GRWG/GDWG Web Meeting 2011-10-26

GSICS Web Meeting on Application of Common DCC Algorithm

The goal of the meeting is to discuss a common way forward, so that by the annual meeting, each center can share their preliminary DCC results.

If you have any DCC results or methods you would like to present at the GSICS DCC meeting, please let Dave know.

Dave has placed on the GSICS wiki the DCC ATBD, intended as a starting point, to discuss a common DCC application across centers.
If you have any questions or suggestions regarding the document or the implementation thereof, please email.
https://gsics.nesdis.noaa.gov/pub/Development/AtbdCentral/GSICS_ATBD_DCC_NASA_2011_09.pdf

Agenda

1. Arata Okuyama (JMA) – Report on JMA's DCC approach and its preliminary result
2. Dave Doelling (NASA) – Review of Proposed Outline ATBD for Deep Convective Cloud

Attendees

Guest Chair: Dave Doelling (NASA)

CMA: Li Yuan, Lin Chen, Scott Hu, Xu Na, Sun Ling

CNES: Bertrand Fougnie (comments relayed in absentia)

EUMETSAT: Tim Hewison, Sebastien Wagner

JMA: Aratu Okuyama, Yoshihiko Tahara, Kenji Date, Hiroaki Tsuchiya, Ryuichiro Nakayama, Yuki Kosaka

NASA: Dave Doelling, Daniel Morstad

NOAA: Fangfang Yu, Fred Wu, Likung Wang, Bob Iacovazzi, Haifeng Qia

Summary

Arata Okuyamam (JMA) presented initial results of the inclusion of deep convective clouds in the calibration of the visible channel of MTSAT-2. This is based on a different algorithm, which takes advantage of multiple IR channels of MTSAT and is based on radiative transfer modelling of the clouds' reflectance based on inputs from MODIS-derived Cloud Optical Thickness.

Dave Doelling (NASA) reviewed the proposed ATBD he has developed for application to inter-calibration the visible channels of all current geostationary imagers against the 0.65μm channel of Aqua/MODIS as a reference. This included an initial error estimate for the algorithm, suggesting total uncertainties of ~2% for the 0.6μm channels of all GEO imagers. During the review several issued were raised, which need further investigation:

• The method used to select the mode of the histogram
• The impact of the calibration of the infrared channels of the GEO imagers - in comparison with the GSICS Correction for these channels
• The relative calibration of different channels on the same instrument
• The applicibility of the proposed method to other channels - particularly the 0.8μm and HRV channels of Meteosat
• The strategy for migrating the reference instrument from Aqua/MODIS to other instruments - e.g. NPP/VIRS
• Further reviewing of the error budget - especially after any changes to the ATBD
• The impact of the BRDF model - in comparison to an RTM-based method.
• The global consistency of the results - including differences over land/sea

Outcome

Action: NOAA, EUMETSAT, JMA and CMA agreed to implement the DCC algorithm developed by Dave Doelling for the visible channels of the current operational geostationary imagers - on a best efforts basis. Each GPRC should produce plots of stacked reflectance histograms and time series of gain changes in the same style as Dave's to allow easy comparison of results - both quantitatively and qualitatively at the next GSICS meeting.

Meanwhile, communication will be by email and through a dedicated topic page on the GSICS Wiki.