*** Document is not yet finalized (1 Oct 07) ***
Inaugural Meeting of the WATER HM Science Working Group
October 29th and 30th, 2007 in Washington D.C.
Meeting Contacts:
Doug Alsdorf alsdorf.1@osu.edu
Lee-Lueng Fu llf@jpl.nasa.gov
Nelly Mognard nelly.mognard@cnes.fr
Yves Menard Yves.Menard@cnes.fr
Scroll down for list of meeting attendees and SWG members
Goal of the SWG
The overall goal of the SWG is to conduct a mission definition study leading to an optimal
preliminary design of the mission given science requirements and technology and cost
constraints.
Overall Meeting Goal
To make decisions and initiate actions that will eventually complete the overall goal of the SWG
as noted above. By the end of the meeting, October 30th, decisions will be made on the issues
described after the agenda.
Daily Agenda
(suggested, confirmed)
Monday October 29th All Day
The Morning Session Focuses on Science Drivers
8:30 to 8:40: Introduction, Accomplishments of WATER HM this past year: Doug Alsdorf
8:40 to 8:50: SWG charge: Lee-Lueng Fu
8:50 to 9:15: Reports from NASA and CNES HQ regarding WATER HM: Eric Lindstrom, Eric
Thouvenot, Herve Jeanjean, Jared Entin, Mike Freilich
9:15 to 9:30: Review of Hydrology Science Questions: Dennis Lettenmaier
9:30 to 9:45: Review of Oceanography Science Questions: Lee-Lueng Fu
9:45 to 11:15: Break-out Session: Prioritization of Science Questions: Two individual groups
will form with one prioritizing hydrology questions and the other oceanography
questions. These questions are not expected to be cross-cutting or conflicting.
Rather, we seek the topmost questions for hydrology and topmost for
oceanography. Hydrology session will be moderated by Doug Alsdorf and Nelly
Mognard. Oceanography session will be moderated by Lee Fu and Yves Menard.
11:15 to 11:30: Coffee Break
11:30 to 12:30: Entire Group, Report of Break-Out Session Findings, Discussion and Finalize
Decisions 1 and 2. Questions will be individually prioritized for hydrology and
oceanography. We will not prioritize an oceanography or hydrology question
above the other. Moderated by Doug Alsdorf, Lee-Lueng Fu, Nelly Mognard, Yves
Menard
12:30 to 1:30: Lunch
The Afternoon Session Focuses on Science Linkages to Mission Design & Technology
1:30 to 1:40: Introduction to Risk Reduction Issues: Doug Alsdorf, Issues include (1) spacecraft
power and orbit, (2) hydrology virtual missions identifying needed spatial and
temporal resolutions, (3) radiometer accuracies over coastal and land surfaces and
alternative strategies, (4) field results of Ka-band radar over rivers, (5) mitigation
of rain rates, and (6) any others
1:40 to 2:10: Hydrology virtual mission: Dennis Lettenmaier
2:10 to 3:45: Spacecraft Power and Orbit, 15 minute presentations by
Tidal aliasing issues: Richard Ray
Tidal aliasing issues: Florent Lyard
Current orbit design: Steve Nerem
Existing spacecraft: Bruno Lazard
JPL studies: Ernesto Rodriguez
3:45 to 4:00: Coffee Break
4:00 to 5:00: Water vapor corrections and radiometer issues: 15 minute presentations by
Issues with coastal zones: Ted Strub
Options with various radiometers: Shannon Brown
CLS perspective on radiometers: CLS Person
5:00 to 5:15: First day meeting wrap-up: Doug Alsdorf
Tuesday October 30th Morning Only
8:30 to 8:50: Field results of Ka-band radar over rivers: Delwyn Moller
8:50 to 9:15: Ka-band radar studies, CNES Pre-Phase A work: Bruno Cugny
9:15 to 10:15: Entire Group, Discussion and Finalize Decisions 3 and 4: issues of rain rates and
Ka-band vs. Ku-band will be raised. Moderated by Doug Alsdorf, Lee-Lueng Fu,
Nelly Mognard, Yves Menard
10:15 to 10:30: Coffee Break
Remainder of the Morning Session Focuses on Naming Team Leaders and Action Items
10:30 to 11:00: Timeline for completion of SWG Goal and related report: Lee-Lueng Fu,
Discussion will focus on report content, assignments, and schedules. Decision 5
will be finalized.
11:00 to 11:30: Mission timelines and funding availability: Eric Lindstrom, Eric Thouvenot,
Herve Jeanjean, Jared Entin, Randy Freidl, Discussion will focus on a potential
schedule that includes submission of SWG report in 2008, pre-project planning
in 2009, and project start in 2010. NASA HQ and CNES will need to comment
on the reality of this scenario and corresponding funding issues. Decision 6 will
be finalized.
