ESSP Missions, Secondary Uses of NASA Satellite Data (OCO, ICE

Final report for the break-out session on “ESSP missions, secondary uses of NASA satellite data (OCO, ICEsat, etc.), and non-NASA missions”.

August 2006

Co-chaired by Hank Margolis (U. Laval) and Marc Simard (JPL) .

The break up session was repeated a second time to allow all interested workshop attendees to actively participated to this theme. The first session had about 15 participants while the second session was attended by 3 people. During the first session, we discussed several sensors, in particular OCO, ICEsat and ALOS/PALSAR, while the discussion during the second session was primarily focused on Hyperion, NPOESS and several broad-band Landsat-type sensors that were not discussed during the first session.

Question #1: What funded, non-systematic NASA missions and now in development, are of greatest importance for Terrestrial Ecology, Biodiversity, and Applied Sciences? What questions will they help us to resolve?

The following “secondary” sensors and satellites have or will have the potential to provide valuable inputs into ecosystem process models for carbon cycle science, biodiversity and ecological forecasting.

ICEsat/GLAS (Geoscience Laser Altimeter System) is a laser altimeter with a footprint of ~60m with sampling every 172m. It was launched in 2003 and due to laser malfunction has a limited temporal coverage (3 months on/off). It has been shown to be helpful under some circumstances in mapping vegetation vertical structure, estimating height, and surface roughness as well as providing ground elevation under vegetation.

OCO (Orbital Carbon Observatory) will provide CO2 source and sink patterns and distributions on a regional scale including fossil fuel emissions and will be very important for constraining bottom-up process models. TE studies will elucidate whether some these sources are natural or artificial.

Quickscat is a Ku-band low resolution (25km or 2.5km binned) scatterometer with daily imaging. It allows for estimation of changes in vegetation biomass (phenology), length of the growth season, freeze-thaw status, and mapping roughness and moisture (soil+vegetation cover).

AMSR-E (on Aqua) – Advanced Microwave Scanning Radiometer A passive microwave instrument designed for precipitation, SST, soil moisture, snow water equivalent. For TE studies, it can provide surface soil moisture and land surface temperature at 25 km resolution. Complementary to Quickscat.

NPOESS/VIRS is the next generation of MODIS. Wide range of land surface variables for ecosystem function + physiology. However, there is a great need for a cal/val program for Terrestrial Ecology.

TRMM (Tropical Rainfall Measurement Mission) currently provides fire products and rainfall in tropical regions and is very useful for Terrestrial Ecology. HYPERION on EO-1 is a pointable, hyperspectral sensor launched in November 2000. It provides species detection, cover typing, canopy water content, and possibly canopy nitrogen and pigments. It was used successfully in the LBA project to provide spectral end-members for analyzing rates of disturbance. It is probably the best available sensor for analysis of coastal waters and coral reefs and may become the only sensor to study coastal ecosystems since the fluorescence measurement capability planned for NPOESS has been eliminated; i.e., the FLH (Fluorescence Line Height) is not going forward. Hyperion could be very useful for studying flooding events with high temporal frequency image acquisitions (day or two).

Until recently, it was flown in formation with Landsat-7, taking ground imagery approximately one minute after Landsat-7. Its orbit was recently lowered, so now it flies under both Landsat-7 and Landsat-5 on a periodic basis. This sensor is particularly valuable for cross-calibration with other sensors since the hyper-spectral bands can be aggregated together to conform to those from various broadband sensors. It is currently being used to cross-calibrate Landsat-5 and -7.

Hyperion is scheduled to continue its data collection until 2007 or 2008. It may be extended past this date.

Question 2: Does NASA need to do more to help/prepare the community to use the observations from these missions? If so, what?

ICEsat/GLAS Although the sensor was not designed specifically for TE studies because its 70 m footprint is generally considered too coarse and there are some geolocation issues, GLAS has proven to be of value for TE. Indeed, there should be much greater involvement of the TE community in the ICESAT follow-on mission. However, despite the seeming availability of data from the DAAC, several potential users mentioned the difficulty of obtaining easily usable data, e.g., there is no Level 2b GLAS product. There is a need for providing easily usable GLAS data or waveforms to the TE community. While Lefsky and Keller are addressing these issues, the data format remains complex and changes regularly. In addition, the GLAS Science Team should schedule a northern summertime data acquisition before the last of the three lasers expires.

OCO Representation of the TE community on the OCO Science Team is limited and this could have major consequences on the ultimate use of the data for TE studies. NASA should accelerate the movement of coherent OCO data products to the TE community and not wait the typical three to four years as done for previous missions. NASA should also prepare the TE community to use OCO datasets and products, as well as enhance the interaction with the Science Team.

Quickscat No follow on mission is planned, so future data availability and continuity is a major issue.

NPOESS/VIRS NASA must plan a robust cal/val effort to support TE.

HYPERION There is currently a proposal submitted to NASA HQ to allow NASA-approved investigators to have tasking (pointing) ability for Hyperion acquisitions at no charge to the investigators. This would advance the use of Hyperion data in TE and potentially soften the impact of the issues related to Landsat data continuity and cross calibration.

Question 3: Are some of these missions so important for Terrestrial Ecology, Biodiversity, and Applied Sciences that we should not be viewing them as secondary or supporting?

