# Presentation: 867155

## NASA ASAP In-Flight Icing Products During ATReC/AIRS-II

**P. Minnis, L. Nguyen, J. J. Murray**
***NASA Langley Research Center, Hampton, VA***
**R. Palikonda, M. M. Khaiyer, J. K. Ayers, D. A. Spangenberg, D. R. Doelling, G. D. Nowicki**
***AS&M, Inc., Hampton, VA***
**P. W. Heck**
***NOAA CIMMS, University of Wisconsin, Madison, WI***
***Data Review, 22 April 2004***

## OBJECTIVES

**• ****Provide satellite-based support for mission planning**
**	*****- determine areas where icing potential exists ***
***	******- provide overview of weather and cloud conditions***
**• ****Validate icing products with in situ & active remote sensing data**
**	*****- compare in situ & satellite μ-physical properties***
***	******- determine where & when icing routine fails***
***	******- compare cloud-base top & height for icing clouds with ******	******a/c altitude & Montreal radar data***
**• ****Improve icing products**
**	*****- adjust definitions of icing based on objective criteria***

## DATA

**• ****GOES-12 imager (4-km, 15-30 min)**
**	*****- *****5 channels*****, use 4 or 3 (VIS, 0.65 μm; SIR, 3.9 μm, IR; 10.8 μm; ******	******  CO2, 13.3 μm)***
**• ****Terra & Aqua MODIS (1-km, 1/day)**
**	*****- *****many channels*****, use 4 (VIS; SIR; IR; SWC, 12 μm)***
**• ****NOAA-16 AVHRR (1-km, 1/day)**
**	*****- *****5 channels*****, use 4 (VIS; SIR; IR; SWC)***
**• ****Rapid Update Cycle (RUC 20-km => 1°, 1/hr)**
**	*****- T(z), RH(z), u(z), v(z)***
***	******- forecast for GOES real time processing***
***	******- reanalysis for MODIS, AVHRR processing & GOES reprocess***
**• ****CERES clear-sky albedo, sfc emissivity maps**
**• ****NOAA snow-ice maps**

## METHODOLOGY

**METHODOLOGY**
**• ****Classify each imager pixel as clear or cloudy **
- 	- determine the confidence of the classification (good, weak,glint, haze)
**• ****Retrieve cloud micro- and macrophysical cloud properties**
- 	- reclassify if no retrievals result (~4% of cloudy pixels)
**• ****Classify pixel according to potential for icing**
- 	- water cloud
- 	- supercooled
- 	- sufficient water

## SATELLITE CLOUD PROPERTIES

*EACH PIXEL*

**CLEAR or CLOUDY****	****	****	****	**
**EFFECTIVE RADIATING TEMP****	****	****	****Tc**
**EFFECTIVE HEIGHT, PRESSURE****	****	****	****Zc, pc**
**TOP/BASE PRESSURE & HEIGHT****	****	****	****p****t****, p****b****, Z****t****, Z****b**
**THICKNESS****	****	****	****	****	****h**
**PHASE (0 - 2)****	****	****	****	****	****P**
**EMISSIVITY****	****	****	****	****	******
**WATER  DROPLET EFFECTIVE RADIUS****	****	****re**
**OPTICAL DEPTH****	****	****	****	******
**LIQUID WATER PATH****	****	****	****	****LWP**
**ICE EFFECTIVE DIAMETER****	****	****	****De**
**ICE WATER PATH****	****	****	****	****IWP **
**ICING POTENTIAL****	****	****	****	****IP****	**

## CLOUD MASK

**• ****To detect clouds, the  radiances for cloud-free (clear) scene must be known**
**• ****Determine clear-sky albedos and surface emissivities after initial processing of data ****	**
**	****- used CERES values (some differences for GOES VIS)**
** **
**• ****Use RUC surface temperatures & profiles to estimate clear-sky brightness temperatures**
**• ****Use bidirectional reflectance models to estimate clear-sky reflectance for each pixel**
**• ****Estimate thresholds based on uncertainties in models & spatial & temporal variability of clear radiances**

