Occurrence and Occurrence and Coverage of Winter Coverage of Winter Season Fog in the Season Fog in the

Northern Mid-AtlanticNorthern Mid-Atlantic

Paul J. Croft & Aaron N. BurtonPaul J. Croft & Aaron N. Burton

   

G&M Department of Geology and MeteorologyKean University

 

Why Fog??Why Fog??

• Low C/V directly impacts aviation as well as regular transportation particularly in the winter season

• Improve forecasts of coverage & occurrence

• Lack of knowledge– Fog studied widely from a micro-physical & mesoscale standpoint– Synoptic considers type of atmospheres that potentially produce fog– Improving forecasting and dispersal techniques

Site InformationSite InformationLocation

NameStation

ID Latitude Longitude Elevation

Allentown, PA ABEN 40 39 W 75 26

394 ft / 120 m

Atlantic City, NJ (Pomona)

ACYN 39 27 W 74 34

72 ft / 22 m

Bridgeport, CT BDR N 41 10 W 73 08 10 ft / 3 m

Central Park, NY

NYCN 40 46 W 73 58

89 ft / 27 m

Georgetown, DE

GEDN 38 41 W 75 22

49 ft / 15 m

Islip, NY ISPN 40 47 W 73 06

98 ft / 30 m

John F. Kennedy

Airport, NY

JFK

N 40 39 W 73 47 10 ft / 3 m

LaGuardia Airport, NY

LGAN 40 46 W 73 54 20 ft / 6 m

Mt. Pocono, PA

MPON 41 08 W 75 23

1916 ft / 584 m

Newark, NJ EWR N 40 42 W 74 10 16 ft / 5 m

Philadelphia, PA

PHLN 39 27 W 75 15

36 ft / 11 m

Reading, PA RDGN 40 22 W 75 58

341 ft / 104 m

Trenton, NJ TTNN 40 16 W 74 49

210 ft / 64 m

Wilmington, DE

ILGN 39 40 W 75 36 49 ft/15 m

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TTNRDG

PHL

MPO

LGAJ FK

ISP

ILG

GED

EWR

NYC

BDR

ACY

ABE

Study Region

0 40 8020 Miles

MethodsMethods• Data collection

– Fog frequencies obtained from F-6 reports @ http://www.erh.noaa.gov

– Study Period: 3 seasons (Dec-Feb)2003-2004, 2004-2005, & 2005-2006

• Synoptic Classification– Classic approach– Microphysical approach– Physiographic approach

• Spatial Distribution & Frequency of fog according to observed Synoptic Type

Methods (cont.)Methods (cont.)

Spatial Coverage DefinedSpatial Coverage Defined• Less than 4 sites report

(<29% of sites): Localized

• 4 -10 sites report (29% to 71% of sites):

Scattered• More than 10 sites report

(>71% of sites): Widespread

Fog CriteriaFog Criteria• Capture as many events

as possible for region – liberal/conservative

• Fog is defined as FG or BR @ 5sm or less

• Criteria for dense fog is visibility <1/4SM

• Fog event defined when any one of the 14 stations reported fog on any day

Methods (cont.)Methods (cont.)

• Each fog event & non-event classified by synoptic type through inspection of DWM series

• Type “A”: High; Type “B”: Low; Type “C”: Frontal• Subtypes determined by location of H/L with

regard to the center of the region & FROPA type• Why Synoptic Typing?

