The Diurnal Temperature Smart Tool

The Diurnal Temperature The Diurnal Temperature Smart Tool Smart Tool

• What is it and why the need for it?What is it and why the need for it?• How is it implemented? How is it implemented? • What are the results? What are the results?

Angie Enyedi Angie Enyedi National Weather Service Jacksonville, FLNational Weather Service Jacksonville, FL

What is it?What is it?

An interpolation methodAn interpolation method of of hourly temperatures between hourly temperatures between forecast maximum and forecast maximum and minimum temperatures in the minimum temperatures in the new graphical forecast new graphical forecast produced by the NWS, the produced by the NWS, the Interactive Forecast Interactive Forecast Preparation System (IFPS). Preparation System (IFPS).

• The default interpolation methods in the The default interpolation methods in the Graphical Forecast Editor (GFE) were either Graphical Forecast Editor (GFE) were either the Cubic Spline or the Linear Interpolation the Cubic Spline or the Linear Interpolation Methods. Methods.

• These methods were used during the These methods were used during the implementation stage of IFPS.implementation stage of IFPS.

Initial Interpolation TechniquesInitial Interpolation Techniques

Both fail to represent abrupt temperature falls Both fail to represent abrupt temperature falls after sunset and temperature rises after sunrise. after sunset and temperature rises after sunrise.

Both have unrepresentative peaks (linear) and Both have unrepresentative peaks (linear) and plateaus (cubic spline) when the daily max or plateaus (cubic spline) when the daily max or min temperature is achieved. min temperature is achieved.

We need an interpolation tool that accounts We need an interpolation tool that accounts for monthly differences in radiational cooling for monthly differences in radiational cooling and insolation between the times of daily and insolation between the times of daily minimum and maximum temperatures! minimum and maximum temperatures!

ANSWER: ANSWER: The Diurnal Temperature ToolThe Diurnal Temperature Tool

Cubic Linear Diurnal

MAE ( F) 4.7 3.4 1.1

Mean Absolute Error

How the Tool was Implemented at JAXHow the Tool was Implemented at JAX1. Stratifying the Data1. Stratifying the Data

7 years of hourly 7 years of hourly ASOS observations ASOS observations were stratified by were stratified by month then by hour month then by hour for site JAX for site JAX (Jacksonville, FL). (Jacksonville, FL). Archived data was Archived data was obtained from NCDC. obtained from NCDC.

Date/Time (Z) Actual Temp

Apr 1, 1995 0200Z 55

Apr 2, 1995 0200Z 53

….etc…

Apr 30, 2001 0200Z 66

2. Averaging the Data2. Averaging the Data

For Example: For Example:

TThour hour for 01 April = 60.30for 01 April = 60.30



All temps in a All temps in a particular hour in a particular hour in a given month were given month were avearged to get an avearged to get an average Taverage Thour. hour.

All Temps for that hour summed, then divided by total number of entries to get Thour.

Average Thour for 02Z in April = 59.56

3. Calculating the ratio, f3. Calculating the ratio, f

Temperatures from 00Z-23Z Temperatures from 00Z-23Z were converted to a range were converted to a range between 5-95% based on the between 5-95% based on the difference between the Tdifference between the Tmax max

and Tand Tminmin each month. each month.

NoteNote: f for T: f for Tmax max = 95 = 95

f for Tf for Tmin min = 5= 5

This was done to reduce the warm This was done to reduce the warm

and cold bias.and cold bias.

(Thour-Tmin)

Tmax-Tmin + 5 = f 90

4. Smart Tool references the “f” Table4. Smart Tool references the “f” Table

The f table is referenced by the The f table is referenced by the diurnal temperature smart tool diurnal temperature smart tool when it calculates hourly when it calculates hourly temperatures (Ttemperatures (Thourhour) between ) between

the forecast daily minimum and the forecast daily minimum and maximum temperatures. maximum temperatures.

Tool will warm & cool Tool will warm & cool temperatures based on monthly temperatures based on monthly diurnal climatological trends. diurnal climatological trends.

