Question & Answer Session Part 3 - NASA Applied Science

NASA Earth Obs ervations for Energy Management
             J une 1 - 22, 2021

                     Question & Answer Session Part 3

Pleas e type your ques tions in the Ques tion Box. We will try our bes t to ans wer all your
       ques tions . If we don’t, feel free to email The POWER Project (larc-power-
 project@mail.nas a.gov), Paul Stackhous e (paul.w.s tackhous e@nas a.gov), or Bradley
                       Macphers on (bradley.macphers on@nas a.gov).

Ques tion 1: When it comes to wind energy, where wind data of a certain hub height is
neces s ary under different lands capes , how do we extrapolate or es timate wind
parameters from the Earth related data (above s ay 200 m above the s urface)? Similarly,
s hade effects of s olar?
Ans wer 1: Directly from MERRA-2, POWER provides s patially averaged wind fields for
the entire gridded area at 50, 10 and 2 m. For wind at arbitrary levels between 10 and
300 m, POWER has implemented a parameterization that us es a s urface roughnes s
exponent bas ed on s urface type, the reques ted elevation, and the winds at 50 and 10
meters to calculate the wind s peed.

Chandler, William S., C.H. Whitlock, P.W. Stackhous e, J r., 2005: Determining Wind
Res ources as a Function of Surface Roughnes s and Height from NASA Global
As s imilation Analys is . Proceedings of the International Solar Energy Society 2005 Solar
World Congres s , Augus t 6-12, Orlando, Florida
Als o s ee the code below:

Due to the s patial res olution of the POWER data, it is not pos s ible to treat the s hading
of s olar irradiance due to large s cale features like mountains or s mall s cale features like
vegetation or buildings .

NASA Earth Obs ervations for Energy Management
             J une 1 - 22, 2021

Ques tion 2: So the radiance is the energy per s econd per s urface then? (W being a
J oule per s econd, right? )
Ans wer 2: Watt is J oule per s econd, s o irradiance is the power per s urface area which
can be expres s ed in the units Wm -2.

Ques tion 3: Is it feas ible to have RE-Nuclear (Renewable Energy) as a combination that
acts as a s afety firewall around the nuclear? This RE may be a s olar array.
Ans wer 3: This ques tion is beyond our level of expertis e, but the POWER data
products could be us ed to as s es s whether the s olar res ource is large enough in
particular areas to act as a s upplemental energy s ource. However, that ques tion would
require an energy as s es s ment and energy grid integration analys is .

Ques tion 4: Wind park s ites can cros s routes of migrant birds which are s eas onal.
Routes could have minor variations over time. Can thes e two as pects be s tudied from
earth obs ervations in the attempts of correct s iting of wind turbines ?
Ans wer 4: Potentially; the POWER wind products are provided at a relatively coars e
s patial res olution (0.5° x 0.625° lat/lon). Thes e products have accuracy s ufficient for a
firs t-cut analys is for s ite s uitability but it is recommended to us e s urface s ite data or
high res olution modeling in later s tages of analys is . The wind information is available
at various time s cales s o the s eas onal dependence of the winds in a region are
provided at different temporal levels .

Ques tion 5: Is the international s atellite cloud climatology project network only in the
USA or Globally?
Ans wer 5: It is a global data s et. All the data products that POWER us es as input and
the data parameters provided are global including the ocean regions .

The ISCCP data products are freely acces s ible to the public through NOAA’s web s ite
at: https ://www.ncdc.noaa.gov/is ccp.

Ques tion 6: Can the us er upload their own datas et and us e the
functionalities /capabilities of the POWER API on their own data?
Ans wer 6: No, currently POWER only s upports the download of data products . But,
POWER does provide parameterizations and equations to allow us ers to expand upon

NASA Earth Obs ervations for Energy Management
             J une 1 - 22, 2021

or us e our proces s es , available in the methodology s ection of the POWER web s ite:
https ://power.larc.nas a.gov/docs /methodology/

Ques tion 7: Do greenhous e gas es in the atmos phere impact the climate parameters
recorded by s atellite s ens ors ?
Ans wer 7: Yes , becaus e greenhous e gas es abs orb and emit thermal infrared energy
which will affect how much energy at thos e wavelengths are obs erved by the s atellite.
There is als o s ome CO 2 abs orption of s olar irradiance. The mos t important gas in this
res pect is the water vapor its elf. Water vapor does abs orb s olar irradiance at the
longer wavelengths (beyond the vis ible wavelengths ) and thus reduces the broadband
s olar irradiance and various s atellite channels at s ens itive to wavelengths .

We do provide information on the thermal infrared radiative fluxes (wavelengths from 4
to 100+ micrometers ) incident to the Earth’s s urface. This information is us ed for
energy efficiency analys is related to cooling of building s tructures , es pecially at night.
Water vapor is the mos t important gas , but the radiative effect of CO 2 gets enhanced
becaus e s mall changes in temperature caus ed by CO 2 changes provide the capability
of the air to hold more water vapor. Global long-term changes in the amount of CO 2
(from s urface meas urements ) and s patial hourly es timates of water vapor are part of
the computation of the s olar and thermal infrared irradiances .

