North American CroplandsRichard Massey & Dr. Teki Sankey

Overview for North America

• Preprocessing • Classification method• Accuracy assessment

Preprocessing MODIS Data (MOQ09Q1, 250 m)

Reprojected MODIS images for North America:

Geographic Lat/LonSinusoidal

• 2000 (1502 tiles, 1.9 TB)• 2001 (2162 tiles, 2.4 TB)• 2002 (2162 tiles, 2.4 TB)• 2003 (2162 tiles, 2.4 TB)• 2004 (2162 tiles, 2.4 TB)• 2005 (2162 tiles, 2.4 TB)• 2006 (2162 tiles, 2.4 TB)

• 2007 (2162 tiles, 2.4 TB)• 2008 (2162 tiles, 2.4 TB)• 2009 (2162 tiles, 2.4 TB)• 2010 (2162 tiles, 2.4 TB)• 2011 (2162 tiles, 2.4 TB)• 2012 (2162 tiles, 2.4 TB)• 2013 (2162 tiles, 2.4 TB)

Preprocessing MODIS Data (MOQ09Q1, 250 m)

Mosaicked MODIS images for North America:• 2000 (1502 tiles, 1.9 TB)• 2001 (2162 tiles, 2.4 TB)• 2002 (2162 tiles, 2.4 TB)• 2003 (2162 tiles, 2.4 TB)• 2004 (2162 tiles, 2.4 TB)• 2005 (2162 tiles, 2.4 TB)• 2006 (2162 tiles, 2.4 TB)

• 2007 (2162 tiles, 2.4 TB)• 2008 (2162 tiles, 2.4 TB)• 2009 (2162 tiles, 2.4 TB)• 2010 (2162 tiles, 2.4 TB)• 2011 (2162 tiles, 2.4 TB)• 2012 (2162 tiles, 2.4 TB)• 2013 (2162 tiles, 2.4 TB)

Band 2 Mosaic

Preprocessing MODIS Data (MOQ09Q1, 250 m)

• NDVI calculated for North America:• 2000 (32 image dates, 1.9 TB)• 2007 (46 image dates, 2.4 TB)• 2008 (46 image dates, 2.4 TB)

NDVI Image

Preprocessing MODIS Data (MOQ09Q1, 250 m)

• NDVI layers stacked for North America:• 2000 (32 image dates, 1.9 TB)• 2007 (46 image dates, 2.4 TB)• 2008 (46 image dates, 2.4 TB)

Preprocessing MODIS Data (MOQ09Q1, 250 m)

• NDVI stacks masked for cloud:• 2000 (32 image dates, 1.9 TB)• 2007 (46 image dates, 2.4 TB)• 2008 (46 image dates, 2.4 TB)

MODIS Classification

• Classification method developed • Classification:• 2008 (46 image dates, 2.4 TB)

Classification Assessment

• Classification outputs• Testing for:• Model development • Model refinement• 20,000 randomly selected pixels

• Accuracy assessment• No extensive assessment• Needs discussion

Crop classification• Subset data with Global Cropland Extent (GCE) version 1.0

Class description Croplands 4 of 4 Croplands 3 of 4 Croplands 2 of 4 Croplands1 of 4

Crop classification• Subset GCE v1.0 with Food and Agricultural Organization’s

Agro Ecological Zones (AEZ)• Classify each AEZ separately

Crop classification• Derive training spectra from USDA Cropland Data Layer (CDL)

CDL availability for conterminous US

2000

2001

2002

2003

2004

2005

2006

2007

2008

2009

2010

2011

0 8 16 24 32 40 48

4

5

16

8

9

8

15

21

48

48

48

48

Number of states

Class Rain-fed % all crop US1 Corn 29.62 Soybeans 22.43 Wheat (w) 12.54 Wheat (s) 6.05 Wheat (d) 0.86 Barley 0.77 Potatoes 0.28 Alfalfa 2.59 Cotton 2.5

10 Rice 0.4

Rainfed Croplands of USA (Source: USDA CDL)

Rainfed Croplands of USA (Source: USDA CDL)

Corn Winter WheatSoybean

Spring Wheat BarleyDurum Wheat

Potatoes CottonAlfalfa

Rice

Rainfed Croplands of USA (Source: USDA CDL)