F Table for April00Z 58 12Z 12

01Z 45 13Z 33

02Z 38 14Z 53

03Z 33 15Z 68

04Z 27 16Z 78

05Z 23 17Z 85

06Z 20 18Z 91

07Z 16 19Z 94

08Z 12 20Z 95

09Z 9 21Z 92

10Z 7 22Z 86

11Z 5 23Z 75

• Note the seasonal variation of the approximate time Note the seasonal variation of the approximate time of the daily max and min temperature. of the daily max and min temperature.

• Note the seasonal variation of temperature decrease Note the seasonal variation of temperature decrease (increase) after sunset (sunrise). (increase) after sunset (sunrise).


MAE ( F) 6.4 3.8 1.7

Mean Absolute Error


MAE ( F) 4.4 3.1 1.8

Mean Absolute Error


MAE ( F) 5.1 3.1 0.8

Mean Absolute Error

Results of the Diurnal Temperature Results of the Diurnal Temperature Interpolation MethodInterpolation Method

Data suggests that the diurnal temperature Data suggests that the diurnal temperature interpolation method better represents interpolation method better represents monthly radiational cooling & insolation monthly radiational cooling & insolation trends when compared to the linear and trends when compared to the linear and cubic spline methodscubic spline methods. .

Benefits of the Diurnal Temperature Benefits of the Diurnal Temperature Interpolation Tool Interpolation Tool

Best represents abrupt diurnal temperature rises Best represents abrupt diurnal temperature rises and falls when compared to the cubic spline and and falls when compared to the cubic spline and linear interpolation techniques. linear interpolation techniques.

Has representative increases and decreases when Has representative increases and decreases when the daily max or min temperature is achieved. the daily max or min temperature is achieved.

Can be customized for each month (and various Can be customized for each month (and various sites across the country) accounting for sites across the country) accounting for differences in radiational warming & cooling. differences in radiational warming & cooling.

Short Comings of the Diurnal Short Comings of the Diurnal Temperature Smart Tool Temperature Smart Tool

Only customized for site JAX in our forecast area. Only customized for site JAX in our forecast area. The tool is run over our entire grid space and may The tool is run over our entire grid space and may not represent radiational cooling or insolation trends not represent radiational cooling or insolation trends at sites further inland nor those close to the coast. at sites further inland nor those close to the coast.

Does not represent sensible heat influences from Does not represent sensible heat influences from convection or latent heat influence from ground convection or latent heat influence from ground moisture. moisture.

Does not account for atypical warming/cooling such Does not account for atypical warming/cooling such as warm air advection at night or cold air advection as warm air advection at night or cold air advection during the day. during the day.

Taking the Diurnal Smart Tool a Taking the Diurnal Smart Tool a Step Further…Step Further…

Data could be further stratified based on cloud Data could be further stratified based on cloud cover, for example: cover, for example:

Diurnal temperature smart tool could be created Diurnal temperature smart tool could be created for sunny/mostly sunny, partly cloudy, and for sunny/mostly sunny, partly cloudy, and clouldy/mostly cloudy days in GFE. clouldy/mostly cloudy days in GFE.

Credits & Where to Get the ToolCredits & Where to Get the Tool

Cheryl Sharpe and Steve Nelson Cheryl Sharpe and Steve Nelson (NWS) (NWS) Created the original Diurnal Temperature Smart ToolCreated the original Diurnal Temperature Smart Tool

Jason HessJason HessIFPS Focal Point NWS Jacksonville, FLIFPS Focal Point NWS Jacksonville, FL

The Diurnal Temperature Smart Tool is available for The Diurnal Temperature Smart Tool is available for download into IFPS at the Smart Tool Repository download into IFPS at the Smart Tool Repository Website.Website.

Thank You!Thank You!

Questions and/or Comments?Questions and/or Comments?

Angie Enyedi Angie Enyedi Forecaster NWS Jacksonville, Climate F.P. Forecaster NWS Jacksonville, Climate F.P.

[email protected]@noaa.gov

The Diurnal Temperature Smart Tool

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