The NOAA-6 AVHRR data sets acquired over South Texas and Mexico during the spring of 1980 and after Hurricane Allen passed inland are analyzed. These data were processed to produce the Gray-McCrary Index (GMI's) for each pixel location over the selected area, which area contained rangeland and cropland, both irrigated and nonirrigated. The variations in the GMI's appear to reflect well the availability of water for vegetation. The GMI area maps are shown to delineate and to aid in defining the duration of drought; suggesting the possibility that time changes over a selected area could be useful for irrigation management

Gray, T. I., Jr.

Mccrary, D. G.

English

NASA Technical Reports Server

  
 
 
N O T I C E 
 
THIS DOCUMENT HAS BEEN REPRODUCED FROM 
MICROFICHE. ALTHOUGH IT IS RECOGNIZED THAT 
CERTAIN PORTIONS ARE ILLEGIBLE, IT IS BEING RELEASED 
IN THE INTEREST OF MAKING AVAILABLE AS MUCH 
INFORMATION AS POSSIBLE 
https://ntrs.nasa.gov/search.jsp?R=19810020967 2020-03-21T12:40:15+00:00Z
Cn	 _
AgR^5`01"`TARS:,
..Mar' s
 available vn&r NWA s;r
in t' a i0ere^t o, eido and
SE'.:"ail9'1 L .` Earth R'AiRCCS "fY^
1w a:?7 Use m;j"z U,r.:eol."
Early Warning and Crop
Condition Assessment, 1-
E81-101910,13 - &o 9'7?
EW-h1-04076
JSC-17132
APR 'l 2 1981
A Joint Program tor
Agriculture and
Resources inventory
Surveys Through
Aerospace
Remote Sensing
C. March 1981
THE ENVIRONMENTAL VEGETATION INDEX
A TOOL POTENTIALLY USEFUL FOR ARID LAND MANAGEMiENTJ
T. I. Gray, Jr. and D. G. McCrary
	 /r^^s^
National Oceanic and Atmospheric Administration
(L.ijl-lul y l)	 ldL LNVj11^-N„c:,iAL VLGETATIGb 	 .ti^1-195 5
1to0E1: A TL'jL FUTLh.IALLY UJhkUL tl:u AhiD
LAoiu MAAA GEMl.ni (ddt1CUaA. GCedL1C dhd
i► t.ri,)j; .:,2L1C A,jM j ri5LLdt1.01,)	 b i+	 Uaci aL
N	 W N	
A jel.lr Ail	 CSCL J-'C	 U^l J1
U.S. Department of Commerce
1050 Bay Area Blvd.
Houston, Texas	 77058
0S0EHT OF COti
ILI
42. Ir
Q	 4W	 ^,o
S , 4r ES Of
4	 '^4 ri	 y\
- `14t,	 -
n
^'	 a	 "no n."I a .rrc,.
Lyndon B. Johnson Space Center
H ouston Texas 77058
1. Repot No.	 2. Goventment Accession No.
E'rl-N I -04076; JSC-17132
4. Title er`4 Subtitle
The Environmental Vegetative Index--A Tool Potentially
I	 Useful For Arid Land i^anageinent
7. Author(x)
Thomas I. Gray, Jr. (AES3)
Dee G. McCrary (EuIS'
9. Performing Organizat i	oma and Address
ir0A4/Nt^S/ESL
Land Sciences Branch
1050 B.Ay Area Boillevard
Houston, Texas	 77053
1. Spcnsori,o Agency Name and Address
Early 'i4arning/Crup Condition Assessment Project, AgRISTARS
10E0 Bay Area Boulevard
1<
3. Recipient'- Catalog No.
5. Report Date
6. Performing Organization Code
8. Performing Orgenization Report No.
10. Work Unit No.
SD0000; 8D4301
11. Contract or Grant No.
12. Type of Report and Period Covered
13. Sponsoring Agency Code
Houston, Texas	 77058
15. Supplementary Notes
1 R. Abstract
NOAA-6 AVHRR data sets acquired over South Texas and Mexico during the spring of 1980
and after Hurricane Alen passed inland are analyzed. These data were processed to
produce the Gray-McCrary Index (GMI's) for each pixel lccation over the selected area,
which area contained rangeland and cropland, bcth irrigated and non-irri gated. The
variations in the GMI's appear to reflect well the availability of water for vegetation.
aMI area maps are shown to delineate and t^ aid in defining the duration of drought;
suggestin g the possibility that time changes over a selected area could be useful for
irrigation management.
17. Key Words (Suggested by Author(%) )	 18. Distribution Statement
19. Security Classif. (of this report)	 20. Security Classif. (of this page)	 21. No. of Pages	 22. Price'
Unclassified	 ^^	 Unclassified	 5
M,	 'Fos sale by the National Technical Infoamation Service, Springfield, Virginia 22161
JSC Form 1424 (34v Nov 75) 	 NASA — JSC
EW-idl-0+076
JSC-17132
THE ENVIRONMENTAL VEGETATIVE INDEX{
A TOOL POTENTIALLY USE?UL FOR ARID I.AND MANAGEMENT
PRINCIPAL INVESTIGATORS
T. I. Gray and D. G. McCrary
APPROVED BY
G. 0. Boatwrigi , Manager
Early Warning/Crop Condition Assessm(,nt Project
AgRISTARS Program
Earth Observations Dvision
Space and Life Sciences Directorate
NATIONAL AERONAUTICS MrD SPACE ADMINISTRATION
LYNDON B. JOHNSON SPACE CENTER
HOUSTON, TEXAS
April 1981
R
Reprinted from Preprint volume cf Extended .Abstracts:
L 1 ' I
4 	
15th Confe"nce un Ajrt^.wture and Forest %letecrology
J and Fifth ConAranc* :n Btometeorology. April 1-7. 19P1,
Anaheim, CLUE. PuLltshed by the American .Naleorolor.cia
Society, Boston, ftass.
THE ENVIRONMENTAL VEGETATIVE INDEX
A TOOL POTENTIALLY USEFUL FOR ARID LAND MANAGEMENT
