Smooothing out Z height with sin()?

Processing Coding Questions
1

Hello I have a sketch here I got watching the great Dan S. , I altered his Perlin noise terrain with some color now I want to be able to get the terrain to smooth out after going into the more extreme levels of z height. Could I put a sin function somewhere in the terrain for loop, I think that’s what is giving the z its height. any help would be greatly appreciated thank you!!!

int cols,rows;
int scl = 80;

int w = 10000; // where the vertexes start 
int h = 40000;

float [][] terrain;

float flying = 0;
float diff = 0;

float deltaH, deltaS, f;
int nbPts;
PVector[] pts;

void setup() {
  fullScreen(P3D);
  // size(600, 600, P3D);
  smooth();
  cols = w / scl;
  rows = h / scl;
  terrain = new float[cols][rows];
  colorMode(HSB, 3);
  

}

void draw() {
  
  flying -= 0.002; // speed of your fly over
  diff -= .0002;
  
  float yoff = flying; // this is what calcuates the infinty for the scene 
  for (int y = 0; y < rows; y++) {
    float xoff = flying;
    for (int x = 0; x < cols; x++) {
      terrain[x][y] = map(noise(xoff/2, yoff), 0, 1, -diff , 2000);
      xoff += diff;
    }
    yoff += diff/2;  
  }

  f = float(frameCount);
  //stroke(1+cos(deltaH-f/280), 1+sin(deltaS+f/220), 2, .15);
  for(int i = 0; i < nbPts; i ++){
    pts[i].x += random(-1.5, 3);
    pts[i].y += random(-3, 3);
  } 
  
  
  
  background(0);
  stroke(255);
  // noFill();
  
  translate(width/2, height/20+2000);
  rotateX(PI/3);
  //frameRate(1);
  // fill(200,0,0);
  translate(-w/2, -h);
  for (int y =0; y < rows-1; y++) {
    beginShape(TRIANGLE_STRIP);
    for (int x = 0; x < cols; x++) {
     stroke(1+cos(deltaH-f/140), 1+sin(deltaS+f/220), 2, 100);
     noFill();
     vertex(x*scl, y*scl, terrain[x][y]); // this is what is drawn / mess with 
     vertex(x*scl, (y+1)*scl, terrain[x][y+1]); // this is what is drawn / mess with
     //rect(x*scl, y*scl, scl, scl);
    }
    endShape();  
  }   

}