Investigating soil moisture-climate
This presentation is the property of its rightful owner.
Sponsored Links
1 / 20

Investigating soil moisture-climate interactions in a changing climate: A review PowerPoint PPT Presentation


  • 43 Views
  • Uploaded on
  • Presentation posted in: General

Investigating soil moisture-climate interactions in a changing climate: A review. Sonia I. Seneviratne ⁎, Thierry Corti, Edouard L. Davin, Martin Hirschi, Eric B. Jaeger, Irene Lehner, Boris Orlowsky, Adriaan J. Teuling Institute for Atmospheric and Climate Science, ETH Zurich, Switzerland.

Download Presentation

Investigating soil moisture-climate interactions in a changing climate: A review

An Image/Link below is provided (as is) to download presentation

Download Policy: Content on the Website is provided to you AS IS for your information and personal use and may not be sold / licensed / shared on other websites without getting consent from its author.While downloading, if for some reason you are not able to download a presentation, the publisher may have deleted the file from their server.


- - - - - - - - - - - - - - - - - - - - - - - - - - E N D - - - - - - - - - - - - - - - - - - - - - - - - - -

Presentation Transcript


Investigating soil moisture climate interactions in a changing climate a review

Investigating soil moisture-climate

interactions in a changing climate:

A review

Sonia I. Seneviratne ⁎, Thierry Corti, Edouard L. Davin, Martin Hirschi, Eric B. Jaeger, Irene Lehner, Boris Orlowsky, Adriaan J. Teuling

Institute for Atmospheric and Climate Science, ETH Zurich, Switzerland


Investigating soil moisture climate interactions in a changing climate a review

Many complex land processes and feedbacks!


Some preliminaries

Some Preliminaries

  • “Evapotranspiration” = net effect of ground evaporation and plant transpiration (mostly the latter)

  • More than half of solar radiation used for land evapotranspiration

  • Soil Moisture controls the partitioning of sensible and latent fluxes (Bowen Ratio) with implication on meteorology.


Clouds due to plant transpiration

Clouds due to Plant Transpiration

  • Dry Season in the Amazon Basin

  • Plants more active in Dry Season!


Role of soil moisture is 2 fold

Role of Soil Moisture is 2-fold:

Coupled through evapotranspiration term

dS/dt = P – E – Rs – Rg

dH/dt = Rn – λE – SH– G


Soil moisture affects climate through evapotranspiration latent heat flux

Soil-Moisture affects climate through Δ Evapotranspiration (Latent heat flux)

Classic Conceptual Framework : 2 regimes

Strong coupling

EF independent of soil moisture

(e.g. Amazon in Summer)

No evaporation

(e.g. Sahara)


Investigating soil moisture climate interactions in a changing climate a review

SM only affects climate in these transitional “hot spots” regions 1. strong SM-EVAP coupling2. large mean EVAP

DRY : EVAP controlled By Soil moisture, but mean too small

WET: large EVAP, but not

controlled by SM

*AGCM ensemble simulations from GLACE


Obs evidence for different sm regimes

OBS evidence for different SM regimes

“SM limited”

“ Transitional ”

“Energy Limited”

Artic tundra

Temperate Forest

Dry Mediterranean

*Different Drivers of SM conspire to make similar EVAP in summer,

despite different climates / land cover


Soil moisture temperature coupling

Soil Moisture – Temperature Coupling

Potential

Positive feedback


Regions of strong sm temp coupling

Regions of strong SM-TEMP coupling

Transitional

“hot spots” zones

Where temperature

Depends on

Soil-moisture

Radiation limited regimes

SM limited regimes


Soil moisture precip coupling

Soil Moisture – Precip Coupling

?? Don’t even know the

Correct sign here!


Regions of strong sm precip coupling

Regions of strong SM-Precip coupling

  • In GLACE models, EVAP sensitivity appears to control both T and P coupling

  • BUT significant inter-model variability

  • GLACE models may not be able to simulate negative SM-Precip feedbacks found in CRM, RCM, and OBS


Other sm climate interactions

Other SM–climate interactions

  • Persistence (“memory”) of soil moisture anomalies

    • SM acts as both water and energy storage

    • Potential implications for subseasonal/seasonal forecasting

    • Again depends on “hot spot” regions where coupling is strong

  • Non-local and Large scale impacts

    • e.g. Advection of dry/hot air over negative SM anomalies

    • Apparently relevant for spread of European heat waves

  • Soil Moisture – Albedo interaction

    • Soil moisture anomalies affect both bare-soil and vegetative albedo

  • Interaction with Biogeochemical cycles

    • CO2 uptake by plants coupled with water loss via transpiration

    • Less water  Less productive plants  More CO2


Soil moisture in a warming world

Δ Soil Moisture in a warming world

Projected Decrease

In precipitation in

mid-Lat and sub-arid

Regions

Drives SM decrease

* Note no change in SM in wet places in spite of increased Precip (“energy-limited” regime)


Investigating soil moisture climate interactions in a changing climate a review

- Again Mediterranean

Hot Spot Clear

  • Changes in

  • Climate Variability

  • Cannot be simply

  • Derived from changes

  • In mean climate


How sm can affect climate variability

How SM can affect Climate Variability

Seasonal cycle

“Radiation-Limited”

Wet regime

“SM-limited”

Transitional regime

If a region shifts to a SM-limited regime and becomes a coupling “hot spot”

 then EVAP variability depends highly on SM and

 then SM is an important driver of TEMP (via Bowen Ratio)


Projected changes in sm temp coupling

Projected changes in SM-Temp coupling

Red = Soil moisture limited regime

Blue = Radiation limited regime

* Projected decrease in Precip causes Central Europe

to switch from Blue to Red


Does sm climate interactions amplify or damp climate variability

Does SM-climate interactions amplify or damp Climate Variability?

  • Wet soil moisture regime

    • EVAP is insensitive to soil moisture and has no effect on CLIVAR

  • Transitional soil moisture regime

    -EVAP very sensitive to soil moisture and significantly impacts climate

  • Dry soil moisture regime

    • EVAP very sensitive to soil moisture, but very limited

  • If Climate changes from :

    Wet  Transitional = Increased Climate Variability

    Transitional  Dry = Decreased Climate Variability


    Challenges and uncertainties

    Challenges and uncertainties

    • Significant divergence among models regarding SM–Precipitation feedbacks

      • Still don’t know what sign is here, let alone magnitude!

      • Evap sensitivity to soil moisture highly variable among LSMs


    Investigating soil moisture climate interactions in a changing climate a review

    Challenges and uncertainties (cont.)

    • Better Diagnostics to validate models

      • Coupling of key processes often more important to climate prediction than absolute values of temp, evap, etc..

    • How to assimilate disparate land data sets

    • More comprehensive ground network given land heterogeneity


  • Login