Sciences and Exploration Directorate

Brief Bio


Dr. Riggs began working on development and implementation of the MODIS snow cover algorithms in the autumn of 1989 after graduating from the University of Montana with a Ph.D. in Forestry.    He began with initial development of the MODIS snow cover and sea ice algorithms and has lead analysis, evaluation and revision of the algorithms and products through several collections to the current Collection 6 versions.  In 2012 he began evaluation of the Suomi-NPP VIIRS snow cover algorithms and data products and has adapted the MODIS snow cover algorithm for use with VIIRS data.  Blending of MODIS snow cover extent product with  snow water equivalent (SWE) products from microwave sensors to get a global view of snow cover extent and SWE has also been an active research interest over recent years. 






























Research Interests


Snow and Ice

Earth Science: Remote Sensing

Remote sensing of snow cover and ice extent using the visible instruments of MODIS and VIIRS to monitor global snow cover extent and duration of snow cover.  Combining the visible snow cover products with snow water equivalent (SWE) products derived from microwave instruments, e.g. AMSR-E, SMMR and SSM/I. 

Current Projects


MODIS Snow Products

Remote Sensing

Revise and maintain the MODIS snow cover extent algorithms and data products for both the Terra and Aqua missions.  Provide documentation of the algorithms and data products, primarily the User Guides.  Provide detailed quality assessment (QA)  regarding the accuracy and error of snow cover detection across all landscapes and viewing conditions. 

Collection 6 (C6) production of the MODIS snow cover algorithms and products, with significant revisions to improve snow cover detection and increased QA information content will begin about September 2014. 


VIIRS Snow Cover Evaluation

Remote Sensing

NPP VIIRS science team member evaluating the VIIRS snow cover Environmental Data Records (EDRs) and contributor to the NASA Suomi-NPP Land Team evaluation report of VIIRS EDRs. 

Adapting the MODIS fractional snow cover extent algorithm to run with VIIRS data inputs and evaluating that new VIIRS fractional snow cover extent product to the standard VIIRS EDRs and MODIS standard data products.   


MODIS Sea Ice Products

Remote Sensing

Revise and maintain the MODIS sea ice extent and ice surface temperature (IST) algorithms and data products for both the Terra and Aqua missions. Provide documentation of the algorithms and data products, primarily the User Guides. Provide detailed quality assessment (QA) regarding the accuracy and error of sea ice extent and temperature.

Collection 6 (C6) production of the MODIS sea ice extent algorithms and products  will begin about September 2014.

Positions/Employment


Lead Support Scientist

SSAI - NASA GSFC

December 2000 - Present


Support/Research Scientist

RDC - NASA GSFC and RDC Greenbelt, MD

October 1989 - November 2000

Education


Ph.D., Forestry, University of Montana, 1989. 
MS, Forestry, Fisheries, and Wildlife, University of Nebraska, 1985
BS, Biology, Nebraska Wesleyan University, 1979

Professional Societies


American Geophysical Union

1994 - Present


ASPRS The Imaging & Geospatial Information Society

1994 - Present

Awards


NASA GSFC Hydrospheric and Biospheric Sciences Laboratory HOBI Award for outstanding scientific and technical support, August 2014.

NASA GSFC Hydrospheric and Biospheric Sciences Laboratory HOBI Award for outstanding scientific and technical support, August 2012.

NASA GSFC Hydrospheric and Biospheric Sciences Laboratory  Peer Award for Outstanding Support Service Contractor, September 2007.

NASA Goddard Technology Transfer Program, Certificate of Recognition for Software technology titled, “MODIS Snow and Sea Ice Maps”, 2003

NASA Goddard Technology Transfer Program, Certificate of Recognition for Software technology titled, “MODIS Snow and Sea Ice Maps – Level 2 Sea Ice, Level 3 Sea Ice Daily”, 2003

Selected Publications


Refereed

Justice, C., M. O. Roman, I. Csiszar, et al. E. Vermote, R. E. Wolfe, S. J. Hook, M. Friedl, Z. Wang, C. B. Schaaf, T. Miura, M. Tschudi, G. Riggs, D. K. Hall, A. I. Lyapustin, S. Devadiga, C. C. Davidson, and E. J. Masuoka. 2013. Land and cryosphere products from Suomi NPP VIIRS: Overview and status J. Geophys. Res. Atmos. 118 (17): 9753-9765 [10.1002/jgrd.50771]