Thomas I. Gray
National Earth Satellite Service
Dee G. McCrary
Envircnmentai Data and Information Service
Houston, Texas
BACKGROUND
Within the past decade, the develop-
ment of techniques to interpret useful agricul-
tural information frcm the remotely-sensed data
acquired by satellite-borne instruments has
shown promising results. Investigations based
upon data sets acquired by the Multi-Spectzal
Scanner (MSS), an instrument aboard each Land-
sat Satellite s y stem, have provided techniques
to delineate crop acreage, crop type (with limi-
tations), and course treasures of vegetative
growtn stages (Ashburn, 1979; Thompson, 1979).
The refinement of these techniques is dependent
upon better temporal distributions of these data
for -ach target -irea; however, this effort has
been handica pped by the Landsat system design
which permits data acquisition for a given tar-
get only once per 18 days per satellite (nine
days if a two-satellite system is operating).
Often, a given target's acquisition was pre-
luded due to extensive cloudiness. Many tem-
poral gaps existed during the Large Area Crop
Inventory Experiment (LACIE) which limited the
LACIE capability adequately to define crop cal-
endars, normal time-dependent vegetative in-
dices, and probable limits for stress detec-
t it n.
J. Hickman, USDA, FAS, CCAD and
D. McCrary recommended investigating the capa-
bilities of the operational environmental satel-
lite systems to monitor agriculture as a task
in the .agriculture and Resources Inventories
Surve y Through Aerospace Remote Sensing program
(AgRISTARS). An investigation was ccmpleted
into the responses of the NO,-A-6 Advan:ed
Very High Resolution Radiometer (A%IHRR) for the
detection of greenness of vegetation and it
was .sere mined that the Local Area Coverage
(LAC) data sets in these data were highly cor-
related to nearl y svnoptic MSS data within iden-
tical target areas (about 1600 sq. k:n) (Gray,
1980), This finding has led to the suggestion
that .1perational processing of NOAH satellite
s y stems data for monitoring global vegetation
should be undertaken. It is expected the var-
iations in the AVHRR resnonses will provide in-
formation about reactions of vegetation to
moisture availability and/or thermal effects.
DATA ACQUISITION AND PROCESFI NG
The spring drought of 1980 in South
Texas offered an opportunity to test this -hesis
with respect to water deficit. Upon advice of
Dr. C. Weigand, USDA/SEA/AR of Weslaco, Texas
this study was begun with AVHRR/LAC data tapes
for the 1930 dates of 22 March, 14 April, 19
April, and 28 April acquired from the Satellite
Data Services Division (SDSD, NCC, EDIS,.NCAA).
Later the data for 18 June, 9 July, 24 August
and 19 CP cober were added.
These sets which contain five data
channel; were edited and processed co provide
calibrated albedo data for Channels 1 and 2 with-
in the selected scene. The AVHRR Channel 1 fil-
ter accepts radiation from .55 to .74 ',m with a
wing between .88 and .96 um., but its principal
band width is .572 to .686 um. The Channel 2
range is .71 to 1.09 um with its principal band
wiith from .715 to .987 um. Calibration, in
this context, converts the digital count as
transmitted from the satellite AVHRR s ystem to
percent albedo using the following linear equa-
tion:
Aijk - IC ijl` a S  + Y 	 (1)
where the subscripts impl y the pixel number,
scan line number and the channel number; A, the
calibrated albedo as a percentage; IC, the raw
digital count of the channel; S, the slope of
the calib r ation line of that channel; and 1', its
intercept on the albedo axis. These data sets
also included data from the 3.33 - 3.93 :.m
and 10.5 to 11.5 um bands, but anal y ses of these
bands have beet postponed.
AVHRR data sets are acquired over
such an expanse that related angles to each pixel
vary greatly. To permiZ comparisons between var-
ious times these data have b.en normalized to a
s^nt'oetic ov,rhead sun. Analvses, then, are
205"
ramps related to Lake Falcon and the Gulf of
Mexico on both the upper and lower graphs of
Figure 1,
Nearly congruent scanline segments
_-_e selected for specific transects within the
area; one, which is presented in theFigure 1,
extends from 26.75°N, 10C 00°W to 26.31 N,
97.00°W. The data are graphed with the arguments
of longitudinal lozation and EVI using each
instantaneous field-of-view (IFOV) of each seg-
ment.
r 0, r• " r1 r1 rl Pt We a3
awn	 nan Luwmd	 ..^
I	 i,
J}f^ 	 li	 ^ry"
,ii
	f	 1
^
_
Lr 	 I	 ^^, M .^ -rT
^L.. •_.	 °-^ --ter
.^
.v rr	 as	 el.'	 we
	
