coaps workshop march 9-11, 2004 wfo site specific seasonal outlook product victor murphy southern...

COAPS Workshop March 9-11, 2004

WFO Site Specific WFO Site Specific Seasonal Outlook ProductSeasonal Outlook Product

Victor MurphyVictor Murphy

Southern Region Climate Southern Region Climate Service Program ManagerService Program Manager

Nicole KempfNicole KempfClimate Services Focal PointClimate Services Focal Point

WFO TulsaWFO Tulsa


OutlineOutline

• What is Downscaling anyway?What is Downscaling anyway?

• Probability of Exceedance (POE)Probability of Exceedance (POE)

• Data UsedData Used

• ErrorError

• Trend AdjustmentTrend Adjustment

• WebpageWebpage

• Time commitment and current statusTime commitment and current status


What is downscaling?What is downscaling?

• Downscaling is the transformation Downscaling is the transformation from a large-scale feature to a small-from a large-scale feature to a small-scale one, not necessarily of the scale one, not necessarily of the same kind. same kind.

• A downscaled forecast is one that A downscaled forecast is one that has been defined in more detail for a has been defined in more detail for a particular location from a forecast for particular location from a forecast for a larger area. a larger area.


What is downscaling…cont.What is downscaling…cont.

• In this case, we are downscaling the In this case, we are downscaling the Climate Prediction Center (CPC) forecast Climate Prediction Center (CPC) forecast for a mega climate division (CD) to a for a mega climate division (CD) to a specific station within a CWA.specific station within a CWA.

• Therefore, we are only ‘tweaking’ the CPC Therefore, we are only ‘tweaking’ the CPC forecast…not making a brand new forecastforecast…not making a brand new forecast

• Method developed at CPC by Method developed at CPC by Barnston, Unger, and He


What is downscaling…cont.What is downscaling…cont.

• Initially, this can be required for LCD Initially, this can be required for LCD sitessites– Additional sites can be added at the Additional sites can be added at the

WFO discretionWFO discretion

• Can be done for any station in the Can be done for any station in the country that has monthly data from country that has monthly data from 1971-2000 (not just Southern 1971-2000 (not just Southern Region)Region)


Probability of ExceedanceProbability of Exceedance

• The probability that a certain value of The probability that a certain value of interest would be exceeded given a interest would be exceeded given a forecast shift in a distribution. forecast shift in a distribution.

• Or in other words, the probability that the Or in other words, the probability that the actual temperature will exceed a particular actual temperature will exceed a particular temperaturetemperature

• http://www.cpc.ncep.noaa.gov/products/prhttp://www.cpc.ncep.noaa.gov/products/predictions/long_range/lead01/poe_index.htedictions/long_range/lead01/poe_index.htmlml


Probability of Exceedance…cont.Probability of Exceedance…cont.


Probability of Exceedance…Probability of Exceedance…cont.cont.

• CPC already downscales for 65 select CPC already downscales for 65 select citiescitieshttp://www.cpc.ncep.noaa.gov/pacdir/NFOhttp://www.cpc.ncep.noaa.gov/pacdir/NFORdir/citydir/citydict.txtRdir/citydir/citydict.txt

http://www.cpc.ncep.noaa.gov/pacdir/NFOhttp://www.cpc.ncep.noaa.gov/pacdir/NFORdir/citydir/explanation_ctydf.htmlRdir/citydir/explanation_ctydf.html


DataData

• 1971-20001971-2000– CPC used 1951-1997 when downscaling CPC used 1951-1997 when downscaling

for the select citiesfor the select cities

• Need data for both the mega CD and Need data for both the mega CD and the stationthe station

• CD data retrieved from CPC websiteCD data retrieved from CPC website

• Station data retrieved from NCDCStation data retrieved from NCDC


Data…cont.Data…cont.

• SeasonalSeasonal Average Average MeanMean Temperature Temperature– SeasonSeason – consecutive 3 month periods – consecutive 3 month periods

(i.e. JFM, FMA, MAM, AMJ, MJJ, etc)(i.e. JFM, FMA, MAM, AMJ, MJJ, etc)– MeanMean – the daily mean temperature – the daily mean temperature

average for a month (found on F-6)average for a month (found on F-6)– AverageAverage – must apply weight to each – must apply weight to each

monthmonth•Ex. JFM: (Tjan * 31 + Tfeb * 29 + Tmar * Ex. JFM: (Tjan * 31 + Tfeb * 29 + Tmar *

31)/9131)/91


Data…cont.Data…cont.

• CPC also makes POE forecasts for CPC also makes POE forecasts for precipitation and degree days precipitation and degree days (heating and cooling)(heating and cooling)

• CPC only makes downscaled CPC only makes downscaled temperature and degree day temperature and degree day (heating and cooling) forecasts for (heating and cooling) forecasts for the select citiesthe select cities

• WFOs will only be downscaling for WFOs will only be downscaling for temperature in the immediate futuretemperature in the immediate future


CPC Mega Climate Divisions (CD)CPC Mega Climate Divisions (CD)


Mega Climate DivisionsMega Climate Divisions


Mega CD vs. StationMega CD vs. Station

• Develop a regression equation Develop a regression equation between the mega CD and the between the mega CD and the stationstation

• Plot the seasonal average mean Plot the seasonal average mean temp from 1971-2000temp from 1971-2000– x-axis = CD tempx-axis = CD temp– y-axis = Station tempy-axis = Station temp


Mega CD vs. Station…cont.Mega CD vs. Station…cont.JFM

y = 0.8878x + 9.9465

R2 = 0.954125

30

35

40

45

50

55

25 30 35 40 45

CD43 Temperatue (F)

TU

L T

em

pe

ratu

re (

F)


JFM

y = 1.198x + 0.0179

R2 = 0.760.00

2.00

4.00

6.00

8.00

10.00

12.00

14.00

0.00 2.00 4.00 6.00 8.00 10.00

CD43 Precipitation (in.)

