NOTICE -- The LBA-ECO Project website is no longer being supported.  This archive is a snapshot, as it existed in 2013, of the LBA-ECO website, maintained by NASA Goddard Space Flight Center, and now archived at the ORNL DAAC.  Links to external websites may be inactive. Final data products from the LBA project can be found at the ORNL DAAC.
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Investigation:

TG-03 (Schafer / Artaxo / Duarte / Setzer)

LBA Dataset ID:

TG03_AERONET_SOLAR_FLUX

Originator(s):

1. SCHAFER, J.S.
2. ECK, T.F.
3. HOLBEN, B.N.
      4. ARTAXO, P.E.
5. YAMASOE, M.A.
6. PROCOPIO, S.

Point(s) of Contact:

ORNL DAAC User Services Office Oak Ridge National Laboratory Oak Ridge, Tennessee 37 (ornldaac@ornl.gov)

Dataset Abstract:

This data set includes photosynthetically active radiation (PAR) from Skye-Probetech SKE-510 PAR sensors and surface irradiance from Kipp and Zonen CM-21 Pyranometer, both unfiltered and filtered with RG695 filter dome, for multiple sites in Brazil during the period from 1999-2004.</b>
The AERONET (AErosol RObotic NETwork) program is an inclusive federation of ground-based remote sensing aerosol networks established by AERONET and PHOTON and greatly expanded by AEROCAN (the Canadian sun-photometer network) and other agency, institute and university partners. The goal is to assess aerosol optical properties and validate satellite retrievals of aerosol optical properties. The network imposes standardization of instruments, calibration, and processing. Data from this collaboration provides globally distributed observations of spectral aerosol optical depths, inversion products, and precipitable water in geographically diverse aerosol regimes. Three levels of data are available from the AERONET website: Level 1.0 (unscreened), Level 1.5 (cloud-screened), and Level 2.0 (Cloud-screened and quality-assured).
Broadband surface irradiance data provided here are processed to Level 1.5, while PAR data are processed to Level 2.0.
Descriptions of program objectives, affiliations, the instrumentation, operational issues, data products, data-base browser demonstrations, research activities, links to similar data sets, NASA EOS links and personnel involved in AERONET may be found at: http://aeronet.gsfc.nasa.gov/. CAUTION: Data presented in the real-time data version at the AERONET web site are unscreened and may not have final calibration reprocessing. NOTICE TO NON-AERONET INVESTIGATORS:</b> To maintain the integrity of the data base and fairness to the individuals who have contributed, use of these data for publication requires an offer of authorship to the AERONET Principal Investigator(s) PI(s). For each site there is a PI, the person responsible for deployment, maintenance and data collection. The PI is entitled to be informed of any use of that site data.

Beginning Date:

1999-01-01

Ending Date:

2004-12-31

Metadata Last Updated on:

2012-11-15

Data Status:

Archived

Access Constraints:

PUBLIC

Data Center URL:

http://daac.ornl.gov/

Distribution Contact(s):

ORNL DAAC User Services Office Oak Ridge National Laboratory Oak Ridge, Tennessee 37 (ornldaac@ornl.gov)

Access Instructions:

PUBLIC

Data Access:

IMPORTANT: The LBA-ECO Project website is no longer being supported. Links to external websites may be inactive. Final data products from the LBA project can be found at the ORNL DAAC. Please follow the fair use guidelines found in the dataset documentation when using or citing LBA data.
Datafile(s):

LBA-ECO TG-03 Solar Surface Irradiance and PAR, Brazilian Amazon: 1999-2004 :  http://daac.ornl.gov/cgi-bin/dsviewer.pl?ds_id=1137

Documentation/Other Supporting Documents:

LBA-ECO TG-03 Solar Surface Irradiance and PAR, Brazilian Amazon: 1999-2004 :  http://daac.ornl.gov/LBA/guides/TG03_AERONET_Solar_Flux.html

Citation Information - Other Details:

Schafer J.S., T. F. Eck, B.N. Holben, P. Artaxo, M.A. Yamasoe, and S. Procopio. 2012 .LBA-ECO TG-03 Solar Surface Irradiance and PAR, Brazilian Amazon: 1999-2004. Data set. Available on-line [http://daac.ornl.gov] from Oak Ridge National Laboratory Distributed Active Archive Center, Oak Ridge, Tennessee, U.S.A. http://dx.doi.org/10.3334/ORNLDAAC/1137

Keywords - Theme:

Parameter Topic Term Source Sensor
PHOTOSYNTHETICALLY ACTIVE RADIATION LAND SURFACE SURFACE RADIATIVE PROPERTIES FIELD INVESTIGATION QUANTUM SENSOR
SOLAR IRRADIANCE LAND SURFACE SURFACE RADIATIVE PROPERTIES FIELD INVESTIGATION PYRANOMETER

Uncontrolled Theme Keyword(s):  BRAZILIAN AMAZON, PHOTOSYNTHETICALLY ACTIVE RADIATION, SOLAR IRRADIANCE

Keywords - Place (with associated coordinates):

Region
(click to view profile)
Site
(click to view profile)
North South East West
  PARA WESTERN (SANTAREM) -1.92350 -15.72950 -54.95170 -67.86890

Related Publication(s):

Echalar, F., P. Artaxo, J.V. Martins, M. Yamasoe, F. Gerab, W. Maenhaut, and B. Holben. 1998. Long-term monitoring of atmospheric aerosols in the Amazon Basin: Source identification and apportionment. Journal of Geophysical Research-Atmospheres 103(D24):31849-31864.

