# Presentation: 285431

## Developing a Consistent Landsat Data Set from MSS, TM/ETM+, and International Data Sources for Land Cover Change Detection

- Feng Gao
- Earth Resources Technology, Inc.
- NASA Goddard Space Flight Center

***Second Landsat Science Team Meeting, Corvallis, OR, June 12-14, 2007***

## Project Objectives

- Process Landsat and foreign Landsat-like data sources into a consistent orthorectified surface reflectance data set
- Use consistent surface reflectance data set for land cover change detection
- Simulate Landsat surface reflectance using MODIS and Landsat data
- Evaluate foreign Landsat-like data for filling possible Landsat data gap

## Activities

- 2006.09 - 2007. 01
- Developed orthorectification module for Landsat and foreign Landsat-like data using previous orthorectified image (e.g., GeoCover data set) as reference
- Produced daily Landsat surface reflectance by fusing MODIS and Landsat data
- Tested BRDF/phenology corrected surface reflectance for ASTER data using MODIS surface reflectance as reference
- 2007.01 - 2007.06
- Developed relative atmosphere correction approach for AWiFS data and started to evaluate product quality
- Started collaboration on the data fusion test using MODIS and Landsat land surface temperature (with Dr. Anderson at USDA)
- Started on land cover change detection and built collaboration on the study of urbanization and its impact to the regional climate change (with Dr. Wu at NASA GSFC)
- Worked on the relative atmosphere correction for MSS data

## Activity I: Relative Atmosphere Correction Using MODIS Products

- MODGHK
- (500m SR)

- MODMGGAD
- (1km angle)

- MOD43B1
- (1km BRDF)

- MODIS Daily
- Nadir BRDF-adjusted
- Surface Reflectance

- BRDF Correction
- using MODIS BRDF Shape and
- Magnitude Inversion

- AWiFS
- (DN)

- Aggregation

- Modis Reprojection
- Tools (MRT)

- Build Constrained Linear Regression with Errors in Both Coordinates

- Apply Correction

**AWiFS Surface Reflectance**

- MOD04
- (10km aersol)

- Estimate
- Intercept

- MODIS Daily NBAR
- in AWiFS Projection

- MODIS2AWiFS
- Bandwidth
- Conversion

**Notes:**
We may use MODIS to AWiFS bandwidth conversion to make atmosphere correction consistent with AWiFS bandwidth, or simply not apply it to make them close to MODIS bandwidth and every sensors will have a consistent surface reflectance like MODIS.

## MODIS Daily 

- MODIS Daily
- Surface Reflectance
- 500m resolution
- (MOD09GHK)
- MODIS tile: h11v04
- Acquired on
- 4/26/2006
- (A2006116)

- View Zenith Angle

- 0	  32	   65

## MODIS Daily

- Nadir BRDF-adjusted
- Surface Reflectance
- Using Magnitude
- Inversion Approach
- 4/26/2006

## Linear Regression with Errors in Both Coordinates

- y = a*x + b
- x: AWiFS DN aggregated to MODIS resolution
- y: MODIS surface reflectance
- samples are extracted in 3km resolution to reduce bowtie effects
- Consider errors from both x and y
- Errors from x are caused by BRDF variations (vzn=0-25 degrees) and geolocation etc., use 5% errors
- Error from y caused by calibration and atmosphere correction etc. According to the Eric Vermote etc., the overall accuracy of MODIS surface reflectance are 0.005, 0.005, 0.014 and 0.006 for band 2-5 respectively.
- Used numeric recipe approach for straight-line data with errors in both coordinates (Deming approach)

## Constrain Linear Regression

- Hard bound
- No aerosol information available
- Assume AOT varies from 0 to 0.5
- Estimate variations of intercept base on the relation between TOA reflectance (or DN) and surface reflectance from physical model
- Use hard bound for intercept if out of range
- Soft bound
- Use aerosol information from MODIS
- Compute distribution of intercept
- Consider a priori knowledge of intercept in the regression

## AWiFS 

- AWiFS
- Digital Number
- (sub-scene D)
- 4/26/2006

## AWiFS

- MODIS

- Red (B3)			NIR (B4)

- MODIS

## Use Relative Atmosphere

- Correction Approach on
- Landsat TM
- TM surface reflectance
- used same day MODIS
- surface reflectance as
- reference
- 4/26/2006

## AWiFS surface 

- AWiFS surface
- reflectance
- used same day
- MODIS surface
- reflectance
- as reference
- 4/26/2006

## Green (B2)

- Red (B3)

- NIR (B4)

- MIR (B5)

- AWiFS

- TM

- Both used
- RAC approach

## Applicability of the Relative Atmosphere Correction Approach

- One step conversion to MODIS-like surface reflectance
- Works without aerosol information
- Works on both morning (Terra) and afternoon (Aqua and NPOESS) satellites
- In theory, biophysical parameter retrieving algorithms used for MODIS products can be applied for AWiFS SR directly
- Can apply to different data sources (such as Landsat, AWiFS and CBERS) and thus make one consistent data set for change detection or time series analysis

## Further Improvements

- Consider AWiFS BRDF effects
- Samples exclude vzn > 15 degrees
- Use typical MODIS BRDF shapes (per land cover) to correct AWiFS angular effects
- Use MODIS aerosol as ancillary information
- Compute probability of intercepts (based on simulations from physical model)
- Use Combined cost function from a priori intercept (parameter space) and samples (data space)
- Use local moving window regression approach
- Account aerosol variation (MODIS 10km)
- BRDF effects (in 80km about 5 degrees)
- Local region should be large enough to include enough good samples (maybe 80km-100km)
- Include quality assessment (interpolate or extrapolate?)

## Activity II: Data Fusion Test on Land Surface Temperature (LST)

- Collaborated study with Dr. Martha Anderson
- Fuse fine spatial resolution Landsat LST and MODIS daily LST

- May 24, 2001

## Activity III: Case Study on Land Cover Change Detection

- Urbanization Detection from Landsat and Foreign Landsat-like Data
- Yangtse Delta: one of the fastest economic growth region in China
- 18 Landsat scenes have been ordered (1973 - 2004)
- CBERS data obtained from China (2003- 2007)
-  Urban Heat Island Effect
- Observed temperature increase in urban area while decrease in surrounding area in last several decades
- Collaborate with NASA GSFC Scientist on the model simulation of the effects of urbanization

**Notes:**
LDCM program provide each science team 30-50 Landsat scenes per year for free and they can be shared among science team and other researchers. Landsat 7 SLC-off scenes will be free from 2003 to current for North American. 

## Near Term Goals

- Continue improve and evaluate relative atmosphere correction (RAC) approach for AWiFS data processing
- Try RAC approach for CBERS data
- Continue collaborate on data fusing test for land surface temperature from Landsat and MODIS data
- Detect urbanization from Landsat (include MSS) and foreign Landsat-like data and collaborate on the evaluation of its impacts to local climate and weather changes

## AWiFS Relative

- Atmosphere Corrected
- Surafce Reflectance
- 4/26/2006

## Landsat 5 TM

- Surface Reflectance
- From LEDAPS
- 4/26/2006

## Green (B2)

- Red (B3)

- NIR (B4)

- MIR (B5)

- AWiFS

- TM

- TM SR from
- LEDAPS
- AWiFS SR from
- RAC approach