Class Irrigated % crop US11 Corn 6.012 Soybeans 3.6

13 Wheat (w) 2.614 Wheat (s) 0.415 Wheat (d) 0.116 Barley 0.217 Potatoes 0.218 Alfalfa 1.019 Cotton 1.420 Rice 1.0

Irrigated Croplands of USA (Source: USDA CDL)

Richard MasseyUpdate: 10/22/2014Richard MasseyUpdate: 10/22/2014

Corn Winter WheatSoybean

Spring Wheat BarleyDurum Wheat

Irrigated Croplands of USA (Source: USDA CDL)

Richard MasseyUpdate: 10/22/2014Richard MasseyUpdate: 10/22/2014

Potatoes CottonAlfalfa

Rice

Irrigated Croplands of USA (Source: USDA CDL)

Crop type curves• 5x5 pixel buffer to extract pure pixels only• Resample 56m to 250m• Maximum of 10,000 random points/crop type/AEZ• Crop classes with <50 available points were discarded

Subset of major crop type fields derived from CDL 2008 Subset of major crop type fields derived from CDL 2008

Randomly selected pixels Rainfed crop type for 2008

Class Crop AEZ3 AEZ4 AEZ5 AEZ6 AEZ7 AEZ8 AEZ9 AEZ10 AEZ11 Total1 Corn 2,969 10,000 10,000 10,000 10,000 10,000 10,000 - 10,000 72,9692 Soybean - 1,026 10,000 10,000 10,000 10,000 10,000 10,000 10,000 71,0263 Winter Wheat 10,000 10,000 10,000 10,000 10,000 10,000 3,912 10,000 84 73,9964 Spring Wheat 10,000 10,000 10,000 10,000 10,000 10,000 - 10,000 - 70,0085 Durum Wheat - 1,005 7,443 10,000 - 66 - - - 18,5816 Barley 7,018 8,566 6,127 9,376 3,383 2,278 - - 36,7507 Potato 5,914 9,922 1,288 249 279 1,065 468 138 - 19,3458 Alfalfa 10,000 10,000 10,000 10,000 9,295 7,565 2,917 1,613 - 61,406 Total 42,968 49,493 44,858 49,625 32,988 30,974 7,305 21,753 122

Note:1. The numbers are 56m pixels 2. Each crop type with more than 10,000 pure sample pixels were capped at 10,000

Random sample pointsIrrigated crop type for 2008

Class Crop AEZ3 AEZ4 AEZ5 AEZ6 AEZ7 AEZ8 AEZ9 AEZ10 AEZ11 Total9 Corn 1,035 6,541 10,000 10,000 10,000 3,602 10,000 10,000 5,151 66,32910 Soybean - 142 10,000 10,000 7,333 1,962 10,000 10,000 3,217 52,65411 Winter Wheat 2,082 10,000 10,000 4,132 3,309 1,544 618 377 - 32,06212 Spring Wheat 956 3,101 3,387 1,582 305 157 - - - 9,48813 Durum Wheat - 210 360 318 - - - - - 88814 Barley 1,239 1,866 534 350 - - - - 3,98915 Potato 2,154 3,546 248 - - 102 - - - 6,05016 Alfalfa 3,728 7,904 5,967 4,423 2,390 220 - - - 24,63217 Cotton - - 4,253 821 332 - 10,000 3,758 122 19,28618 Rice - - - 73 8,163 7,082 10,000 1,500 1,816 28,634 Total 11,194 33,310 44,749 31,699 31,832 14,669 40,618 25,635 10,306

Note:1. The numbers are 56m pixels 2. Each crop type with more than 10,000 pure sample pixels were capped at 10,000

Classification:Decision treeCorn + Soybean (AEZ6)

No AEZ=6

No Region subset (.shp)

No Temporal/Spectral Window

No Max NDVI location=12±2

No Max NDVI(0.6<NDVI<0.9)

Corn/Soybean

Cropland extent

Accuracy Assessment

Change Parameters

10

10

10

10

10

No

Parameters for classification:

NDVI curve identification

NDV

I

0 5 10 15 20 25 30

-0.2

0

0.2

0.4

0.6

0.8

1

NDVI

Upper Bound

Lower Bound

Input NDVI

Upper limit of Max NDVI

Lower limit of Max NDVI

Max NDVI location

Maximum NDVI window

Classification window

Unique NDVI

Classified ImageCorn + Soybean (AEZ6)

