!"#$%&"'()*+%&",#$-.("&/(01"-*()/2$&$.#+"#$%& !"#$%%&#$'!(&%')(&*#+,$'-,(.+/#* 3"4"#(5$&/'$.67(!)0)(809: :%&#+$;,#$%&.(<+%2= 0>)?(@*"27(0>A0
Importance of Satellite Soil Moisture Limitations in measuring global soil moisture: ! Ground measurements of soil moisture are sparse and have limited coverage ! Higher frequency (X-band) Space-borne sensors have relatively low sensitivity and resolution
Objectives of Satellite soil moisture missions Objective of a Soil Moisture mission is to provide high-resolution and frequent- revisit global maps of soil moisture. Science and applications addressed by SMOS and SMAP: ! Understand processes that link the terrestrial water, energy and carbon cycles ! Estimate global water and energy fluxes at the land surface ! Quantify net carbon flux in boreal landscapes ! Enhance weather, flood and drought prediction ! Other applications such as agricultural productivity and human health
!)0)((B"+#6(A;.*+C$&D(0"#*''$#*(9'**# International Satellites ! SMOS (ESA) ! ASCAT (ESA) ! GCOM-W (JAXA) :%,+#*.E(%<(#6*(8%//"+/(F$.,"'$G"#$%&(H";
Microwave Sensing ! "#$%&'#(#)*+&,-.&/-01,1+.&(+-(21(&$%+&(2#*&#(&3,(4+.&)5&6*27.(&,-.&8+9+$,$#2-:&;<$#6,*&(+-(21(&2<+1,$+&)5& 3+,(71#-9&(6,$$+1+.&(7-*#9%$&,-.&,1+&=.,5$#3+&2-*5>: ! ?#612@,8+(&6,-&<+-+$1,$+&$%1279%&6*27.(&,-.&8+9+$,$#2-A&2<+1,$+&.,5&,-.&-#9%$A&,-.&,1+&%#9%*5&(+-(#$#8+& $2&$%+&@,$+1&#-&$%+&(2#*&.7+&$2&$%+&6%,-9+&#-&$%+&(2#*&3#612@,8+&.#+*+6$1#6&<12<+1$#+(:
Measurement Approach (Physical Basis) Emission Backscatter s L p + T Bp t = T Bp v + T Bp sv T Bp (Emission) s L pq 2 + " pq v + " pq t sv " pq = " pq (Backscatter) ! • Equations for p = H, V (radiometer) and pq = VV, HH, HV (radar) ! • Contributions include three terms: soil, vegetation, and soil-vegetation interaction • Soil moisture is the dominant contributor to the signal • L is the vegetation attenuation factor, exp( - ! o / cos " ) • Retrievals invert these equations to obtain soil moisture, IJ"-K.%&("&/(A � !*$''7( !"""#$%&'()#%"*+, 7(LMNOPQ with corrections for vegetation, roughness and surface temperature
Microwave Soil Moisture Sensing 012"3. :);! 456'789 456'789 <)!= !!)@; >5?'789 4A'789 >5?'789 # /(R 4?5?'789 [(\ & > # R(S"C*'*&D#6 ! >& R(T2 U3*<+"-#$C*(T&/*VW ?%X*+()##*&,"#*.(".( - YGZ/ Effective sensing depth Vegetation attenuation increases with decreases with increasing increasing measurement frequency measurement frequency L-band provides significant improvements in soil moisture sensing capability over previous missions (e.g. AMSR-E at C-band)
Satellite Soil Moisture Data Characteristics Mission SM Spatial Temporal Orbit Product Duration Coverage 1 Revisit Resolution AMSR-E 2002-2011 Global land 2-3 days (1:30 pm asc / 1:30 25 km am desc) GCOM- 2012-Present Global land 2-3 days (1:30 pm asc / 1:30 25 km W(AMSR2) am desc) WindSat 2004-? Global land 2-3 days Sun synch (6:00 am 25 km (DoD) asc/ 6:00 desc) ASCAT 2009-Present Global land Sun synch (9:30pm 12.5 km/25 asc / 9:30am desc) km SMOS 2009-Present Global land 2-3 days Sun-synch (6am asc 25 km / 6pm desc) Aquarius 2011-2015 Global land 8 days Sun-synch (6pm asc 100 km / 6 am desc) SMAP 2015-Present Global land 2-3 days Sun-synch (6am 3 km/9 desc / 6pm asc) km/36 km SAOCOM 2022-? Argentina ? ? 1 km Pampas NISAR 2021/2022-? US and India 12 days ? 1 km land
AMSR Soil Moisture ! AMSR-E was the first satellite mission to develop a soil moisture product ! AMSR-E provided invaluable environmental data products (precipitation, cloud water, soil moisture, snow, sea ice) from 2002 to 2011 ! AMSR2 was launched by JAXA in July 2012 and provides an opportunity to extend this data record ! AMSR2 products will be invaluable for a more complete understanding of the climate system ! AMSR-E and AMSR2 are both part of NASA’s A-train satellites ! Goal Accuracy: 0.05 m 3 /m 3 for regions with vegetation water contents (VWC) < 2 kg/m 2 , 0.10 m 3 /m 3 for VWC 2-5 kg/m 2 .
AMSR-E and AMSR2 SCA VSM Comments ! Global soil moisture maps. Data represent long term averages for the month of July. ! Maps show similar spatial structure and consistency between the two SCA retrievals. ! Areas with dense vegetation masked out.
