Behavior of the humidity and the convergence of mass in the surroundings of the Madrid Barajas airport in days with mountain breezes. Behavior of the humidity and the horizontal mass convergence in the surroundings of the Madrid Barajas airport in days with mountain breezes. Darío Cano & Enric Terradellas

Behavior of the humidity and the convergence of mass in the surroundings of the Madrid Barajas airport in days with mountain breezes. The experience in the simulations of fog events at Madrid airport has been evidencied that the vertical moutions and the humidity advection near of the soil are very important parameters not well simulated by the LAM. In order to solve this problem it is necesary to obtain climatological values in each specific place.

Behavior of the humidity and the convergence of mass in the surroundings of the Madrid Barajas airport in days with mountain breezes. The aerea of study Madrid

Precipitable Water SEVIRI (LPW data) Divergence of mass 6 anemocinemographes located in the airport. AVAILABLE DATA Behavior of the humidity and the convergence of mass in the surroundings of the Madrid Barajas airport in days with mountain breezes.

Coordinates (in km) of the anemocinemographs. F = div V horiz The divergence is obtained from data recorded by 6 wind sensors every 10 ‘. If ρ =ct then the horizontal divergence is the flow across the area that contains the polygon that the sensors delimit. Airport map and polygon used in the calculation of the flow. Behavior of the humidity and the convergence of mass in the surroundings of the Madrid Barajas airport in days with mountain breezes. Convergence of mass in Madrid AVAILABLE DATA

Uso de herramientas de seguimiento, desarrolladas en SAF para el diagnóstico de nieblas en la Meseta Sur de la Península Ibérica: Behavior of the humidity and the convergence of mass in the surroundings of the Madrid Barajas airport in days with mountain breezes. LPW “ precipitable water by layers” The LPW provide information on the water vapor contained in a vertical column of unit cross-section area in three layers in the troposphere: Boundary Layer (BL): 1013hPa-840 hPa Middle Layer (ML): 840hPa-437hPa High Layer (HL): <437hPa

Uso de herramientas de seguimiento, desarrolladas en SAF para el diagnóstico de nieblas en la Meseta Sur de la Península Ibérica: Behavior of the humidity and the convergence of mass in the surroundings of the Madrid Barajas airport in days with mountain breezes. Convergence of mass in Madrid The mountains breeze is the main mesoβ signal not well represented in LAM. The katabatic flows are a very important mechanisme in the formation of fog. In this work we select mountain breeze days following two criteria: 1./ The wind is from the North during the nigth (less than 5 Kts) and from the South during the day. 2./ Clear days.

In clear days, a moderate flow ( ~10 Kts) from the South- West invades the valleys, go up to the mountains. At the botton of the valley there is a horizontal mass divergence that originates a downard motion. In the top of the mountains there is a convergence. Behavior of the humidity and the convergence of mass in the surroundings of the Madrid Barajas airport in days with mountain breezes. Mountain Breezes in Madrid

Uso de herramientas de seguimiento, desarrolladas en SAF para el diagnóstico de nieblas en la Meseta Sur de la Península Ibérica: Use of Nowcasting tools, developed in SAF for the diagnosis of fogs in the South Plateau of the Iberian Peninsula. Breezes of mountains: Katabatic flow In clear nights, a weak flow (< 5 Kts) from the East invades the valleys, comming from the mountains. At the botton of the valley there is a mass convergence that originates ascent motion. At the top of the mountains there is a returned descendent warm flow. Warm slope zone

Uso de herramientas de seguimiento, desarrolladas en SAF para el diagnóstico de nieblas en la Meseta Sur de la Península Ibérica: Behavior of the humidity and the convergence of mass in the surroundings of the Madrid Barajas airport in days with mountain breezes. Convergence of mass in Madrid Average divergence in breezes days over Barajas airport -0,01 -0, ,005 0,01 00:00:0001:00:0002:00:0003:00:0004:00:0005:00:0006:00:0007:00:0008:00:0009:00:0010:00:0011:00:0012:00:0013:00:0014:00:0015:00:0016:00:0017:00:0018:00:0019:00:0020:00:0021:00:0022:00:0023:00:00 HOUR DIVERGENCE (S-1) DICIEMBR E ENERO FEBREO MARZO ABRIL MAYO NOVIEMB RE OCTUBRE There is a very evident diurnal cycle in the evolution of thehorizontal divergence in surface: Nocturnal convergence and diurnal divergence

