# Presentation: 487597

## PenAir Based TAMDAR Related Impacts on Short-Range Mesoscale Forecasts over Alaska

- Meredith Croke1, Peter Childs1, Neil Jacobs1 and Yubao Liu2
- 1AirDat LLC, Morrisville, NC 27560
- 2National Center for Atmospheric Research , Boulder, CO 80307

## Challenges of Forecasting in Alaska

- Rugged & diverse terrain
- Lack of observations
- Size- Largest state
- > 2X’s size of Texas
- Population
- Lowest pop density in Nation
- AK Coastline = 6,640 mil
- ∑ (Contiguous Coastline)

- 1/5 size of contiguous U.S.

## Solution

- Equip planes with TAMDAR
- 83 Planes equipped in Contiguous U.S.
- June 2007:
-  PenAir began equipping 10 Saab 340s
- TAMDAR:
- Humidity, pressure, temperature, winds aloft, icing and turbulence along with corresponding location.

## TAMDAR-CONTRACT

**TAMDAR-CONTRACT**

## TAMDAR-CONTRACT

**TAMDAR-CONTRACT**

## Potential-TAMDAR (In discussions)

**Potential-TAMDAR (In discussions)**

## Potential-TAMDAR (In discussions)

**Potential-TAMDAR (In discussions)**

## Potential-TAMDAR (In discussions)

**Potential-TAMDAR (In discussions)**

## TAMDAR & VIS5D

- The combination of TAMDAR and VIS5D allows improved visualization of wind structure around complex terrain.

## Where PenAir Planes Fly

- PenAir Hub’s include:
- Anchorage
- Cold Bay
- Dillingham
- Dutch Harbor
- King Salmon

- Anchorage

- Cold Bay

- Dillingham

- Dutch Harbor

- King Salmon

- Bethel

- McGrath

- Nuiqsut

## Goals

- Long-term
**** AK observations
- Improve weather forecasting in Alaska
- Improved forecasts for Contiguous U.S.
- Short-term
- Evaluate current weather forecasting capabilities

## Model Configuration

- WRF-ARW: fully compressible, nonhydrostatic mesoscale model.
- Domain:
- 220 x 220
- 420 x 420
- Horizontal grid spacing:
- 12 km
- 4 km
- Forty hybrid-sigma levels.

## Methodology

- Two model runs:
- Control:
- Full MADIS data feed
- Experimental:
-   Full MADIS data feed + TAMDAR data streams
- Verification:
- NARR
- RAOB observations
- Surface observations

## Individual Days- Anchorage

- April 2, 2008
- 500 hPa
- AVG Temp Improvement: 0.07C
- 4.4% Reduction in Error
- 850 hPa
- Avg. Temp Improvement: 0.10C
- 12.76%  Reduction in Error

## PANC- April 2 12Z

- Control

- Experimental

- Notice difference in low level winds

## PANC Sounding 12 UTC

- Actual sounding  NW wind at surface
- TAMDAR sounding NW wind at Surface.
- Control sounding  SE wind 1000-700 hPa

## Case Study: 13 November 2007

- Extreme event
- More difficult to predict
-  TAMDAR observations =  forecast predictability
- 2 records set in Valdez, AK
- 12.9” (327.66mm) of snowfall
- Previous record of 6.0 (152.40mm)”
- Liquid equivalent = 0.95” (24.13mm)
- Previous record of 0.93” (23.62mm)

## Results - 2m Temperature

- 9 ASOS Stations
- CTL = |ASOS – Control|
- EXP = |ASOS – Experimental|
- Average improvement
- 0.56 C
- 19% reduction in error

- Temp Difference (OC)

- Forecast Hour

## Results - 850 hPa Temperature

- 9 ASOS Stations
- CTL = |NARR- Control|
- EXP = |NARR –                		Experimental|
- Largest improvement:
- FHr: 10-18 and after 30
- Average Improvement
- 0.25 C
- ~13% reduction in error

- Temp Difference (OC)

- Forecast Hour

## Results - Relative Humidity

- Anchorage, AK  6 hour Forecast

- Relative Humidity (%)

- Relative Humidity (%)

- Pressure (hPa)

- Pressure (hPa)

## Results-  (U,V) Wind

- EXP and CTL  forecasted higher winds between 750 & 500 hPa

- 12 Hr Forecast- Anchorage, AK

- Pressure (hPa)

- Pressure (hPa)

- Wind (ms-1)

- Wind (ms-1)

## NWS Alaska RegionTAMDAR Alaska Experiment

- “The Alaska Aviation Weather Unit (AAWU) and Center Weather Service Unit (CWSU) have seen great utility in the data, especially for Low Level Wind Shear events.”
- 				-TAMDAR Quarterly Report
- “TAMDAR data provides data values for atmospheric analysis that are not available through any other method or system.  We are finding ourselves increasingly reliant on TAMDAR data.”
- 						-CWSU Report

## Conclusions

- Encouraging results demonstrate the potential impact additional TAMDAR observations may have over data-sparse Alaska.
- More case studies need to be conducted to better understand TAMDAR impact and limitations.
- Long-term statistical analysis is underway to isolate trends from the noise of case studies.

## FUTURE WORK

- Significant improvement with implementation of:
- 4 KM WRF runs
- RTFDDA
- 4DVAR

## Acknowledgements

- Stan Benjamin and Bill Moninger (NOAA/ERL/FSL) for thoughts on newly equipped PenAir fleet.
- Computer support provided by NCAR
- NASA Aeronautics Research Office’s Aviation Safety Program
- PenAir