we	 a3	 vo
A"	 w(J1 Lo-C 4
	 r s+.
F.i.gwte 1. Co-Located EVI scan.tines. Uppet
pai,t i.tturtA rtes deeteas.cng EVI with
dn.ough.t. Line 80191 o6 toweA pait depicts
continued d4ougltt white 80237 occuAAed
a;SteA Hultt.icane AJ.ten. Shaded ateas or
uppe-t and tDwet graphs ate cAoptands, and
et-uds, Lespectivety.
The mean EVI decreased over the
range land and native vegetation (that por'.fon
of the graphs westward of 98.75°W) from a ratan
level of 4.53 on 14 April 1980 (80105) to 2.77
on 28 April 1980 (80119). Duting this same
period, the Crop Moisture Index (CMI) (	 , 1980)
decreased from about -1 to less than -2 	 Note
that east of this zone are several locatfon3
where the EVI's for 28 April 1980 are greater
than those of 14 April. In each case, irrigated
crops exist on either side of three major high-
ways located at 38.60 , 98.1 0 , and 97.75°W on
these scanlines. These EVI increases are ex-
pected with normal crop practices in these areas.
Table 1 presents the probable nor-
mal levels of the EVI with time. The average
rainfall over the area and some data ranges from
these satellite data sett were analyzed with
LACIE technology for this estimation.
TABLE 1
	
Mar	 Apr
	
May	 Jun
	
Jul	 Aug	 Sep	 Oct
	
5	 9	 13	 14	 12	 12	 16	 17
is
based upon calibrated, solar-zenith corrected
al'-edo values for Channels 1 and 2 from the
'10AA-6 AJHRR instrument.
	
3.	 DATA INTERPRETATION -%,n ANALYSIS
	
3.1	 Sensor Evaluation
The response capabilities of the
NOAH operational AVHRR system were investigated.
This evaluarion was made using the pre-launch
response curves of the AVHRR channel filters and
four ground-based spectra of a soil, well-watered
wheat, alfalfa, and wheat under a water-deficit
stress (Jackson, 1980). The synthesized dif-
ferences (Channel 2 minus Channel 0 for the
NOAA-6 ins,-iment show values to be 0.9, 22.5,
16.4 and 16.8 respectively. The ratios (Channel
2 divided by Channel 1) are 1.1, 12.4, 9.8, and
6.3.
Likewise, the spectra of clouds and
water indicate the Channel 1 albedos exceed
ti,ose of Channel 2. A complete range of spectra
for various crops and for the variations with
time were not available but the .00ve samples
indicate the AVHRR data res^on:._;. cat; be used to
evaluate the areal extent and state-of-health
of vegetation. Of course, signal degradation
for those targets which contain non-vegetative
areas, such as water bodies, urban developments,
geological outcroppings, bare soil, etc. can
be anticipated. For this reason, areas of in-
terest are selected which are nearly homogenous
and l.vrge enough that errors in location are not
critical.
	