Oliveira, P.H.F., P. Artaxo, C. Pires, S. De Lucca, A. Procopio, B. Holben, J. Schafer, L.F. Cardoso, S.C. Wofsy, and H.R. Rocha. 2007. The effects of biomass burning aerosols and clouds on the CO2 flux in Amazonia. Tellus Series B-Chemical and Physical Meteorology 59(3):338-349.

Procopio, A. S., P. Artaxo, Y. J. Kaufman, L. A. Remer, J. S. Schafer, and B. N. Holben (2004), Multiyear analysis of amazonian biomass burning smoke radiative forcing of climate, Geophys. Res. Lett., 31, L03108, doi:10.1029/2003GL018646.

Schafer, J. S., T. F. Eck, B. N. Holben, P. Artaxo, and A. F. Duarte (2008), Characterization of the optical properties of atmospheric aerosols in Amazonia from long-term AERONET monitoring (1993-1995 and 1999-2006), J. Geophys. Res., 113,D04204, doi:10.1029/2007JD009319.

Schafer, J.S., B.N. Holben, T.F. Eck, M.A. Yamasoe, and P. Artaxo. 2002. Atmospheric effects on insolation in the Brazilian Amazon: Observed modification of solar radiation by clouds and smoke and derived single scattering albedo of fire aerosols. Journal of Geophysical Research-Atmospheres 107(D20):Article-8074.

Schafer, J.S., T.F. Eck, B.N. Holben, P. Artaxo, M.A. Yamasoe, and A.S. Procopio. 2002. Observed reductions of total solar irradiance by biomass burning aerosols in the Brazilian Amazon and Zambian Savanna. Geophysical Research Letters 29(17):Article-1823.

Yamasoe, M.A., C. von Randow, A.O. Manzi, J.S. Schafer, T.F. Eck and B.N. Holben. 2006. Effect of smoke and clouds on the transmissivity of photosynthetically active radiation inside the canopy. Atmos. Chem. Phys., 6, 1645-1656.

Data Characteristics (Entity and Attribute Overview):

Data Characteristics:

Solar flux measurements (broadband surface irradiance (PYR), filtered broadband surface irradiance (FIL), and photosynthetically active radiation PAR)) were obtained at numerous sites across the Amazon Basin and are most accurately representative of ?????? conditions within a 10km radius of the observation points.



Each site's data record of each data type (PYR, FIL, PAR) is recorded in its own data file. There is no data record between the pre-LBA field work (1993-1995) and the resumption of field activities beginning in 1999. Not all sites have data for all measurement years (1999-2004).

- The surface irradiance data provided here are processed to Level 1.5 (cloud-screened) and

- the PAR data was processed to Level 2.0 (cloud-screened and quality assured).



Parameter/Variable



Date(dd-mm-yyyy)


Time(hh:mm:ss)


Julian_Day
xxxx

?????

?????





Example data records:

PYR: Broadband Surface Irradiance

==> AF.1999_2004.L15.pyr <==

26:01:1999,09:30:09,26.395937,36.065449

26:01:1999,09:31:09,26.396632,36.065449

26:01:1999,09:32:09,26.397326,36.065449

26:01:1999,09:33:09,26.398021,36.065449

26:01:1999,09:34:09,26.398715,36.065449

26:01:1999,09:35:09,26.399410,35.432722

26:01:1999,09:36:09,26.400104,36.065449

26:01:1999,09:37:08,26.400787,41.443630

26:01:1999,09:38:08,26.401481,41.759994

26:01:1999,09:39:08,26.402176,41.759994





FIL: Filtered Broadband Surface Irradiance

==> AF.2003_2004.L15.fil <==

25:10:2003,19:32:06,298.813958,291.063332

25:10:2003,19:34:06,298.815347,284.042709

25:10:2003,19:36:05,298.816725,277.022086

25:10:2003,19:38:05,298.818113,207.985959

25:10:2003,19:40:05,298.819502,93.900834

25:10:2003,19:42:06,298.820903,86.295159

25:10:2003,19:44:05,298.822280,87.757789

25:10:2003,19:46:05,298.823669,94.193360

25:10:2003,19:48:05,298.825058,102.676613

25:10:2003,19:50:06,298.826458,103.846716



PAR: Photosynthetically Active Radiation

==> AF.1999_2004.L20.par <==

26:01:1999,09:30:09,26.395937,28.482538

26:01:1999,09:31:09,26.396632,28.482542

26:01:1999,09:32:09,26.397326,23.065620

26:01:1999,09:33:09,26.398021,28.482550

26:01:1999,09:34:09,26.398715,23.065627

26:01:1999,09:35:09,26.399410,23.065630

26:01:1999,09:36:09,26.400104,23.065633

26:01:1999,09:37:08,26.400787,23.065636

26:01:1999,09:38:08,26.401481,16.600271

26:01:1999,09:39:08,26.402176,28.657313

Data Application and Derivation:

