reorder a WP_Query, using a dropdown

I guess the problem is

$qry = new WP_Query(array('category_name'=>$GLOBALS['city'],'order'=>$orderby)); 

Let’s just say $orderby is orderby=title&order=ASC

Then the order argument of WP_Query will be like this:

'order'=>'orderby=title&order=ASC'

However, order argument only accepts: ASC and DESC.

You should do somethings like this:

WP_Query('category_name=".$GLOBALS["city'].'&'.$orderby);