Longterm Water Cycle Observation by the Advanced Microwave

Long-term Water Cycle Observation by the Advanced Microwave Scanning Radiometer (AMSR) Series: AMSR-E, AMSR 2 and Follow-on M. Kachi 1), H. Fujii 1), T. Kubota 1), T. Maeda 1), N. Ono 1), M. Kasahara 1), and N. Ebuchi 1), 2) 1) Japan Aerospace Exploration Agency 2) Hokkaido University 5 October, 2018 @ Seoul, South Korea 9 th International Precipitation Working Group Workshop

JAXA Earth Observation Satellite missions Targets (JFY: Apr-Mar) 2012 2013 2014 2015 2016 2017 2018 2019 2020 2021 2022 Disasters & Resources JERS 1/OPS, SAR (1992 -1998) ADEOS-I/AVNIR ALOS/AVNIR 2, PALSAR (20062011) Climate System • Water Cycle ADEOS-I/AMSR (1996 -1997) Aqua/AMSR-E (2002 -2010) [Land disaster monitoring] ALOS-4 ALOS-2 / PALSAR-2 ALOS-2 CIRC ISS/CIRC TRMM / PR 1997 -2015 [Precipitation 3 D structure] with NASA ALOS-3 Feasibility study DPR F/O GPM / DPR with NASA [Wind, SST , water vapor, precipitation] AMSR 2 F/O GCOM-W / AMSR 2 [Vegetation, aerosol, cloud, SST, ocean color] • Climate change GCOM-C / SGLI ADEOS-I/OCTS (1996 -1997) ADEOS-II/GLI (2003) [Cloud and aerosol 3 D structure] with ESA Earth. CARE [CO 2, CH 4, • Greenhouse gases GOSAT / FTS, CAI 2009~ with MOE JMA meteorological satellites Mission status MTSAT-1 R (Himawari-6) MTSAT-2 (Himawari-7) GOSAT 3 GOSAT-2 [Cloud, aerosol, SST] [Cloud, SST] On orbit [CO 2, CH 4, CO] Himawari-8/AHI Himawari-9 (standby) Development Study Pre-phase-A

Development of AMSR Series Sensor MOS-1/MSR ADEOS-II/AMSR Aqua/AMSR-E GCOM-W/AMSR 2 Coverage Direct receive only Global Swath 317 km 1600 km 1450 km 1617 km Frequencies (GHz) 2 (23, 31) 9 (6. 9, 10, 18, 23, 36, 50, 52, 89) 6 (6. 9, 10, 18, 23, 36, 89) 7 (6. 9, 7. 3, 10, 18, 23, 36, 89) Polarization Mixed V and H Antenna Size 0. 5 m 2. 0 m 1. 6 m 2. 0 m Spatial Res. 8 x 14 km @36 GHz 7 x 12 km @36 GHz 23 km @31 GHz AMSR 3? 1987 2002 2012 GCOM-W 3

Overview of GCOM-W and AMSR 2 Instrument Advanced Microwave Scanning Radiometer 2 (AMSR 2) Altitude 705 km Orbital inclination 98. 2 deg Local sun time at Ascending node 13 : 30 Launch vehicle H-IIA Launch May 18, 2012 Designed lifetime 5 years üSuccessor of Aqua/AMSR-E (launched in May 2002), providing continuous data for climate studies and operational applications üJoining A-train constellation (same as Aqua) and also GPM constellation üCarrying AMSR 2, a multi-polarization and multi-frequency microwave imager üObserving various water-related ECVs at high spatial resolution üImproving on-board calibration target has resulted reduction of annual TB variation due to calibration and improvement of TB stability üAchieved designed mission life (5 -year) on May 18, 2017, and continues observation üEnough fuels to keep current orbit for more than 15 years 4

AMSR 2 Geophysical Parameters Total Precipitable Water Integrated Cloud Liquid Water Sea Surface Temperature Sea Surface Wind Speed Snow Depth Soil Moisture Content Descending orbit on 8 May 2013. Precipitation Sea Ice Concentration

