Notes from 3-4 May 2001 Meeting

Mr. Emmitt requested any comments with regards to notes/report from the August 2000 meeting. There were no comments or changes to previous report.

Action Items - Previous Meeting - Update/Status

Simpson Weather Associates (SWA) has established a web site for the working group. Address is: http://www.swa.com/hydrawg/

Posting of original draft of White Paper - this has been posted and is available at the following web site: http://lshp.gsfc.nasa.gov/Post2002/hydrasat/hydrasat2.html

Responses to reviews of white paper - have not been done yet

Lettenmaier - can respond without rewrite of white paper - not sure white paper needs to be redone

Emmitt - also does not feel a rewrite of white paper is required

Lettenmaier - suggests that the reviews of white paper be posted on web site

Need to develop a template for proposal formulation

Need to have paper dealing with science justification

Need to have charts/graphs

Write article for EOS - provide idea of concept - would help to broaden community knowledge - would be a good follow-on to Vorosmarty paper

Need to provide Jasinski with information for inclusion in NRA

    what is primary data product objective (density, accuracy, data assimilation)    

    why is Hydrasat important - scientific community already knows discharge at
    mouth of river

Vorosmarty - need to plan strategy; need to know delivery to coastal zone;   what is happening across entire earth's continent; put forth time varying elements;  runoff observations for 2000 do not present a clear picture like the 80's did

Lettenmaier - US gage network is useful for validation - need to do global network - not just the U.S.

Lettenmaier -  can model surface storage; need to understand continental global storage, balance

Emmitt - not going to have controlled basin measurements

Notional concepts - sensors - radars, lidar, imager

Hydrasat platform - well defined mission - instruments/measurements - will be confined by box/programs put into

Safaeinili - high resolution data not currently available

There is a need to articulate what science is - NRA - can project piggyback on another project (i.e., GLAS - ESSP misison?)

Birkett - there is a meeting coming up in Canada in October which might provide an opportunity for a paper on HydraSat - will send details

GPM was sold as a tool to help in hurricane forecasting - might provide a way to deploy Hydrasat

Charge of WG -- what are the priorities, tie into ESSP, map to overall plan

A possible application is that it will provide a way to predict flood/drought globally

Vorosmarty - land coverage change affects climate change - this is a global issue

Alsdorf - need large water body to use altimetry - SAR can determine how much it changed

Could altimetry be control point?

Smith - question of effective width vs increases in discharge -- point out wide spots in river versus small areas -- braided rivers appear ~ 1 m deep

Comments: in looking at multi-parameter variables it is best to develop generalized tool

Rothermel - SW experiment - have a ground penetrating radar on helicopter - GPR cross-sectional lidar - cross surface velocity - radar

Doppler lidar - can provide surface returns, wind fields, vertical profile measurements -- characterize atmospheric velocity at surface

No trouble distinguishing water from land - questionable distinguishing water surface

Will be studying surface signal variant with 2-10 m lidar - need high frequency pulse - space lidar to measure

Vorosmarty - need to articulate what is to be gained with a velocity measurement

Emmitt - gave an overview of the Emmitt, O'Handley and Spiers paper (see attached viewgraphs)

Kosuth - provided an overview of stream flow measurements in Amazon Basin - measurements were made with acoustic Doppler lidar - twin measurements of slopes - measuring two water levels at one time - tide affected measurements - imager as tool to measure albedo

        Q = 1/N I1/2 S R2/3 = 1/N I1/2 L y5/3 (can currently measure I and y)

Vorosmarty - need to develop set of hydrologic relations which could be detected from space - depth/width?