Foster, J., G. S. Jackson, H. Meng, et al. J.-J. Wang, G. Riggs, P. J. Kocin, B. T. Johnson, J. Cohen, D. K. Hall, S. V. Nghiem, and J.-J. Wang. 2012. Passive microwave remote sensing of the historic February 2010 snowstorms in the Middle Atlantic region of the USA Hydrol. Processes 26 (22): 3459-3471 [10.1002/hyp.8418]

Hall, D., J. Foster, N. DiGirolamo, and G. Riggs. 2012. Snow cover, snowmelt timing and stream power in the Wind River Range, Wyoming Geomorphology 137 (1): 87-93 [10.1016/j.geomorph.2010.11.011]

Foster, J. L., D. K. Hall, J. B. Eylander, et al. G. A. Riggs, S. V. Nghiem, M. Tedesco, E. J. Kim, P. M. Montesano, R. E. Kelly, K. A. Casey, and B. J. Choudhury. 2011. A blended global snow product using visible, passive microwave and scatterometer satellite data International Journal of Remote Sensing 32 (5): 1371-1395 [10.1080/01431160903548013]

Akyurek, Z., D. K. Hall, G. A. Riggs, and A. Sensoy. 2010. Evaluating the utility of the ANSA blended snow cover product in the mountains of eastern Turkey International Journal of Remote Sensing 31 (14): 3727-3744 [10.1080/01431161.2010.483484]

Hall, D. K., G. A. Riggs, J. L. Foster, and S. V. Kumar. 2010. Development and evaluation of a cloud-gap-filled MODIS daily snow-cover product Remote Sens Environ 114 (3): 496-503 [10.1016/j.rse.2009.10.007]

Hall, D. K., and G. A. Riggs. 2007. Accuracy assessment of the MODIS snow products Hydrological Processes 21 (12): 1534-1547 [10.1002/hyp.6715]

Hall, D. K., J. Key, K. A. Casey, G. A. Riggs, and D. J. Cavalieri. 2004. Sea ice surface temperature product from the Moderate Resolution Imaging Spectroradiometer (MODIS) IEEE Trans Geosci Remote Sensing 42 1076-1087

Hall, D. K., G. A. Riggs, V. V. Salomonson, N. DiGirolamo, and K. J. Bayr. 2002. MODIS snow-cover products Remote Sensing of Environment 83 181-194

Riggs, G. A., D. K. Hall, and S. A. Ackerman. 1999. Sea ice extent and classification with the Moderate Resolution Imaging Spectroradiometer Airborne Simulator (MAS) Remote Sensing of Environment 68 (2): 152-163

Talks, Presentations and Posters


Invited

Suomi NPP Snow Cover EDR Evaluation.

February 23, 2013

Oral presentation regarding evaluation of the VIIRS Snow Cover EDRs given at the NASA NPP Science Team Review, 23-25 January 2013, at GSFC.  Purpose of review was to evaluate current status of the VIIRS products and use that information to develop plans for direction of the NPP program. 


Other

Tracking Seasonal Mountain Snow Cover with MODIS Snow Products

July 4, 2014

Oral presentation given an the Eastern Snow Conference, 3-5 June 2014, Boone NC.  Demonstrated a technique using the daily MODIS snow cover product (MOD10A1) that can be used to track seasonal snow cover in a mountains region, allowing the user to determine the duration of seasonal snow cover extent. 


Riggs, G. & Hall, D. 2012. Suomi NPP VIIRS Snow Cover Products Initial Evaluation, poster presentation at the NASA NPP Science Team Meeting, Greenbelt, MD, 10-11 May 2012

June 10, 2012

Initial evaluation of the accuracy and error of the VIIRS Snow Cover Environmental Data Records (EDRs).  Evaluation was based on analysis of the algorithms and the comparative analysis of snow cover extent maps to ground station data and corresponding MODIS snow cover extent maps.