将2D数组转换为CSV-prematch问题

I trying to convert a scraped table to csv file. It works fine.

But when I add preg_match to extract only values of tempatures, I got an error:

Array to string conversion in C:\xampp\htdocs\simple_dom\Scrape.php on line 65

Can anyone help me to figure it out?:)

CSV file:

"17,7 �C";"3,0 �C";"12,1 �C";"16,9 �C";"2,9 �C";"-0,8 �C"

"15,6 �C";"2,7 �C";"10,4 �C";"15,0 �C";"3,9 �C";"2,9 �C"

"17,2 �C";"2,2 �C";" ";" ";" ";" "

"16,8 �C";"2,6 �C";"11,5 �C";"15,9 �C";"5,3 �C";"0,8 �C"

My code:

$table = $html->find('table');
        $Data=array();
        $i=0;
        $k=1;

        foreach(myFind($table,'td') as $cell) {

            $tpr= $cell->innertext;

            $pattern = "(-?\d{1,2}\,\d)";
            preg_match($pattern , $tpr, $match);

            $rowData[] =$match;          
            $i++;

            if(fmod($i, 7)==0){
               $Data[$k]=array_slice($rowData,1);
               $rowData=array();
               $k++;
               $i=0;  
            }
        }

        convertCSV($Data);

function convertCSV($Data){

            $fp = fopen('file.csv', 'w');
            foreach ($Data as $fields){ 
            fputcsv($fp, $fields, $delimiter = ";");
            }
            fclose($fp);
 }