Due to large data set (U.S.) can look at discharge/flow - need to articulate discharge to determine retrieval

Fekete - currently optimizing synthetic rating function
    need to average
    need to have 2263 stations world-wide to get adequate discharge data

 

Charges to Working Group:

Articulate science objectives within ESE science plan framework
Draft charts expressing mission vision: why, how, what
Draft material for NRA
Draft plan for field experiment - proof-of-concept - get visibility
Do aircraft flights

Lettenmaier - make contact with Science Team Leader for GLAS - what is needed to get discussion started - is it possible to meet HydraSat objectives

Other projects: GPM - laser altimeter interferometry; JASIN2 (Lindstrom contact at Hq); JPL (wide swath - Ernesto Rodriques -- Safaenili - is a possibility but would need to test and then do follow-up if successful) -

Birkett - new project EMISAT - check on science objectives -have spoken to science team leader and is interested in Hydrasat

Charges:

Application side - science objective

Morel - closing water cycle is not important

Vorosmarty - close water cycle to get towards carbon cycling is important

Analyze existing data (imagery) - altimetry - JRS; SAR; JRS-1 (r-band)

Identify existing/down pike sources of remote sensing data

Propose field programs to fill in gaps - slope, velocity width, surface velocities

Types of rivers, widths, slopes, source - dense vs bare vegetation?; braided?

Lettenmaier - define river characteristics, slopes, vegetation; do data collections at same sites to validate -- need ground truth data (surface winds, waves, etc.)

Look at:

    What is needed
    What can be gotten
    What will need to be gotten

    Key variables: discharge/diversity/climate

Science Justification

Morel - just knowing what is going on is not enough of a justification

Lettenmaier - improve water budget predictability over land

 

Improve Climate Models - Jasinski - why do we need a satellite?

    - precipitation (GPM) - large error
    - soil moisture
    - ds/dt (GRACE) - discharge?
    - ds/dr (top of atmosphere to surface)
    - surface water (HydraSat)
    - storage (altimeter/imager)
    - Q (HydraSat)
    - E (model estimate) - evaporation

    How long to measure? ~ 5 yrs?

Jasinski - cannot improve climate models long term

Morel - can improve models

Fekete - 50% of land surface is monitored

Run-off gages - 50% of world is covered

Hydrology Forecasting (see white paper forward for requirements) - different time/space scales, application/implementation 
    interannual (natural hazards)
    agriculture/recreation
    seasonal (droughts)

Defining Forces (characterizing, understanding and predicting of forces on other components of Earth System)
    biogeochemistry
    ground water storage
    ecosystems
    ocean - fresh water budgets
    carbon

Vorosmarty -
    define error bound
    what is discharge rate
    different issues/applications may require different error bounds not just
        ocean discharge

    Best coverage of width, discharge, height velocity - is there technology to
    do this?

Lettenmaier - might want to look at ice cover on river discharge

Jasinski - difficult to validate climate analysis models

Emmitt - diagnostic improvement not predictive for models

Vorosmarty - need to validate earth system models to close the budgets

Wood - close budgets necessary - model can perform these forecast

Validations

    velocity vs discharge (mean velocity cross-sectional)
    surface velocity vs discharge
    width vs discharge
    stage vs discharge

Field Studies

    Vs vs Q (surface velocity vs discharge) (different weather conditions, different
    river topography) (V function x,z)

    a/c - L-band vs X-band radar trade
          - ground truth (bank vegetation, heights, humidity) seasons

    Interferiometer (SAR) - use of banks for representativeness 
                                      - moving platform distortion

    DWL LOS returns from water surface
        - SNR/accuracy
        - representativeness

    Laser altimetry
        - accuracy
        - size of grid

    Need vegetated/non-vegetated test sites for radars
    How many sites
    Types of sites - large vs small; steady vs fluctuating
    When?

Measurements 
    - slope
    - velocity
    - rapidly flowing

    Time period- a few days

Question as to whether all instruments would fly together or separately - but should be like areas if not together - sites with truth

Required personnel - 5-10 not to exceed 20

Emmitt -- requested that Ali Safaeinili bring some plots to next meeting of JPL data


Next meeting - first part of November in vicinity of JPL