Toward All-Sky Assimilation for Microwave Radiances (Part II)

1

Toward All-Sky Assimilation for Toward All-Sky Assimilation for Microwave RadiancesMicrowave Radiances

(Part II)(Part II)

1,21,2Min-Jeong KimMin-Jeong Kim

11Emily Liu, Emily Liu, 11Yanqiu Zhu, Yanqiu Zhu, 11Daryl Kleist, Daryl Kleist, 11Andrew Collard, and Andrew Collard, and 11John DerberJohn Derber

and and

1. 1. NCEP/EMCNCEP/EMC

2. CIRA/Colorado State University2. CIRA/Colorado State University

2

• Introductions to our current all-sky radiance DA system and its current status were presented in the previous talk by Emily Liu.

• This talk will focus on assessment of the system to diagnose issues and to build strategies to improve.

• In addition, roles of GFS moisture physics schemes in all-sky radiance data assimilation and impacts of using them on GFS model forecasts will be presented.

• Ongoing work and outstanding tasks will be addressed.

Outline

3

GFS Forecast Impact Experiments

• Ensemble-3DVAR Hybrid GSI (operational)

• Test resolution: T254 (Note: NCEP operational resolution is T582)

• Test period: 07/01/2012 – 07/31/2012

#1 other instrument observations + Clear sky AMSU-A (operational GSI)

#2 other instrument observations + Clear sky AMSU-A + cloudy sky AMSU-A (without moisture physics)

#3 other instrument observations + Clear sky AMSU-A+ cloudy sky AMSU-A (with moisture physics)

Experiments:

4

SH Geopotential Height AC (500 hPa)

Control (clear sky radiance DA)

ECMWF obs. error model

Estimate obs. Error from GFS O-F

Control

• For now, assimilating cloud affected AMSU-A radiances making slight positive impacts on Southern Hemisphere.

• Neutral impacts elsewhere..

GFS Forecast Impact Experiments

5

Assessments (Part I)

Clear sky AMSU-A (Operational GSI)

vs.

Clear+Cloudy Sky AMSU-A (No Moisture Physics Used.)

6

CNTL: Clear sky DATEST: Clear + Cloudy Sky (Cloud microphysics not used), Obs.err estimated from cycled results

GFS Model 24 hr Forecast Errors: 500 hPa Geopotential HeightGFS Model 24 hr Forecast Errors: 500 hPa Geopotential Height

Allsky Error - ClearSky Error

Regions with positive impacts (near sea ice edge..)

7


GFS Model 24hr Forecast Errors: 500 hPa TemperatureGFS Model 24hr Forecast Errors: 500 hPa Temperature

Allsky Error- ClearSky Error

Regions with positive impacts (near sea ice edge)

8


Analysis Increment: 500hPa TemperatureAnalysis Increment: 500hPa Temperature

All Sky Clear Sky

AllSky - ClearSky

Compared to results from operational GSI, all-sky radiance assimilation system increases atmospheric temperature near 60°S

9


Analysis Increment: Total Column Cloud WaterAnalysis Increment: Total Column Cloud Water

All Sky Clear Sky

AllSky - ClearSky

Compared to results from operational GSI, all-sky radiance assimilation system makes lots of clouds near 60°S

10

• We are currently applying cloudy radiance data assimilation system in ocean surface only.

• It seems like some parts of sea ice edge are defined as ocean in the current system. Therefore, we see observations with warm signal from sea ice are split into (1) increasing atmospheric temperatures(2) generating clouds

11

Assessments (Part II)

Cloudy sky AMSU-A without moisture physics

vs.

Cloudy sky AMSU-A with moisture physics

1212

GFS Model Moisture Physics

Deep convection scheme

Shallow convection

scheme

Grid-scale condensation

scheme

Precipitation scheme

Surface rain rates

cw, T, q profiles

TL/AD codes are completed and currently being tested.

Not yet developedNeeds debugging

13

Moisture physics (TL,AD)

Inner loop

Outer loop

CRTM

Role of GFS Moisture Physics in All-Sky MW Radiance DA

1. Generating clouds even when we don’t have clouds in background..

2. Ensuring balance between water vapor and clouds. (e.g. prevent generating clouds in dry environment.)

1414

• All-sky AMSU-A included.

• Setting no clouds in the background.

• Including “moisture physics(mp)” in the inner loop.

