSICS Executive Panel, Boulder, 15-16 May 2015

Peng Zhang, Jun Gao

Satellite Introdution

GF-1 satellite mission• GF-1 satellite is the first CHEOS constellation satellite launched on April 26, 2013 • Four Wide Field of View (WFV) sensors with the spatial resolution of 16m and 200km

swath each.• Two Panchromatic and Multi-Spectral (PMS) sensors with the spatial resolution of

8m(MS) and 2m(Pan). The swath is 60km by integrating two cameras.

HY-2A satellite mission• HY-2A satellite is the first ocean dynamics environment satellite in China• Dual-band radar Altimeter (working on Ku-band and C-band) – used to measure sea

levels, significant wave heights and wind speeds • Ku-band microwave Scatterometer for measuring sea surface wind field• Scanning microwave Radiometer (6.6,10.7, 18.7, 23.8 & 37GHz) for measuring Sea

surface temperature, atmospheric water vapor, et al.• The design lifetime of HY-2A satellite is 3 years. By far, HY-2A satellite has

been operating on orbit more than three years.

GSICS-EP-16, Boulder, 15-16 May 2015

Satellite calibration and validation facilities and activities

Land observing satellite-geometry


Digital geometric calibration site in Yili, XinjiangArea:100km*20km, scale: 1:1000

Digital geometric calibration site in HebeiArea:500km*100km, scale: 1:5000


GF-1 Operation phase


After compared with MODIS over the Dunhuang calibration site, the radiometric stability of WFV camera is investigated. Then the radiometric calibration of WFV camera is accomplished with the reference MODIS sensor by means of the radiometric cross-calibration method.


GF-1 Operation phaseInter-cross calibration method is proposed to reduce the radiometric

inconsistency of adjacent GF-1 WFV camera. Statistical analysis and simulation

methods are adopted to build the correlation models of DN and TOA radiances

between adjacent WFVs according to the overlap region of different phase image.

WFV1 and WFV2 WFV2 and WFV3

WFV3 and WFV4

Before After Before After

Before After


HY-2 Commissioning Phase • Examining the received telemetry of each instrument source packet for the

HY-2A satellite and confirm whether the instrument telemetry is within the expected ranges. This activity is ongoing in operational phase.

• The synchronous observation experiment in the South China Sea is used to validate the significant wave height, sea surface temperature, wind vectors, air temperature, relative humility,

air pressure, atmospheric sounding, et al.• The HY-2A satellite product was validated

by comparing with in-situ buoy (NDBC,

Chinese, et al) observations, Jason-2 data,

ASCAT, NCEP FNL Operational Global

Analysis data,et al.



HY-2 Operation Phase • Range absolute calibration: Based on the altimeter reconstructive transponder.

The HY-2A altimeter receives the responding signals from the transponder and generates ranges. Pertinent reference ranges are obtained from the POD data and the transponder’s coordinate. Using the ranges from the radar altimeter and the reference ranges, the time tag bias between the POD data and the HY-2A altimeter observations can be estimated. During the HY-2A altimeter calibration campaign from August 9, 2012, to July 20, 2014, 17

GSICS-EP-16, Boulder, 15-16 May 2015Fig. The HY-2A satellite altimeter transponderFig. Time tag bias and the standard deviation of each HY-2A altimeter transponder measurement


HY-2 Operation Phase • SSH : Using GPS buoys.

In the first GPS buoy test experiment, the in-situ water levels jointly measured by the tidal gauge and the GPS buoy at Shazikou lasting for approximately 5 h were used to ensure the measurement homogeneity


Fig. The GPS buoy test locations and field

instruments

Fig. SSH observed by the GPS buoy and

tidal gauge


HY-2 Operation Phase For HY-2A altimeter:• The SSH cross-calibration has been carried out using Jason-2 GDR product by

crossover points.• The altimeter product validation has been implemented by comparing with

Jason-2 GDR data and in-situ buoy observations.• Sigma0 monitoring: Based on sigma0 measurement over Amazon Rainforest. • Sigma0 calibration : Using scatterometer transponders and ocean calibration

method. • The wind vector validation : By comparing

HY-2A altimeter products against in-situ

NDBC buoy observations, ASCAT and NCEP

FNL Operational Global Analysis data.


The follow-up plans and ideas

• Focus on the radiometric calibration of high spatial resolution observing satellite sensor (<30m) and gradually form the cross-calibration system of high spatial resolution observing satellite sensor.

• Start cross-calibration of HY-2 and JASON• Start cross-calibration of thermal band of CERBS-04

with international sensors• Start cross-calibration of GF-4 with international

sensors


Documents

Report from CNSA 16th GSICS Executive Panel, Boulder, 15-16 May 2015 Peng Zhang, Jun Gao