# Presentation: 012338

## Cloud Emissivity Change

- NAMX, ops NAM:The cloud _*layer*_ emissivity (E) associated with a cloud optical depth (D) is currently parameterized as E = 1-.exp(-0.75*D),
- where D=∑ (awqw+aiqi)dp   (0.75 from Harshvardhan)
- NAMY: E=1.-exp(-1.66*1.5*D)
- The 1.66 factor agrees with the equation in the WRF RRTM (depends on angle, frequency)
- The extra 1.5 factor accounts for larger absorption coefficients (aw, ai) used in NCAR's RRTM to convert from cloud mixing ratios to optical cloud depths.

## Low Bias in LWdn 

## 2006021012 (E. Coast snowstorm) NMM Launcher Run w/ NAM ICs

**NMM Control**

**Increased Cloud**
**Emissivity**

## NMM Control

**NMM Control**

**Increased Cloud**
**Emissivity**

## NMM Control

**Increased Cloud**
**Emissivity**

## NMM Control

**Increased Cloud**
**Emissivity**

## NMM Control

**Increased Cloud**
**Emissivity**

## 2-m T verif over East(2006021012 snowstorm)

**NMM Control**

**Increased Cloud**
**Emissivity**

## 2-m T verif over West(2006021012 snowstorm)

**NMM Control**

**Increased Cloud**
**Emissivity**

## 2-m T verif over CONUS(2006021012 snowstorm)

**NMM Control**

**Increased Cloud**
**Emissivity**

## 2-m T verif over CONUS(2005070912 -- “Dennis” + AQ)

**NMM Control**

**Increased Cloud**
**Emissivity**

## 84h precip from latest parallel runs

## Sample 54-h LWdn from latest parallel run

## Total column-integrated condensate (water + ice) at 54 h

## Additional tests – motivated by NAMX cold bias (>500 mb) & low heights

- Microphysical experiments
- Many more ice particles at colder temps(problem – persistent anvil over SE part of grid for 2005070912 case – “Zhao-like”)
- Played with “RHgrd”
- Fixed values (0.975, 0.95) => currently 1.0
- Decreasing RHgrd with height / model thickness
- Precip and ice fields were surprisingly insensitive;some impacts on (low?) liquid water clouds
- Mixed results for objective verification
- 48h runs were pretty insensitive to microphysics changes

## NAMX cold biasafter 48h 2006022400 cycle

- Saved _[2006022400 parallel forecast page](http://wwwt.emc.ncep.noaa.gov/mmb/bf/namx.2006022400/)_
- _[700-mb NAMX-NAM temperatures](http://wwwt.emc.ncep.noaa.gov/mmb/bf/namx.2006022400/diff.na.700t_animate.html)_
- _[2006022400 sounding page](http://www.emc.ncep.noaa.gov/mmb/bf/wrfpll.sndverif/2006022400/)_

## 700-mb NAMX-NAM T (48-84h)

## 500-mb NAMX-NAM Z (48-84h)

## 850-mb NAMX-NAM T (48-84h)

## 2-m NAMX-NAM T (48-84h)

## Bismarck, ND (48, 60, 72h)OBS (black)  NAM (red)  NAMX (green)

## Aberdeen, SD (48, 60, 72h)OBS (black)  NAM (red)  NAMX (green)

## International Falls, MN (48, 60, 72h)OBS (black)  NAM (red)  NAMX (green)

## Minneapolis, MN (48, 60, 72h)OBS (black)  NAM (red)  NAMX (green)

## Green Bay, WI (60, 72, 84h)OBS (black)  NAM (red)  NAMX (green)

## Alpena, MI (60, 72, 84h)OBS (black)  NAM (red)  NAMX (green)

## Supplemental Slides

- 48-72, 60-84h precip
- 48-84h total condensate

## 48-72h precip (top)60-84h precip (bottom),NAM (left), NAMX (right)

## Total column condensateNAM, NAMX (48h)

## Total column condensateNAM, NAMX (60h)

## Total column condensateNAM, NAMX (72h)

## Total column condensateNAM, NAMX (84h)