World Meteorological Organization Symposium on Nowcasting - WMO
World Meteorological Organization Symposium on Nowcasting - WMO
World Meteorological Organization Symposium on Nowcasting - WMO
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80<br />
4.5<br />
6.8 Towards the Blending of NWP with Nowcast - Operati<strong>on</strong> Experience in B08FDP<br />
A Comparis<strong>on</strong> of Visibility Measurements obtained during FRAM-S project during<br />
freezing fog and warm fog events<br />
I.Gultepe[1], R. Rasmussen[2], L. Malenfant[3], R. K. Ungar[4], S. Cober[1], and R.<br />
Nitu[5][1]Cloud Physics and Severe Weather Research Secti<strong>on</strong>, Science and Tech Branch,<br />
Envir<strong>on</strong>ment Canada, Tor<strong>on</strong>to, Ontario, M3H5T4[2]Nati<strong>on</strong>al Center for Atmospheric<br />
Research, PO Box 3000, Boulder, CO 80307[3]ATS Services Ltd., ATS Technology Systems<br />
Inc., 183 Briancrest Road, Halifax, NS B2T 1Z9[4]Verificati<strong>on</strong> and Incident M<strong>on</strong>itoring<br />
Radiati<strong>on</strong> Protecti<strong>on</strong> Bureau, 775 Brookfield Road, AL6302D1, Ottawa, Ontario K1A<br />
1C1[5]Atmospheric M<strong>on</strong>itoring and Water Survey Directorate, Envir<strong>on</strong>ment Canada, Tor<strong>on</strong>to,<br />
Ont. M3H5T4<br />
[1]Cloud Physics and Severe Weather Research Secti<strong>on</strong>, Science and Tech Branch,<br />
Envir<strong>on</strong>ment Canada, Tor<strong>on</strong>to, Ontario, M3H5T4[2]Nati<strong>on</strong>al Center for Atmospheric<br />
Research, PO Box 3000, Boulder, CO 80307[3]ATS Services Ltd., ATS Technology Systems<br />
Inc., 183 Briancrest Road, Halifax, NS B2T 1Z9[4]Verificati<strong>on</strong> and Incident M<strong>on</strong>itoring<br />
Radiati<strong>on</strong> Protecti<strong>on</strong> Bureau, 775 Brookfield Road, AL6302D1, Ottawa, Ontario K1A<br />
1C1[5]Atmospheric M<strong>on</strong>itoring and Water Survey Directorate, Envir<strong>on</strong>ment Canada, Tor<strong>on</strong>to,<br />
Ont. M3H5T4<br />
The purpose of this work is to compare the visibilities (Vis) obtained from the five sensors to<br />
human-based observati<strong>on</strong>s of Vis values to better understand issues related to low visibility<br />
c<strong>on</strong>diti<strong>on</strong>s. The ground-based observati<strong>on</strong>s from the Fog Remote Sensing and Modeling<br />
Project in St. John’s (FRAM-S), which took place during April of 2009, were being used for<br />
comparis<strong>on</strong>s. The instruments used to measure Vis were 1) the Biral HSS VPF-730<br />
Combined Visibility & Present Weather Sensor, 2) Sentry VIS sensor, 3) Vaisala FD12P<br />
present weather sensor, 4) Vaisala PWD12 sensor (two of them), and 5) Belfort Vis sensor.<br />
Human-based Vis observati<strong>on</strong>s were also available during the project. In the analysis, the<br />
measurements of Vis were compared to human-based Vis observati<strong>on</strong>s and to each other. In<br />
additi<strong>on</strong>, validati<strong>on</strong>s were performed estimating Vis from the particle measurements of a)<br />
MetOne aerosol sensor (for small wetted aerosols and droplets; 0.3-10 micr<strong>on</strong>), b) DMT Fog<br />
Measuring Device (FMD; 2-50 micr<strong>on</strong>), and 3) DMT Ground Cloud Imaging Probe (GCIP; 7.5-<br />
900 micr<strong>on</strong>). Results representing various freezing fog, drizzle, and snow c<strong>on</strong>diti<strong>on</strong>s will be<br />
presented in the talk and probability curves developed earlier based <strong>on</strong> <strong>on</strong>ly FD12P<br />
measurements will be discussed. Possible applicati<strong>on</strong>s of the results will be offered for<br />
nowcasting issues.<br />
Wai-kin W<strong>on</strong>g [1], Linus H.Y. Yeung [1]; Ying-chun Wang [2], Min Chen [2]<br />