The radiometer makes two basic measurements, either direct sun or sky, both within several programmed sequences. The direct sun measurements are made in eight spectral bands requiring approximately 10 seconds. Eight interference filters at wavelengths of 340, 380, 440, 500, 670, 870, 940 and 1020 nm are located in a filter wheel which is rotated by a direct drive stepping motor. The 940 nm channel is used for column water abundance determination. A preprogrammed sequence of measurements is taken by these instruments starting at an airmass of 7 in the morning and ending at an airmass of 7 in the evening. Optical thickness is calculated from spectral extinction of direct beam radiation at each wavelength based on the Beer-Bouguer Law. Attenuation due to Rayleigh scatter, and absorption by ozone (from interpolated ozone climatology atlas), and gaseous pollutants is estimated and removed to isolate the aerosol optical thickness (AOT).

Quality Assessment (Data Quality Attribute Accuracy Report):

Quality Assessment:

The data undergo preliminary processing (real time data), reprocessing (final calibration ~6 mo. after data collection), quality assurance, archiving and distribution from NASA\'s Goddard Space Flight Center master archive.



Calibration relies upon determination of the calibration coefficients needed to convert the instrument output digital number (DN) to a desired output, in this case aerosol optical thickness (AOT), precipitable water, and radiance (W/m2/sr/um).



The Langley Plot is a logarithm of the DN taken during these times plotted against the optical airmass between a range of 5 and 2 (between 3.5 and 2 for 340 nm), where the intercept is the calibration coefficient (zero airmass DN) and the slope is the optical thickness. Langley plots from NOAA\'s Mauna Loa Observatory have been made to determine the spectral extraterrestrial voltage for these instruments since 1994. The observatory\'s high altitude and isolation from most local and regional sources of aerosols provides a very stable irradiance regime in the mornings, and is ideally suited to our purposes.



AERONET reference instruments are typically recalibrated at NOAA\'s Mauna Loa Observatory every 2-3 months using the Langley plot technique. The zero air mass voltages [Vo, instrument voltage for direct normal solar flux extrapolated to the top of the atmosphere (Shaw, 1983)] are inferred to an accuracy of approximately 0.2 to 0.5% for the MLO calibrated reference instruments (Holben et al., 1998). Therefore the uncertainty in AOT due to the uncertainty in zero airmass voltages for the reference instruments is better than 0.002 to 0.005.



The Sun-sky radiometers at sites other than GSFC are intercalibrated against a MLO calibrated AERONET reference instrument both before deployment in the field and post- deployment. A linear rate of change in time of the zero airmass voltages is then assumed in the processing of the data from field sites. Our analysis suggests that this results in an uncertainty of approximately 0.01 - 0.02 in AOT (wavelength dependent) due to calibration uncertainty for the field instruments.



A sequence of three AOT measurements are taken 30 seconds apart creating a triplet observation per wavelength. During the large airmass periods direct sun measurements are made at 0.25 airmass intervals, while at smaller airmasses the interval between measurements is typically 15 minutes. The time variation of clouds is usually greater than that of aerosols causing an observable variation in the triplets that can be used to screen clouds in many cases. Additionally the 15-minute interval allows a longer temporal frequency check for cloud contamination.

Process Description:

Data Acquisition Materials and Methods:

Data are transmitted hourly or half hourly from the memory of the sun photometer microprocessor via the Data Collection Systems (DCS) to either of three geosynchronous satellites GOES, METEOSAT or GMS and then retransmitted to the appropriate ground receiving station. The data can be retrieved for processing by Internet linkage resulting in near real-time acquisition from almost any site on the globe excluding poleward of 80 degrees latitude. The DCS is a governmental system operated for the purpose of transmitting low volume environmental data from remote sites for various institutions and government agencies.



The frequencies, channels and transmission windows are assigned by NOAA NESDIS for GOES, EUMETSAT for METEOSAT and GMS which are broadcast in the 401 to 402 MHz range. The satellite transmitter module used is a Vitel VX1004 which is commercially modified for use with the CE 318 A (The Vitel VX1004/2 is used by the PHOTON group but it is no longer in production). The antenna is conical approximately 40 cm in diameter and 40 cm long. The transmitter system is battery operated and charged by a 10 watt solar panel.



Platform/Sensor/Parameters measured include:

* FIELD INVESTIGATION / KIPP & ZONEN CM-21 PYRANOMETER / SOLAR IRRADIANCE

* FIELD INVESTIGATION / KIPP & ZONEN CM-21 PYRANOMETER WITH RG695 FILTER DOME / SOLAR IRRADIANCE

* FIELD INVESTIGATION / SKYE-PROBETECH SKE-510 PAR SENSOR / PHOTOSYNTHETICALLY ACTIVE RADIATION

References:

None.

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