29:null 2a:["$","title",null,{"children":"NOAA Solar Calculations | Dan Smith | Observable"}] 2f:T536,{ // Style variables const num_style = 'style="text-align: right; padding: 1px 10px 1px 1px; font-variant-numeric: tabular-nums;"' const rotate = (deg) => `style="display: inline-block; transform: rotate(${deg}deg)"`; // Time format constructor const pad = (num, places) => String(num).padStart(places, '0'); const format_time = (dec) => { const hours = pad(Math.trunc(dec * 24), 2); const minutes = pad(Math.trunc(dec * 24 % 1 * 60), 2); const seconds = pad(Math.trunc((dec * 24 % 1 * 60) % 1 * 100), 2); return `${hours}:${minutes}:${seconds}` }; // Observation Angles const alt = solar_elevation_angle_corr; const az = solar_azimuth_angle; // Html table document yield html`

Apparent Sunrise	Apparent Sunset	Solar Noon	Altitude	Azimuth
${format_time(sunrise_time)}	${format_time(sunset_time)}	${format_time(solar_noon)}	${alt.toFixed(2)}° ↑	${az.toFixed(2)}° ↑

` }30:[] 2d:{"id":"6456e5f8388ecb94","slug":"noaa-solar-calculations","title":"NOAA Solar Calculations","thumbnail":"ac018a399f9f1ad785a608359046dd12f0ce5fb8bec1a598bbaf7d2a76118644","access_level":"public","create_time":"$D2020-07-16T06:40:39.036Z","update_time":"$D2020-10-17T04:39:27.908Z","view_time":null,"first_public_time":"$D2020-10-17T00:38:01.394Z","has_unpublished_edits":null,"fork":false,"stars":2,"starred":false,"owner":{"type":"team","id":"a208ef4b438a00c9","login":"danleesmith","name":"Dan Smith","avatar_url":"https://avatars-next.observableusercontent.com/34b285b1f7d70eb14f6aba1b6b862e6804f3e311b56902e9a238615fb8d83874","tier":"starter_2024"},"version":1337,"publish_version":1337,"role":null,"authored":false,"authors":[{"type":"individual","id":"41f0e305735b677b","login":"danleesmith","name":"Dan Smith","avatar_url":"https://avatars-next.observableusercontent.com/34b285b1f7d70eb14f6aba1b6b862e6804f3e311b56902e9a238615fb8d83874","tier":null}],"members":[{"type":"individual","id":"41f0e305735b677b","login":"danleesmith","name":"Dan Smith","avatar_url":"https://avatars-next.observableusercontent.com/34b285b1f7d70eb14f6aba1b6b862e6804f3e311b56902e9a238615fb8d83874","tier":null,"role":"editor"}],"comments":[],"custom_thumbnail":false,"trashed":false,"lapsed":null,"subscribed":null,"forks":6,"collection":null,"type":"notebook","body":{"title":"NOAA Solar Calculations","cells":[{"id":0,"value":"md`\n# NOAA Solar Calculations\n\nThe calculations presented here replicate those released by the United States National Oceanic and Atmospheric Administration (NOAA) on the Global Monitoring Laboratory, Earth Systems Research Laboratories [Solar Calculator Page](https://www.esrl.noaa.gov/gmd/grad/solcalc/).\n\nTo the best of my knowledge the NOAA calculations are generally based on the equations detailed in the book [*Astronomical Algorithms*](https://www.willbell.com/math/mc1.htm) by [Jean Meeus](https://en.wikipedia.org/wiki/Jean_Meeus) which which have already been presented here on Observable with some alacrity by [Vladimir Agafonkin](https://observablehq.com/@mourner/sun-position-in-900-bytes).\n\nThe mechanics of these calculations are necessarily complex. I am currenlty writing a [companion notebook](https://observablehq.com/@danleesmith/meeus-solar-position-calculations) that directly implements Meeus's calculations as they appear in the book to improve my knowledge of how they interact.