11:30 to 12:00: 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
12:00 to 12:15: Meeting wrap-up: Doug Alsdorf
Decisions to be Made During Meeting
Decision 1: Define the science questions
The overall science agenda for WATER HM includes physical oceanography and
hydrology. We need to ensure that our science goals can be answered by the spatial and
temporal resolutions and the height and slope accuracies of the KaRIN instrument. Specific
science questions tied with the technology studies (below) need to be finalized. Potential
other science targets (bathymetry, land topography, etc.) should be identified, but only those
that avoid science and technology creep.
Decision 2: Prioritize the science questions
The science drivers should be prioritized in terms of ″critical and must have″ (e.g.,
determination of storage changes in lakes and reservoirs) to those of less importance but
still valuable (e.g., land surface topography). This prioritization should focus the mission
and prohibit science, technology, and cost creeps.
Decision 3: Identify linkages between science and technology issues
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). Some studies have already been
conducted or are in progress. For example, field experiments showing Ka-band radar returns
from rivers, data assimilation to determine river discharge, and assessments of SRTM for
estimating discharge have already been conducted. A hydrology virtual mission study is
now fully funded by NASA and will provide trade-offs between various sampling strategies
and the derived discharge and storage changes.
Decision 4: 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). Such studies recognize that the oceanographic community at the Hobart
OST meeting endorsed non-sun-synchronous orbits. Additional needed studies will 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; etc. Prioritizing
the needed studies and securing their funding are functions of the SWG.
Decision 5: Name individuals to lead tasks and resolve related issues
People in the SWG were selected for their expertise related to the issues outlines in
Decisions 1-4 and detailed below. 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.
Decision 6: 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 riskreduction 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 (http://earthsciences.osu.edu/water/) for
archiving preliminary and final study results, providing links to risk-reduction models,
Action Item 3: Continue to develop the 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?).
Details of Agenda:
I. Decisions 1 and 2 focus on science questions:
The suggested top priority hydrology question is focused on the terrestrial surface water
contribution to the global water cycle. The suggested top priority oceanography question is
focused on the dynamics of kinetic energy in ocean currents. The prioritization of all
WATER HM science questions is a task for the entire SWG. Additional hydrology science
questions under consideration include those related to flood hazards, water resource
management, carbon evasion, and health issues. Additional oceanographic science questions
include those related to coastal zones, contributions to climate data records, improving
hurricane forecasts, and operational needs like those related to transportation, pollution, and
wasted disposal.
These questions need careful articulation. For example, saying that WATER HM will answer
the question of ″how much surface water is on the Earth″ is not exactly true. Rather, WATER
HM will address the question of ″what is the spatial and temporal variability of terrestrial
surface waters around the globe″. Questions related to sea level also need clarification
because WATER HM may not be explicitly designed to address the question of ″what is the
rate of sea level rise″. Rather, WATER HM will make high-resolution measurements of
ocean surface topography and issues related to the mean sea surface. Oceanographic
questions will need to carefully consider internal tides, which operate at ~100 km spatial
scales and external tides, which are ~1000 km scales. Internal tides are a function of the
thermocline and operate on spatial scales similar to meso-scale currents, thus they can be a
source of error. Both internal and external tides are a source of error via aliasing.
All questions need to be refined so that the height and spatial accuracies required for
answering the question are cost effective (see next section). For example, hydrology is
proceeding with a NASA funded study, the Virtual Mission, which will define the accuracy
trade-offs associated with coarse vs. fine samplings and how effective these are for
constraining the global terrestrial water cycle, improving flood hydraulics, and the other
hydrology questions. A key consideration for all questions is the design lifetime of the
satellite mission. Costs increase markedly for longer mission lifecycles, e.g., 3 years
compared to 5 years. Thus questions should be focused on those that can be answered in a
minimal amount of time.
There is a certain degree of ″excitement″ that needs to be enveloped by the science questions.
For example, measuring vector winds does not engage the general public, whereas the entire
world is keenly interested in hurricanes. Similarly, floods have a tremendous economic
impact, especially in developing countries. While WATER HM is not a flood chasing
satellite, it should provide new insights toward understanding how floods evolve.
Applications of WATER HM measurements are important, but we should view WATER HM
as a demonstrator of science. Essentially, the science questions will need to have some
degree of direct applicability while focusing on unanswered science questions of great
impact.
We also welcome other science questions, particularly those related to ocean bathymetry and
sea ice. Synergies with these questions need to be developed so that new science questions do
not lead to costly technology creep. For example, if the optimal WATER HM orbit
configuration does not extend well into Arctic ocean, then is the additional cost to cover the
ice pack too prohibitive?