AMSR2 Cal/Val Sites ! USA (7) ! Spain (1) ! Canada (2) ! Netherlands (1) ! Argentina (1) ! Mongolia (1) ! Australia (2)
Summary Statistics for AMSR2 Soil Moisture JAXA SCA LPRM ubRMSE Bias RMSE ubRMSE Bias RMSE ubRMSE Bias RMSE R R R (m 3 /m 3 ) (m 3 /m 3 ) (m 3 /m 3 ) (m 3 /m 3 ) (m 3 /m 3 ) (m 3 /m 3 ) (m 3 /m 3 ) (m 3 /m 3 ) (m 3 /m 3 ) Avg. AMSR2 0.059 -0.089 0.111 0.502 0.055 -0.047 0.080 0.569 0.088 0.100 0.137 0.601 All AMSR2 (VWC 0.049 -0.068 0.085 0.533 0.048 -0.035 0.069 0.593 0.083 0.077 0.115 0.655 < 2 kg/m2) ! Not much difference between A and D for a specific AMSR2 algorithm ! Each AMSR soil moisture product has different performance assessment (compared to in situ observations) ! SCA and JAXA meet the ubRMSE accuracy mission goal ! LPRM has high bias but good correlation
The SMOS Mission • Need for soil moisture and sea surface salinity fields • Only passive L band suitable SMOS is the second Earth Explorer opportunity mission (1st round) • Real aperture systems currently not An ESA/CNES/CDTI project adequate (antenna size) ==>Synthetic Selected in 1999, initiated in 2000 antenna Launched in November 2009 A new technique (2D interferometry) to provide global measurements from space of key variables (SSS and SM) for the first time . SMOS : 2010-Present ]"&&(*#("'P
SM SMOS • SMOS was the first dedicated soil moisture L-band mission in space • SMOS is performing great but is impacted by RFI
SMAP Overview SMAP objective is to provide high-resolution and frequent-revisit global mappings of soil moisture and landscape freeze/thaw state !)<-';3*#,+B$3#':(3C&D+,"#&(3 =".", 9+*^,*&-E=(LP_`(8aG( ?%'"+$G"#$%&.=(FF7(aa7(aF( 3*.%',#$%&=(b(K2 3*'"#$C*()--,+"-E=(LPc(/5(daa("&/(FFe7(LPf(/5(daFe =".&(B$#$, 9+*^,*&-E=(LP[L(8aG( ?%'"+$G"#$%&.=(a7(F7(b +/ g([ #6 0#%K*. 3*.%',#$%&=([c(K2 3*'"#$C*()--,+"-E=(LPb(h !E",$.'<3#$33" 6-m diameter deployable mesh antenna Conical scan at 14.6 rpm Constant incidence angle: 40 degrees 1000 km-wide swath Swath and orbit enable 2-3 day global revisit F,G&# 0,&Y.E&-6+%&%,.7(`("2Z12(%+;$#7( >HI'JB "'#$#,/* Launch: Jan. 31, 2015 from Vandenberg Air Force Base in California onboard a Delta II. )&**&(3'FK$,"#&(3* !"#"$ Y a$D6(.1"#$"'(+*.%',#$%&(dLYb(K2e(;,#(2%+*(.*&.$#$C*(#%(.,+<"-*(+%,D6&*..("&/(C*D*#"#$%& • bYE*"+(;".*'$&*(2$..$%& !"#%&'()($* Y a$D6("--,+"-E(d'*..($&<',*&-*/(;E(+%,D6&*..("&/(C*D*#"#$%&e(;,#(-%"+.*+(.1"#$"'(+*.%',#$%&(d[c(K2e • :(BG&3$.'=".",1=".&(B$#$,' 1+%/,-#(1+%C$/*.(%1#$2"'(;'*&/(%<(+*.%',#$%&("&/("--,+"-E(#%(2**#(.-$*&-*(+*^,$+*2*&#. • • i&$^,*&*..=( :%&#$&,%,.(%;.*+C"#$%&.(*C*+E(_Yb(/"E.
SMAP Level 1 Science Requirements 0&""1"2 !"#$%&"'"() *+%,-.+%/)$&" 3456 B+(2*7$#2- 7-5(8 9:-;' C&43 B+01+(% B,$+ C&.,5( D&.,5( EFG <=<> I63 C J63 C K EDG LMN& ECG H6671,65 O71,$#2- CP&32-$%( dLe( !%+#6(%<([f � !(H"#$#,/* d_e( j(C%',2*#+$-(X"#*+(-%&#*(LY.$D2" dbe( j(-'"..$<$-"#$%&("--,+"-E(d;$&"+E=(9+**G*( %+(@6"Xe(( ?&+8$@) B5)5- B"/@&%C)%+( *4+&)-A5'" !"/+,$)%+( D9E03EF%!"/ O,#*5 Q*2),* R23<2(#$+ S1++T+JU%,@ V$,$+ FWC&43 D9E*.E? O,#*5 Q*2),* R23<2(#$+ B,.#23+$+1 V2#* ?2#($71+ CP&43 D9E*.EG? B5%,H I,+J5, K+'C+/%)" G@)%L"M?5//%L" *+%, .+%/)$&" 7-;' D>E*. V710,6+ X B22$ Y2-+ V2#* ?2#($71+ Z&43 D>EK R,1)2- [+$ \62(5($+3 \]6%,-9+ Z&43
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