Extended  Abstract
Introduction
Like every other human activity, military activities are also affected by weather conditions. From a military perspective, climate studies are very important. In wartime, air and topography are more influential than any other physical factor, such as weapons, equipment, and logistics. These factors have been somehow effective in most victories and defeats. Therefore, military forces need special equipment, special training and adaptation to environmental conditions. Military commanders pay special attention to the daily mean minimum and maximum temperature, as well as very high or very low temperature. Troops usually need two weeks to adapt to climate conditions, but in extreme heat they may never reach their full efficiency. The importance of climatology in military plans is summarized in two stages: first, a preliminary stage in which time and location for the establishment of bases and deployment of military equipment are predicted, and the second stage in which atmospheric phenomena are linked and connected with the planed military operations. Accurate understanding of climate elements and their effects can lead to the discovery of positive and negative points and, as a result, a better planning for the promotion of military operations. Therefore, researchers have always been interested in climate parameters and investigating the effects of these parameters on defense, military, and passive defense discussions have always been inevitable.
Keywords: Military forces, climate, geographic information system, FTOPSIS
 
Materials and Methods
After performing secondary research and reviewing different resources, the most important climate parameters affecting the performance of military forces were identified and the initial database was formed. Data was received from Iran Meteorological Organization for 21 weather stations in Khuzestan province regarding a period of 25 years (1988-2013). Then, database was compiled using the received data and the geographic features of the stations (longitude, latitude and elevation). These parameters include:
Long-term average annual rainfall, average number of dusty days in each year, mean maximum temperature, long-term average of wind speed, wind direction, long-term average of sunshine duration, average humidity
In order to map climate parameters, each parameter-related layer was prepared using interpolation method and IDW model. Then, each layer was weighted using decision-making process. Afterward, each layer was classified into 5 categories, each of which was weighed according to its importance. In the next step, the fuzzy TOPSIS model was used to analyze collected data.
 
Results and discussion
Investigating the characteristics of precipitation layer and the weight of each category proved that the highest weight is related to the 670-570 category and the lowest weight is related to the 200-100 mm category. The highest level of precipitation (670-570 mm category) has occurred in Dehdez and Izeh, and the lowest level of precipitation (200-100 mm category) has occurred in Bostan, Hanijan, Mahshahr, Shadegan and Abadan stations.
The maximum temperature layer in Khuzestan province showed that the highest temperature (44-48 ° C) had a weight of 4.52, while the lowest temperature in 19-26 ° C category had a weight of 0.73. Gotvand and Ahwaz agricultural research station have the highest wind speed (7.28-8.59 knot) and a weight of 2.17 and the lowest average wind speed (with the weight of 1.33) is recorded in Hendijan, Omidieh, Behbahan, Lali and Dehdez. The province wind direction layer showed that western winds had the highest weight (2.18) and southern winds had the lowest weight (0.96).
 
Conclusion
Understanding climate and its impact on transportation of troops, flight of fighters, movement of naval fleets, transport of heavy equipment, and performance of weapons in both sides of the war are among the most important determinants of victory or defeat in wars. Climate is one of the most important factor that directly affect military plans, and even national strategies, tactics, doctrines, command, organizational structure, optimal combination and type of navy-land forces, military and space equipment, collection of military information and clothes, maintenance, construction and support.
In this study, eight factors including rain, temperature, dust, wind speed, wind direction, sunshine duration, humidity, and altitude were used in a combined approach. Geographic Information System and FTOPSIS model were applied in this approach. Results indicate that Khuzestan province is classified into five categories (from very unfavorable to very desirable) in regard to military activities. Most of the northeastern mountainous areas of the province are highly desirable, with excellent defensive capabilities. In Dehdez and Izeh, the proportion is somehow favorable. Eastern and southern parts of the province are very undesirable regarding the impact of climate parameters. The results also showed that wind speed and temperature are the most effective factors influencing the performance of military forces in the province.