COSMOS Soil Moisture and Water Vapor and Carbon Dioxide Fluxes

Russell Scott

SECA consists of an array of eddy covariance towers placed throughout southern Arizona to address a number of issues related the functioning of ecosystems in semiarid areas.

Creosote Shrubland

Grassland

Riparian Woodland

Savanna

Grassland

Riparian Grassland and Shrubland

Walnut Gulch Experimental Watershed

How do interannual and intra-annual variations on precipitation affects H2O and CO2 exchange in semiarid ecosystems

1. Cosmos and TDR soil moisture2. Cosmos and ET3. Cosmos and CO2 flux

Site Layout KN?

TDR profiles, Watershed Flume

Cosmos, Metflux, Phenocam

Flux sites

0 50 100 150 200 250 3000

0.05

0.1

0.15

0.2

0.25

0.3

0.35

day, 2012

VW

C

0-5 cm15 cm35 cm50 cm

From TDR profiles

B horizon clays inhibit deep infiltration

0 50 100 150 200 250 3000

0.05

0.1

0.15

0.2

0.25

day 2012

VW

C

0-10cm0-18cm0-5cmcosmos

  0-5 cm 10 cm 15 cm 0-10 cm 0-18 cm 0-25 cmR2 0.88 0.88 0.60 0.91 0.90 0.86

0 50 100 150 200 250 300 350 400-10

0

10

20

30

40

50

day

P [mm]

ET [mm/day*10]

Evaporation

Faster decay when plants inactive

slower decay when plants active

7 mm runoff

Not Active ActiveET ET/Eto ET ET/Eto

R2 0.35 0.35 0.58 0.74

4 6 8 10 12 14 16 18 20-0.2

0

0.2

0.4

0.6

0.8

1

1.2

ET/

ET

o

[%]

Active plants

100 150 200 250 300

-10

-5

0

5

10

15

COSMOS & CO2 Flux

day

[0-25 cm]FC [mol m-2 s-1]

Carbon dioxide flux

rele

ase

upta

ke

100 150 200 250 3000

2

4

6

8

10

12

14

16

18

Reco

GEP

Ecosystem respiration and photosynthesis

4 6 8 10 12 14 16 18 200

1

2

3

4

5

6

Reco

GEP

These thresholds are really important for modeling but more information relative to shallow or deep moisture is critical

200 210 220 230 240 250 260 270

4

6

8

10

12

14

16

18

20

Rsoil [10*g/m2]

0 10 200

1

2

3

Rso

il - 1

day

lag R2=0.68

Soil respiration

Conclusions

NeedsEffective depth seems too deep

Modeled disaggregated products needed (very shallow and deep soil moisture) from assimilation of COSMOS data into soil moisture models

Good news Cosmos provides soil moisture at a

spatial resolution commensurate with EC fluxes

Preliminary comparisons show that Cosmos data is highly complementary to understanding water and CO2 fluxes