Microwave Sub-Group Web Meeting 2024-08-28

GSICS Microwave Subgroup General Meeting Agenda

1100-1300 UTC August 28, 2024

The meeting will be used to communicate status and path forward plans for the Focus Groups.

1. [100 mins] Focus Groups (Shengli Wu – CMA and Flavio Iturbide-Sanchez - NOAA)

Progress and status briefings from established Focus Groups [80 min]

• Direct MW Radiometer Inter-comparison Method Focus Group (Tim Hewison – 20 min)
  • A meeting was held on August 8^th
  • Discussions revolved around simultaneous nadir overpass (SNO) collocation region choice, screening methods, weighting based on scene variability, and methods to determine uncertainty due to space and time variability that surfaces in bias variability.
  • Sentinel 6/ Advance Microwave Radiometer was introduced.
    • This radiometer has relatively small footprints and frequent sampling, but is nadir looking only and suffers from some RFI in the unprotected 34GHz channel.
    • Variograms showing brightness temperature uncertainty as a function of time (and associated spatial) variability. It reveals that different uncertainties related to various atmospheric phenomena at different time scales can quickly eclipse instrument noise variability if not carefully considered.
  • The ESA Arctic Weather Satellite (AWS) launched on 16 August 2024. The radiometer on this mission will be compared with ATMS, AMSU-A/MHS using 2 SNO methods.
  • Experimenting with 2-D Variograms, which would allow regions with relatively low variability to be determined and used to relax SNO time and space difference criteria.
  • Questions and Comments
    • Shengli – Collocation area for sensors may sample different from collocation area by several kilometers. If we use several hundred pixels that may be averaged out.
      • Tim - Bigger area means you have more pixels but there is a tradeoff in scan angle, spatial variability in the scene and dynamic range. If scene variability was white noise, then not an issue, but it is not.
      • Analysis could find locations on Earth have the smallest variability.
    • Cheng-zhi – Does the asymmetry have impact on the SNO? For example, most SNOs will have a different number of samples between the northern/southern side of the SNO point.
      • Tim – This is not yet considered this in the variogram analysis. For IR found systematic differences in time between instruments at a collocation. So, we may want to check on the distribution of the time difference of collocations. Also, what if view angle on average is different? We need to analyze this as well - although it could be account for by a "Geometric Adjustment Function".
        
        
• MW Radiometer Technology and Instrument Pre-Launch Testing and Post-Launch Characterization Focus Group (Dazhen Gu and Juyang Hu – 20 min)
  • Broad expertise and affiliation coverage over the members
  • The first meeting was held on July 31^st, with four persons attending.
  • Quarterly meetings will be held
  • Participants expressed their topics of interest in relation to the group:
    • Tim - NEDT, gain stability, inter-calibration methods, hyperspectral radiometric measurements
    • Raffaele - Noise diode applications, post-launch sensor monitoring, long-term decadal satellite operation, quality assurance, inter-comparison with ground-based radiometers
    • Tiger - SI Traceability, establishment of mw cal standards, extend traceability path to sat measurement and transfer standards, alternate tech for cal artifacts, recommended to reach out to Ed Kim
    • Dazhen - Improvements of NIST blackbody (BB) prototype, Electromagnetic and thermal val of BB standards, Next generation standard for small satellites, uncertainty analysis for the microwave, NOAA NEON SMBA mission
  • Questions and Comments
    • Siena – Did you talk about hosting a workshop in this meeting? This is a way for the group to be informed about trends and developments in microwave radiometers
      • This was not brought up in the meeting, but we plan one for next year.
      • ACTION(Dazhen): Will create a plan to hold a GSICS MW Subgroup technical workshop based on this group's topics of interest by our next December general meeting.
    • Shengli – Suggest to invite some people with expertise in pre-launch microwave radiometer development and testing, since most of us do post-launch research. For agencies, ESA, NASA, JAXA maybe they do not have opportunity to talk about new sensor plans?
      • Dazhen - Will contact Ed Kim of NASA, and start with that.
      • The meetings can have technical talks, but don’t want to add too much overhead to the meetings.
      • Tim – Too much emphasis on sensor development averts from the GSICS mission goals.
      • Tiger – In other meetings, there is often general updates of sensor programs.
        