3.2	 Data Aoalvsis
Two tech.;iques have been used in
this stud y to evaluate the AVHRR LAC data as a
tool for arid land management: 1) false color
displays through the Integrated Multivariant
Oata Analysis and Classification System (IMDACS)
of the Foreign Agricultural Service, Crop Condi-
tion Analysis Division (FAS, CCAD) computer
facility, and 2) scanline graphs across the
areas of interest. The analyses of interest
areas with IMDACS images were restricted to a
qualitative level, only, by the operational
characteristics of the system.
The more useful tool is the scan-
line graph of AVHRR data. Of particular utility,
the Environmental Vegetative Index (EVI), de-
fined to be near infrared albedo minus the red-
yellow visible albedo (see synthesize differenc-
es above) is formulated.
EVI - Air - Avis	 ^)
which expressed In terms of equation 1 is
EVI Ij
 - A, J2
 - A ijl	 (3)
In Figure 1 each negative EVI has been set to
a -0.5 ramp if the channel 1 albedo was less
than 10.01; -1.5 ramp, greater than 20.00; and
-1.0 ramp, otherwise. These ramped classes are
assumed to be water, cloud, and mixed content
targets, respectively. These ramps can be keys
to verif y locations of scanline data. Note the
206••
When the lover pair of curves is
examined. the mean EVI for 9 July 1)80 (80191)
of 3.bt+ for the native vegetation zone is con-
siderabl y below the estimated value for that
date in the table - about 9 points lover. At
this time, the LMI was less than 04.
Ashburn, P., 1979, "Utilization of the Vegeta-
tive Index `umber in the USSR", lechnical
Memorandum 011, USDA, FAS, Oct. 1979.
REFERENCES
The 80237 curve is for 24 August
1 Q 80, about 5 daps after the wiiespread inunda-
rion of the area b y 4urrlcane Allen. For this
date the mean EVI for the native vegetation has
increased to 7.19 and even more dramatically
for the areas of cultivation (average greater
than 111.0). Note the separation hot.een the
80191 and 80237 curves. The area east of 98,21
contains considerable cloudiness, surface water
and mixed content pixels for .nis later date.
The -'141 for lb August 1980 was +3.
CONC'-VSIONS A
N
D REC04%ENDATION
The results depicted in the graphs
indicate the EV1 responded t) plant growth
stress due to water deficits.' Although suf-
ti:ient data to establish a firmly reliable
"nor-nil" tine distribution of EVI's for all
--cops or regions are vet to be acquired, the
EVI is responsive to changes in vegetation due
to drought and subsequent recover-. , with ade-
quate rainfall.
An additional AgRISTARS task is
propose, to acquire more trequent data sets for
the Mississippi Valley - 6reat Plains area to
help define the prop year in terms of the EVI.
Further, research may be extended into foreign
,trews.
The data for all channels of the
AVHRR instrements are continuously broadcast by
the satellite transmitters and ma y be acquired
as long as the satellite is within the field of
^iew of any receiving station. The engineering
designs for such stations are available from
NOAA or NASA for nominal costs (Schwalb 1978).
The custom cost of these stations is about one
quarter million dollars; however, a sparcan
station sigh' be built under S50h using off-
the-shelf items of antennas, disk -irives, mini
computers and servo mechanisms.
It is suggested that operational
use of locally acquired NOAA-7, etc. data can
provide information useful for and land man-
agement. This experiment demonstrated that
the EVI lderived from NOAA-n AVHRR data) .foes
provide an index of vegetative greenness.
Cray, T. I. and McCrary , D. G., I a 80, "Meteoro-
logical Satellite Data, A Tool to Describe
the Health of the World's Agriculture",
AgRISTARS Report in preparation, Houston.
Jackson, R. D., Pinter, P. J., J., Regi-^ato,
R. J., and Idso, S. B., 1980, "Handheld
Radiometry", L'SDA, SEA, Agricultural Reviews
:-d '.Manuals, ARM-W-19, Oct. 1980.
Sehwalb, A., 1978, "The TIROS-N/NOAA A-6
Satellite Series", NOAA Technical
Memorandum NESS 95, Washington, D.C.,
March 1978.
Thompson, D. R. and Wehmanen, D. A., 197x,
"Using Landsat Digital Data to Detect Moisture
Stress", Fhotogrammetric F.neineering and
Remote Sensing, +51=):201-207, teb. 1974.
1980, "The Crop Moisture Index",
Weekly Weather and Crop Bulletin, b7(1b1:27,
b7(28):23, 6'(34):19, Washington, D.C.
207••


The environmental vegetation index: A tool potentially useful for arid land management

Abstract

Similar works

Full text

Available Versions

NASA Technical Reports Server