Uso de herramientas de seguimiento, desarrolladas en SAF para el diagnóstico de nieblas en la Meseta Sur de la Península Ibérica: Behavior of the humidity and the convergence of mass in the surroundings of the Madrid Barajas airport in days with mountain breezes. Convergence of mass in Madrid The nocturnal convergence has the same value during all year. The diurnal divergence increases in summer days. Average Divergence in days with mountain breezes over Barajas airport -0,01 -0, ,005 0,01 00:00:0001:00:0002:00:0003:00:0004:00:0005:00:0006:00:0007:00:0008:00:0009:00:0010:00:0011:00:0012:00:0013:00:0014:00:0015:00:0016:00:0017:00:0018:00:0019:00:0020:00:0021:00:0022:00:0023:00:00 HOUR DIVERGENCE (S-1) winter(nov;dic;ene)spring (feb;mar;abr;may)outon (sept;oct)

Uso de herramientas de seguimiento, desarrolladas en SAF para el diagnóstico de nieblas en la Meseta Sur de la Península Ibérica: Behavior of the humidity and the convergence of mass in the surroundings of the Madrid Barajas airport in days with mountain breezes. Specific Humidity in surface A diurnal oscillation is detected in the evolution of the specific humidity. There are two different evolutions: one in winter (nov, dec, jan, feb) and another one the rest of the year.

Uso de herramientas de seguimiento, desarrolladas en SAF para el diagnóstico de nieblas en la Meseta Sur de la Península Ibérica: Behavior of the humidity and the convergence of mass in the surroundings of the Madrid Barajas airport in days with mountain breezes. Specific Humidity in surface AVERAGE SPECIFIC HUMIDITY IN DAYS WITH BREEZE 0,002 0,003 0,004 0,005 0,006 0,007 00:00:0001:00:0002:00:0003:00:0004:00:0005:00:0006:00:0007:00:0008:00:0009:00:0010:00:0011:00:0012:00:0013:00:0014:00:0015:00:0016:00:0017:00:0018:00:0019:00:0020:00:0021:00:0022:00:0023:00:00 HOURS HUM ESPCF g/Kg WINTER(nov,dec,jan,feb) SPRING(mar,apr,may) OCTOBER The behavior in winter is characterized by nocturnal decreasing of humidity and increase of humidity during daytime. The behavior the rest of the year is characterized by a nocturnal decreasing and another arround noon. There are two periods where the humidity increases: one at dawn and another Starting at 18 UTC.

Uso de herramientas de seguimiento, desarrolladas en SAF para el diagnóstico de nieblas en la Meseta Sur de la Península Ibérica: Behavior of the humidity and the convergence of mass in the surroundings of the Madrid Barajas airport in days with mountain breezes. LPW “ precipitable water by layers” 1.- The variation can be explained by the mountain-breeze cycle. At night, the upward motion transports humidity from low to medium levels. The air at the bottom of the valley becomes relatively dry. After stopping the upward motion, the humidity is advected back downwards. 2.- All the variation (about 1 mm) is due to the exchange between low and medium levels. The exchange air-surface (evaporation/condensation) is small (about 0.1 mm).

Uso de herramientas de seguimiento, desarrolladas en SAF para el diagnóstico de nieblas en la Meseta Sur de la Península Ibérica: Behavior of the humidity and the convergence of mass in the surroundings of the Madrid Barajas airport in days with mountain breezes. LPW “ precipitable water by layers” 1.- During the night the low levels behave as katabatic in winter. 2.- At dawn, the humidity decreases in the low levels but increases near the surface probabily by mixture mechanisms. 2.- When the anabatic is established there is a decrease, the water is transported up through the mountain slopes and dry air moves down over the center of the Valley. 3.-In the Afternoon the increase of water in the low levels must be advected from the surroundings, not from the middle level.

Behavior of the humidity and the convergence of mass in the surroundings of the Madrid Barajas airport in days with mountain breezes. LPW “ precipitable water by layers” BPW Conceptual model of the anabatic cell During the early morning there is a decrease of BPW, the water is transported up through the mountain slopes and dry air moves down over the center of the Valley. There is an increase or MPW.

From 9 to 12 UTC the BPW increases due to the South advection. Conceptual model of the anabatic cell Behavior of the humidity and the convergence of mass in the surroundings of the Madrid Barajas airport in days with mountain breezes. LPW “ precipitable water by layers” BPW

When the anabatic flow stops, the ground inversion and the katabatic flow are established. A rapid decrease of humidity is observed in the low level. The katabatic advects dry air from the mountains. Conceptual model of katabatic cell Behavior of the humidity and the convergence of mass in the surroundings of the Madrid Barajas airport in days with mountain breezes. LPW “ precipitable water by layers” BPW

Behavior of the humidity and the convergence of mass in the surroundings of the Madrid Barajas airport in days with mountain breezes. conclusions 1.- A diurnal cycle is detected in the evolution of the horizontal mass divergence at surface. 2.- A diurnal cycle is detected in the humidity behavior. 3.- The main features of this behavoir can be explained by the mountain breeze model.