[1] H<strong>on</strong>g K<strong>on</strong>g Observatory, H<strong>on</strong>g K<strong>on</strong>g, China; [2] Institute of Urban Meteorology, Beijing,<br />
China<br />
One of the major advancements achieved in the Beijing 2008 Forecast Dem<strong>on</strong>strati<strong>on</strong> Project<br />
(B08FDP), under the <str<strong>on</strong>g>World</str<strong>on</strong>g> Weather Research Programme of the <str<strong>on</strong>g>World</str<strong>on</strong>g> <str<strong>on</strong>g>Meteorological</str<strong>on</strong>g><br />
<str<strong>on</strong>g>Organizati<strong>on</strong></str<strong>on</strong>g>, was the incorporati<strong>on</strong> of numerical weather predicti<strong>on</strong> (NWP) model outputs in<br />
an attempt to extend the nowcast of precipitati<strong>on</strong> and c<strong>on</strong>vective storm development bey<strong>on</strong>d<br />
the radar extrapolati<strong>on</strong> technique. In several participating nowcasting systems in B08FDP,<br />
storm-scale NWP models with horiz<strong>on</strong>tal resoluti<strong>on</strong> at several kilometres were operated <strong>on</strong> a<br />
real-time basis to simulate the evoluti<strong>on</strong> of severe weather systems. Various types of<br />
observati<strong>on</strong>s from the automatic weather stati<strong>on</strong>s, wind profilers, Global Positi<strong>on</strong>ing System<br />
(GPS), radars and satellites were assimilated in the models in order to better describe the<br />
initial c<strong>on</strong>diti<strong>on</strong>s and produce more skilful numerical guidance for blending computati<strong>on</strong>. The<br />
analyses and short-term forecasts from the NWP models also provided valuable reference to<br />
forecasters for their subjective assessment of the potential of c<strong>on</strong>vective storm development<br />
and related decisi<strong>on</strong> making.In this paper, the impact of NWP models in blending with radar<br />
nowcast techniques <strong>on</strong> aspects like quantitative precipitati<strong>on</strong> forecasts (QPF), c<strong>on</strong>vective<br />
storm development and storm tracking will be discussed. In particular, the phase correcti<strong>on</strong><br />
technique adopted in the H<strong>on</strong>g K<strong>on</strong>g Observatory nowcasting system to correct the locati<strong>on</strong><br />
of model QPF, the methodology to adjust the model rainfall intensity and the blending<br />
algorithm to seamlessly merge the radar-based QPF with that from NWP models will be<br />
illustrated by cases. By applying the time-lagged ensemble approach to the rapidly updated<br />
NWP model forecasts and blending computati<strong>on</strong>, probabilistic precipitati<strong>on</strong> nowcast products<br />
were also developed, the performance and potential benefits of which in nowcast applicati<strong>on</strong>s<br />
will be discussed. On the other hand, the Beijing rapid update cycle system (BJ-RUC) based<br />
<strong>on</strong> the Weather Research and Forecasting (WRF) model was developed with the primary<br />
goal to improve the very short range forecasts (3-12h) and to support nowcast operati<strong>on</strong>.<br />
The applicati<strong>on</strong> of analyses and forecasts from BJ-RUC including the model output<br />
soundings, stability indices and wind shear to predict the evoluti<strong>on</strong> of near storm envir<strong>on</strong>ment<br />
will be presented. The experience gained during B08FDP operati<strong>on</strong> will be summarized, and<br />
suggesti<strong>on</strong>s and views <strong>on</strong> the future development and applicati<strong>on</strong> of the NWP products and<br />
blending techniques in nowcasting will be presented.<br />
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