Classified Image Corn + Soybean Layer from CDL 2008

Preliminary AccuracyCorn + Soybean (AEZ6)

Parameters AEZRegion subset

NDVI Comparison

Tolerance

Left Limit

Right Limit

Shift Up

Shift Down Shift

Maximum Location

widthUnique NDVI 1

Unique NDVI Location 1

Unique NDVI 2

Unique NDVI Location 2

Unique NDVI 3

Unique NDVI Location 3

Unique NDVI 4

Unique NDVI Location 4

Cumulative NDVI

Left Limit (Cumulative NDVI)

User’s accuracy

Producer’s accuracy

AEZ6Corn+ Soybean 6 1 1 3 8 22 0.05 -0.05 0 14 3 10 <0.5 15 >0.52 16 >0.55 >9 1 96 89Winter Wheat 6 1 1 2 6 21 0 0 0 12 2 16 <0.5 73 76Spring Wheat + Durum wheat + Barley 6 0 1 5 1 23 0 0 0 15 >0.2 15 <0.5 10 >0.24 82 79

Alfalfa 6 0 1 3 3 25 0.1 -0.1 0 >3.5 5 73 75

Cotton 6 0 1 5 2 26 0 0 9 <0.3 14 >0.55 1.8 1 81 79

Algorithm parameters for AEZ 6

Model refinement

• Total of 20,000 points for each crop type per AEZ (irrigated + rainfed)• Accuracy calculated for each crop class in each AEZ• Reiterating the algorithm with modified parameters

for higher accuracy

List of accuracies for all AEZsAEZ Parameter User’s accuracy (%) Producer’s accuracy (%)

AEZ3Barley + Spring Wheat + Winter Wheat 93 72Alfalfa 81 72

AEZ4

Corn + Soybean 83 86Durum Wheat + Barley + Spring Wheat 73 76Winter Wheat 71 68Alfalfa 73 75

AEZ5

Corn + Soybean 88 86Winter Wheat 81 79Alfalfa 75 71

AEZ6

Corn + Soybean 96 89Winter Wheat 73 76Durum Wheat + Barley + Spring Wheat 82 79Alfalfa 73 75Cotton 81 79

AEZ7

Corn + Soybean 94 90Winter Wheat 81 79Spring Wheat + Durum Wheat + Barley 96 90Alfalfa 84 85

AEZ8

Corn + Soybean 94 90Winter Wheat 96 90Spring Wheat + Durum Wheat + Barley 80 85Alfalfa 69 80

AEZ9

Corn + Soybean 80 85Winter Wheat 63 71Cotton 78 71

AEZ10Corn + Soybean 79 81Alfalfa 63 71

AEZ11 Corn + Soybean 79 84

Cropland Extent• Cropland Extent derived from mosaicking binary crop maps

of AEZs• Compared with cropland extent from CDL 2008• CDL extent is reference class

Fractions of CDL areaClassified map

subset by GCEv2.0 CDL GCEv1.0

4 of 4 0.49 1.00 0.59

3 of 4 added 0.51 1.00 0.98

2 of 4 added 1.12 1.00 1.92

1 of 4 added 2.60 1.00 5.59

Irrigation Vs Rainfed

• Irrigated and Rainfed crops separated by MODIS irrigated map for 2001 (Ozdogan et al., 2010)• Irrigated and rainfed spectra shows different

cumulative NDVI in classification Window

Crop type map for all USA

Class All % US1 Corn

80.12 Soybeans3 Wheat (w) 6.694 Wheat (s)

11.135 Wheat (d)6 Barley7 Potatoes8 Alfalfa 0.6059 Cotton 0.81

10 Rice

Crop Intensity

• Identify number of NDVI maximums• Identify location of maximums• Separation > 4 image dates, classify as double crop

Cropland Extent NDVI

No Number of Maximum>1

NoLocation of

Maxima separation > 4

Double Crop

Accuracy Assessment

Change Parameters

10

10

No

Looking Forward• Automated optimization of the preselected parameters• Produce cropland map for another year and compare with

CDL• Extrapolate to the entire continent of North America at 250m• Implementation of algorithm via Google Earth Engine on

multiple years of MODIS data

Thank you