# Presentation: 663351

## Results from Atlantic THORPEX Regional Campaign (ATREC 2003): Dropsonde Impact Evaluation 

**Yucheng Song**              IMSG at EMC/NCEP
**Zoltan Toth**                     EMC/NCEP/NWS
**Sharan Majumdar**              Univ. of Miami

- http://wwwt.emc.ncep.noaa.gov/gmb/targobs

## About the ATREC

- Took place  Oct 15 – Dec 17 2003
- The Atlantic THORPEX Regional Campaign (ATREC) was a collaborative effort between EUCOS (EUMETNET Composite Observing System) program and THORPEX to test the targeting ability of a wide range of observational platforms in a real-time quasi-operational environment. It involved high degree of coordination and collaboration among UK Met office, ECMWF, Meteo-France, NRL, NASA, U of North Dakota, Meteorological Service of Canada, NCEP, FSL, NCAR and U of Miami
- Both ETKF and SV methods were used to identify the areas where supplemental observations might help to mitigate forecast errors in regions selected for verification over Europe and the eastern US.
- A variety of observing platforms were deployed where data were collected from instruments aboard or released from these platforms. They include aircraft, AMDAR, ASAP ships, GOES rapid-scan winds and radiosondes to supplement the routine observational network.

## Evaluation methodology

- Compare two parallel analysis/forecast cycles with the NCEP GFS (T126L28 resolution)
- Operational: including dropsondes and all other available data from ATReC
- Control: excluding dropsonde data in the targeted area
- Effect of other targeted data (eg, aircraft, radiosondes, etc) not assessed here
- Due to telecommunication problems, only 8 out of 16 flights dropsonde data arrived at NCEP for operational processing.
- Verify against observations over the pre-selected area of interest (verification region)
- Use rawinsonde observations for surface pressure, 1000-250mb temperature, wind speed and moisture
- 10 verification regions associated with 8 evaluated flights

## An example by ETKF method from NCEP

- Target area spotted by NCEP ETKF

- Dec 10, 12Z,2003

- Signal variance evolution

## Red dots mark the flight track of NOAA9

- An Example by SV method from ECMWFand METEO-FRANCE

- NOAA9    17:09	42.5 -46.3
- NOAA9    17:18	42.0 -44.9
- NOAA9    17:28	41.5 -43.2
- NOAA9    17:39	41.0 -41.3
- NOAA9    17:51	40.4 -39.4
- NOAA9    18:00	40.1 -38.0
- NOAA9    18:09	40.8 -36.5
- NOAA9    18:14	41.2 -35.7
- NOAA9    18:18	41.6 -35.0
- NOAA9    18:28	42.3 -33.4
- NOAA9    18:24	42.0 -34.2
- NOAA9    18:32	42.7 -32.7
- NOAA9    18:37	43.0 -32.0
- NOAA9    18:46	43.0 -32.9
- NOAA9    18:54	42.9 -33.9
- NOAA9    19:01	42.9 -34.9
- NOAA9    19:08	42.8 -35.8
- NOAA9    19:20	42.7 -37.6
- NOAA9    19:32	42.6 -39.4
- NOAA9    19:44	42.5 -41.2
- NOAA9    19:58	42.5 -43.3
- NOAA9    20:14	42.5 -45.7
- NOAA9    20:33	42.5 -48.7

- Target area spotted by ECMWF SV method

## Forecast Impact for Dec 10, 18Z

**250mb Height**

**SLP**

## Forecast Impact for Dec 10, 18Z

**500mb Height**

**Precipitation**

## Forecast verification for Dec 10,18Z

**250mb Height**

**SLP**

## Results for Surface Pressure

- Of the 10 cases:
-   7 improved
-   0 neutral
-   3 degraded

## Results for Temperature

- Of the 10 cases:
-   8 improved
-   0 neutral
-   2 degraded

## Results for Vector Wind

- Of all 10 cases:
-     7 improved
-     0 neutral
-     3 degraded

## Results for Specific humidity

- Of all 10 cases:
-   7 improved
-   0 neutral
-   3 degraded

## Breakdown for cases

| Variable | # cases improved | # cases neutral | #cases degraded |
| --- | --- | --- | --- |
| Surface pressure | 7 | 0 | 3 |
| Temperature | 8 | 0 | 2 |
| Vector Wind | 7 | 0 | 3 |
| Humidity | 7 | 0 | 3 |

## Individual Case Comparison

-   **1    denotes positive effect**
**  ****0    denotes neutral effect**
** ****-1  denotes negative effect**

**          **
**       **
**8 OVERALL POSITIVE             **
**0  OVERALL  NEUTRAL **
**2**** OVERALL  NEGATIVE**
**           ****80*****% improved***
***           ******20****** ******% degraded***

- OVERALL EFFECT:

- OBSDATE    P    T    V  OVERALL   REGION  FHOUR
- 20031024,  1,   1,   1,   1       5E ,60N   ,66
- 20031115, -1,  -1,  -1,  -1       2E ,37N   ,42
- 20031123,  1,   1,   1,   1       0E ,57N   ,54
- 20031202,  1,   1,  -1,   1      10E ,65N   ,42
- 20031205,  1,   1,   1,   1      75W ,40N   ,42
- 20031206,  1,   1,   1,   1      20W ,40N   ,42
- 20031206,  1,   1,   1,   1      20W ,55N   ,42
- 20031206, -1,  -1,  -1,  -1      75W ,40N   ,42
- 20031210, -1,   1,   1,   1       3E ,54N   ,42
- 20031213,  1,   1,   1,   1      75W ,38N   ,42

- verification regions

## Summary

- Surface pressure and temperature forecasts show more improvement than wind and humidity
- Overall 80% of investigated targeted forecasts improved
- Only dropsonde data impact for 8 out of 16 flights is evaluated here
- Overall results are similar to that of WSR04 except that humidity and vector wind improvements are not as significant
-  _[http://](http://www.emc.ncep.noaa.gov/gmb/targobs/ATOST)__[www.emc.ncep.noaa.gov/gmb/targobs/ATOST](http://www.emc.ncep.noaa.gov/gmb/targobs/ATOST)_

## Discussion

- Impact of all ATREC data must be larger than dropsondes only
- Further evaluation needed?
- Results must be compared with those from other centers
- These new results supersede preliminary NCEP evaluation
- NCEP would like more interaction with rest of ATREC science group
- Comparative evaluation of various targeting methods is of interest
- Check ATREC records as to which flight plan was based on what guidance?
- Is there enough data?
- Design of experiment
- In the future, evaluation plans should be prepared in advance of field phase