https: //www. gportal. jaxa. jp/gp/ AMSR 2 Standard Products G E O Product Coverage Resolution Release Accuracy Standard Accuracy Target Accuracy Validation Result Latest version Brightness Temperature Global 5 -50 km ± 1. 5 K ± 1. 0 K (bias) ± 0. 3 K(random) < 1. 4 K Ver. 2. 2 Total Precipitable Water Global Ocean 15 km ± 3. 5 kg/m 2 ± 2. 0 kg/m 2 1. 5 kg/m 2 Ver. 2. 1 Cloud Liquid Water Global Ocean 15 km ± 0. 10 kg/m 2 ± 0. 05 kg/m 2 ± 0. 02 kg/m 2 0. 04 kg/m 2 Ver. 2. 1 Precipitation Global (except high latitude) 15 km Ocean ± 50 % Land ± 120 % Ocean ± 20 % Land ± 80 % Ocean 48% Land 86% Ver. 2. 1 Sea Surface Temperature Global Ocean 50 km ± 0. 8 ºC ± 0. 5 ºC ± 0. 2 ºC (zonal mean) 0. 5 ºC < 0. 2 ºC (zonal) Ver. 3. 0 Sea Surface Wind Speed Global Ocean 15 km ± 1. 5 m/s ± 1. 0 m/s Ver. 3. 0 Sea Ice Concentration Ocean in high latitude 15 km ± 10 % ± 5% 9% Ver. 3. 0 Snow Depth Land 30 km ± 20 cm ± 10 cm 18 cm Ver. 2. 1 Soil Moisture Land 50 km ± 10 % ± 5 % 4% Ver. 3. 0 6

http: //suzaku. eorc. jaxa. jp/GCOM_W/research/resdist_j. html AMSR 2 Research Products and Accuracy Products All-weather sea surface wind speed High-resolution (10 -GHz) SST Soil moisture and vegetation water content based on the land data assimilation Area Resolution Ocean 60 km Ocean 30 km Africa, Australia (at first stage) 25 km Target accuracy ± 7 m/s for strong wind (>17 m/s) ± 0. 8 ºC Status Ver. 3. 0 released 4. 07 m/s Ver. 3. 0 released 0. 55 ºC soil moisture: ± 8% vegetation water: ± 1 kg/m 2 forest area: ± 3 ºC nondense vegetation: ± 4 ºC Ver. 1. 0 released 3 ºC (forest) 4 ºC (nondense vegetation) Under development Land surface temperature Land 15 km Vegetation water content High resolution sea ice concentration Land Ocean in high latitude 10 km ± 1 kg/m 2 Under evaluation 5 km ± 15 % Under evaluation Thin ice detection Global 15 km ± 80 % (answered correctly) 2 components: 3 cm/s Consideration to release 92. 4 % for Okhotsk sea Sea ice moving vector Total Precipitable Water over Land Released to public Ocean in high latitude Land (except ice and vegetation) To be released 50 km 15 km ± 6. 5 kg/m 2 Under evaluation Newly Proposed 2. 59 kg/m 2 vs. GPS Newly proposed 7

Land Surface Temperature Product • Algorithm provided by Tom Jackson (USDA) based on Holmes et al. (2009) • Retrieval of LST by single equation using 36 GHz V TB – Equation is obtained by using linear regression between AMSR 2 LST and LST at ground observation sites in Europe and US • Observing top of forest over forest area • Capable to obtain frequent LST for both day & night • Released in February 2018 through http: //suzaku. eorc. jaxa. jp/GCOM_W/research/resdist_j. html – Detailed validation results are also available at the web site DAY June 2017 NIGHT June 2017 8

AMSR-E Reprocess Product Status • Toward consistent dataset between AMSR 2 and AMSR-E for long-term analysis, JAXA has reprocessed AMSR-E product applying the latest AMSR 2 algorithms. – Level 1 & 3 (brightness temperature): Released from G-Portal • Level 1 B & 1 R in AMSR 2 format (HDF 5) – Level 2 & 3 (geophysical parameters): Preparation for public release • Applying the current (latest) AMSR 2 L 2 algorithms and format (HDF 5) • Validation is underway (to be released by early 2019) SST Total Precipitable Water 9

AMSR-E L 1 Product Ver. 4 • L 1 reprocessing summary – Brightness temperature (TB) between AMSR-E and AMSR 2 is not adjusted – Swath width of AMSR-E (1450 km, 196 pixels for low-freq. Ch. / 392 for high-freq. Ch. ) is extended to be equivalent to that of AMSR 2 (1620 km, 243 pixels for low-freq. Ch. / 486 for high-freq. Ch. ) – AMSR-E L 1 R (resampling) product, which is highly requested by users, are newly developed • Improvements in L 1 B Algorithm – Bias correction of TB is applied to scan edges to extend swath width – Improved method to calculate hot load temperature correction by using two orbit paths to resolve gaps between Ascending and Descending orbit products – Improved geometric parameters • AMSR-E L 1 products (ver. 4) has been released to public through GPortal since April 2018. – https: //www. gportal. jaxa. jp/gp/ 10

AMSR-E L 1 Ver. 4: Extend Swath Width 0 deg. Satellite flight direction -61 deg. +61 deg. Antenna rotating direction -75 deg. AMSR-E original Equivalent to AMSR 2 +75 deg. Swath width 1450 km (193 pix for low-freq. / 392 for high-freq. ) Swath width 1620 km (243 for low-freq. / 486 for high-freq. ) 11