## CLOUD RETRIEVAL METHODOLOGY

**• ****Compute ice & water solution, select most likely based on**
**	****model fits, temperature, LBTM classification, 1.6-μm reflectance**
**• ****No retrievals: reclassify as clear or status quo, 3-4%**
_**RETRIEVAL METHODS**_
**    ****DAY:**** Visible Infrared Solar-Infrared Split-Window Technique (****VISST****)**
***	******	******	******	******	******see Minnis et al. (1995, 1998)***
**    ****NIGHT:**** Solar-infrared Infrared Split-Window Technique (****SIST****)**
**	****	****	****	****	*****see Minnis et al. (1995, 1998)***
**    ****SNOW (DAY):**** Solar-Infrared Infrared Near-Infrared Technique (****SINT****)**
**	****	****	****MODIS only ****	*****see Platnick (JGR, 2001)***** **

## ICING

**ICING CONDITIONS ARE DETERMINED BY CLOUD**
- liquid water content, *LWC  **	***positive w/ intensity**
- temperature, *T(z)**	**	**	***negative w/ intensity**
- droplet size distribution, *N*(*r*)	***r***** positive w/ intensity**
**SATELLITE REMOTE SENSING CAN DETERMINE CLOUD**
- optical depth, ****
- effective droplet size, *re*
- liquid water path,* LWP*
- cloud top temperature, *Tc*
- thickness, *h*									***IN CERTAIN CIRCUMSTANCES***

## CLOUD PRODUCTS VS. ICING PARAMETERS

**• *****re***** = f[*****N*****(*****r*****)****]**
**• *****Tc***** & *****h***** can yield depth of freezing layer**
**• *****z******t***** is top of icing layer**
**• ****cloud base height (ceiling)**** =  *****z******t***** -***** h***

- IN MANY CASES, SATELLITE REMOTE SENSING
-  SHOULD PROVIDE ICING INFORMATION

**CLOUD PRODUCTS VS. ICING PARAMETERS**

## METHODOLOGY FOR EACH IMAGE TIME

**GOES**
**Radiance**
**Pixel Tile**

**RUC**
**Analysis**

**Surface **
**emissivity**
**map**

**Surface type**
**map**

**Clear-sky **
**albedo**
**map**

- Compute clear
- reflectance

- Compute clear
- temperatures

- Compute atmos
- corrections

- lat, lon
- time

- Mask:
- cloudy?
- or clear

- Clear values
- update

- VISST/SIRS
- Retrieve cloud
- properties

- No

- clear
- data

- cloudy
- pixels

**GOES**
**clear/cloud**
**Pixel Tile**

**Process each image as a sequence of pixel groups (tiles)**

## Summary

- • Nocturnal clouds much improved over poles, but not perfect
- 	- Need more ground truth
- • Twilight transition is better than before
- • Decrease in nonpolar clouds due to inclusion of sfc emissivity in all aspects of the mask, only used in retrievals previously

_**value**_**	**_**	**__**Criteria**__**	**__**                                                **_**    ****	**_** icing intensity**_**                                                                                **
**0 ****	****clear or water cloud (w/Tcld > 272 K or others) or**
**	****	****	****ice cloud w/OD < 8 ****	****	****no ice**
**1 ****	****ice cloud****	****	****optical depth > 8.0 ****	****	****indeterminate**
**2****	****re > 11 μm ****	****LWP > 100 ****	****Tcld < 272 K      ****	****low**
**3****	****re > 11 μm ****	****LWP > 200 ****	****Tcld < 272 K        ****	****mid**
**4****	****re > 11 μm ****	****LWP > 300 ****	****Tcld < 272 K ****	****high**
**5****	****re > 9 μm****	****LWP > 400 ****	****Tcld < 272 K ****	****low**
**6****	****re >  9 μm ****	****LWP > 500 ****	****Tcld < 272 K ****	****mid**
**7 ****	****re > 11 μm ****	****LWP > 300****	****Tcld < 253 K****	****high**
**8****	****re >  9 μm****	****LWP > 400,****	****Tcld <  253 K****	****high**