– To help determine the coverage according to the synoptic regime and local physiographic features

– Isolate the primary factors related to fog coverage during those regimes and improve regional forecast

Combined Weekly Frequency Plot

0

20

40

60

80

100

120

140

160

180

200

# of Sites Reported

17

15

18

61

23

30

25

23

23

2017

24

26

22

All Dense Events

9799

93

114

142

103

159

112

138

104

129

111

103

115

All Events

Total Frequency (days) Fog by LocationTotal Frequency (days) Fog by Location

Subtype FrequenciesSubtype FrequenciesAll Types

81, 38%

71, 33%

63, 29%

High

Low

Frontal

Low Pressure Frequencies

22, 31%

13, 18%14, 20%

22, 31%

W-NW

Over

S-SW

E-NE

Frontal Subtype Frequencies

14, 22%

33, 52%

6, 10%

5, 8%5, 8%

Warm

Cold

Stationary

Trough

Occluded

High Pressure Frequencies

30, 37%

18, 22%

9, 11%

9, 11%

15, 19%

OverS-SWS-SEN-NEW-NW

High Pressure FrequenciesHigh Pressure Frequencies

21

39

22

43

16

19

35

23

45

1512

19

23

26

All High Pressure Events

2

1

2

8

1

3

4

0

5

01

1

4

2

Dense High Pressure Events

Very SparseNE Urban Minimum

55

57

46

65

49

53

57

48

47

4948

51

47

45

All Low Pressure Events

9

7

6

8

26

13

18

13

11

1212

14

11

10

Dense Low Pressure Events

Low Pressure FrequenciesLow Pressure Frequencies

Northern Preference

Frontal FrequenciesFrontal Frequencies

38

46

35

51

32

40

46

33

37

3533

41

33

44

All Frontal Events

6

7

9

9

88

4

9

10

27

12

10

11

10

Dense Frontal Events

Orographic/Marine Influences

Western Preference/MPO

Max

CompositesComposites

Conclusions/FindingsConclusions/Findings

• Prime Locations – MPO, ISP, RDG• Although type “A” (High) was most frequent of all

synoptic types, type “B” (Low) & “C” (Front) were more prolific & efficient at generating fog

• “B” and “C” also had greater coverage & intensity

• Warm Fronts and Low ‘S-SW’ significant– Maximum percentage of dense events occurred with

the warm frontal events– Events associated with a Low S-SW were widespread

• Forecast & Verification aspects to be considered

ReferencesReferences• Baker, R., Cramer, J., and Peters, J., year: Radiation fog: UPS airlines conceptual

models and forecast methods.• Bendix, J., 2002: A satellite-based climatology of fog and low-level stratus in

Germany and adjacent areas. J. Atmos. Res., 64: 3-18.• Bott, A., and Trautmann, T., 2002: PAFOG: A new efficient forecast model of

radiation fog and low-level stratiform clouds. J. Atmos. Res., 64: 191-203.• Croft, P. J., 2002: Encyclopedia of Atmospheric Sciences - Fog, Edited by James

R. Holton, John Pyle, and Judith A. Curry December 2002, Elsevier / Academic Press, ISBN: 0-12-227090-8

• Croft, P. J., Pfost, R., Medlin, J., Johnson, A., 1997. Fog forecasting in the southern region: A conceptual model approach. Weather and Forecasting, 12, 545-556.

• Chang, Kang-tsung. Introduction to Geographic Systems. New York, New York, 2004.

• Fuchs, W., Schickel, K. P., 1995: Aircraft icing in visual meteorological conditions below low stratus clouds. J. Atmos. Res., 36: 339-345.

• George, J. J., 1963: Weather forecasting for Aeronautics. Eastern Airlines – Atlanta, Georgia.

• Leipper, D. F., 1994: Fog on the U. S. west coast: A review. Bull. Amer. Met. Soc., 75, 229-240.

AcknowledgementsDepartment of Geology and Meteorology faculty and staff at Kean University

The Department in access to GIS software and laboratory resources

Dr. John F. Dobosiewicz and Will Heyniger

Philadelphia NWS and the Office of the New Jersey State Climatologist

Thankful for their support and helpful insights during the completion of this project.

The images provided by the NOAA-CIRES Climate Diagnostics Center, Boulder Colorado

http://www.cdc.noaa.gov/ based on the NCEP Re-Analysis data. NCEP Reanalysis data provided by the NOAA-CIRES Climate Diagnostics Center, Boulder, Colorado, USA

Thank you!