Ques tion 8: Hello, will thes e data be always free of charge to us e?
Ans wer 8: Yes , that is the plan for the fores eeable future.

Ques tion 9: We have been hearing about s un and earth energy evaluations mos tly to
be us ed on s olar panels and wind power energy. Is there anyone working on thermal
difference energy within water mas s es (oceans , large lakes ) and how to harnes s it?
Ans wer 9: We don’t currently have data products related to thermoelectric energy.
This would require finer res olution data on water temperature and mas s , of which we
don’t currently have acces s . Data for tidal energy has the s ame limitations at this time.

Ques tion 10: With regard to Power data, could you elaborate further pos s ible
applications of GIS datas et?
Ans wer 10: Yes , currently POWER provides image and feature s ervices connected to
the data. You can pull that into QGIS or Arc. Our goal is to have image s ervices related
to long term temporal periods .

NASA Earth Obs ervations for Energy Management
            J une 1 - 22, 2021

Ques tion 11: What are the parameters through which we meas ure s olar irradiance data
quality? Can you elaborate?
Ans wer 11: We compare our es timates of s urface s olar irradiance (“All Sky Ins olation
Incident on a Horizontal Surface “) to s urface meas urements and provide a s tatis tical
overview of the agreement. Highly calibrated meas urements from the globally
dis tributed Bas eline Surface Radiation Network (BSRN) are us ed to determine quality.
Our methodology documentation gives a more thorough des cription.

Ques tion 12: Are there any attempts to make this data available via Google Earth
Engine or as plugins on QGIS?
Ans wer 12: Currently there is no plan but we are working to make the POWER data
products available in AWS as part of a Space Act Agreement to provide Earth
Obs ervation Data for Sus tainability. This s hould make it more acces s ible to other
platforms . Time s eries is available without a plugin in GeoJ SON format therefore an
import into QGIS and ArcGIS is pos s ible. We are open to any s ys tem to make the
POWER data more acces s ible.

Ques tion 13: What are the pos s ible reas ons for the deviation between the recorded
data and the es timated data?
Ans wer 13: This depends on which meas urements in which you are referring. Solar
irradiance from POWER repres ents an area of 1°x1° lat/lon (approximately 100 km)
while the s urface meas urements are point meas urements . Differences on the monthly
or longer time s cales are mos t likely due to s ys tematic bias es in the various inputs to
the flux algorithms , s uch as water vapor and/or aeros ol optical properties . Cloud
proces s es s tatis tically vary but inaccuracies in cloud repres entation of certain clouds
can occur. If there are pers is tent cloud features within a 1°x1° area, s uch as near
coas ts or mountain regions , bias es can occur when comparing point locations to the
entire region. At s horter time s cales , cloud configurations are more likely to res ult in
nois e that tends to average out with temporal averaging. Some regions with brighter
s urfaces , s uch as over des erts or s now/ice covered s urfaces , have more difficulty in
detecting thin clouds .
For the meteorological fields , differences between meas urements and obs ervations are
s imilar to s olar differences due to the comparis on of the point meas urements to a
gridded average quantity (0.5° x 0.625°). Additionally, elevation differences and local

NASA Earth Obs ervations for Energy Management
             J une 1 - 22, 2021

features (e.g., s maller bodies of water like lakes and rivers ) can caus e bias es relative to
the regional average for temperatures , humidities , etc.

Ques tion 14: How do you effectively filter through cloud data while s canning for Smoke
from fire zones us ing EO? As in, how do you know to s pot Smoke and s moke drift and
not get that data muddled with filtered out cloud data?
Ans wer 14: Smoke is an is s ue in cloud detection. Cloud detection algorithms can
mis take thick s moke for clouds . This can lead to inaccuracies in the es timate of the
s olar irradiance becaus e the s moke particles are more obs er. Utilizing different s pectral
bands from s atellite obs ervations can aid in dis cerning between s moke and cloud. If
s moke is identified, an es timate of the amount of s olar radiation is computed. Smoke
particles abs orb more of the incoming s olar radiation.

Ques tion 15: Is there any data related on interaction of radiations impacting atm from
s pace or outs ide Earth?
Ans wer 15: We only cons ider the vis ible through the thermal IR wavelengths . We
as s ume the amount of energy within the s ys tem comes from the s un or emitted from
the atmos phere and earth.

Ques tion 16: Is GEOJ s on data format a unique data format or is it s omewhat s imilar to
gdb, s hp, xml format?
Ans wer 16: GeoJ SON is a unique data format that has been around for ~15 years . We
follow the GeoJ SON Standard (RFC7946) s tandard. It has metadata related to the
geographic location and includes the POWER data as a time s eries .