Modeling is increasingly important for understanding the global water cycle and oceanic
circulation issues. Satellite measurements are never sufficiently frequent enough to measure
the full dynamics of water movement (e.g., every second), however the spatial density of
wide-swath samples allows a high-resolution and broad-scale application in modeling. We
need to determine the requirements of models and ensure that our colleagues from the
various hydrologic, ocean circulation and climate modeling communities are involved in
WATER HM planning and its eventual measurements.
In summary, hydrology science questions to be directly addressed by WATER HM are at the
zero-order level, i.e., highly important and with immediate impact. The great achievements
resulting from Topex/Poseidon and its successors allow oceanography to ask higher-order
questions on the kinetic energy of the ocean that is of great importance to both climate
science and practical applications.
II. Decisions 3 and 4 focus on trade studies
Discussions will focus on the various activities that are designed to address the trade-offs
between science questions, technology required to address the questions, and the involved
costs.
Hydrology is conducting a series of ″Virtual Mission″ (VM) studies which include data
assimilation. A VM consists of a water balance model which supplies rainfall generated
runoff at a coarse grid scale (e.g., 0.5 degree) to a fine-scale (~100 m) hydrodynamic model
which routes water through a channel and across a floodplain. The routing results in water
surfaces which are then sampled with an instrument simulator designed with various error
characteristics (e.g., layover, thermal noise, etc.). These measurements represent the KaRIN
instrument and are subsequently used in a data assimilation scheme designed to assess the
importance of the errors in constraining discharge estimates and storage change
measurements. Published first-results are promising and represent a new avenue for working
with spaceborne surface water measurements.
Hydrology is also using SRTM elevation measurements as a proxy for KaRIN. Although
SRTM is at least an order of magnitude lower in accuracy than the design of KaRIN,
published first-results using a simple Mannings n approach suggest that SRTM is capable of
supplying discharge estimates from large rivers such as the Amazon, Ohio, and Missouri.
Ka-band radar has now been tested from several bridges over terrestrial water bodies. A
reservoir and two rivers in Ohio were chosen as targets representing surface water
characteristics of wind advected wave action across a standing body of water and different
turbulent conditions for moderate and large rivers (i.e., the Muskingum River at ~300 m3/s
and Ohio River at ~3000 m3/s). Results demonstrate that Ka-band will provide significant
backscatter energy at the look-angles proposed for KaRIN, including angles beyond 6
degrees off-nadir. As a general characterization of all surface conditions, the change in dB is
only ~10 dB or less from peak at nadir to the returns registered at 6 degrees off-nadir.
Radiometer studies are needed that will characterize height errors related to atmospheric
water vapor over coastal and terrestrial areas. Both CNES and JPL have made preliminary
studies with somewhat similar conclusions. Options suggest a large antenna to acquire
sufficient km-scale resolutions or a smaller, multi-frequency antenna. This Fall, a coastal
altimetry workshop is being held and it is suggested that WATER HM be represented at this
meeting to further our collaborations with this important community.
CNES is advancing their previous studies which were based on WSOA and the WatER
concept (a sun-synchronous orbit with the KaRIN wide-swath instrument and the AltiKa
nadir altimeter). CNES is now conducting a Phase Zero study to investigate the power
requirements and fit with the Pleiades platform (i.e., the PASO study). This would be an
upgrade from the WatER design using the PRIMA platform. Initial power studies suggest
that solar panels on a non-sun-synchronous platform would require 21 square-meters for
1000 watts and 33 sq-m for 1600 watts. These studies need to verify the number of
articulation points used in the design of the solar panels. The new generation of platforms
may not accommodate such large solar panel arrays, thus it is suggested to decrease the solar
panel sizes, hence decrease the power requirements. The SWG will need to determine if it is
acceptable to decrease the power requirements, hence decrease the height accuracy of
KaRINs measurements. A broader scope of spacecraft study involving US aerospace
industries should be conducted to fully evaluate the options for flying the mission in a nonsun-synchronous orbit to meet the oceanographic objectives.
CNES has developed a tool capable of simulating multi-mission configurations (e.g.,
WATER HM and Jason) and the related orbit and tidal aliasing issues. The tool is designed
to understand how variance can be reduced through multiple altimeters.
CNES is also working on an intriguing idea of using the ONERA powered glider toward
understanding Ka-band radar and interferometric altimetry. This work is in the planning
stage and is not yet implemented.
In summary, its clear that key studies are being advanced at JPL, CNES, and various
universities, principally OSU and UW. 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.