Clouds are generated using the information from observations (wv cw)

Role of GFS Moisture Physics in All-Sky MW Radiance DA

1515

With Moisture physics Without Moisture physics620hPa

CW increment

Water Vapor increment

RH >80 % in analysis

16

GFS Model 24 hr Forecast Errors: 500 hPa TemperatureGFS Model 24 hr Forecast Errors: 500 hPa Temperature

CNTL: Clear + Cloudy Sky (Cloud microphysics not used)TEST: Clear + Cloudy Sky (Cloud microphysics used)

Error(MoistPhy)- Error(Without MoistPhy)

Currently, including moisture physics increase temperature forecast errors especially near the Tropics.

17


Analysis Increment: Total Column Cloud WaterAnalysis Increment: Total Column Cloud Water

With MoistPhy Without MoistPhy

With MoistPhy - Without MoistPhyClouds are generated less when using moisture physics.. •Good to see that near the sea ice edge •But maybe making not enough clouds near Tropics .. ?•Increasing water vapor instead of clouds near Tropics ..??

18


Analysis Increment: Total Column Water VaporAnalysis Increment: Total Column Water Vapor

With MoistPhy Without MoistPhy

With MoistPhy - Without MoistPhy Using moisture physics in the optimization increases water vapor near Tropics

19

Summary

- We starts to see our all-sky microwave radiance system makes slight positive impacts on Southern Hemisphere.

- We need to improve the way discriminate sea ice from ocean surface for all-sky radiance assimilation

- Moisture physics degrading results especially near the Tropics for now. It shows the tendency evaporating clouds maybe too much. Further investigation is ongoing.

202020

Ongoing & Future Plans

2020

21

Systematic Bias Increasing with CLWPSystematic Bias Increasing with CLWP

22

How to deal with precipitation we couldn’t removed from QC

(1) Revisit QC to remove moderate/lightly precipitating observations

(2) Enhance radiance bias correction scheme for all-sky microwave radiance assimilation See Yanqiu Zhu’s presentation tomorrow

(3) Include precipitation in the background fields

23

Revisit Quality ControlRevisit Quality Controlfor cloud affected radiance data in “non-precipitating” skyfor cloud affected radiance data in “non-precipitating” sky

Evaluating QC using Observed (retrieved) TMI surface rainrates

Detecting “heavy” rain with scattering

Missing“moderate/light” rain without scattering

not assimilatedassimilated

15211 454.0)0049.0241.2( chchchch TBTBTBTBdsval 2

6

2

8.0106

chTBdsval

factch factch6 > 1.0 : precipitating in operational GSI

24

How to deal with precipitation we couldn’t removed from QC

Deep convection

scheme

Shallow convection

scheme

Grid-scale condensation

scheme

Precipitation scheme

Surface rain rates

cw,t, q profiles

GFS moisture physics

Brad Ferrier kindly helped us calculate the rain and snow mixing ratio profiles using GFS large-scale precipitation scheme

(1) Revisit QC to remove moderate/lightly precipitating observations

(2) Enhance radiance bias correction scheme for all-sky microwave radiance assimilation See Yanqiu Zhu’s presentation tomorrow

(3) Include precipitation in the background fields

25

Cloud water error statistics show “non-Gaussian” distribution

Moisture Control VariablesMoisture Control Variables

Available options for moisture control variables in GSI

• cw – Currently being used

• rhtot – Needs work for Ensemble side

• cw/σcw – Set up in GSI. Needs to build background error covariance for global analysis

26

Thank you !

Any comments or questions?

27

BACKUP SLIDES

28

1. Screening Precipitating sky:factch6(>1) for all surface type : screening ch1-6, 15Based on scattering index (sval) and channel 6 O-F

2. Screening thick cloudy sky:Screening thick cloudy sky: factch4(>0.5) for all surface type: screening ch1-5, 15Based retrieved cloud liquid water path and channel 4 O-F 3. Sensitivity of Tsim to Surface emissivity for ocean surface

4. Topography : inflating error for ch 6 (z>2km) or ch 7(z>4km)

5. Transmittance

6. Inflated near Tropics ( 0.75 at 0°, and 1 at 25°N & 25°S)

Cloud affected radiance DA

Quality ControlQuality Control

29

Scan angle dependence

Observation Error Varying with AMSU-A Scan Angle

30

AMSU-A Cloudy Radiance Data

METOP-A CH 2 TBs

Hurricane Sandy (10/28, 00Z, 2012)

Remove precipitation & thick clouds

QC in “operational” GSI

Remove precipitation KEEP thick clouds

QC in all-sky GSI

31

Documents

Toward All-Sky Assimilation for Microwave Radiances (Part II)