The building of Citi Field right behind Shea stadium will have move impact than a significant lack of parking.  Although Shea Stadium is naturally considered a pitcher’s or neutral park due to dimensions of the park, due to the construction of Citi Field, Shea Stadium will have a feature in the outfield.

In order to understand the physics of the influence of Citi Field, one must examine the velocity of air flow around the overall stadiums combined, the tightening of the meso (small scale) gradient between the two stadiums, and finally other micro scale influences above 10 meters.  

Calculation and Procedures

I produced this study based on observations from past games including data from the National Weather Service from Brookhaven National Laboratories and personal game tapes and on line video data base from MLB.com.  Pictures of Citi Field and the position in relation to Shea stadium was provided by online sources from Mets.com and Metsblog.com.  Finally, calculations were made using basic velocity, pressure gradient, and wind shear stress equations.  These equations can be found at any college or graduate level physics literature.  Calculations were made based on a level of 10 meters or higher.  Calculations below 10 meters lead to significant error due to micro level influences like seat position and terrain (pitcher’s mound, dug outs, etc.).  

Before Citi

Before the construction of Citi Field, a strong 10 to 20 mph wind from the west, northwest, and north-north west would have a significant impact in the trajectory of a fly ball.  In most cases, a fly ball would be influenced by increased friction and thus peak and fall at a much faster rate.  Conversely, winds from the northeast, east, and southeast at a speed of 10 to 20 mph would support an increase in distance of the flight of a ball.  Finally, winds from the south and north would produce a wind trajectory from left field to right field and visa versa.  In most cases, this will have a neutral impact with winds below 15 mph.  However, above this speed, a baseball velocity will be impacted with, depending on the direction of the wind, would veer to the left or right.  This would decrease the distance of the fly ball from start to end, but also cause some rather tricky fielding conditions especially with a pop up fly ball.  

Post Citi

There are several impacts to consider with the Citi Field stadium nearly complete.  

Winds from W to NNW:

Based on the latest pictures seen on Mets.com and Metsblog.com, the impacts of west, northwest, and north-northwest winds will be significantly limited below 20 meters, which generally covers any fly ball hit at Shea Stadium.  There will be no inhibitor to a fly ball on windy days like in previous years.  However, this wind direction will not enhance a fly ball either.  In short, this wind direction will have a neutral influence when before there was a negative influence.  

Winds from E to SE:

When I looked at the influences of Citi Field on Shea Stadium from the winds listed above, the impacts become complicated and frankly rather interesting from a micro and meso meteorological point of view.  Citi field acts like wind blocker for Shea Stadium.  The air that flows into the stadium becomes trapped in a circulation for a time.  For winds under 10 mph, I calculated that the influences will generally remain neutral.  However, for winds above 10 mph, there is an increasing potential for a micro-scale low pressure circulation that would develop over the stadium.  This circulation develops due to what we call wind speed shear.  The reason why this shear develops is because the winds at field level will be much lower than at the Mezzanine and Upper box levels.  For example, a 15 mph wind at the Upper box levels will translate before the circulation begins to roughly 5 mph.  Now, this shear produces a circulation over time just above the field.  This circulation will produce a micro-scale “jet stream” directly over Shea stadium and carry over left and center field straight to Citi field.  As such, many fly balls that reach the Lodge and Mezzanine Levels or higher will in most cases become positively influenced and the velocity will increase along with the magnitude of distance.  Velocity will be influenced by speed rather than direction in this case.  In this case, winds above 10 mph will turn Shea stadium into a hitter’s park in my opinion.  

Winds from the South and North:

The main impact from Citi Field on Shea with this wind direction is the development of a strong jet stream from left to right and visa vera depending on wind direction.  Based on my calculations, these winds will have several minor impacts attributed to the stadium.  Pop ups over the outfield and in field will be influenced by a weak circulation that will generally circulation along the outline of Shea stadium.  In other words, while the jet stream described in the previous section will enhance the speed vector, this circulation will influence the directional vector.  So, if a fly ball is hit to right field with a southerly wind, the ball would be influenced to drift towards center.  Also, a potential home run ball with a southerly wind, with a direction towards right field might instead end up being blown foul.  These influences will have to be examined on a day to day basis.  

Conclusion

Based on the calculations I have produced, for the first time in Shea stadium history, this ball park will become a hitter’s park on days with the wind above 10 mph.  There will be limited negative impact to the trajectory of a baseball in the air with Citi Field situated currently.