Project Funding: 2011 - 2014

NRA: 2010 NASA: NPP Science Team for Climate Data Records   

Funded by NASA

Abstract:
The NASA Earth Science Division has recognized Land Surface Temperature and Emissivity (LST&E) as a key Earth System Data Record (ESDR) defined by NASA as a unified and coherent set of observations of a given parameter of the Earth system. Land Surface Temperature (LST) is an important long-term climate indicator, and accurate knowledge of the Land Surface Emissivity (LSE) is critical for deriving the LST and as inputs to climate models and data assimilation systems. We will evaluate and improve the accuracy of the LST product generated from the Visible Infrared Imaging Radiometer Suite (VIIRS) on the National Polar Orbiting Environmental Sensor Suite (NPOESS) Preparatory Project (NPP) to ensure that it is suitable for use as an ESDR. Currently a dual split-window (DSW) approach is used to generate the VIIRS LST product. This approach works well for surfaces whose emissivity can be correctly assigned based on a land classification scheme (e.g. water, vegetation) but less well for surfaces where the LSE differs from the assigned emissivity (e.g. bare surfaces). A similar split-window approach is currently used to generate one of the LST products from MODIS data and has been shown to be in error by as much as 12 K when the surface emissivity is incorrectly assigned. A 12 K error far exceeds the 1 K accuracy specification for the MODIS product and the 2.5 K accuracy specification for the VIIRS product. Moreover since the classification is fixed in the MODIS and VIIRS LST algorithms, any dynamic changes in emissivity also result in large LST errors. Dynamic changes can occur as a result of rainfall, wildfires or seasonal vegetation changes. For example, a 10 K error in the MODIS LST product was observed in the area covered by the recent Station fire in Southern California due to a change in the surface emissivity that was not captured in the MODIS land classification scheme used in the MODIS LST product. The VIIRS product will extend the LST measurements begun by AVHRR (1978 - present) and MODIS (2000 to present) to provide a 50-year continuous data record and it is essential that this record is well characterized and accurate. This study will quantify uncertainties in the VIIRS LST product and produce a dynamic emissivity product that can be used to improve the accuracy of the existing VIIRS LST product over semi-arid and arid regions. We will assess the accuracy of the product using cross-sensor intercomparisons combined with data from a global set of validation sites and specific case studies designed test whether the product accurately responds to dynamic Earth system changes such as wildfires.

Publications:

Guillevic, P. C., Biard, J. C., Hulley, G. C., Privette, J. L., Hook, S. J., Olioso, A., Gottsche, F. M., Radocinski, R., Roman, M. O., Yu, Y., Csiszar, I. 2014. Validation of Land Surface Temperature products derived from the Visible Infrared Imaging Radiometer Suite (VIIRS) using ground-based and heritage satellite measurements. Remote Sensing of Environment. 154, 19-37. DOI: 10.1016/j.rse.2014.08.013

2015 NASA Carbon Cycle & Ecosystems Joint Science Workshop Poster(s)

• HyspIRI, HyTES and ECOSTRESS   --   (Simon J. Hook, William R. Johnson, Pierre C. Guellivic)   [abstract]

2013 NASA Terrestrial Ecology Science Team Meeting Poster(s)

• Land Surface Temperature and Emissivity (LST&E) products and their uncertainties   --   (Glynn C. Hulley, Simon J. Hook)   [abstract]

2011 NASA Carbon Cycle & Ecosystems Joint Science Workshop Poster(s)

• Validation of Mid and Thermal Infrared Remotely Sensed Data In-Flight Using Automated Validation Sites at Lake Tahoe CA/NV, USA and Salton Sea CA, USA   --   (Simon J. Hook)   [abstract]

More details may be found in the following project profile(s):

• NASA Terrestrial Ecology (TE) Project Profile