Hosted by: Doug Alsdorf, Ohio State Lee-Lueng Fu, JPL Nelly Mognard, LEGOS-CNES Yves Menard, LEGOS-CNES Funding from CNES, NASA, JPL, and Ohio State University Welcome to the inaugural meeting of the WATER HM Science Working Group SWG Goal To formulate the mission’s science goals and requirements and to conduct a mission definition study leading to an optimal preliminary design of the mission given science requirements and technology and cost constraints. Meeting Goal To make decisions and initiate actions that will eventually complete the overall goal of the SWG. By the end of the meeting, October 30th, decisions will be made on the issues described in the agenda.

Meeting Conclusion Are the science questions articulated and prioritized? Are the risk reduction studies aligned with the science questions and prioritized? Are funding sources identifiable for these trade-off studies? Are the team leaders identified? Do we have a timeline? This is not an informational or science presentation meeting like AGU. This is a meeting where ideas will be presented and decisions made, thus keeping WATER HM moving forward. Feel free to share your ideas and thoughts.

Monday Morning 8:30 - 8:40: Introduction, Accomplishments of WATER HM this past year Doug Alsdorf 8:40 - 8:50: The Science Working group Charge Lee Fu 8:50 - 9:15: Updates from CNES and NASA HQ Eric Lindstrom, Eric Thouvenot, Herve Jeanjean, Jared Entin, Mike Freilich 9:15 - 9:30: Review of Hydrology Science Questions Dennis Lettenmaier 9:30 - 9:45: Review of Oceanography Science Questions Lee Fu 9: :15: Break-Out Session on Science Questions 11: :30: Coffee Break 11: :30: SWG Consensus on Science Questions moderated by: Doug Alsdorf, Lee Fu, Nelly Mognard, Yves Menard 12:30 - 1:30: Lunch By the end of the morning session we will define and prioritize the science questions.

1:30 - 1:40: Introduction to Risk Reduction Issues Doug Alsdorf 1:40 - 2:10: Hydrology virtual mission Dennis Lettenmaier 2:10 - 3:45: Spacecraft Power and Orbit, 15 minute presentations Tidal aliasing issues: Richard Ray Tidal aliasing issues: Florent Lyard Current orbit design: Steve Nerem Spacecraft and associated key points: Bruno Lazard JPL studies: Ernesto Rodriguez 3:45 - 4:00: Coffee Break 4:00 - 5:00: Water vapor corrections and radiometer issues, 15 minute presentations Issues with coastal zones: Ted Strub Options with various radiometers: Shannon Brown CLS perspective on radiometers: Estelle Obligis 5:00 - 5:15: First day meeting wrap-up Doug Alsdorf Monday Afternoon The afternoon session is focused on science drivers to mission design and technology.

8:30 - 8:50: Field results of Ka-band radar over rivers, Delwyn Moller 8:50 - 9:15: Ka-band radar studies, CNES Pre-Phase A work, Bruno Cugny 9: :15: Entire Group, Discussion and finalize risk reduction studies, issues of rain rates and Ka-band vs. Ku-band will be raised, Moderated by Doug Alsdorf, Lee-Lueng Fu, Nelly Mognard, Yves Menard 10: :30: Coffee Break 10: :00: Timeline for completion of SWG Goals and related report: Discussion will focus on report content, assignments, and schedules. People will be named to lead risk reduction studies. Moderated by Lee-Lueng Fu 11: :30: Mission timelines and funding availability: Discussion will focus on a potential schedule that includes submission of SWG report in 2008, pre-project planning in 2009, and project start in NASA HQ and CNES will need to comment on the reality of this scenario and corresponding funding issues. Timeline will be finalized. Eric Lindstrom, Eric Thouvenot, Herve Jeanjean, Jared Entin, 11: :00: Open Forum: What are the issues on the horizon? How will we handle the massive data volume from WATER HM? To what degree and how should the SWG connect with society and policy? Should we engage international agencies? To what degree and how should the SWG connect with operational applications/operational agencies? Moderated by: Doug Alsdorf, Lee-Lueng Fu, Nelly Mognard, Yves Menard 12: :15: Meeting wrap-up: Doug Alsdorf Tuesday Morning The first morning session is focused on prioritizing the risk reduction studies.

WATER HM Accomplishments this past year AGU Special Session December 2006 Selected by the NRC Decadal Survey January 2007 Publication of EOS and Reviews of Geophysics articles June 2007 Mission featured in Columbus Dispatch June 2007 Formation of the Science Working Group Result of letters of agreement exchanged between NASA HQ and CNES August 2007 Ocean Sciences ASLO Special Session March 2008 Additional Accomplishments Various meetings during the year, e.g., Charles Elachi, JPL; Mike Freilich NASA HQ Interactive WATER HM web page with new participants added regularly

Charge to Oceanography and Hydrology Break-Out Groups Identify science questions and prioritize them: Is this the list of questions that you think are most appropriate for WATER HM? Is the priority ordering correct? Do you suggest modifications? Note that we are prioritizing only within the hydrology or only within the oceanography category. We should have one key, overarching science question for oceanography and similarly one for hydrology. Hopefully, these questions will be nearly self-evident regarding their importance. A goal of the break-out session is to word-for-word identify the respective key science question. Because WATER HM is a wide-swath altimeter, the questions should focus on the measurements collected from KaRIN. Hydrology Science Questions Might Include: 1.What is the spatial and temporal variability in the world's terrestrial surface water storage and how can we predict these variations more accurately? 2.How much water is stored on a floodplain and subsequently exchanged with its main channel? 3.What are the policy implications that freely available water storage data would have for water management? 4.How much carbon is potentially released from inundated areas? 5.Can health issues related to waterborne diseases be predicted through better mappings? Oceanography Questions Might Include: 1.What is the small-scale variability of ocean surface topography that determines the velocity of ocean currents? How are fronts and eddies formed and evolving? How is oceanic kinetic energy dissipated? 2.What is the synoptic variability of coastal currents? How do the coastal currents interact with the open ocean variability? What are the effects of coastal currents on marine life, ecosystems, waste disposal, and transportation? 3.How does a hurricane interact with the small-scale variability of the upper ocean heat storage? What is the ocean's dynamic response to hurricanes? How is the new knowledge to be used to improve hurricane forecast?