Ques tion 17: GeoJ SON is a unique data format. In that cas e how will ArcGIS recognize
it?
Ans wer 17: The GeoJ SON format is recognized natively by the ArcGIS s oftware.

Ques tion 18: GES DISC does not have the option of country s election in the area
s election variables . Why is that?
Ans wer 18: To get an accurate ans wer, you s hould s ubmit a ques tion to them but we
believe that NASA’s s ubs etting capability at Earth Data Search and other tools is s till
latitudinally and longitudinally bas ed and does n’t provide for polygon or s hapefile
s earches at this time.

NASA Earth Obs ervations for Energy Management
             J une 1 - 22, 2021

Ques tion 19: Is it pos s ible to make meas urements of s olar irradiation during a s olar
s torm event? Are thes e events recorded on a timeline?
Ans wer 19: The total s olar irradiance that we us e as input to our calculations is only
s lightly s ens itive to s olar s torm activity. We us ed SORCE and now us e TSIS
meas urements (https ://las p.colorado.edu/home/s orce/)
(https ://las p.colorado.edu/home/mis s ions -projects /quick-facts -ts is /), which are
provided on a daily bas is , s o the effect of s olar s torms on the TSI is captured.
However, the larges t effects of s olar s torms are s een in the wavelengths outs ide of
thos e we us e for s urface s olar irradiance calculations , particularly at very s hort
wavelengths like UV.

Ques tion 20: Do Photos ynthetic active radiation (PAR) data exis t in POWER data
archive? If not, what other parameters related to PAR exis t?
Ans wer 20: Yes ! This is a parameter that is carried in both the GEWEX SRB and
CERES data s ets . The upcoming POWER vers ion (now in beta) contains an es timate
of the PAR irradiance that is orderable through the Data Acces s Viewer (DAV) and API.

Ques tion 21: How do you s elect the s uitable s olar radiation out of the different
products available on Power (GEWEX AND CERES)?
Ans wer 21: This depends upon your s pecific application. If you need hourly data time
s eries , then you would s pecify a data reques t to begin in J anuary 2001 us ing the new
vers ion which is currently s till in beta (https ://power.larc.nas a.gov/beta). For long-term
averages and time s eries of daily, monthly or annual averages , the time reques ted will
determine which s ource you receive.

NASA Earth Obs ervations for Energy Management
              J une 1 - 22, 2021

Ques tion 22: Is there any information for s hade analys is for s olar s ys tem des ign?
Ans wer 22: There is no information on s hading currently (mountain ranges , complex
terrain). Trees and buildings at local levels would be impos s ible to res olve at the
res olution of the POWER data.

Ques tion 23: The data from The POWER Project can only be analyzed at a given point
or can you define regions of interes t?
Ans wer 23: We are optimized for point data but one can des ign a s cript, with help by
us ing our tutorials (https ://power.larc.nas a.gov/beta/docs /tutorials / ), to repeatedly reques t
adjacent points to do this . Additionally, the Data Acces s Viewer has a s mall regional
data reques t and will have a global capability in the beta vers ion.

Ques tion 24: Does POWER have applications for e.g. developing climate change
adaptation s cenarios ?
Ans wer 24: This is on our lis t for future improvements . Within 1-2 years we s hould
develop this . Pleas e provide feedback in the s urvey to help us better refine thes e
s cenarios .

NASA Earth Obs ervations for Energy Management
             J une 1 - 22, 2021

Ques tion 25: How do you cite this data in your res earch reference?
Ans wer 25: From the POWER web s ite here is one recommendation on how to cite:

When POWER data products are us ed in a publication, we reques t the following
acknowled gment be included:
"Thes e data were obtained from the NASA Langley Res earch Center (LaRC) POWER
Project funded through the NASA Earth Science/Applied Science Program."

The POWER Project kindly reques ts a reference, web link and/or a reprint of any
publis hed papers or reports or a brief des cription of other us es (e.g., pos ters , oral
pres entations , etc.) of data products that we have dis tributed. This will help us
determine the us e of data that we dis tribute, which is helpful in optimizing product
development. It als o helps us to as s es s our value to the community. Pleas e contact us
at POWER Project Team for additional information on s ending reference material.

Ques tion 26: For a water dis pos al project, is it pos s ible to us e s olar radiation data for
evaporation? What kind of data do I need?
Ans wer 26: Yes , but you als o need information on temperature and water vapor in that
area. A POWER data us er developed an app for evapotrans piration, which might be
adaptable for a general evaporation us age:
Maldonado, W., T. T. B. Valeriano, and G. de Souza Rolim, 2019: EVAPO: A
s martphone application to es timate potential evapotrans piration us ing cloud gridded
meteorological data from NASA-POWER s ys tem. Computers and Electronics in
Agriculture, 156, 187–192, https ://doi.org/10.1016/j.compag.2018.10.032.
The MERRA-2 products have evaporative flux data and we may be able to add that to
POWER in the future.