Status of AMSR 2 follow-on sensor (AMSR 3) • AMSR 2 is now flying more than six years exceeding designed life. • In response to users’ requests, AMSR 2 follow-on mission has been in pre-project phase (Phase A) since September 1, 2018. – Mission Definition Review (MDR): April to June 2018 – Project Preparation Review: July 2018 • The new satellite will become a joint mission of AMSR 2 follow-on sensor and GOSAT-2/TANSO-2 successor sensor (advanced spectrometer to monitor greenhouse gases). – Orbit definition is currently under negotiation with TANSO-2 successor mission but we will keep early afternoon orbit around 13: 00 or 13: 30 in LT • AMSR 2 follow-on sensor (AMSR 3) specification – Almost equivalent sensor specification to the current AMSR 2 (antenna size, channels) except additional higher frequency channels of 166 & 183 GHz for snowfall retrievals and water vapor analysis in NWP – New products including snowfall, TPW over land, high-resolution SST, allweather sea surface wind speed & high-resolution sea ice concentration 12

JAXA Research Announcement (RA) • The next RA was just announced for the three-year period JFY 20192021. – The JAXA integrated Research Announcements for various missions and release “Research Announcements on the Earth Observations”. – This RA includes almost all EO missions in the JAXA (GPM, GCOM-W, AMSR 3, GCOM-C, Earth. CARE, ALOS-2/3/4, and MOLI). Deadline is the end of November 2018. – https: //www. eorc. jaxa. jp/en/research/ra/2 nd_ra_eo/index. html – The next RA includes not only GCOM-W, but also AMSR 3!

Summary • JAXA’s GCOM-W mission is now flying more than 6 -years without any serious problem. Satellite and sensor (AMSR 2) is in healthy condition. – AMSR 2 products are distributed to public via internet. Transfer to G-Portal (https: //www. gportal. jaxa. jp/gp/) has completed in June 2018 – 8 standard geophysical parameters and 3 research products are now available, and 2 research products (including candidate) are close to release • AMSR-E reprocessing products applying AMSR 2 format and algorithms are in preparation, expecting contribution to CDRs – L 1 B and L 1 R (resampling: new) products are already available at G-Portal – L 2 products are now validated and show accuracy equivalent to AMSR 2 • AMSR 2 follow-on sensor (AMSR 3) and TANSO-2 successor sensor will be joint mission and has been in Phase A since Sep. 1, 2018. – Will keep early afternoon orbit – Sensor specification of AMSR 3 will be equivalent to AMSR 2 except additional 166/183 GHz channels for solid precipitation retrievals and water vapor analysis in NWP 14

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AMSR-E L 1 Ver. 4: Hot Load Correction • Parameters to correct hot load temperature are calculated using half orbit data previously, but gaps are found at boundary of A/D products. • In new version, two orbits path data (1 orbit before and after) are used for calculation and gaps are resolved. New method Hot Load temperature Previous method Descending Ascending 16

AMSR-E L 2 Ver. 8: Current Validation Status Product (ID) Ver. 7 (Current ver) Ver. 8 (Reprocess ver. ) Accuracy definition of AMSR 2 (Standard/Target) Total Precipitable Water (TPW) 1. 89 kg/m 2 1. 65 kg/m 2 3. 5 / 2. 0 kg/m 2 Integrated Cloud Liquid Water (CLW) 0. 0395 kg/m 2 0. 0273 kg/m 2 0. 05 / 0. 02 kg/m 2 0. 0261 kg/m 2 (Jan. /Jul. 2003) * Data spread (total accuracy including parameter dependency: CLW accuracy = Worst STD. + Worst Bias) Ocean： 94. 87% Land： 123. 54% Ocean： 65. 92% Land： 91. 13% Ocean 50 / 20 % Land 120 / 80 % Sea Surface Temperature (SST) RMSE 0. 62 deg. C RMSE 0. 54 deg. C 0. 5 deg. C@RSME / 0. 2 deg. C@Bias Sea Surface Wind Speed (SSW) 1. 164 m/s 1. 079 m/s 1. 0 / 1. 0 m/s Sea Ice Concentration (SIC) N. H. 6. 66% S. H. 8. 10% N. H. 7. 01% S. H. 8. 02% 10 / 5 % Snow Depth (SND) GSOD 17. 0 cm GSOD 17. 7 cm 20 / 10 cm Soil Moisture Content (SMC) Mongolia 3. 07%vol U. S. LR 3. 87%vol Mongolia 2. 16%vol 10 / 5 %vol * MAE of instantaneous observation U. S. LR 4. 88%vol Precipitation (PRC) (Jan. /Jul. 2003年) (Whole period) * RMSE of instantaneous observation * Relative error at 50 km average (RMSE ratio against averaged precipitation rate) * Standard: Global monthly average of RMSE * Target: Monthly bias average at each 10 -deg lat. * Global monthly average of RMSE * RMSE of instantaneous observation * MAE of instantaneous observation 17