        
• MW Radiometer Lunar Calibration Focus Group (Tiger Yang – 20 min)
  • Scope microwave lunar RTM model development
    • Three different models: Thermophysical model (TPM), RTM model, Model by Nuitao Lui (Fudan). RTM model has been shared open source.
    • Thomas compared the different models using a common reference, and using the same satellite data set. Results were given as a ratio between satellite and model simulation, where a value of 1 is agreement, and more or less than 1 means there is a bias.
    • Want to know the root cause of difference. Niutao Liu did a study on why they may be different. Tangent loss plays an important role in RTM performance. This needs further work.
  • Lunar radiance measurements based on satellite observations
    • Presented results on update lunar Tb datasets. Improvements were outlined, and a path forward for further process included.
    • Beam pointing, antenna pattern, and smearing due to rotation are factors to account for in Lunar cal. Martin did some work with this.
    • CMA did work on FY-3C MWHS-II did work on deep space view lunar intrusions
  • Action Items
    • Completed: Sharing code using GitHub and Provided the sat Moon Tb datasets for the community
    • In Process
      • Compare Fudan model with Tiger’s RTM
      • Compare Fudan lunar model with TPM (further work needed for Fudan model inter-comparison)
      • Provide info in FT3 MWTS/MWHS level-1 dataset for lunar samples collection
        
        
• MW Radiometer Applications Focus Group (Cheng-zhi Zou – 20 min)
  • Provided vision statement to develop, assess and apply methods to create FCDR and CDRs
  • Provided a list of data products that includes the name, developing agency, sensors, satellite, time period and applications
  • Recent activities include climate change monitoring, comparison of GPS RO data with MW sounder reference dataset, using the Moon to validate MW and IR sounder cal drift, Data assimilation in NWP systems
  • Showed example of FCDR Data Assimilation in Climate Reanalysis, and climate change monitoring using CDRs
  • Tim – Comment – The extreme warm anomaly this year. The uncertainty of the method is small?
    • Uncertainty from inter-calibration is very small. Very small inter-satellite biases. Change mainly coming from ATMS.
    • Graphs showing extremity of warming this year, which is lasting beyond the El Nino.
    • There was a Bulletin of the American Meteorological Society climate report released last week.

Proposal to merge focus groups conentrating their efforts on Direct MW Radiometer Inter-comparison Method, MW Radiometer Vicarious Calibration, and Radiative Transfer Model (RTM) Facilitated MW Radiometer Inter-calibration [20 min]

• Tim – Point of the focus groups is to focus on one topic. The focus groups may become too diluted if they attempt to become too broad in scope.
• There currently is no leader for RTM Inter-cal FG.
• Vicarious does make sense for the SNO group. Could piggyback on other ideas.
• DECISION: A leadership call will be sent to the agency points of contact in regards to the RTM Inter-cal FG.
  • ACTION(Fabien): Will ask James Hocking from the UK Met Office if he would be interested in leading this group.
  • ACTION(Siena): If James Hocking does not accept, then send out a broad call to the agency points of contact.

2. [20 mins] Other Business (Shengli Wu – CMA and Flavio Iturbide-Sanchez - NOAA)

None

Attendees

Meeting Co-Chairs: Flavio Iturbide-Sanchez (NOAA) and Shengli Wu (CMA)

CMA: Shengli Wu

DWD: Karsten Fennig

ECMWF: Neils Bormann

EUMETSAT: Tim Hewison and Vinnia Mattioli

NIST: Dazhen Gu

NOAA: Flavio Iturbide-Sanchez, Siena Iacovazzi, Cheng-zhi Zou, Ninghai Sun

UK Met Office: Fabien Carminati

University of Maryland: Hu Yang and Jun Zhou

Summary

The meeting communicated the status and path forward plans for the four active focus groups, and detailed notes are given above. Regarding the two inactive focus groups, the decision has been made to try to find a leader for the Radiative Transfer Model (RTM) Facilitated MW Radiometer Inter-calibration Focus Group, instead of merging this focus group with other focus groups. Meanwhile, the decision made during the GSICS Annual Meeting to dissolve the separate MW Radiometer Vicarious Calibration Focus Group and absorb its topics into the other focus groups as appropriate.

Outcome

Actions:

A.GMW.20240828.1: Dazhen Gu (NIST) to contact Ed Kim regarding possible topics related to pre-launch microwave instrument characterization

A.GMW.20240828.2: Dazhen Gu (NIST) to create a plan to hold a GSICS MW Subgroup technical workshop based on this the Technology and Testing Focus Group's topics of interest by our next December general meeting.

A.GMW.20240828.3: Fabien Carminati (UKMO): Will ask James Hocking from the UK Met Office if he would be interested in leading the RTM-based inter-calibration focus group.

A.GMW.20240828.4: Siena Iacovazi (NOAA): If James Hocking does not accept, then send out a broad call to the agency points of contact, soliciting offers to lead the RTM-based inter-calibration focus group.