\n`","pinned":false,"hidden":false,"mode":"ojs","author":"$undefined","summary":"$undefined","output":"$undefined","database":"$undefined"},{"id":159,"value":"md`## Input Parameters`","pinned":false,"hidden":false,"mode":"ojs","author":"$undefined","summary":"$undefined","output":"$undefined","database":"$undefined"},{"id":1024,"value":"viewof coords = coordinates({\n title: \"Location\",\n description: \"Enter the geographic coordinates of the observer\",\n value: [144.983431, -37.819982],\n submit: true\n})","pinned":false,"hidden":false,"mode":"ojs","author":"$undefined","summary":"$undefined","output":"$undefined","database":"$undefined"},{"id":105,"value":"viewof d = date({\n title: \"Date\",\n value: \"2020-06-21\"\n})","pinned":false,"hidden":false,"mode":"ojs","author":"$undefined","summary":"$undefined","output":"$undefined","database":"$undefined"},{"id":107,"value":"viewof t = time({\n title: \"Time\",\n step: 1,\n value: \"10:00:00\"\n})","pinned":false,"hidden":false,"mode":"ojs","author":"$undefined","summary":"$undefined","output":"$undefined","database":"$undefined"},{"id":116,"value":"viewof utc = select({\n title: \"UTC Offset\",\n options:[\"-12:00\",\"-11:00\",\"-10:00\",\"-09:30\",\"-09:00\",\"-08:00\",\"-07:00\",\"-06:00\",\"-05:00\",\"-04:00\",\"-03:30\",\"-03:00\",\"-02:00\",\"-01:00\",\"+00:00\",\"+02:00\",\"+03:00\",\"+03:30\",\"+04:00\",\"+04:30\",\"+05:00\",\"+05:30\",\"+05:45\",\"+06:00\",\"+06:30\",\"+07:00\",\"+08:00\",\"+08:45\",\"+09:00\",\"+09:30\",\"+10:00\",\"+10:30\",\"+11:00\",\"+12:00\",\"+12:45\",\"+13:00\",\"+14:00\"],\n value: \"+10:00\"\n})","pinned":false,"hidden":false,"mode":"ojs","author":"$undefined","summary":"$undefined","output":"$undefined","database":"$undefined"},{"id":480,"value":"md`## Results\n*Gives the sunrise, sunset and solar noon times in local time at the observer location, and the position of the sun in the sky in the relative to the observer*\n`","pinned":false,"hidden":false,"mode":"ojs","author":"$undefined","summary":"$undefined","output":"$undefined","database":"$undefined"},{"id":1037,"value":"$2f","pinned":false,"hidden":false,"mode":"ojs","author":"$undefined","summary":"$undefined","output":"$undefined","database":"$undefined"},{"id":1162,"value":"map = {\n let container = DOM.element('div', { style: `width:${width}px;height:${width/1.6}px` });\n yield container;\n let map = L.map(container).setView([coords[1], coords[0]], 10);\n let base_map = L.esri.basemapLayer(\"Topographic\").addTo(map);\n let marker = L.marker([coords[1], coords[0]]).addTo(map)\n .bindPopup(`Observer Location:
${address}`)\n .openPopup();\n}","pinned":false,"hidden":false,"mode":"ojs","author":"$undefined","summary":"$undefined","output":"$undefined","database":"$undefined"},{"id":466,"value":"md`## Datetime Functions`","pinned":false,"hidden":false,"mode":"ojs","author":"$undefined","summary":"$undefined","output":"$undefined","database":"$undefined"},{"id":111,"value":"datetime = new Date(`${d}T${t}${utc}`)","pinned":false,"hidden":false,"mode":"ojs","author":"$undefined","summary":"$undefined","output":"$undefined","database":"$undefined"},{"id":403,"value":"loc_time_mins = (datetime.getHours() * 60) + datetime.getMinutes() + (datetime.getSeconds() / 60)","pinned":false,"hidden":false,"mode":"ojs","author":"$undefined","summary":"$undefined","output":"$undefined","database":"$undefined"},{"id":371,"value":"utc_offset_to_mins = {\n if (utc.startsWith(\"-\")) {\n return (parseInt(utc.slice(1,3)) + 12) * 60 + parseInt(utc.slice(4,5))\n } else {\n return parseInt(utc.slice(1,3)) * 60 + parseInt(utc.slice(4,5))\n }\n}","pinned":false,"hidden":false,"mode":"ojs","author":"$undefined","summary":"$undefined","output":"$undefined","database":"$undefined"},{"id":131,"value":"JD = (datetime.getTime() / 86400000) + 2440587.5","pinned":false,"hidden":false,"mode":"ojs","author":"$undefined","summary":"$undefined","output":"$undefined","database":"$undefined"},{"id":146,"value":"T = (JD - 