Yes. It was clear during the discussions of the first and second break-out sessions that ICESAT/GLAS, OCO, ALOS (see Question 4 for ALOS) and HYPERION are critical sensors to advance the use of remote sensing for Terrestrial Ecology, Biodiversity and Applied Sciences.

Question 4: What non-NASA missions (other U.S. and foreign) in development are of greatest importance for Terrestrial Ecology, Biodiversity an Applied Sciences? What questions will they help us resolve? How should we indicate our scientific support for these missions?

ALOS (Advanced Land Observing Satellite) by JAXA (Japanese Aerospace Exploration Agency) was launched in February 2006. It provides a systematic and global observation of the Earth with three sensors: PALSAR -2, PRISM and AVNIR-2. PALSAR is a polarimetric L-band SAR with a spatial resolution varying between 10 and 100m for swaths between 70 and 350km. PALSAR will very useful for TE studies, providing information on vegetation structure and biomass (up to ~100t/ha), and useful for monitoring disturbances and evaluating their impact. PRISM is a single band (0.52-0.77um) optical sensor with 3 looks (forward/nadir/back) and a resolution of 2.5m covering a swath of 35-70km. It will provide high resolution mapping of elevation and potentially vegetation height. AVNIR is a 4-band sensor (between 0.42 and 0.89 m) with a resolution greater then 10m and swath of 70km and may be used for land cover classification. NASA should proceed with the planned data buy for ALOS. Need to establish data agreements or consider additional data buys to ensure easy access.

Terra SAR-X (Tandem X) – German Space Agency and COSMOS – Italian Space Agency are X-band and L band radars, respectively. They will allow high resolution interferometry for vegetation height and ground elevation. They will be very useful for land cover mapping, change detection, and flood mapping.

HES-CW sensor on GOES-R will be useful for vegetation physiology and stress as well as estimating PAR and incoming short wave radiation. It will be very important for coastal water studies (water quality, habitat studies).

ENVISAT – European Space Agency ASAR (Advanced Synthetic Aperture Radar) is a C-band polarimetric radar, a follow-on of ERS-2. It can be used to estimate biomass for sparse forest - grassland systems as well as vegetation structure. SCIAMACHY is used to measure trace gases and MERIS (Medium Resolution Imaging Spectrometer) is a sensor similar to MODIS.

There seems to be significant issues in obtaining data from ENVISAT with reports that they have a difficult data-sharing policy. However, researchers may go through the proposal process. VIIRS on NPOESS A climate change signal is difficult to detect, so good cal/val is essential to terrestrial ecology’s use of this sensor, in particular to relate MODIS data to VIIRS. The cal/val issue is a major concern for this instrument and needs to be done independently (or at least with significant oversight). There needs to be a NASA science budget or some other means of funding NASA-related science for VIIRS since NOAA’s science budget for this instrument may not go to research directly relevant to terrestrial ecology. Indeed there should be a NASA science budget for other non-NASA missions if GEOSS and related activities are to succeed.

CBERS, RESOURCE-SAT, and SPOT Given the problems with Landsat-7’s line scanner and the various difficulties surrounding LDCM, it may become crucial to use alternative Landsat-type sensors for gap-filling. This is not the optimal solution but could reduce a total data void. CBERS is a series of joint Chinese and Brazilian land resource satellites that collects data almost exclusively over these two countries because of duty cycle and data transmission issues. Resource-Sat is an Indian satellite series similar to CBERS. SPOT is a French satellite that is fairly well known in our community, but its imagery is quite expensive. Receiving stations, agreements to collect data in other parts of the world,and funding researchers for cross-calibration would be helpful.

How do these missions/priorities fit into GEOSS and NASA’s role in GEOSS? GEOSS is an international framework to coordinate data characteristics such as formats and calibration from a large range of sensors. Inter-calibration between sensors is critical and appropriate guidelines for a common cal/val effort were proposed but proper funding was not in place. This is true for different satellites that are part of GEOSS even if they do not fly in formation. With its new orbit, Hyperion is performing common underpasses of other satellites and could play an important role in cal/val activities for GEOSS.

By participating and using data from non-NASA and foreign missions, the NASA Terrestrial Ecology community could actively participate in the development of data formats and inter- calibration as well as assimilate these diverse and important datasets for Terrestrial Ecology, Biodiversity and Applied Science research.

Web Forum Comments:

Credit should be given to the Terrestrial Ecology and the Land Cover Land-Use Change program which has been supportive of the MODIS land team’s activities in coordinating international cal/val activities through the CEOS Land Product Validation subgroup. Furthermore, the EOS program had an explicit solicitation related to cal/val. Admittedly, there is not a centralized “charge number” for cal/val and more could be done. However there are some examples of NASA programs providing support for this critical activity which are worth considering for future efforts. From the previous and existing support we can figure out what worked, what was worthwhile, and what makes sense for the future. – submitted by Jeffrey (Jeff) Morisette at 2006-08-24 09:25:47

A generic problem identified for ESSP and other non-systematic missions is data accessibility by the terrestial ecology community. The design of PI missions with limited budgets and team size necessarily limits data access. Perhaps for future and even existing non-systematic missions, some limited amount of funds ought to be dedicated to a community outreach efforts (short courses?) and funding to support personnel to serve researchers not on the science team? – submitted by Michael Keller at 2006-08-21 17:16:21