SWG Consensus on Science Questions Identify science questions and prioritize them: Potential other science targets (bathymetry, land topography, etc.) should be identified, but only those that avoid science, technology, and cost creep. e.g., sea-ice could be a target but probably should not drive the orbit selection. The science drivers should be prioritized in terms of ″critical and must have″ to those of less importance but still valuable. This prioritization should focus the mission and prohibit creep. e.g., measuring surface water storage changes is critical whereas measuring sea ice freeboard is not. Questions need careful articulation and accuracy in their wording. e.g., “how much surface water” vs. “what is the spatial and temporal variability in surface water” Technology and Mission Considerations:  Mission lifetime is 3 to 5 years, with increasing costs for longer times. Science questions should be answerable with data collected during mission timeframe.  Questions should be answerable by the accuracy and resolutions provided by KaRIN. Additional Considerations:  Modeling is increasingly important for understanding the global water cycle and oceanic circulation issues. What do models require? Decisions 1 & 2

Introduction to Risk Reduction Issues Spacecraft power and orbit Sun-Synch = smaller, non-rotating solar panels non-SS = articulated solar panels, batteries Issues lead to mass requirements, which drive launch vehicle and platform selection Essentially, the orbit is the key issue Hydrology “Virtual Missions” identifying needed spatial and temporal resolutions Spatial resolutions <100 m, but how much smaller? Temporal sampling is not strictly limited Order of magnitude difference in down-linked data amounts when comparing 2x30 m and 16x50 m pixels Radiometer accuracies over coastal and land surfaces and alternative strategies What is the method for removing water vapor errors? Field results of Ka-band radar over rivers (Tuesday Morning) Ka-band does produce off-nadir reflections over rivers. Mitigation of rain rates (Tuesday group discussion) Ka vs. Ku band discussion

SWG Consensus on Risk Reduction Studies Identify mission risks and studies to mitigate these: Our science questions need to drive the technology. For example, oceanographic science questions define the need for certain orbits whereas hydrologic science requires high-spatial resolutions to sample rivers with smaller widths (less than 100m). This sampling may require a certain amount of power to ensure a signal-to-noise ratio capable of supplying the needed height accuracies. Power requirements are a function of the orbit. CNES developed initial studies necessary for submitting the WatER proposal to ESA whereas JPL has a large investment in WSOA related studies. The SWG needs to update these previous studies by ensuring that the hydrology and oceanographic science drivers are within a reasonable budget (i.e., develop cost trade-offs). Prioritize Risk Reduction Studies:  Various studies have been discussed such as a need to update the CNES WatER power consumption study which focused on sun-synchronous orbits with stationary solar panels instead of a non-sun-synchronous orbit with solar panels rotating once per orbit (or other configurations).  Additional needed studies might include:  the usage of DEMs to mitigate spacecraft roll errors and to correct errors from atmospheric water vapor  determining the power necessary to meet the required height accuracies  the degree to which rain rates are mitigated  height accuracy over small rivers  Prioritizing the needed studies and securing their funding are functions of the SWG.  The SWG will facilitate the organization and cooperation of these studies, especially as WATER HM heads toward implementation of Phase A. A key issue is to integrate these studies so that spatial, temporal, and height accuracies implied by the science studies are fit into the technology studies to determine related costs. Decisions 3 & 4

Team Leaders and Action Items Leadership of Risk Reduction Studies: People in the SWG were selected for their expertise related to the issues outlined in Decisions 1-4. We expect that individuals from the SWG will lead the risk reduction studies and provide final reports upon conclusion of the studies. A key aspect of leading a risk-reduction team is to ensure that the optimal number of researchers are immediately available to conduct the work. Timeline:  A timeline is needed to ensure that the mission makes steady forward progress and so that CNES and NASA can make plans for funding key activities. A job of the SWG is to ensure timely funding for these trade-off studies. Action Item 1, Ensure funding sources:  Post-meeting actions will immediately focus on securing funds for the highest priority risk-reduction studies. NASA, JPL, and CNES have all indicated willingness to engage in funding key studies. Action Item 2, Communicate with team leaders:  We need to develop a routine of regular interaction with risk-reduction teams. Telecoms will be used as well as the WATER HM web page for archiving preliminary and final study results, providing links to risk-reduction models. Action Item 3, Continue to develop joint science community:  A key aspect of the SWG is to ensure that the global community of oceanographers and hydrologists recognize the importance of bringing together our two communities. This will likely require regular WATER HM presentations at international and specialized meetings, occasional open meetings hosted by the SWG, publication of results, and interactions with key leaders at CNES and NASA HQ (and perhaps other Federal and National agencies?). Decisions 5 & 6

Meeting Conclusion Open Forum What are the issues on the horizon? How will we handle the massive data volume from WATER HM? To what degree and how should the SWG connect with society and policy? Should we engage international agencies? To what degree and how should the SWG connect with operational applications/operational agencies? Are the science questions articulated and prioritized? Are the risk reduction studies aligned with the science questions and prioritized? Are funding sources identifiable for these trade-off studies? Are the team leaders identified? Do we have a timeline?