The effect of targeted dropsonde observations during the 1999 winter storm reconnaissance program

I. Szunyogh, Z. Tóth, R. E. Morss, S. J. Majumdar, B. J. Etherton, C. H. Bishop

Research output: Contribution to journalArticle

102 Citations (Scopus)

Abstract

In this paper, the effects of targeted dropsonde observations on operational global numerical weather analyses and forecasts made at the National Centers for Environmental Prediction (NCEP) are evaluated. The data were collected during the 1999 Winter Storm Reconnaissance field program at locations that were found optimal by the ensemble transform technique for reducing specific forecast errors over the continental United States and Alaska. Two parallel analysis-forecast cycles are compared; one assimilates all operationally available data including those from the targeted dropsondes, whereas the other is identical except that it excludes all dropsonde data collected during the program. It was found that large analysis errors appear in areas of intense baroclinic energy conversion over the northeast Pacific and are strongly associated with errors in the first-guess field. The "signal," defined by the difference between analysis-forecast cycles with and without the dropsonde data, propagates at an average speed of 30° per day along the storm track to the east. Hovmöller diagrams and eddy statistics suggest that downstream development plays a significant role in spreading out the effect of the dropsondes in space and time. On average. the largest rms surface pressure errors are reduced by 10%-20% associated with the eastward-propagating leading edge of the signal. The dropsonde data seem to be more effective in reducing forecast errors when zonal flow prevails over the eastern Pacific. Results from combined verification statistics (based on surface pressure, tropospheric winds, and precipitation amount) indicate that the dropsonde data improved the forecasts in 18 of the 25 targeted cases, while the impact was negative (neutral) in only 5 (2) cases.

Original languageEnglish
Pages (from-to)3520-3537
Number of pages18
JournalMonthly Weather Review
Volume128
Issue number10
Publication statusPublished - Oct 2000

Fingerprint

winter
surface pressure
zonal flow
storm track
error analysis
effect
forecast
programme
eddy
transform
diagram
weather
prediction
statistics
analysis

ASJC Scopus subject areas

  • Atmospheric Science

Cite this

Szunyogh, I., Tóth, Z., Morss, R. E., Majumdar, S. J., Etherton, B. J., & Bishop, C. H. (2000). The effect of targeted dropsonde observations during the 1999 winter storm reconnaissance program. Monthly Weather Review, 128(10), 3520-3537.

The effect of targeted dropsonde observations during the 1999 winter storm reconnaissance program. / Szunyogh, I.; Tóth, Z.; Morss, R. E.; Majumdar, S. J.; Etherton, B. J.; Bishop, C. H.

In: Monthly Weather Review, Vol. 128, No. 10, 10.2000, p. 3520-3537.

Research output: Contribution to journalArticle

Szunyogh, I, Tóth, Z, Morss, RE, Majumdar, SJ, Etherton, BJ & Bishop, CH 2000, 'The effect of targeted dropsonde observations during the 1999 winter storm reconnaissance program', Monthly Weather Review, vol. 128, no. 10, pp. 3520-3537.
Szunyogh I, Tóth Z, Morss RE, Majumdar SJ, Etherton BJ, Bishop CH. The effect of targeted dropsonde observations during the 1999 winter storm reconnaissance program. Monthly Weather Review. 2000 Oct;128(10):3520-3537.
Szunyogh, I. ; Tóth, Z. ; Morss, R. E. ; Majumdar, S. J. ; Etherton, B. J. ; Bishop, C. H. / The effect of targeted dropsonde observations during the 1999 winter storm reconnaissance program. In: Monthly Weather Review. 2000 ; Vol. 128, No. 10. pp. 3520-3537.
@article{253dedf3b5bd4845b87caec0e38efd48,
title = "The effect of targeted dropsonde observations during the 1999 winter storm reconnaissance program",
abstract = "In this paper, the effects of targeted dropsonde observations on operational global numerical weather analyses and forecasts made at the National Centers for Environmental Prediction (NCEP) are evaluated. The data were collected during the 1999 Winter Storm Reconnaissance field program at locations that were found optimal by the ensemble transform technique for reducing specific forecast errors over the continental United States and Alaska. Two parallel analysis-forecast cycles are compared; one assimilates all operationally available data including those from the targeted dropsondes, whereas the other is identical except that it excludes all dropsonde data collected during the program. It was found that large analysis errors appear in areas of intense baroclinic energy conversion over the northeast Pacific and are strongly associated with errors in the first-guess field. The {"}signal,{"} defined by the difference between analysis-forecast cycles with and without the dropsonde data, propagates at an average speed of 30° per day along the storm track to the east. Hovm{\"o}ller diagrams and eddy statistics suggest that downstream development plays a significant role in spreading out the effect of the dropsondes in space and time. On average. the largest rms surface pressure errors are reduced by 10{\%}-20{\%} associated with the eastward-propagating leading edge of the signal. The dropsonde data seem to be more effective in reducing forecast errors when zonal flow prevails over the eastern Pacific. Results from combined verification statistics (based on surface pressure, tropospheric winds, and precipitation amount) indicate that the dropsonde data improved the forecasts in 18 of the 25 targeted cases, while the impact was negative (neutral) in only 5 (2) cases.",
author = "I. Szunyogh and Z. T{\'o}th and Morss, {R. E.} and Majumdar, {S. J.} and Etherton, {B. J.} and Bishop, {C. H.}",
year = "2000",
month = "10",
language = "English",
volume = "128",
pages = "3520--3537",
journal = "Monthly Weather Review",
issn = "0027-0644",
publisher = "American Meteorological Society",
number = "10",