TU

L P

rec

ipit

ati

on

(in

.)

JJA

y = 0.6747x + 0.7434

R2 = 0.2962

0.00

2.00

4.00

6.00

8.00

10.00

12.00

0.00 2.00 4.00 6.00 8.00 10.00

CD43 Precipitation (in.)

TU

L P

reci

pit

atio

n (

in.)

Synoptic-scale systems

Meso- /storm-scale systems

WHY?WHY?


ErrorError

• At least as great as the CPC POE At least as great as the CPC POE forecast errorforecast error

• Uncertainty Uncertainty increasesincreases as correlation as correlation between the mega CD and station between the mega CD and station decreasesdecreases

• A lot of uncertainty with precipitationA lot of uncertainty with precipitation


Trend AdjustmentTrend Adjustment

• Weights the slope and intercept of the Weights the slope and intercept of the regression equation to the last decaderegression equation to the last decade– Past 10 years = CPC Optimal Climate Past 10 years = CPC Optimal Climate

NormalNormal

• Cold decades followed by warm decades Cold decades followed by warm decades can create a biascan create a bias– This is more pronounced between dry and This is more pronounced between dry and

wet decadeswet decades– A way of adjusting for urbanizationA way of adjusting for urbanization


Trend Adjustment…cont.Trend Adjustment…cont.

D iff D iff D iffyear year year

1

1

0 5 1 0 0 5

1

0 5 1 0 0 51 1 0( . * ) .*

( . * ) .*

2

4

6

8

10

12

1961 1971 1981 1991 2001

SLC-CD83 Trend

Tst

atio

n –

Tcd

(ºF

)


WebpageWebpage

• http://www.srh.noaa.gov/tulsa/climathttp://www.srh.noaa.gov/tulsa/climate/downscale/climfcst.phpe/downscale/climfcst.php

• Uses .php to create webpageUses .php to create webpage– Each office up-loads graphics and a text Each office up-loads graphics and a text

file (per downscaled station) to the file (per downscaled station) to the regional server and webpage is created regional server and webpage is created by user inputby user input


Time CommitmentTime Commitment

• Downscaling to be done by the Downscaling to be done by the Climate Services Focal Point (CSFP)Climate Services Focal Point (CSFP)– An assistant CSFP and/or another person An assistant CSFP and/or another person

should also be trainedshould also be trained

• Takes about ½ hour or less per Takes about ½ hour or less per station (once proficient) for the datastation (once proficient) for the data

• Another ½ hour or less per station to Another ½ hour or less per station to beautify the charts for the webpagebeautify the charts for the webpage


Time Commitment…cont.Time Commitment…cont.

• CSFP will be given a template and CSFP will be given a template and step-by-step instructionsstep-by-step instructions

• Will be completed for the selected Will be completed for the selected stations once per month, within 7 days stations once per month, within 7 days of the issuance of the CPC productof the issuance of the CPC product– CPC product issued on the 3CPC product issued on the 3rdrd Thursday of Thursday of

each month at 8:30 ameach month at 8:30 am

• May need to do verification/analysis to May need to do verification/analysis to see how well it workssee how well it works


Current StatusCurrent Status

• Experimental product with a Product Experimental product with a Product Description Document (PDD) is available on Description Document (PDD) is available on the WFO TSA webpage.the WFO TSA webpage.

• Still seeking feedback from experts in this field Still seeking feedback from experts in this field for tweaks to the templates and method.for tweaks to the templates and method.

• Trying to identify our customers.Trying to identify our customers.

• Trying to create/package a product that can be Trying to create/package a product that can be easily used and understood by our customers.easily used and understood by our customers.


Current Status…cont.Current Status…cont.

• Awaiting feedback on current Awaiting feedback on current experimental product from CPC, NWSH experimental product from CPC, NWSH CSD, other Regions, customers.CSD, other Regions, customers.

• Will provide training to other SR CSFP as Will provide training to other SR CSFP as needed.needed.

• NWSH timeline is for local climate products NWSH timeline is for local climate products to be downscaled from CPC forecast to be downscaled from CPC forecast products by the end of FY05.products by the end of FY05.


Sample of Current ProductSample of Current Product


Sample of Current ProductSample of Current Product

Probability to go above TemperatureProbability to stay

below

20% 61.8 °F 80%

40% 60.8 °F 60%

60% 59.8 °F 40%

80% 58.8 °F 20%


Any questions or Any questions or comments?comments?

coaps workshop march 9-11, 2004 wfo site specific seasonal outlook product victor murphy southern...

Documents

coaps workshop

forecast shift

downscaled forecast

probability of exceedancecont

cpc forecastnot

cities cpc

particular temperature

current status slide