2451545.0) / 36525","pinned":false,"hidden":false,"mode":"ojs","author":"$undefined","summary":"$undefined","output":"$undefined","database":"$undefined"},{"id":167,"value":"md`## Calculations`","pinned":false,"hidden":false,"mode":"ojs","author":"$undefined","summary":"$undefined","output":"$undefined","database":"$undefined"},{"id":170,"value":"geom_mean_long = 280.46646 + T * (36000.76983 + T * 0.0003032)","pinned":false,"hidden":false,"mode":"ojs","author":"$undefined","summary":"$undefined","output":"$undefined","database":"$undefined"},{"id":174,"value":"geom_mean_anom = 357.52911 + T * (35999.05029 - 0.0001537 * T)","pinned":false,"hidden":false,"mode":"ojs","author":"$undefined","summary":"$undefined","output":"$undefined","database":"$undefined"},{"id":176,"value":"eccent_earth_orbit = 0.016708634 - T * (0.000042037 + 0.0000001267 * T)","pinned":false,"hidden":false,"mode":"ojs","author":"$undefined","summary":"$undefined","output":"$undefined","database":"$undefined"},{"id":178,"value":"sun_eq_of_ctr = Math.sin(Math.radians(geom_mean_anom)) * (1.914602 - T * (0.004817 + 0.000014 * T)) + Math.sin(Math.radians(2 * geom_mean_anom)) * (0.019993 - 0.000101 * T) + Math.sin(Math.radians(3 * T)) * 0.000289","pinned":false,"hidden":false,"mode":"ojs","author":"$undefined","summary":"$undefined","output":"$undefined","database":"$undefined"},{"id":201,"value":"sun_true_long = geom_mean_long + sun_eq_of_ctr","pinned":false,"hidden":false,"mode":"ojs","author":"$undefined","summary":"$undefined","output":"$undefined","database":"$undefined"},{"id":210,"value":"sun_true_anom = geom_mean_anom + sun_eq_of_ctr","pinned":false,"hidden":false,"mode":"ojs","author":"$undefined","summary":"$undefined","output":"$undefined","database":"$undefined"},{"id":220,"value":"sun_rad_vec = (1.000001018 * (1 - eccent_earth_orbit * eccent_earth_orbit)) / (1 + eccent_earth_orbit * Math.cos(Math.radians(sun_true_anom)))","pinned":false,"hidden":false,"mode":"ojs","author":"$undefined","summary":"$undefined","output":"$undefined","database":"$undefined"},{"id":222,"value":"sun_app_long = sun_true_long - 0.00569 - 0.00478 * Math.sin(Math.radians(125.04 - 1934.136 * T))","pinned":false,"hidden":false,"mode":"ojs","author":"$undefined","summary":"$undefined","output":"$undefined","database":"$undefined"},{"id":229,"value":"mean_obliq_elliptic = 23 + (26 + (21.448 - T * (46.815 + T * (0.00059 - T))) / 60) / 60","pinned":false,"hidden":false,"mode":"ojs","author":"$undefined","summary":"$undefined","output":"$undefined","database":"$undefined"},{"id":231,"value":"obliq_corr = mean_obliq_elliptic + 0.00256 * Math.cos(Math.radians(125.04 - 1934.136 * T))","pinned":false,"hidden":false,"mode":"ojs","author":"$undefined","summary":"$undefined","output":"$undefined","database":"$undefined"},{"id":234,"value":"sun_rt_ascen = Math.degrees(Math.atan2(Math.cos(Math.radians(obliq_corr)) * Math.sin(Math.radians(sun_app_long)), Math.cos(Math.radians(sun_app_long))))","pinned":false,"hidden":false,"mode":"ojs","author":"$undefined","summary":"$undefined","output":"$undefined","database":"$undefined"},{"id":247,"value":"sun_declin = Math.degrees(Math.asin(Math.sin(Math.radians(obliq_corr)) * Math.sin(Math.radians(sun_app_long))))","pinned":false,"hidden":false,"mode":"ojs","author":"$undefined","summary":"$undefined","output":"$undefined","database":"$undefined"},{"id":933,"value":"y = Math.tan(Math.radians(obliq_corr / 2)) ** 2","pinned":false,"hidden":false,"mode":"ojs","author":"$undefined","summary":"$undefined","output":"$undefined","database":"$undefined"},{"id":252,"value":"eq_of_time = 4 * Math.degrees(y * Math.sin(2 * Math.radians(geom_mean_long)) - 2 * eccent_earth_orbit * Math.sin(Math.radians(geom_mean_anom)) + 4 * eccent_earth_orbit * y * Math.sin(Math.radians(geom_mean_anom)) * Math.cos(2 * Math.radians(geom_mean_long)) - 0.5 * y ** 2 * Math.sin(4 * Math.radians(geom_mean_long)) - 1.25 * eccent_earth_orbit ** 2 * Math.sin(2 * Math.radians(geom_mean_anom)))","pinned":false,"hidden":false,"mode":"ojs","author":"$undefined","summary":"$undefined","output":"$undefined","database":"$undefined"},{"id":261,"value":"ha_sunrise = Math.degrees(Math.acos(Math.cos(Math.radians(90.833)) / (Math.cos(Math.radians(coords[1]) * Math.cos(Math.radians(sun_declin)))) - Math.tan(Math.radians(coords[1])) * Math.tan(Math.radians(sun_declin))))","pinned":false,"hidden":false,"mode":"ojs","author":"$undefined","summary":"$undefined","output":"$undefined","database":"$undefined"},{"id":311,"value":"solar_noon = (720 - 4 * coords[0] - eq_of_time + utc_offset_to_mins) / 1440","pinned":false,"hidden":false,"mode":"ojs","author":"$undefined","summary":"$undefined","output":"$undefined","database":"$undefined"},{"id":389,"value":"sunrise_time = solar_noon - ha_sunrise * 4 / 1440","pinned":false,"hidden":false,"mode":"ojs","author":"$undefined","summary":"$undefined","output":"$undefined","database":"$undefined"},{"id":391,"value":"sunset_time = solar_noon + ha_sunrise * 4 / 1440","pinned":false,"hidden":false,"mode":"ojs","author":"$undefined","summary":"$undefined","output":"$undefined","database":"$undefined"},{"id":393,"value":"sunlight_duration = 8 * ha_sunrise","pinned":false,"hidden":false,"mode":"ojs","author":"$undefined","summary":"$undefined","output":"$undefined","database":"$undefined"},{"id":417,"value":"true_solar_time = (loc_time_mins + eq_of_time + 4 * coords[0] - utc_offset_to_mins) % 1440","pinned":false,"hidden":false,"mode":"ojs","author":"$undefined","summary":"$undefined","output":"$undefined","database":"$undefined"},{"id":433,"value":"hour_angle = {\n if (true_solar_time / 4 < 0) {\n return true_solar_time / 4 + 180; \n } else {\n return true_solar_time / 4 - 180; \n }\n}","pinned":false,"hidden":false,"mode":"ojs","author":"$undefined","summary":"$undefined","output":"$undefined","database":"$undefined"},{"id":435,"value":"solar_zenith_angle = Math.degrees(Math.acos(Math.sin(Math.radians(coords[1])) * Math.sin(Math.radians(sun_declin)) + Math.cos(Math.radians(coords[1])) * Math.cos(Math.radians(sun_declin)) * Math.cos(Math.radians(hour_angle))))","pinned":false,"hidden":false,"mode":"ojs","author":"$undefined","summary":"$undefined","output":"$undefined","database":"$undefined"},{"id":437,"value":"solar_elevation_angle = 90 - solar_zenith_angle","pinned":false,"hidden":false,"mode":"ojs","author":"$undefined","summary":"$undefined","output":"$undefined","database":"$undefined"},{"id":439,"value":"approx_atmosph_refract = {\n if (solar_elevation_angle < -0.575) {\n return (1 / 3600) * (-20.774 / Math.tan(Math.radians(solar_elevation_angle)))\n } else if (solar_elevation_angle > -0.575 && solar_elevation_angle < 5) {\n return (1 / 3600) * (1735 - 518.2 * solar_elevation_angle + 103.4 - 12.79 * solar_elevation_angle + 0.711 * solar_elevation_angle) \n } else if (solar_elevation_angle > 5 && solar_elevation_angle < 85) {\n return (1 / 3600) * ((58.1 / Math.tan(Math.radians(solar_elevation_angle))) - (0.07 / (Math.tan(Math.radians(solar_elevation_angle) ** 3))) + (0.000086 / (Math.tan(Math.radians(solar_elevation_angle) ** 5))))\n } else {\n return 0.0\n }\n}","pinned":false,"hidden":false,"mode":"ojs","author":"$undefined","summary":"$undefined","output":"$undefined","database":"$undefined"},{"id":446,"value":"solar_elevation_angle_corr = solar_elevation_angle + approx_atmosph_refract","pinned":false,"hidden":false,"mode":"ojs","author":"$undefined","summary":"$undefined","output":"$undefined","database":"$undefined"},{"id":448,"value":"solar_azimuth_angle = {\n if (hour_angle > 0) {\n return (Math.degrees(Math.acos((Math.sin(Math.radians(coords[1])) * Math.cos(Math.radians(solar_zenith_angle)) - Math.sin(Math.radians(sun_declin))) / (Math.cos(Math.radians(coords[1])) * Math.sin(Math.radians(solar_zenith_angle))))) + 180) % 360 \n } return (540 - Math.degrees(Math.acos((Math.sin(Math.radians(coords[1])) * Math.cos(Math.radians(solar_zenith_angle)) - Math.sin(Math.radians(sun_declin))) / (Math.cos(Math.radians(coords[1])) * Math.sin(Math.radians(solar_zenith_angle)))))) % 360 \n}","pinned":false,"hidden":false,"mode":"ojs","author":"$undefined","summary":"$undefined","output":"$undefined","database":"$undefined"},{"id":475,"value":"md`## Math Functions`","pinned":false,"hidden":false,"mode":"ojs","author":"$undefined","summary":"$undefined","output":"$undefined","database":"$undefined"},{"id":191,"value":"Math.degrees = (r) => {\n return r * 180 / Math.PI;\n}","pinned":false,"hidden":false,"mode":"ojs","author":"$undefined","summary":"$undefined","output":"$undefined","database":"$undefined"},{"id":188,"value":"Math.radians = (d) => {\n return d * Math.PI / 180;\n}","pinned":false,"hidden":false,"mode":"ojs","author":"$undefined","summary":"$undefined","output":"$undefined","database":"$undefined"},{"id":1300,"value":"md`## Geocoding Functions`","pinned":false,"hidden":false,"mode":"ojs","author":"$undefined","summary":"$undefined","output":"$undefined","database":"$undefined"},{"id":1274,"value":"address = {\n // Adapted from: \"https://observablehq.com/@pierreleripoll/geocoding-nominatim\"\n let string = \"\";\n if (geocode.address.house_number) string += geocode.address.house_number + \" \";\n if (geocode.address.road) string += geocode.address.road + \", \";\n if (geocode.address.city) string += geocode.address.city + \", \";\n if (geocode.address.town) string += geocode.address.town + \", \";\n if (geocode.address.postcode) string += geocode.address.postcode + \", \";\n if (geocode.address.country) string += geocode.address.country;\n return string;\n}","pinned":false,"hidden":false,"mode":"ojs","author":"$undefined","summary":"$undefined","output":"$undefined","database":"$undefined"},{"id":1241,"value":"geocode = await fetch(\n `https://nominatim.openstreetmap.org/reverse?format=json&lat=${coords[1]}&lon=${coords[0]}`,\n { method: 'GET', referrer: \"https://observablehq.com/@danleesmith/noaa-solar-calculations\" }\n ).then(\n response => response.json()\n ).catch(\n error => `Address not found for lat=${coords[1]} & lon=${coords[0]}`\n )","pinned":false,"hidden":false,"mode":"ojs","author":"$undefined","summary":"$undefined","output":"$undefined","database":"$undefined"},{"id":142,"value":"md`## Requirements`","pinned":false,"hidden":false,"mode":"ojs","author":"$undefined","summary":"$undefined","output":"$undefined","database":"$undefined"},{"id":103,"value":"import {coordinates, date, time, select} from \"@jashkenas/inputs\"","pinned":false,"hidden":false,"mode":"ojs","author":"$undefined","summary":"$undefined","output":"$undefined","database":"$undefined"},{"id":1153,"value":"L = {\n // Load Leaflet and it's CSS file\n const L = await require(\"leaflet@latest\");\n if (!L._css) {\n document.head.appendChild(\n (L._css = html`\n \n `)\n );\n }\n\n // Load plugins\n L.esri = await require(\"esri-leaflet@latest\");\n\n return L;\n}","pinned":false,"hidden":false,"mode":"ojs","author":"$undefined","summary":"$undefined","output":"$undefined","database":"$undefined"}],"files":"$W30","stdlib":"1","titling":"auto"}} 2e:"$2d:body"