}

TY - JOUR

T1 - The effect of targeted dropsonde observations during the 1999 winter storm reconnaissance program

AU - Szunyogh, I.

AU - Tóth, Z.

AU - Morss, R. E.

AU - Majumdar, S. J.

AU - Etherton, B. J.

AU - Bishop, C. H.

PY - 2000/10

Y1 - 2000/10

N2 - In this paper, the effects of targeted dropsonde observations on operational global numerical weather analyses and forecasts made at the National Centers for Environmental Prediction (NCEP) are evaluated. The data were collected during the 1999 Winter Storm Reconnaissance field program at locations that were found optimal by the ensemble transform technique for reducing specific forecast errors over the continental United States and Alaska. Two parallel analysis-forecast cycles are compared; one assimilates all operationally available data including those from the targeted dropsondes, whereas the other is identical except that it excludes all dropsonde data collected during the program. It was found that large analysis errors appear in areas of intense baroclinic energy conversion over the northeast Pacific and are strongly associated with errors in the first-guess field. The "signal," defined by the difference between analysis-forecast cycles with and without the dropsonde data, propagates at an average speed of 30° per day along the storm track to the east. Hovmöller diagrams and eddy statistics suggest that downstream development plays a significant role in spreading out the effect of the dropsondes in space and time. On average. the largest rms surface pressure errors are reduced by 10%-20% associated with the eastward-propagating leading edge of the signal. The dropsonde data seem to be more effective in reducing forecast errors when zonal flow prevails over the eastern Pacific. Results from combined verification statistics (based on surface pressure, tropospheric winds, and precipitation amount) indicate that the dropsonde data improved the forecasts in 18 of the 25 targeted cases, while the impact was negative (neutral) in only 5 (2) cases.

AB - In this paper, the effects of targeted dropsonde observations on operational global numerical weather analyses and forecasts made at the National Centers for Environmental Prediction (NCEP) are evaluated. The data were collected during the 1999 Winter Storm Reconnaissance field program at locations that were found optimal by the ensemble transform technique for reducing specific forecast errors over the continental United States and Alaska. Two parallel analysis-forecast cycles are compared; one assimilates all operationally available data including those from the targeted dropsondes, whereas the other is identical except that it excludes all dropsonde data collected during the program. It was found that large analysis errors appear in areas of intense baroclinic energy conversion over the northeast Pacific and are strongly associated with errors in the first-guess field. The "signal," defined by the difference between analysis-forecast cycles with and without the dropsonde data, propagates at an average speed of 30° per day along the storm track to the east. Hovmöller diagrams and eddy statistics suggest that downstream development plays a significant role in spreading out the effect of the dropsondes in space and time. On average. the largest rms surface pressure errors are reduced by 10%-20% associated with the eastward-propagating leading edge of the signal. The dropsonde data seem to be more effective in reducing forecast errors when zonal flow prevails over the eastern Pacific. Results from combined verification statistics (based on surface pressure, tropospheric winds, and precipitation amount) indicate that the dropsonde data improved the forecasts in 18 of the 25 targeted cases, while the impact was negative (neutral) in only 5 (2) cases.

UR - http://www.scopus.com/inward/record.url?scp=0033661480&partnerID=8YFLogxK

UR - http://www.scopus.com/inward/citedby.url?scp=0033661480&partnerID=8YFLogxK

M3 - Article

AN - SCOPUS:0033661480

VL - 128

SP - 3520

EP - 3537

JO - Monthly Weather Review

JF - Monthly Weather Review

SN - 0027-0644

IS - 10

ER -