# Presentation: 071918

## MODIS Validationand Real-Time Modeling 

**Steven W. Running **
**and **
**Faith Ann Heinsch**
**NTSG, The University of Montana**
**2002 Ameriflux Science Meeting**
**October 23, 2002**

## MOD17 Algorithm

***The Monteith equation....***
- GPP =  APAR  *   **
*GPP =** **(**Rnet*0.45*Fpar**)** ***** **{****max*** [m**Tmin**] [m**vpd**] **}*
*NPP=**** GPP – R**m**- R**g*

***Absorbed***
***Photosynthetically Active***
***Radiation***

***Radiation***
***Use***
***Efficiency***

## Slide 3

## MODIS Land Cover: Northern Hemisphere (2001)

## Difference in GPP: |(Grid – Tower)|

**Notes:**
This is the absolute value of the difference in GPP between the GPP of the tower pixel with the 5X5 grid cell, showing how representative each tower is of the grid surrounding it.

## Blodgett Forest, CA

**1 = ENF    5 = Mixed Forest**

**Notes:**
This is a grid of the land cover surrounding the Willow Creek tower.

## Gainesville, FL (Austin-Carey)

**1 = ENF    2 = EBF    3 = DNF    8 = Woody Savanna    12 = Cropland**

**Notes:**
This is a grid of the land cover surrounding the Willow Creek tower.

## Daily GPP over the U.S., July 20~27, 2001

**Daily GPP over the U.S., July 20~27, 2001**

*Credit:*
*Sinkyu Kang, *
*NTSG*

## Validation of Meteorological Inputs, CA

*Credit:*
*Maosheng*
*Zhao,*
*NTSG*

## Validation of Meteorological Inputs, CA

*Credit:*
*Maosheng*
*Zhao,*
*NTSG*

**Validation of Meteorological Inputs, CA**

## Sensitivity of 8-day Average Meteorology

- Julian day:

***Credit:  Markus Reichstein***

**Sensitivity of 8-day Average Meteorology**

## MODIS GPP over the Northern Hemisphere (2001)

*Credit: Maosheng Zhao, NTSG*

## Daily GPP by Biome Type, July 20~27, 2001

**Daily GPP by Biome Type, July 20~27, 2001**

*Credit: Sinkyu Kang, NTSG*

## GPP Estimates of 5X5 km Grid

**Notes:**
This is the GPP of the 5X5 km grid surrounding each tower site.

## Willow Creek, WITower Site

**Willow Creek, WI****Tower Site**

**Chequamegon-Nicolet National Forest **

## Willow Creek, WI, Daily Results

**Notes:**
AT THE TOWER PIXEL
This is the MODIS daily GPP, net PSN as calculated using DAO Met data.

## Willow Creek, WI

**Notes:**
This graph shows the comparison between the 8day and daily GPP.  This shows the tower crowd that 8day averages are actually an accurate estimation of daily measurements – this is, of course, one of the best of the bunch!

## Willow Creek, WI

*Data Obtained from: B. Cook, U. of Minnesota & ChEAS Project Scientist*
*P.I. For ChEAS Project:  Ken Davis, Pennsylvania State University*

## Willow Creek, WI

**4 = EBF       5 = Mixed Forest     12 = Cropland**

**Notes:**
This is a grid of the land cover surrounding the Willow Creek tower.

## Willow Creek, WI

**Willow Creek, WI**

**Notes:**
Willow Creek’s tower is actually pretty representative of the grid, some towers don’t do such a good job, but that is a problem when working in complicated areas such as Baltimore or Gainesville.

## BOREAS NSA – Old Black Spruce

## Harvard Forest, MA

## Park Falls/WLEF, WI

## Real-Time Modeling Effort

## Goal at NTSG:  To facilitate MODIS—BIOME-BGC—Tower  inter-comparison

We are able to provide weekly estimates of 
	ET, GPP, NEE and NEP for participants.

Meteorological data requested are half-hourly averages of Tair, PPT, PAR, RH, WS.

- We are able to provide weekly estimates of
**	****ET, GPP, NEE and NEP** for participants.
- Meteorological data requested are half-hourly averages of **Tair, PPT, PAR, RH, WS**.

**Real-Time Modeling Effort**

## Participating Tower Response

## Participating Sites

- Barrow, AK
- Blodgett Forest, CA
- Duke Forest, NC
- Harvard Forest, MA
- Kruger, South Africa
- Metolius, OR
- Young site
- Morgan Monroe State Forest, IN
- Park Falls, WI

- Sky Oaks, CA
- Old site
- Young site
- University of Michigan Biological Station, MI
- Walker Branch, TN
- Willow Creek, WI
- Wind River Crane Site,
-         WA

## Conclusions

- 8day MODIS GPP/NPP cutouts are now automatically cut and sent to the Oak Ridge DAAC where they are available for download.
- There are currently 14 sites involved in the real-time modeling effort, and we would like to expand this modeling effort with Ameriflux researchers.
- BIOME-BGC is currently being used with default ecological parameters and could be improved by using site-specific values.

## Conclusions

- The most direct validation for the MOD17 algorithm is tower GPP data, while  NEE data is useful for comparison with BIOME-BGC
- Land cover and LAI maps of tower sites can also be used for validation of inputs to MOD17.