How to pass variables values from .post response to PHP

How to pass variables values from .post response to PHP

I'm trying to run Geocode from Google Maps Api with my wp-admin plugin. I
have my own post type where is input for address of place, and jQuery code
watching for click on div. So that's my code:
Plugin Code [PHP]:
add_action( 'wp_ajax_generate_geocode', array($this, 'generate_geocode') );
[...]
//here is my test function that is waiting for response and doing something.
public function generate_geocode() {
print_r($_POST);
die();
}
AJAX Code [JS with jQuery]:
jQuery(document).ready(function() {
var lat = '';
var lng = '';
jQuery('#generate-geocode').on('click', function() {
var address = jQuery('#address').val();
// alert(address);
var geocoder = new google.maps.Geocoder();
geocoder.geocode({address: address}, function(results, status) {
//alert(status);
if (status == google.maps.GeocoderStatus.OK) {
lat = results[0].geometry.location.lat();
lng = results[0].geometry.location.lng();
alert(lat + ' ' + lng);
}
});
data = {
action: 'generate_geocode',
lat: lat,
lng: lng
};
jQuery.post(ajaxurl, data, function(response) {
alert(response);
});
});
});
My problem is that I don't know how to pass lat and lng variables or it's
values (value of results[0].geometry.location.lat() and
results[0].geometry.location.lng()) to my PHP code. So for a now I have in
my alert:
Array
(
[action] => generate_geocode
[lat] =>
[lng] =>
)
Can You tell me how to pass that values? And maybe there is better way? :)