**PROTOTYPE ICING CATEGORIES**

## Imagery of all types available

**Imagery of all types available**
_**GOES-12**_
- VIS (0.65 μm); 3.9 μm; 6.8 μm
- IR (10.7 μm); IR w/color
- 3.9-10.7 μm; 10.7-13.3 μm
- pseudo-color: 	RGB (1,2-4,4)
- 		RGB(2,4,2-4)
**AVHHR**: similar channels

- VIS

- IR w color

- pseudo-color

## http://www-angler.larc.nasa.gov/bangor/goes12.html

**FOR IMAGERY GO TO**

- Select GOES-12, then use pull down menus to select channel or channel combination and date, times, & number of frames

## Aircraft flight track overlays

**Aircraft flight track overlays**
**On GOES VIS & IR Images**

**Example: VIS, Nov 26**

- Overview: centered on middle of flight, includes all tracks including Aqua, plane altitude given in inset box

- Interval: same as overview, except flight segment centered on image time with smaller time segments indicated in colors.
- Time covered by segment depends on the time between images.

## http://www-angler.larc.nasa.gov/bangor/goes12.html

**FOR FLIGHT TRACKS GO TO**

- Click on NASA ER2 or Citation (does not matter which at this point),
- Click on desired date and choose your desired dataset

## CLOUD PRODUCTS

**CLOUD PRODUCTS**

**Example: **
**Nov 13, 1515 UTC**

- Phase

- Cloud top ht.

- re

- LWP

**icing**

## Aqua Products

**Aqua Products**
**Only a few days analyzed so far, will reanalyze in the next 2 weeks and include all overpasses during the experiment. Available Terra data also to be processed**
**Example: Nov 19**

- VIS

- IR

- phase

- Tcld

- opt depth

## NOAA-16 Products

**NOAA-16 Products**
**All days analyzed so far, will reanalyze in the next 2 weeks. Effective radii generally smaller by 1 or 2 μm than GOES**
**Example: Nov 30**

- VIS

- re

- LWP

- Ztop

- icing

## http://www-angler.larc.nasa.gov/bangor/goes12.html

**FOR LARGE AREA PRODUCTS GO TO**

- Click on GOES-12, NOAA-16, Terra, or Aqua,
- Click on desired date and choose your desired parameter
- GOES gives loops

## FLIGHT-MATCHED PRODUCT IMAGERY; In PROGRESS

**FLIGHT-MATCHED PRODUCT IMAGERY; In PROGRESS**

**DIRECT LINK IN FUTURE**

## Click on Citation under cloud products, select date and times,

- _[http://www-angler.larc.nasa.gov/bangor/goes12.html](http://www-angler.larc.nasa.gov/bangor/goes12.html)_

**FOR FLIGHT MATCHED PRODUCTS GO TO**

- ER-2 to come later

- Plots and ascii printouts of data are available on the plot page

## Click on Montreal site under cloud products, select date and times

- _[http://www-angler.larc.nasa.gov/bangor/goes12.html](http://www-angler.larc.nasa.gov/bangor/goes12.html)_

**FOR PRODUCTS OVER THE SURFACE SITE GO TO**

- Plots and ascii printouts of data are available on the plot page

## COMPARISONS 

**• ****VERY LITTLE QUANTITATIVE TO DATE**
**• ****NOV 30 CASE; icing verified by Citation report,  but heights differ**
**Citation notes cloud top at 7200' (****2.2 km****) VISST => ****2.5 - 3.5 km**** (257 K, -16C)**

**Nearest sounding: -16C at ****~3.1 km**

**Structure of RUC profiles evident in large scale retrievals**

## DESIRED COMPARISONS

**• ****Citation****: ****μ-physics, Rosemont, TAMDAR**
**• ****ER-2****: ****NAST, CPL, MAS**
**• ****Montreal****: ****radar, MWR LWP, Canadian in situ data**

## OTHER FUTURE WORK

**• ****Reprocess GOES, NOAA, Aqua, & Terra data**
**• ****Complete flight-track matched imagery, redo matched datasets**
**• ****Analyze data outside domain for additional comparisons with ER-2**