Improved CanSIPS Initialization from Offline CLASS Simulation and Data Assimilation

Aaron BergCanSISE Workshop

Contribution area:

• A2.2: Improving CanSIPS snow/land surface initialization

• Contributors: Aaron Berg, William Merryfield, Stephane Belair, Marco Carrera

Initialization of hydrological stocks (snow, soil moisture) in Land Surface Models

•Over large scales estimates of the initial hydrological state must be model derived

•This requires forcing data (i.e. radiation, precipitation) of both high spatial and temporal resolution (3-hourly)

•Much of the needed observations are not presently available except in re-analysis products, however reanalysis have bias

Absolute differences of the mean annual precipitation (mm/day1) from 1989 to 2006 between GPCC and (a) CRU, (b) CPC, (c) ERA -Interim, (d) MERRA (Modern-Era Retrospective Analysis for Research and Applications), and (e) CFSR (Climate Forecast System Reanalysis (Lorenz and Kunstmann 2012).

“…the performance of all three reanalyses in reproducing the hydrological cycle still causes doubts in the use of such models for climate trend analyses and long-term water budget studies.” Lorenz and Kunstmann, 2012

Differences in the annual mean temperatures at 2 m between (a) ERA-Interim, (b) MERRA, and (c) CFSR and CRU (Lorenz and Kunstmann 2012)

Development of Forcing Products for Offline Simulation of Initial Hydrological State

• Bias corrected forcing data set created (Alavi et al. 2011), could be updated to near present

• Run land surface model (CLASS) to generate offline initialization of land surface hydrology

• Offline initialization scaled to climatology of CanSIPS

Using the bias corrected forcing we have made global estimates of the soil moisture state (e.g. Alavi et al. 2011)

We have compared the global soil moisture product to satellite soil moisture observations from AMSR-E (Alavi et al. 2011)

Assessment of land surface hydrology (soil moisture) initialization impacts on retrospective

seasonal climate prediction in CanSIPS using GLACE-2 approach (Koster et al. 2011)

Initialized CanCM3 with realistic land surface

hydrology

Perform Ensembles of retrospective seasonal

climate forecasts

Evaluate forecasts with observations

Series 1

Initialized CanCM3 with “scrambled” land surface hydrology

Series 2

Perform Ensembles of retrospective seasonal

climate forecasts

Evaluate forecasts with observations

Skill assessment is difference (series 1 – series 2) in the square of anomaly correlation coefficient with statistical significance (to account for field significance) assessed using a Monte Carlo approach

Improvements to long-lead temperature forecasts in the Canadian Centre for Climate Modelling and Analysis General Circulation model (CanCM3) used for seasonal weather prediction when soil moisture is properly initialized

Drewitt et al. 2012

Research Tasks: Assessment of Forcing Products Used for Initialization of CanSIPS

• Survey of available products suitable for operational initialization in CanSIPS – Ideally an offline initialization product will be globally

available with limited lag time– Use of Reanalysis may not be appropriate?– Evaluate current method of Alavi et al. (2011) with forcing and

data sets from CaLDAS, GLDAS and Reanalysis (MERRA, ERA) for accuracy of cold season processes within stand-alone CLASS

– identification of appropriate offline forcing data for initialization of CanSIPS

– Offline initialization scaling to climatology of CanSIPS

Assessment of Hydrological Processes in CLASS

• Assessment of land surface hydrology realism in CLASS (Snow cover, SWE, soil moisture)

• Assessment of the relationships of SWE anomalies to soil moisture anomalies (as soil moisture anomalies are long lived and have well established connection to land/atmosphere coupling)

• Few locations to study these processes at “representative” scales

Networks sensors are at only one location

• Instrumented for soil moisture, soil freeze thaw, eddy flux tower for meteorological variables

• Snow surveys (several years)

• Collaborators: Brenda Toth (EC); Jessika L’Heureux (AAFC) Warren Helgason (Usask)

• HQP (U Guelph) Travis Burns (MSc. 0.5)

Brightwater Creek Watershed (Saskatchewan Canada)Collaboration with CCRN network

Stream Gauge

effective basin area

fluxtower

soil moisture grid

Guelph station

• Instrumented for soil moisture, soil freeze thaw, eddy flux tower for meteorological variables

• Snow surveys (several years)

• Collaborators: Bill Quinton (WLU)http://taigaplains.ca/

• HQP (U Guelph) Rebecca Warren (MSc. 0.25)

Scotty Creek Watershed (NWT Canada)Collaboration with CCRN network

Soil moisture site

Chasmer et al. 2013

Summary

• PDF to begin January and to evaluate the offline initialization process in CLASS for CanSIPS

• Ongoing work (observation and modelling) at two observatories where we can use this data to assess CLASS realism