# Presentation: 276667

## FLUXNET Data Activities

- Dick Olson, Susan Holladay,
- Les Hook, Ned Nikolov
- ORNL DAAC
- October 2000
- NASA EOS Validation Program
- NASA EOSDIS DAAC

**CARBOEUROFLUX**

## Highlights

- 3 Regional Networks (AmeriFlux, CARBOEUROPE, AsiaFlux)
- 148 towers registered
- 62 active towers (submitted data or start year defined)
- 306 years of observations for active towers
- 103 site-years of data submitted to FLUXNET
- 11 years of record at a tower (Harvard)
- 12 sites with gap-filled, aggregated data available
- 21 site-years of gap-filled, aggregated data available
- >3700 ancillary data records (climate, vegetation, LAI, NPP, etc)
- >260 parameters in data dictionary
- >300 Flux scientists on FLUXNET email server
- >3000 Flux related bibliographic citations

## FLUXNET Tower Sites

**FLUXNET Tower Sites**

**Site characteristics data maintained in a RDBMS**
**     ****- static views currently on the Web**
**     ****- will provide dynamic Web-based access**
**Flux data aggregated to daily, monthly, and yearly values**

- http://daac.ornl.gov/FLUXNET/

## Gap-Filled Flux data

**Gap-Filled Flux data**
**available on FLUXNET**

## Slide 6

## Flux Data for Synthesis

- 33 sites (EUROFLUX - 14, AmeriFlux - 19)
- 89 site-years (average of 2.7 years/site)
- 42 sites-years with 12 months of data
- gaps in NEE:  1/2 hr - 29%, >14 days - 16%
- gaps in LE : 1/2 hr - 27%, >14 days - 16%
- 47 site-years with <12 months of data (average 6.5 mon/site-year)
- gaps in NEE: 1/2 hr - 26%, >14 days - 23%
- gaps in LE: 1/2 hr - 27%, >14 days - 23%

## AmeriFlux Sites in Synthesis

- Atqasuk +
- Blodgett +
- Bondville +
- Barrow +
- Duke Forest -
- Howland  -
- Happy Valley -
- Harvard Forest +
- Little Washita +
- Metolius -
- Manaus +
- Niwot Ridge +

- BOREAS Old Aspen
- BOREAS Old Black Spruce +
- Ponca City -
- Shilder -
- Sky Oaks - Old Stand +
- Sky Oaks - Young Stand +
- Upad -
- Walker Branch +
- Willow Creek
- Wisconsin Tall Tower
- Wind River Crane +
- * + Ustar correction, - no correction

## FLUXNET core variables

- Photosynthetic Active Radiation, **PAR**
- Air temperature, **T(air)**
- Precipitation, **PPT **
- Relative humidity, **RH**
**Wind **speed & direction
- Vapor Pressure Deficit, **VDP**
- Soil temperature, **T(soil)**
- Carbon dioxide concentration, **CO2**

- Net Ecosystem Exchange from eddy correlation**, **CO2 flux** (NEE)**
- Sensible heat from eddy correlation, **H**
- Latent heat from eddy correlation, **LE**
- Net radiation, **R(net)**
- Soil heat flux, **G(soil heat)**

## Selected Ancillary Data*

- Vegetation type	      104
- Species				72
- Elevation				90
- Tower height			61
- Stand age			54
- Annual Temp/PPT		78
- LAI					57
- NPP					28
***based on 125 flux tower sites, June 2000**

## Data Processing Challenges

- Applying Ustar correction
- how to determine if we should use Ustar
- ask site scientists
- examine regression statistics
- how to set threshold Ustar values
- Filling large gaps (>14 days)
- Establishing standard site IDs (several versions currently are used)
- Compiling site characteristics data
- Compiling instrument characteristics

## FLUXNET: 2001

- Distribute EUROFLUX CD
- Provide support Synthesis activity
- Process flux data - gap filled, aggregated
- AmeriFlux  >25 sites
- EUROFLUX >15 sites
- Distribute data from Synthesis activity
- Add new networks:
- CARBOEUROFLUX
- LBA
- ASIAFLUX
- Oznet
- Post real-time validation data results
- Modeled NPP/NEP results
- MODIS derived products (LAI, NPP)