The WATER HM Science Working Group includes these participants
Name
Aaron Boone
Anny Cazenave
Dennis Lettenmaier
Detlef Stammer
Doug Alsdorf
Dudley Chelton
Ernesto Rodriguez
Florent Lyard
Gregg Jacobs
Jacques Verron
Lee-Lueng Fu
Nelly Mognard
Paul Bates
Pierre-Yves Le Traon
Richard Ray
Rosemary Morrow
Yi Chao
HOGC
H
HO
H
O
H
O
OG
O
OC
O
O
H
H
O
OG
O
C
Specialty
modeling global water cycle
sea level rise, surface water
global water cycle
global ocean modeling/assimilation
remote sensing hydrology
ocean eddies and altimetry sampling
ocean winds, radar engineering
ocean tides modeling, orbits
US Navy oceanography/applications
ocean modelling assimilation
altimetry
hydrology
surface water hydrodynamics
Oceanography/applications
ocean tides and satellite orbit
ocean eddies and altimetry sampling
coastal ocean modeling/assimilation
Agency
MeteoFrance
LEGOS-CNES
UW
U. Hamburg
Ohio State Univ.
Oregon St. Univ.
JPL
CNES-LEGOS
NRL
INPG
JPL
LEGOS-CNES
Univ. Bristol
IFREMER
NASA Goddard
CNES-LEGOS
JPL
Country
France
France
USA
Germany
USA
USA
USA
France
USA
France
USA
France
UK
France
USA
France
USA
Yves Menard
O
altimetry
CNES-LEGOS
France
The WATER HM Science Working Group includes these headquarters people
Name
Eric Lindstrom
Eric Thouvenot
Herve Jeanjean
Jared Entin
HOGC
O
O
H
H
Specialty
Program Manager Oceanography
Program Manager Oceanography
Program Manager Hydrology
Program Manager Hydrology
Agency
NASA HQ
CNES
CNES
NASA HQ
Note: HOGC refers to H = Hydrology, O = Oceanography, G = Geodetic Science, C = Coastal
Zone
List of Invited Meeting Attendees
(as of: October 1, 2007)
Name
Aaron Boone
Anny Cazenave
Bruno Cugny
Bruno Lazard
C.K. Shum
Delwyn Moller
Dennis Lettenmaier
Detlef Stammer
Doug Alsdorf
Dudley Chelton
Eric Dombrowsky
Eric Lindstrom
Eric Thouvenot
Eric Wood
Ernesto Rodriguez
Florent Lyard
Gregg Jacobs
Herve Jeanjean
Jacques Verron
Jared Entin
Jay Famiglietti
John Melack
Kostas Andreadis
Larry Smith
Lee-Lueng Fu
Mike Durand
Mike Freilich
Nelly Mognard
Pascale Ultre-Guerard
Paul Bates
Will Attend Meeting
Yes
Yes
Yes
Yes
Yes
Yes
Yes
Yes
Yes
No
Yes/No
Yes
Yes
No
Yes
Yes
Yes
Yes
No
Yes
No/Yes
Yes
Yes
Yes
Yes
Yes
Yes (likely)
Yes
No
Yes
Notes
Monday Only
Attend only Monday afternoon?
Will try to change schedule
Meeting is on his schedule
Country
USA
FRANCE
FRANCE
USA
Pierre-Yves Le Traon
Pierre de May
Randy Freidl
Richard Ray
Rosemary Morrow
Shannon Brown
Steve Nerem
Ted Strub
Yi Chao
Yves Menard
No
Yes
Yes
Yes
Yes/No
Yes
Yes
Yes
Yes
Confirmed = 34
Cannot attend = 5
Need to hear from = 1
Potential Total = 35
Hotel Information:
Marriott Residence Inn, located at 333 E St. SW, Washington D.C. 20024. Their phone is xxxxxx-xxxx (web: http://www.capitolmarriott.com/ ). Please note that we have reserved 24 rooms
at the government per-diem rate of $201 per night. The hotel is across the street from NASA HQ.
You will also note that it is a very short walk to the National Air & Space Museum as well as the
many other museums and attractions on the ″Mall″. I believe all are free of charge to visit.
Note that there are a couple of nearby Metro stations. L’Enfant Plaza station is a one-train ride
from Reagan Washington National Airport (DCA) whereas a train-transfer is required to make it
to the Federal Center SW station.
From DCA airport to the hotel via the Metro: follow the signs inside the airport to the Metro
station. Its outside of the airport and on an upper level. Take the Yellow Line toward Fort
Totten. The fourth stop should be L’Enfant Plaza station. You can exit there and have nice walk
to the airport or transfer trains to the Blue Line (head toward Largo Town Center) or to the
Orange Line (head toward New Carrolton). Go one station and get off at Federal Center SW.
From IAD (Dulles) airport to the hotel via the Metro: take the “Dulles Airport Bus” from the
stop at Curb 2E. Board the “5A Bus” toward L’Enfant Plaza. I have never done this, but it should
be straightforward. Click this link for a PDF with greater details.
Link to Metro System:
http://www.wmata.com/metrorail/systemmap.cfm
Map of Hotel: or click this link for the full-size PDF