Database
[{"car_description":"Audi","sales":["India/Mumbai","India/Delhi","India/Chennai","India/Kolkata","America/Sao_Paulo"]},{"car_description":"BMW","sales":["India/Chennai","India/Kolkata","America/Sao_Paulo"]}]
Query
db.collection.aggregate([{$match:{"sales":{$elemMatch:{$regex:"^India\/",$options:"i"}}}},{$set:{sales:{$filter:{input:"$sales",as:"sale",cond:{$eq:[{$toLower:{$arrayElemAt:[{$split:["$$sale","/"]},0]}},"india"]}}}}}])